Lesson summary of the genetic basis of the selection of organisms. Theoretical foundations of selection

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Introduction

Breeding (from Latin - choice, selection) is the science of ways and methods of creating new and improving existing varieties of cultivated plants, breeds of domestic animals and strains of microorganisms with valuable features and properties for practice.

The tasks of breeding follow from its definition - this is the development of new and the improvement of existing varieties of plants, animal breeds and strains of microorganisms. A variety, breed and strain are called a stable group (population) of living organisms, artificially created by man and having certain hereditary characteristics. All individuals within the breed, variety and strain have similar, hereditarily fixed morphological, physiological, biochemical and economic characteristics and properties, as well as the same type of reaction to environmental factors. The main areas of selection are:

High yield of plant varieties, fertility and productivity of animal breeds; product quality (for example, taste, appearance, keeping quality of fruits and vegetables, the chemical composition of grain - the content of protein, gluten, essential amino acids, etc.);

Physiological properties (precocity, drought resistance, winter hardiness, resistance to diseases, pests and adverse climatic conditions);

Intensive path of development (in plants - responsiveness to fertilizers, watering, and in animals - "payment" for feed, etc.).

1. Theoretical foundations of selection

In recent years, the selection of a number of insects and microorganisms used for the biological control of pests and pathogens of cultivated plants has acquired particular importance.

Selection must also take into account the needs of the market for agricultural products, satisfying specific branches of industrial production. For example, to bake high-quality bread with elastic crumb and crispy crust, strong (glassy) varieties of soft wheat are needed, with a high content of protein and elastic gluten. For the manufacture of the highest varieties of cookies, good floury varieties of soft wheat are needed, and pasta, horns, vermicelli, noodles are made from durum wheat.

A striking example of selection taking into account the needs of the market is fur farming. When growing such valuable animals as mink, otter, fox, animals with a genotype corresponding to the constantly changing fashion in terms of color and fur shades are selected.

In general, the development of selection should be based on the laws of genetics as the science of heredity and variability, since the properties of living organisms are determined by their genotype and are subject to hereditary and modification variability.

The theoretical basis of selection is genetics. It is genetics that paves the way for effective management of heredity and variability of organisms. At the same time, selection is also based on the achievements of other sciences: taxonomy and geography of plants and animals, cytology, embryology, biology of individual development, molecular biology, physiology and biochemistry. The rapid development of these areas of natural science opens up completely new perspectives. Already today, genetics has reached the level of purposeful design of organisms with the desired features and properties.

Genetics plays a decisive role in solving almost all breeding problems. It helps rationally, on the basis of the laws of heredity and variability, to plan the selection process, taking into account the characteristics of the inheritance of each specific trait. Achievements in genetics, the law of homologous series of hereditary variability, the use of tests for early diagnosis of the selection prospects of the source material, the development of various methods of experimental mutagenesis and distant hybridization in combination with polyploidization, the search for methods for controlling recombination processes and the effective selection of the most valuable genotypes with the desired set of traits and properties gave the ability to expand the sources of source material for breeding. In addition, the widespread use in recent years of biotechnology methods, cell and tissue cultures have made it possible to significantly speed up the selection process and put it on a qualitatively new basis. This far from complete list of the contribution of genetics to breeding gives an idea that modern breeding is unthinkable without the use of the achievements of genetics.

The success of the breeder's work largely depends on the correct choice of the source material (species, varieties, breeds) for breeding, the study of its origin and evolution, and the use of organisms with valuable traits and properties in the breeding process. The search for the necessary forms is carried out taking into account the entire world gene pool in a certain sequence. First of all, local forms with the desired characteristics and properties are used, then methods of introduction and acclimatization are used, i.e., forms growing in other countries or in other climatic zones are involved, and, finally, methods of experimental mutagenesis and genetic engineering.

In order to study the diversity and geographical distribution of cultivated plants, N. I. Vavilov from 1924 until the end of the 30s. organized 180 expeditions to the most inaccessible and often dangerous regions of the globe. As a result of these expeditions, N. I. Vavilov studied the world's plant resources and found that the greatest diversity of species forms is concentrated in those areas where this species arose. In addition, a unique, world's largest collection of cultivated plants was collected (by 1940, the collection included 300,000 specimens), which are annually propagated in the collections of the All-Russian Institute of Plant Industry named after N.I. Vavilov (VIR) and are widely used by plant breeders as source material for creating new varieties of grain, fruit, vegetable, industrial, medicinal and other crops.

Based on the study of the collected material, Vavilov identified 7 centers of origin of cultivated plants (Appendix 1). The centers of origin of the most important cultivated plants are connected with the ancient centers of civilization and the place of primary cultivation and selection of plants. Similar foci of domestication (centers of origin) have also been found in domestic animals.

2 .Selection value

The goals and objectives of breeding as a science are determined by the level of agricultural technology and animal husbandry, the level of industrialization of crop production and animal husbandry. For example, in conditions of fresh water shortage, varieties of barley have already been bred that give satisfactory yields when irrigated with sea water. Breeds of chickens have been bred that do not reduce productivity in conditions of high crowding of animals in poultry farms. For Russia, it is very important to create varieties that are productive in conditions of frost without snow in clear weather, late frosts, etc.

One of the most important achievements of man at the dawn of his formation and development was the creation of a constant and fairly reliable source of food by domesticating wild animals and cultivating plants. The main factor in domestication is the artificial selection of organisms that meet human requirements. Cultivated forms of plants and animals have highly developed individual features, often useless or even harmful to their existence in natural conditions, but useful to humans. For example, the ability of some breeds of chickens to produce more than 300 eggs per year is devoid of biological meaning, since a chicken will not be able to incubate such a number of eggs. The productivity of all cultivated plants is also significantly higher than that of related wild species, but at the same time they adapt worse to constantly changing environmental conditions and do not have means of protection against eating (bitter or poisonous substances, thorns, thorns, etc.). Therefore, under natural conditions, cultural, that is, domesticated forms cannot exist.

Domestication led to a weakening of the effect of stabilizing selection, which sharply increased the level of variability and expanded its spectrum. At the same time, domestication was accompanied by selection, at first unconscious (the selection of those individuals that looked better, had a more peaceful disposition, possessed other qualities valuable to humans), then conscious, or methodical. The widespread use of methodical selection is aimed at the formation in plants and animals of certain qualities that satisfy humans. The experience of many generations of people made it possible to create methods and rules for selection and form selection as a science.

The process of domestication of new species of plants and animals to meet human needs continues in our time. For example, in order to obtain fashionable and high-quality furs, a new branch of animal husbandry has been created in this century - fur farming.

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3. Plant breeding, methods

Unlike the selection of microorganisms, plant breeding does not operate with millions and billions of individuals, and the rate of their reproduction is measured not in minutes and hours, but in months and years. However, compared to animal breeding, where the number of offspring is single, plant breeding is in a better position. In addition, methodological approaches to the selection of self- and cross-pollinated plants that reproduce vegetatively and sexually, annual and perennial plants, etc., also differ.

The main methods of plant breeding are selection and hybridization. Selection requires the presence of heterogeneity, i.e., differences, diversity in the group of individuals used. Otherwise, the selection does not make sense, it will be inefficient. Therefore, hybridization is carried out first, and then, after the appearance of splitting, selection.

If the breeder lacks the natural diversity of traits, the existing gene pool, he uses artificial mutagenesis (gets gene, chromosome or genomic mutations - polyploids), to manipulate individual genes - genetic engineering, and to speed up the selection process - cellular. However, hybridization and selection have been and remain classic breeding methods.

There are two main forms of artificial selection: mass and individual.

Mass selection is the selection of a whole group of individuals with valuable traits. More often it is used when working with cross-pollinated plants. In this case, the variety is not homozygous. This is a population variety with complex heterozygosity for many genes, which provides it with plasticity in difficult environmental conditions and the possibility of manifesting a heterotic effect. The main advantage of the method is that it allows relatively quickly and without much effort to improve local varieties, and the disadvantage is that the hereditary conditionality of the selected traits cannot be controlled, which is why the selection results are often unstable.

A cross in which the parental forms differ in only one pair of alternative traits is called a monohybrid. Mendel, before crossing different forms of peas, carried out their self-pollination. When crossing white-flowered peas with the same white-flowered ones, he received only white-flowered ones in all subsequent generations. A similar situation was observed in the case of purple-flowered. When Peas with purple flowers were crossed with white-flowered plants, all hybrids of the first generation P1 had purple flowers, but when they self-pollinated among hybrids of the second generation P2, in addition to purple-flowered plants (three parts), white-flowered plants (one part) appeared.

Crossing, in which parental forms differ in two pairs of alternative traits (in two pairs of alleles), is called dihybrid.

By crossing homozygous parental forms with yellow seeds with a smooth surface and green seeds with a wrinkled surface, Mendel obtained all plants with yellow smooth seeds and concluded that these traits are dominant. In the second generation after self-pollination of P1 hybrids, he observed the following splitting: 315 yellow smooth, 101 yellow wrinkled, 108 green smooth and 32 green wrinkled. Using other homozygous parental forms (yellow wrinkled and green smooth), Mendel obtained similar results in both the first and second generations of hybrids, i.e. splitting in the second generation in a ratio of 9: 3: 3: 1.

With individual selection, offspring are obtained from each plant separately with mandatory control of the inheritance of the traits of interest. It is used in self-pollinators (wheat, barley). The result of individual selection is an increase in the number of homozygotes. This is due to the fact that during self-pollination of homozygotes, only homozygotes will be formed, and half of the descendants of self-pollinated heterozygotes will also be homozygotes. With individual selection, clean lines are formed. Pure lines are a group of individuals that are descendants of one homozygous self-pollinated individual. They have the highest degree of homozygosity. However, there are practically no absolutely homozygous individuals, since a mutation process continuously occurs that violates homozygosity. In addition, even the most strict self-pollinators can sometimes cross-pollinate. This increases their adaptability to conditions and survival, since people with artificial selection also act on all organic forms.

Natural selection plays an important role in breeding, since when artificial selection is carried out, the breeder cannot avoid that the breeding material is not exposed to environmental conditions. Moreover, breeders often involve natural selection to select forms that are most adapted to growing conditions - humidity, temperature, resistance to natural pests and diseases.

Since one of the breeding methods is hybridization, the choice of the type of crosses plays an important role, i.e. crossing system.

Crossbreeding systems can be divided into two main types: closely related (inbreeding - breeding in itself) and crossing between unrelated forms (outbreeding - unrelated breeding). If forced self-pollination leads to homozygotization, then unrelated crosses lead to heterozygotization of offspring from these crosses.

Inbreeding, i.e. forced self-pollination of cross-pollinated forms, in addition to the degree of homozygosity progressing with each generation, also leads to disintegration, decomposition of the original form into a number of pure lines. Such pure lines will have a reduced viability, which, apparently, is associated with the transition from the genetic load to the homozygous state of all recessive mutations, which in. are mostly harmful.

Pure lines obtained as a result of inbreeding have different properties. They have different symptoms in different ways. In addition, the degree of decrease in viability is also different. If these pure lines are crossed with each other, then, as a rule, the effect of heterosis is observed.

Heterosis is a phenomenon of increased viability, productivity, and fecundity of hybrids of the first generation, exceeding both parents in these parameters. Already from the second generation, the heterotic effect fades. The genetic bases of heterosis are not unambiguously interpreted, but it is assumed that heterosis is associated with a high level of heterozygosity in hybrids of pure lines (interline hybrids). The production of pure corn material using so-called cytoplasmic male sterility has been extensively studied and commercialized in the USA. Its use eliminated the need to castrate the flowers, remove the anthers, since the male flowers of the plants used as female ones were sterile.

Different pure lines have different combinational abilities, i.e., they give an unequal level of heterosis when crossing with each other. Therefore, having created a large number of pure lines, the best combinations of crosses are experimentally determined, which are then used in production.

Distant hybridization is the crossing of plants belonging to different species. Distant hybrids, as a rule, are sterile, which is associated with the content in the genome of various chromosomes that do not conjugate during meiosis. As a result, sterile gametes are formed. To eliminate this cause, in 1924 the Soviet scientist G. D. Karpechenko proposed to use the doubling of the number of chromosomes in distant hybrids, which leads to the formation of amphidiploids.

In addition to triticale, many valuable distant hybrids were obtained by this method, in particular, perennial wheat-couch grass hybrids, etc. In such hybrids, the cells contain a complete diploid set of chromosomes of one and the other parent, therefore the chromosomes of each parent conjugate with each other and meiosis proceeds normally. By crossing with the subsequent doubling of the number of chromosomes of blackthorn and cherry plum, it was possible to repeat the evolution - to produce a resynthesis of the domestic plum species.

Such hybridization makes it possible to completely combine in one species not only chromosomes, but also the properties of the original species. For example, triticale combines many of the qualities of wheat (high baking qualities) and rye (high content of the essential amino acid lysine, as well as the ability to grow on poor sandy soils).

This is one example of the use of polyploidy, more precisely alloploidy, in breeding. Autopolyploidy is even more widely used. For example, tetraploid rye is cultivated in Belarus, varieties of polyploid vegetable crops, buckwheat, and sugar beets have been bred. All these forms have a higher yield compared to the original forms, sugar content (beet), content of vitamins and other nutrients. Many crops are natural polyploids (wheat, potatoes, etc.).

Breeding of new highly productive varieties of plants plays an important role in increasing productivity and providing the population with food. In many countries of the world there is a "green revolution" - a sharp intensification of agricultural production by breeding new varieties of plants of an intensive type. Valuable varieties of many agricultural crops have also been obtained in our country.

Using new breeding methods, new plant varieties have been obtained. Thus, Academician N.V. Tsitsin bred perennial wheats by distant hybridization of wheat with wheatgrass and subsequent polyploidization. Promising varieties of the new grain crop triticale were obtained by the same methods. For the selection of vegetatively propagated plants, somatic mutations are used (they were also used by I.V. Michurin, but he called them bud variations). Many methods of I. V. Michurin have been widely used after their genetic understanding, although some of them have not been theoretically developed. Great success has been achieved in using the results of mutational breeding in breeding new varieties of cereals, cotton and fodder crops. However, the greatest contribution to all cultivated varieties was made by samples of the collection of the world gene pool of cultivated plants, collected by N. I. Vavilov and his students.

4. Animal breeding, methods

Although the basic principles of animal breeding do not differ significantly from the principles of plant breeding, they nevertheless have a number of characteristic features. So, in animals there is only sexual reproduction, the change of generations occurs rarely (after a few years), the number of individuals in the offspring is small. The modifying influence of environmental factors is especially pronounced in them, and the analysis of the genotype is difficult. Therefore, the analysis of the totality of external features characteristic of the breed acquires an important role.

The domestication of animals began probably 10-12 thousand years ago. It occurred mainly in the same areas where the centers of diversity and origin of cultivated plants are located. Domestication led to a weakening of the effect of stabilizing selection, which sharply increased the level of variability and expanded its spectrum. Therefore, domestication was immediately accompanied by selection. Apparently, at first it was an unconscious selection, i.e., the selection of those individuals who looked better, had a more peaceful disposition, etc. or other human needs in given specific natural and economic conditions. The experience of many generations has made it possible to create methods and rules for breeding selection and selection and form animal breeding as a science.

Crossbreeding types and breeding methods have been introduced into animal breeding, often by extrapolation from plant breeding. This was due to the fact that the introduction of genetic knowledge into plant breeding began much earlier than into animal breeding due to the high cost of animal objects, their smaller number in the family, etc. Such extrapolation, carried out without taking into account the specifics of the object, often gave negative results. results. Thus, in particular, the inbreeding method was introduced from the selection of self-pollinating plants to the selection of animals as the main method, although later it was established that its widespread use was unreasonable, since animal breeds rather correspond to varieties-populations of cross-pollinators. Breeds are complex polyheterozygous complexes, the genotypes within which are given in a certain system. Therefore, the main type of crosses is outbreeding, although inbreeding is also used in breeding - inbreeding between brothers and sisters or between parents and offspring. Since inbreeding leads to homozygosity, it weakens the animals, reduces their resistance to environmental conditions, and increases the incidence. Nevertheless, when breeding new breeds, it often becomes necessary to inbreed in order to fix characteristic economically valuable traits in the breed, prevent their “dissolution”, and smooth out in unrelated crosses. Sometimes it is practiced even for several generations in order to obtain some important trait in its pure form, and then outbreeding is necessarily used and heterotic offspring are bred. Unrelated crossing within a breed and even between breeds leads to the maintenance and enhancement of the valuable qualities of the breed, if such crossing is accompanied by the selection of characteristic features.

A good example of interbreeding can be the highly productive White Steppe Ukrainian pig breed bred by Academician M.F. Ivanov from crossing local outbred Ukrainian pigs with highly productive White English (at the first stage). Then repeated interbreeding was used, several generations of inbreeding, which gave rise to several selected pure lines that were crossed with each other. Thus, paying due attention to the selection of initial producers, their quality, combining outbreeding, inbreeding and using strict selection of offspring according to the necessary characteristics, the breeder realizes his idea, his plans, his idea of the breed.

The main methods for the analysis of hereditary economically valuable traits in breeding animals are the analysis of the exterior and the evaluation of the offspring. To develop a new breed of animals that has a complex of valuable traits in accordance with the breeder's plan and production requirements, the correct selection and assessment of the quality of the original producers are of great importance. The assessment is made primarily on the exterior, i.e. phenotype. The exterior is understood as the whole set of external forms and signs of animals, including their physique, the ratio of parts of the animal’s body and even the color and the presence of its own exterior “label” for each breed. At the same time, for an experienced breeder, insignificant signs of interest are not of interest, they choose the main ones. But at the same time, by examining the correlative relationships between traits, it is possible, by purely external, insignificant phenotypic manifestations, to trace the inheritance of difficult-to-control, economically valuable traits associated with them.

Since the selection of sires is in a certain sense a decisive factor, in order to avoid mistakes, breeders often use a kind of "shooting" preliminary experiment, the essence of which is to evaluate sires by offspring, which is especially important when evaluating traits that do not appear in males. For evaluation, male producers are crossed with several females, productivity and other qualities of the offspring are determined. In order to assess the quality of heredity, for example, sires for milk fat, roosters for egg production, etc., the traits of the resulting offspring are compared with the average breed and maternal traits.

The distant hybridization of domestic animals is less productive than in plants, since it is impossible to overcome the sterility of distant hybrids if it is manifested. True, in some cases, distant hybridization of species with related chromosome sets does not lead to disruption of meiosis, but leads to normal fusion of gametes and embryo development in distant hybrids, which made it possible to obtain some valuable breeds that combine the useful features of both species used in hybridization. For example, fine-fleeced merino breeds have been obtained, which, like argali, can use high mountain pastures that are inaccessible to fine-fleeced merino. Successfully completed attempts to improve the breeds of local cattle by crossing it with zebu and yaks.

It should be noted that it is not always necessary to achieve fertile offspring from distant hybridization. Sometimes sterile hybrids are useful, as, for example, mules have been used for centuries - sterile hybrids of horse and donkey, distinguished by endurance and durability.

Selection of microorganisms, methods

Microorganisms include, first of all, prokaryotes (bacteria, actinomycetes, mycoplasmas, etc.) and unicellular eukaryotes - protozoa, yeast, etc. Of the more than 100 thousand species of microorganisms known in nature, several hundred are already used in human economic activity, and the number is growing. A qualitative leap in their use occurred in the last 20-30 years, when many genetic mechanisms for the regulation of biochemical processes occurring in the cells of microorganisms were established.

Microorganisms play an extremely important role in the biosphere and in human life. Many of them produce dozens of types of organic substances - amino acids, proteins, antibiotics, vitamins, lipids, nucleic acids, enzymes, pigments, sugars, etc., widely used in various fields of industry and medicine. Such branches of the food industry as baking, the production of alcohol, some organic acids, winemaking and many others are based on the activity of microorganisms.

The microbiological industry imposes stringent requirements on producers of various compounds that are important for production technology: accelerated growth, the use of cheap substrates for vital activity, and resistance to infection by microorganisms. The scientific basis of this industry is the ability to create microorganisms with new, predetermined genetic properties and the ability to use them on an industrial scale.

The selection of microorganisms (as opposed to the selection of plants and animals) has a number of features:

the breeder has an unlimited amount of material to work with - in a matter of days, billions of cells can be grown in Petri dishes or test tubes on nutrient media;

more efficient use of the mutation process, since the genome of microorganisms is haploid, which makes it possible to detect any mutations already in the first generation;

The organization of the bacterial genome is simpler: there are fewer genes in the genome, and the genetic regulation of gene interaction is less complex.

These features leave their imprint on the methods of selection of microorganisms, which in many respects differ significantly from the methods of selection of plants and animals. For example, in the selection of microorganisms, their natural ability to synthesize any compounds useful to humans (amino acids, vitamins, enzymes, etc.) is usually used. In the case of using genetic engineering methods, it is possible to force bacteria and other microorganisms to produce those compounds, the synthesis of which in natural conditions has never been inherent in them (for example, human and animal hormones, biologically active compounds).

Natural microorganisms, as a rule, have a low productivity of those substances that are of interest to the breeder. For use in the microbiological industry, highly productive strains are needed, which are created by various breeding methods, including selection among natural microorganisms.

The selection of highly productive strains is preceded by the selective work of the breeder with the genetic material of the original microorganisms. In particular, various methods of gene recombination are widely used: conjugation, transduction, transformation, and other genetic processes. For example, conjugation (the exchange of genetic material between bacteria) made it possible to create a strain capable of utilizing oil hydrocarbons. Often they resort to transduction (transfer of a gene from one bacterium to another, by means of bacteriophages), transformation (transfer of DNA isolated from one cell to another) and amplification (increase in the number of copies of the desired gene).

Thus, in many microorganisms, the genes for the biosynthesis of antibiotics or their regulators are located in the plasmid, and not in the main chromosome. Therefore, an increase in the number of these plasmids by amplification can significantly increase the production of antibiotics.

The most important stage in breeding work is the induction of mutations. Experimental obtaining of mutations opens up almost unlimited prospects for creating initial material in breeding. The probability (frequency) of mutations in microorganisms (10-10 - 10-6) is lower than in all other organisms (10-6 -10-4). But the probability of isolating mutations for this gene in bacteria is much higher than in plants and animals, since it is quite simple and fast to obtain multimillion offspring in microorganisms.

To isolate mutations, selective media are used, on which mutants are able to grow, but the original parental individuals of the wild type die. Selection is also carried out according to the color and shape of the colonies, the growth rate of mutants and wild forms, etc.

Selection for productivity (for example, antibiotic producers) is carried out according to the degree of antagonism and inhibition of the growth of a sensitive strain. For this, the producer strain is sown on the "lawn" of a sensitive culture. The size of the spot, where there is no growth of a sensitive strain around the colony of the producer strain, is used to judge the degree of activity (in this case, antibiotic). Naturally, the most productive colonies are selected for reproduction. As a result of selection, the productivity of producers can be increased hundreds to thousands of times. For example, by combining mutagenesis and selection in working with the fungus Penicillium, the yield of the antibiotic penicillin was increased by about 10,000 times compared to the original wild strain.

The role of microorganisms in the microbiological, food industry, agriculture and other areas can hardly be overestimated. It is especially important to note that many microorganisms use industrial waste, oil products to produce valuable products and thereby destroy them, protecting the environment from pollution.

5.Biotechnology, genetic and cell engineering

Biotechnology is the conscious production of products and materials necessary for man with the help of living organisms and biological processes.

Since time immemorial, biotechnology has been used mainly in the food and light industries: in winemaking, baking, fermentation of dairy products, in the processing of flax and leather based on the use of microorganisms. In recent decades, the possibilities of biotechnology have expanded enormously. This is due to the fact that its methods are more profitable than conventional methods for the simple reason that in living organisms, biochemical reactions catalyzed by enzymes proceed under optimal conditions (temperature and pressure), are more productive, environmentally friendly and do not require chemicals that poison the environment.

The objects of biotechnology are numerous representatives of groups of living organisms - microorganisms (viruses, bacteria, protozoa, yeast fungi), plants, animals, as well as isolated cells and subcellular components (organelles) and even enzymes. Biotechnology is based on the physiological and biochemical processes occurring in living systems, which result in the release of energy, the synthesis and breakdown of metabolic products, the formation of chemical and structural components of the cell.

The main direction of biotechnology is the production of biologically active compounds (enzymes, vitamins, hormones), drugs (antibiotics, vaccines, serums, highly specific antibodies, etc.), as well as valuable compounds (feed additives, for example, essential amino acids, feed proteins, etc.). Genetic engineering methods have made it possible to synthesize in industrial quantities such hormones as insulin and somatotropin (growth hormone), which are necessary for the treatment of human genetic diseases.

One of the most important areas of modern biotechnology is also the use of biological methods to combat environmental pollution (biological treatment of wastewater, polluted soil, etc.).

Thus, bacterial strains capable of accumulating uranium, copper, and cobalt can be widely used to extract metals from wastewater. Other bacteria of the genera Rhodococcus and Nocardia are successfully used for emulsification and sorption of oil hydrocarbons from the aquatic environment. They are capable of separating water and oil phases, concentrating oil, and purifying wastewater from oil impurities. By assimilating oil hydrocarbons, such microorganisms convert them into proteins, B vitamins and carotenes.

Some of the strains of halobacteria have been successfully used to remove fuel oil from sandy beaches. Genetically engineered strains have also been obtained that are capable of splitting octane, camphor, naphthalene, xylene, and efficiently utilizing crude oil.

The use of biotechnology methods to protect plants from pests and diseases is of great importance.

Biotechnology is penetrating into heavy industry, where microorganisms are used to extract, transform and process natural resources. Already in antiquity, the first metallurgists obtained iron from swamp ores produced by iron bacteria, which are able to concentrate iron. Now methods have been developed for the bacterial concentration of a number of other precious metals: manganese, zinc, copper, chromium, etc. These methods are used to develop dumps of old mines and poor deposits where traditional mining methods are not economically viable.

Genetic engineering is one of the most important methods of biotechnology. It involves the purposeful artificial creation of certain combinations of genetic material capable of functioning normally in the cell, i.e., multiplying and controlling the synthesis of end products. There are several varieties of the genetic engineering method, depending on the level and features of its use.

Genetic engineering is used mainly on prokaryotes and microorganisms, although recently it has also begun to be applied to higher eukaryotes (for example, plants). This method includes the isolation of individual genes from cells or the synthesis of genes outside cells (for example, based on messenger RNA synthesized by a given gene), targeted rearrangement, copying and reproduction of isolated or synthesized genes (gene cloning), as well as their transfer and inclusion in the subject to change. genome. In this way, it is possible to achieve the incorporation of “foreign” genes into bacterial cells and the synthesis of compounds important for humans by bacteria. Thanks to this, it was possible to introduce the insulin synthesis gene from the human genome into the E. coli genome. Insulin synthesized by bacteria is used to treat diabetic patients.

The development of genetic engineering became possible thanks to the discovery of two enzymes - restriction enzymes that cut the DNA molecule in strictly defined areas, and ligases that sew pieces of different DNA molecules together. In addition, genetic engineering is based on the discovery of vectors, which are short circular DNA molecules that reproduce independently in bacterial cells. With the help of restriction enzymes and ligases, the necessary gene is inserted into the vectors, subsequently achieving its inclusion in the genome of the host cell.

Cell engineering is a method of constructing a new type of cell based on their cultivation, hybridization and reconstruction. It is based on the use of cell and tissue culture methods. There are two areas of cell engineering: 1) the use of cultured cells for the synthesis of various compounds useful for humans; 2) the use of cultivated cells to obtain regenerated plants from them.

Plant cells in culture are an important source of the most valuable natural substances, since they retain the ability to synthesize their own substances: alkaloids, essential oils, resins, and biologically active compounds. Thus, ginseng cells transferred to culture continue to synthesize, as in the composition of a whole plant, valuable medicinal raw materials. Moreover, any manipulations can be carried out with cells and their genomes in culture. Using induced mutagenesis, it is possible to increase the productivity of cultured cell strains and carry out their hybridization (including distant hybridization) much easier and simpler than at the level of the whole organism. In addition, they, as well as with prokaryotic cells, can be genetically engineered.

By hybridizing lymphocytes (cells that synthesize antibodies, but grow reluctantly and for a short time in culture) with tumor cells that have potential immortality and are capable of unlimited growth in an artificial environment, one of the most important tasks of biotechnology at the present stage has been solved - hybridoma cells capable of endless synthesis of highly specific antibodies of a certain type.

Thus, cell engineering makes it possible to design cells of a new type using the mutation process, hybridization, and, moreover, to combine individual fragments of different cells (nucleus, mitochondria, plastids, cytoplasm, chromosomes, etc.), cells of various types, related not only to different genera, families, but also to kingdoms. This facilitates the solution of many theoretical problems and is of practical importance.

Cellular engineering is widely used in plant breeding. Hybrids of tomato and potato, apple and cherry have been bred. Plants regenerated from such cells with altered heredity make it possible to synthesize new forms, varieties that have useful properties and are resistant to adverse environmental conditions and diseases. This method is also widely used to "rescue" valuable varieties affected by viral diseases. Several apical cells that have not yet been infected by the virus are isolated from their sprouts in culture, and healthy plants are regenerated from them, first in a test tube, and then transplanted into the soil and propagated.

Conclusion

In order to provide itself with benign food and raw materials and at the same time not lead the planet to an ecological catastrophe, humanity needs to learn how to effectively change the hereditary nature of living organisms. Therefore, it is no coincidence that the main task of breeders in our time has become to solve the problem of creating new forms of plants, animals and microorganisms that are well adapted to industrial methods of production, stably endure adverse conditions, efficiently use solar energy and, most importantly, allow obtaining biologically pure products without excessive environmental pollution. Fundamentally new approaches to solving this fundamental problem are the use of genetic and cell engineering in breeding.

Biotechnology solves not only specific problems of science and production. It has a more global methodological task - it expands and accelerates the scale of human impact on wildlife and contributes to the adaptation of living systems to the conditions of human existence, i.e. to the noosphere. Biotechnology thus acts as a powerful factor in anthropogenic adaptive evolution.

Biotechnology, genetic and cell engineering have promising prospects. With the appearance of more and more new vectors, a person will use them to introduce the necessary genes into the cells of plants, animals and humans. This will gradually get rid of many hereditary human diseases, force the cells to synthesize the necessary drugs and biologically active compounds, and then directly proteins and essential amino acids that are eaten.

Bibliography

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2. Kolesnikov S.I. Ecology. - Rostov-on-Don: Phoenix, 2003. - 384 p.

3. Lemeza N.A., Kamlyuk L.V., Lisov N.D. Biology.- M.: Iris-press, 2005. 512p.

4. Petrov B.Yu. General biology. - St. Petersburg: Chemistry, 1999. - 420s

5. Petrov K.M. Interaction of society and nature: Textbook for universities. - St. Petersburg: Chemistry, 1998. - 408 p.

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Class- 9 "A" and "B"

Duration- 40 minutes

Teacher - Zhelovnikova Oksana Viktorovna

Lesson topic: "Genetic bases of selection of organisms"

Form of the educational process: cool lesson.

Lesson type: a lesson in communicating new knowledge.

Target: To acquaint with the genetic bases of selection of organisms.

Lesson objectives:

1. expand knowledge about the selection of organisms as a science;

2. introduce a brief history of selection;

3. deepen knowledge about the variety, breed and strain of organisms;

4. to form knowledge about the main methods of selection of organisms;

5. reveal the fundamental role of genetic patterns and laws for breeding practice.

Equipment: ICT presentation "Fundamentals of selection" textbook edited by I.N. Ponomareva,

magazine "Biology at school" No. 1-1998, tables "Methods of plant breeding", "Methods of animal breeding", dummies of hybrids of fruit crops.

During the classes.

1.Updating the knowledge of students:

What role did the general properties of all organisms - heredity and variability - play in the development of selection?

What is the essence of genetic laws and what is their role in selection?

2. Studying new material

The teacher's story is accompanied by a presentation

slide 1 Cultivated plants and domestic animals were formed in the prehistoric period. The cultivation of plants and the domestication of animals provided people with both food and clothing. The first attempts to domesticate animals and cultivate plants date back to the 20th - 30th millennium BC. In Central Asia, Transcaucasia, southern Russia, wheat was known in the Stone Age. At the beginning of the 7th millennium BC. in mountainous Kurdistan (Iraq) they cultivated wheat - wild einkorn. In the 10th millennium BC. began to cultivate many plants and domesticate animals.

Domestic animals and cultivated plants are descended from wild ancestors.

Man at the dawn of his formation tamed the animals he needed.

Question to the class: What animals have been tamed by humans?

banking chicken (chicken) argali (sheep) wolf (dog)

A man collected seeds of useful plants and sowed them near his dwelling, cultivated the land and selected the largest seeds for new crops.

Long-term selection of plants and animals contributed to the emergence of cultural forms with special properties needed by man.

However, the main role in the evolution of cultivated plants and domestic animals belongs to mutations, selection and selection.

Teacher: What do you understand by selection?

Selection (lat. "selectio" - selection)

Children think, answer, then the teacher shows the correct answer. Slide number 2

This is a science that studies the biological foundations and methods for creating and improving animal breeds, plant varieties and strains of microorganisms.

This is a branch of agricultural production engaged in the practical breeding of new varieties and hybrids of cultivated plants, animal breeds and strains of microorganisms with the properties necessary for humans.

Teacher: Please name the tasks of selection. ( students answer)

slide number 3

1.increasing the yield of plant varieties, the productivity of animal breeds,

strains of microorganisms.

2. Creation of varieties and breeds resistant to diseases and climatic conditions.

3. obtaining varieties, breeds and strains suitable for mechanized or industrial cultivation and breeding.

At present, given the growth of the world's population, a wider production of agricultural products is required. The decisive role in solving this global problem for the whole world is assigned to the selection of plants, animals, microorganisms

3. Physical education minute.

1.exercises for the spine

2.exercises for the eyes.

slide 4 BREED, VARIETY, STRAIN - these are artificially obtained populations of animals, plants, fungi and bacteria with traits necessary for humans.

slide 5 THEORETICAL BASIS OF SELECTION - genetics. Genetics is the study of heredity and variation. The properties of living organisms are determined by their GENOTYPE, subject to variability, so the development of selection is based on the laws of genetics.

slide 6 GENERAL SELECTION METHODS ARTIFICIAL SELECTION. HYBRIDIZATION. MUTAGENESIS. POLYPLOIDY.

Slide 7 ARTIFICIAL SELECTION is the choice by a person of the most valuable for him individuals of animals and plants of a given species, breed or variety in order to obtain offspring from them with desirable properties. Ch. Darwin laid the theoretical foundations of this method, identified two areas: UNCONSCIOUS and METHODOLOGICAL (CONSCIOUS)

Slide 8 Artificial selection for individual traits of interest to a person. Unconscious selection has been carried out since ancient times: according to external signs, the best are selected and propagated. Methodical artificial. Selection is the purposeful creation of new forms of cultivated plants and animals using breeding methods and various technologies.

Slide 9 Hybridization is the process of creating hybrids from two parent organisms that differ in genotype and reproduce sexually.

Slide 10 HYBRIDIZATION Intraspecific (within the same species between individuals of different forms.) Interspecific, or distant (between individuals of different species)

slide 11 HETEROSIS The phenomenon of the superiority of the first generation of hybrids over both parental forms in a number of ways is called HYBRID POWER or HETEROSIS. - higher productivity in animal husbandry - higher productivity in crop production. - when crossing F 1 hybrids, the effect of heterosis weakens and disappears. - hybrids obtained by distant hybridization are often infertile. (Mule is a hybrid of a horse with a donkey.)

slide 12 MUTAGENESIS is the process of the occurrence of hereditary changes (mutations) under the influence of physical and chemical factors. (mutagens) MUTATIONS - natural (spontaneous) - - artificial (induced)

slide 13 MUTAGENESIS Some mutations improve the properties of an organism, turn out to be interesting and beneficial for humans, and are used in breeding.

Slide 14 POLYPLOIDY - a hereditary change in which the haploid set of chromosomes increases many times over. It occurs as a result of a violation of the divergence of chromosomes in mitosis or meiosis under the influence of environmental factors. - ionization. - low temperatures. -chemical substances.

slide 15 POLYPLOIDY Large sizes Resistant to adverse conditions. The content of many substances valuable to humans has been increased. Used in plant breeding.

Independent work with the textbook(filling in the table)

Selection Methods

			Use in breeding
			plants		animals

	Related (outbreeding)	intraspecies, interspecies, Interbreeding, leading to heterosis to get heterozygous populations with high productivity		Crossbreeding distant breeds, different features, to get heterozygous populations and heterosis. Offspring may be infertile
	closely related (inbreeding)	self pollination cross-pollinating plants by artificial creating clean lines		Crossing between close relatives to get homozygous clean lines with desirable traits
Artificial selection	mass	Applies to cross-pollinating plants		Not applicable
	individual	Applies to self-pollinating plants clean lines stand out offspring of one self-pollinating individual		A rigorous selection is applied for economic value, endurance, exterior
Selection	experimental obtaining polyploids	Used to get more productive and productive forms of polyploids		Not applicable
	Experimental mutagenesis	It is used to obtain the source material for the selection of higher plants and microorganisms

5. Reflection So let's sum it up:

1. What is selection studying?

2. What is a variety, breed, strain?

3. Our next task is to recall the main selection methods.

artificial selection(unconscious, conscious)

Hybridization(intraspecific, interspecific)

Mutagenesis(natural and artificial mutations)

polyploidy

6. Homework: §27, terms p. 109 questions 1, 2, 3 orally.

1. The structure of modern breeding

2. Theory of the selection process

3. Artificial selection

4. History of breeding in Russia

5. Private breeding of plants, animals and microorganisms

1. The structure of modern breeding

Selection (from Latin selectio, seligere - selection) is the science of methods for creating highly productive plant varieties, animal breeds and strains of microorganisms.

Modern selection - This is a vast area of human activity, which is a fusion of various branches of science, agricultural production and its complex processing.

In the course of selection, stable hereditary transformations of various groups of organisms occur. According to the figurative expression of N.I. Vavilov, "... selection is an evolution directed by the will of man." It is known that the achievements of selection were widely used by Charles Darwin in substantiating the main provisions of evolutionary theory.

Modern selection is based on the achievements of genetics and is the basis of efficient highly productive agriculture and biotechnology.

Tasks of modern breeding

Creation of new and improvement of old varieties, breeds and strains with economically useful features.

Creation of technological highly productive biological systems that maximize the use of raw materials and energy resources of the planet.

Increasing the productivity of breeds, varieties and strains per unit area per unit of time.

Improving consumer qualities of products.

Reducing the share of by-products and their complex processing.

Reducing the share of losses from pests and diseases.

The structure of modern breeding

The doctrine of modern selection was our outstanding compatriot - agronomist, botanist, geographer, traveler, world-renowned authority in the field of genetics, breeding, plant breeding, plant immunity, a major organizer of agricultural and biological science in our country - Nikolai Ivanovich Vavilov (1887-1943). Many economically useful traits are genotypically complex, due to the combined action of many genes and gene complexes. It is necessary to identify these genes, to establish the nature of the interaction between them, otherwise the selection can be carried out blindly. Therefore, N.I. Vavilov argued that genetics is the theoretical basis of selection.

N.I. Vavilov singled out the following sections of selection:

1) the doctrine of the original varietal, species and generic potential;

2) the doctrine of hereditary variability (patterns in variability, the doctrine of mutations);

3) the doctrine of the role of the environment in the identification of varietal characteristics (the influence of individual environmental factors, the doctrine of the stages in the development of plants in relation to selection);

4) the theory of hybridization both within related forms and distant species;

5) the theory of the selection process (self-pollinators, cross-pollinators, vegetatively and apogamously propagating plants);

6) the doctrine of the main directions in breeding work, such as selection for immunity, for physiological properties (cold resistance, drought resistance, photoperiodism), selection for technical qualities, chemical composition;

7) private breeding of plants, animals and microorganisms.

The teachings of N.I. Vavilov about the centers of origin of cultivated plants

The doctrine of the source material is the basis of modern breeding. The source material serves as a source of hereditary variability - the basis for artificial selection. N.I. Vavilov established that there are areas on Earth with a particularly high level of genetic diversity of cultivated plants, and identified the main centers of origin of cultivated plants (initially, N.I. Vavilov identified 8 centers, but then reduced their number to 7). For each center, the most important agricultural crops characteristic of it have been established.

1. tropical center - includes the territories of tropical India, Indochina, South China and the islands of Southeast Asia. At least one quarter of the world's population still lives in tropical Asia. In the past, the relative population of this territory was even more significant. About one third of the currently cultivated plants originate from this center. It is home to plants such as rice, sugar cane, tea, lemon, orange, banana, eggplant, as well as a large number of tropical fruits and vegetables.

2. East Asian Center - includes temperate and subtropical parts of Central and Eastern China, Korea, Japan and most of about. Taiwan. Approximately one quarter of the world's population also lives in this territory. About 20% of the world's cultural flora originates from East Asia. This is the birthplace of such plants as soybeans, millet, persimmons, and many other vegetable and fruit crops.

3. Southwest Asian center - includes the territories of the inner mountainous Asia Minor (Anatolia), Iran, Afghanistan, Central Asia and North-Western India. The Caucasus also adjoins here, the cultural flora of which, as studies have shown, is genetically related to Western Asia. Homeland of soft wheat, rye, oats, barley, peas, melons.

This center can be subdivided into the following foci:

a) Caucasian with many original types of wheat, rye and fruit. For wheat and rye, as shown by comparative studies, this is the most important world focus of their species origin;

b) Western Asian , including Asia Minor, Inner Syria and Palestine, Transjordan, Iran, Northern Afghanistan and Central Asia together with Chinese Turkestan;

c) Northwest Indian , which includes, in addition to Punjab and the adjacent provinces of North India and Kashmir, also Balochistan and Southern Afghanistan.

About 15% of the world's cultural flora originates from this territory. Wild relatives of wheat, rye and various European fruits are concentrated here in exceptional species diversity. Until now, it is possible to trace here for many species a continuous series from cultivated to wild forms, that is, to establish preserved connections between wild forms and cultivated ones.

4. Mediterranean Center - includes countries located on the shores of the Mediterranean Sea. This remarkable geographical center, characterized in the past by the greatest ancient civilizations, has given rise to approximately 10% of the cultivated plant species. Among them are durum wheat, cabbage, beets, carrots, flax, grapes, olives, and many other vegetable and fodder crops.

5. Abyssinian Center . The total number of cultivated plant species associated in their origin with Abyssinia does not exceed 4% of the world's cultural flora. Abyssinia is characterized by a number of endemic species and even genera of cultivated plants. Among them are coffee tree, watermelon, teff cereal (Eragrostis abyssinica), nougat oil plant (Guizolia ahyssinica), a special kind of banana.

Within the New World, an amazingly strict localization of the two centers of speciation of the main cultivated plants has been established.

6. Central American Center, covering a vast area of North America, including southern Mexico. Three centers can be distinguished in this center:

a) Mountain southern Mexican,

b) Central American,

c) West Indian island.

About 8% of various cultivated plants originate from the Central American center, such as corn, sunflower, American long-staple cotton, cocoa (chocolate tree), a number of beans, pumpkins, many fruits (guayava, anone and avocado).

7. Andean Center, within South America, confined to the Andean ridge. This is the birthplace of potatoes and tomatoes. This is where the cinchona tree and the coca bush originate.

As can be seen from the list of geographical centers, the initial introduction of the vast majority of cultivated plants into culture is associated not only with floristic regions that are distinguished by rich flora, but also with ancient civilizations. Only comparatively few plants were introduced in the past into cultivation from the wild flora outside the listed main geographical centers. The seven indicated geographical centers correspond to the most ancient agricultural cultures. The South Asian tropical center is associated with a high ancient Indian and Indochinese culture. The latest excavations have shown the deep antiquity of this culture, synchronous with the Near East. The East Asian center is associated with ancient Chinese culture, and the Southwest Asian center is associated with the ancient culture of Iran, Asia Minor, Syria, Palestine and Assyro-Babylonia. The Mediterranean for many millennia BC concentrated the Etruscan, Hellenic and Egyptian cultures. The peculiar Abyssinian culture has deep roots, probably coinciding in time with the ancient Egyptian culture. Within the New World, the Central American center is associated with the great Mayan culture, which reached great success in science and art before Columbus. The Andean center in South America is combined in development with the remarkable pre-Inca and Inca civilizations.

N.I. Vavilov singled out a group of secondary crops that originated from weeds: rye, oats, etc. N.I. Vavilov found that "an important point in assessing the material for selection is the presence in it of a variety of hereditary forms." N.I. Vavilov distinguished the following groups of initial varieties: local varieties, foreign varieties, and varieties from other regions. When developing the theory of introduction (implementation) of other regional and foreign varieties, “it is necessary to distinguish primary centers of morphogenesis from secondary ones.” For example, in Spain, "an exceptionally large number of varieties and species of wheat" was found, but this is due to the "attraction here of many species from different foci." N.I. Vavilov attached great importance to new hybrid forms. Diversity of genes and genotypes in N.I. Vavilov called the genetic potential of the source material.

The development of the teachings of N.I. Vavilov about the centers of origin of cultivated plants.

Unfortunately, many ideas of N.I. Vavilov were not properly appreciated by his contemporaries. Only in the second half of the 20th century were large centers for the conservation of the gene pool of cultivated plants and their wild relatives established in the Philippines, Mexico, Colombia and other foreign countries.

In the second half of the XX century. new data on the distribution of cultivated plants appeared. Taking into account these data, Academician P.M. Zhukovsky developed the teachings of N.I. Vavilov about the centers of origin of cultivated plants. He created the theory of megacenters (genetic centers, or genecenters), uniting the primary and secondary centers of origin of cultivated plants, as well as some of their wild relatives. In his book "The World Plant Gene Pool for Breeding" (1970) P.M. Zhukovsky identified 12 megacenters: Chinese-Japanese, Indonesian-Indochinese, Australian, Hindustanian, Central Asian, Western Asian, Mediterranean, African, European-Siberian, Middle American, South American, North American. The listed mega centers cover vast geographic regions (for example, the entire territory of Africa south of the Sahara is assigned to the African Center). At the same time, P.M. Zhukovsky singled out 102 microgencentres, in which individual forms of plants were found. For example, sweet pea, a popular ornamental plant, is home to Fr. Sicily; unique forms of wheat originate from some regions of Georgia, in particular, Zanduri wheat, which is a supraspecific complex resistant to many fungal diseases (in addition, forms with cytoplasmic male sterility were found among these wheats).

Law of homologous series

Systematizing the doctrine of the source material, N.I. Vavilov formulated the law of homological series (1920):

1. Species and genera that are genetically close are characterized by similar series of hereditary variability with such regularity that, knowing the number of forms within one species, one can foresee the occurrence of parallel forms in other species and genera. The closer genera and species are genetically located in the general system, the more complete is the similarity in the series of their variability.

2. Whole families of plants are generally characterized by a certain cycle of variability passing through all the genera and species that make up the family.

According to this law, genetically close species and genera have similar genes that give a similar series of multiple alleles and trait variants.

Theoretical and practical significance of the law of homologous series:

N.I. Vavilov clearly distinguished between intraspecific and interspecific variability. At the same time, the species was considered as an integral, historically established system.

N.I. Vavilov showed that intraspecific variability is not unlimited and is subject to certain patterns.

The law of homologous series is a guide for breeders to predict the possible variations of traits.

N. I. Vavilov was the first to carry out a targeted search for rare or mutant alleles in natural populations and populations of cultivated plants. Nowadays, the search for mutant alleles to increase the productivity of strains, varieties and breeds continues.

Identification of the level of biological diversity and its conservation

To find the centers of diversity and richness of plant forms, N.I. Vavilov numerous expeditions, which for 1922 ... 1933. visited 60 countries of the world, as well as 140 regions of our country.

It is important to emphasize that the search for cultivated plants and their wild relatives did not go blindly, as in most countries, including the United States, but was based on a strict strict theory of the centers of origin of cultivated plants developed by N.I. Vavilov. If before him botanists-geographers were looking "in general" for the homeland of wheat, then Vavilov was looking for centers of origin of individual species, groups of wheat species in various regions of the globe. At the same time, it was especially important to identify areas of natural distribution (ranges) of varieties of this species and to determine the center of the greatest diversity of its forms (botanical-geographical method). To establish the geographical distribution of varieties and races of cultivated plants and their wild relatives, N.I. Vavilov studied the centers of the most ancient agricultural culture, the beginning of which he saw in the mountainous regions of Ethiopia, Western and Central Asia, China, India, in the Andes of South America, and not in the wide valleys of large rivers - the Nile, Ganges, Tigris and Euphrates, as scientists had previously claimed. .

As a result of the expeditions, a valuable fund of world plant resources was collected, numbering over 250,000 samples. A similar collection was created in the United States, but it was significantly inferior to the Vavilov collection both in terms of the number of specimens and the species composition.

Collection samples collected under the guidance of N.I. Vavilov, were kept in Leningrad at the All-Union Institute of Plant Industry (VIR), created by N.I. Vavilov in 1930 on the basis of the All-Union Institute of Applied Botany and New Cultures (formerly the Department of Applied Botany and Breeding, even earlier - the Bureau of Applied Botany). During the Great Patriotic War, during the siege of Leningrad, VIR employees were on duty around the clock at the collection of seeds of grain crops. Many VIR employees died of starvation, but the invaluable species and varietal wealth, from which breeders around the world still draw material to create new varieties and hybrids, was preserved.

In the second half of the 20th century, new expeditions were organized to collect samples to replenish the VIR collection; at present, this collection includes up to 300,000 plant specimens belonging to 1,740 species.

To store the source material in a living form, a variety of plantations are used: collection nurseries, collection-uterine, uterine and industrial plantations. A variety of methods are used to preserve collection samples: storage of seeds with periodic re-sowing, storage of frozen samples (cuttings, buds), maintenance of tissue-cell cultures. In 1976, the National Seed Vault for the VIR gene pool was built in the Kuban, with a capacity of 400,000 samples. In this storage, seeds are stored at a strictly defined temperature, which allows them to maintain germination and prevent the accumulation of mutations, incl. at liquid nitrogen temperature (–196 °С).

The systematic study of the world's plant resources of the most important cultivated plants has radically changed the idea of the varietal and species composition of even such well-studied crops as wheat, rye, corn, cotton, peas, flax and potatoes. Among the species and many varieties of these cultivated plants brought from expeditions, almost half turned out to be new, not yet known to science. The collected richest collection is carefully studied using the most modern methods of selection, genetics, biotechnology, as well as with the help of geographical crops.

Decreasing genetic diversity at the population level is a sign of our time

Many modern varieties of plants (grain legumes, coffee tree, etc.) originate from a few founding individuals. Hundreds of breeds of domestic animals are on the verge of extinction. For example, the development of industrial poultry farming has led to a sharp reduction in the breed composition of chickens throughout the world: only 4 ... 6 of the known 600 breeds and varieties are most widely used. The same situation is typical for other agricultural species. A significant role in the process of reducing the level of diversity is played by irrational economic management, which ignores the evolutionarily established systemic organization of both natural and agricultural populations, their natural subdivision into genetically different subpopulations. Ideas N.I. Vavilov about the need to identify and preserve diversity were developed in the works of A.S. Serebrovsky, S.S. Chetverikov and other domestic scientists. Selection methods aimed at the conservation of biological diversity will be discussed below.

Currently, the source material for breeding are:

Varieties and breeds currently cultivated and bred.

Varieties and breeds that have gone out of production, but are of great genetic and breeding value in certain parameters.

Local varieties and native breeds.

Wild relatives of cultivated plants and domestic animals: species, subspecies, ecotypes, varieties, forms.

Wild species of plants and animals, promising for introduction into culture and domestication. It is known that only 150 species of agricultural plants and 20 species of domestic animals are currently cultivated. Thus, the huge species potential of wild species remains unused.

Experimentally created genetic lines, artificially obtained hybrids and mutants.

Nowadays, it is generally accepted that both local and foreign source material should be used as source material. The source material should be sufficiently diverse: the greater its diversity, the greater the possibility of choice. At the same time, the source material should be as close as possible to the ideal image (model) of the selection result - variety, breed, strain (see below). Currently, the search for mutant alleles to increase the productivity of varieties, breeds and strains continues.

induced mutagenesis.

Experimental obtaining of mutations in plants and microorganisms and their use in breeding

Effective methods for obtaining the starting material are methods induced mutagenesis – artificial obtaining of mutations. Induced mutagenesis makes it possible to obtain new alleles that cannot be found in nature. For example, highly productive strains of microorganisms (producers of antibiotics), dwarf varieties of plants with increased precocity, etc. have been obtained in this way. Experimentally obtained mutations in plants and microorganisms are used as material for artificial selection. In this way, highly productive strains of microorganisms (producers of antibiotics), dwarf varieties of plants with increased precocity, etc. have been obtained.

To obtain induced mutations in plants, physical mutagens (gamma radiation, X-ray and ultraviolet radiation) and specially created chemical supermutagens (for example, N-methyl-N-nitrosourea) are used.

The dose of mutagens is selected in such a way that no more than 30 ... 50% of the treated objects die. For example, when using ionizing radiation, such a critical dose ranges from 1...3 to 10...15 and even 50...100 kiloroentgens. When using chemical mutagens, their aqueous solutions with a concentration of 0.01 ... 0.2% are used; processing time - from 6 to 24 hours or more.

Processing is subjected to pollen, seeds, seedlings, buds, cuttings, bulbs, tubers and other parts of plants. Plants grown from treated seeds (buds, cuttings, etc.) are designated M1 (first mutant generation). In M1, selection is difficult because most of the mutations are recessive and do not show up in the phenotype. In addition, along with mutations, non-inherited changes are often encountered: phenocopies, terates, morphoses.

Therefore, the isolation of mutations begins in M2 (the second mutant generation), when at least some of the recessive mutations appear, and the probability of preserving non-hereditary changes decreases. Usually, selection continues for 2–3 generations, although in some cases it takes up to 5–7 generations to cull non-inherited changes (such non-hereditary changes that persist for several generations are called long-term modifications).

The resulting mutant forms either directly give rise to a new variety (for example, dwarf tomatoes with yellow or orange fruits) or are used in further breeding work.

However, the use of induced mutations in breeding is still limited, since mutations lead to the destruction of historically established genetic complexes. In animals, mutations almost always lead to reduced viability and/or infertility. A few exceptions include the silkworm, with which intensive breeding work was carried out using auto- and allopolyploids (B.L. Astaurov, V.A. Strunnikov).

somatic mutations. As a result of induced mutagenesis, partially mutant plants (chimeric organisms) are often obtained. In this case, one speaks of somatic (kidney) mutations. Many varieties of fruit plants, grapes, and potatoes are somatic mutants. These varieties retain their properties if they are reproduced vegetatively, for example, by grafting buds (cuttings) treated with mutagens into the crown of non-mutant plants; in this way, for example, seedless oranges are propagated.

Polyploidy. As you know, the term "polyploidy" is used to refer to a wide variety of phenomena associated with a change in the number of chromosomes in cells.

Autopolyploidy is a multiple repetition in the cell of the same chromosome set (genome). Autopolyploidy is often accompanied by an increase in cell size, pollen grains, and overall size of organisms. For example, the triploid aspen reaches gigantic sizes, is durable, and its wood is resistant to decay. Among cultivated plants, both triploids (bananas, tea, sugar beets) and tetraploids (rye, clover, buckwheat, corn, grapes, as well as strawberries, apple trees, watermelons) are widespread. Some polyploid varieties (strawberries, apple trees, watermelons) are represented by both triploids and tetraploids. Autopolyploids are characterized by high sugar content, high content of vitamins. The positive effects of polyploidy are associated with an increase in the number of copies of the same gene in cells, and, accordingly, in an increase in the dose (concentration) of enzymes. As a rule, autopolyploids are less fertile than diploids, but the decrease in fertility is usually more than offset by an increase in fruit size (apple, pear, grape) or an increased content of certain substances (sugars, vitamins). At the same time, in some cases, polyploidy leads to inhibition of physiological processes, especially at very high levels of ploidy. For example, 84 chromosome wheat is less productive than 42 chromosome wheat.

Allopolyploidy - This is the union of different chromosome sets (genomes) in a cell. Often, allopolyploids are obtained by distant hybridization, that is, by crossing organisms belonging to different species. Such hybrids are usually sterile (they are figuratively called "plant mules"), however, by doubling the number of chromosomes in the cells, their fertility (fertility) can be restored. In this way, hybrids of wheat and rye (triticale), cherry plum and blackthorn, mulberry and tangerine silkworm were obtained.

Polyploidy in breeding is used to achieve the following goals:

Obtaining highly productive forms that can be directly introduced into production or used as material for further selection;

Restoration of fertility in interspecific hybrids;

Transfer of haploid forms to the diploid level.

Under experimental conditions, the formation of polyploid cells can be caused by exposure to extreme temperatures: low (0 ... +8 ° C) or high (+38 ... + 45 ° C), as well as by treating organisms or their parts (flowers, seeds or plant sprouts, eggs or animal embryos) by mitotic poisons. Mitotic poisons include: colchicine (an alkaloid of autumn colchicum - a well-known ornamental plant), chloroform, chloral hydrate, vinblastine, acenaphthene, etc.

In the lesson, we will look at how the regularity discovered by genetics in medicine and agriculture is applied in practice, we will learn the basics of selection of organisms, how selection contributes to the breeding of animal breeds with traits necessary for humans.

Of course, it’s unlikely that such a sign would have given this pe-to-hu-hu-you-to-hold a competitive struggle and natural selection in the environment -zha-yu-schey environment. But this sign is for-in-te-re-co-val che-lo-ve-ka, and this ro-da was co-created. In addition, from-whether home-made forms from wild ones also have their very large fruit-to-vi-that-stu, this is the main quality, for the sake of -that-ro-th man-lo-age and began to create these breeds. For example, the egg-tse-nose-bone of chickens in the white leg-horn is about 350 eggs per year, and the egg-tse-nose-bone of their di-ko-th pre-ka ban-ki-vskoy ku-ri-tsy composes 18-20 eggs per year (Fig. 2).

Rice. 2. White Leghorn Chicken and Banking Chicken ()

From these examples, you can-ve-sti for-da-chi co-time se-lec-tion, to them from-no-sit-sya:

1. Po-lu-che-ing of new you-with-uro-zhai-ny and resistant-chi-to-for-bo-le-va-ing of animal breeds and varieties of races -ny.

2. Better eco-lo-gi-che-ski plastic varieties and breeds, that is, those who can live in different eco-lo- gi-che-sky conditions-vi-yah.

3. Po-lu-che-breeds and varieties that are convenient for industrial mice-len-no-go you-ra-schi-va-nia and me-ha-ni-zi-ro-van- noah cleaning.

Arose-la-se-lecture at the dawn of man-lo-ve-che-stva, about 20-30 thousand years ago, when people became an accidental way of dressing mach-ni-vat zhi-here-nyh, someone is around them. The main criterion was that animals can multiply in captivity and have a hundred-accurate but good character , it is convenient to keep them. This served as a precursor to the development of the science of breeding. Shi-ro-some odo-mash-ni-va-nie na-cha-elk somewhere in the 8-6 centuries BC, and already at that moment they were all odo-mash-not-we this time, animals and ocul-tu-re-na races, but it was still not science. Pi-o-ne-rum of the science of selection in our country was Ni-ko-lai Iva-no-vich Va-vi-lov (Fig. 3).

Rice. 3. N.I. Vavilov (1887-1943) ()

Va-vi-lov believed that in the basis of the os-no-ve se-lecture lies the right choice for ra-bo-you is-mo-no-go ma-te-ri-a-la , genetic diversity and the influence of the environment on the manifestation of hereditary properties signs with gi-bri-di-za-tion or-ga-niz-mov. In-is-kah is-hot-no-go ma-te-ri-a-la for-lu-che-niya new hybrids Wa-vi-lov or-ga-ni-zo-val in the years 1920-30 de-syat-ki ex-pe-di-tsy around the globe. During these ex-pe-di-tions, he managed to collect more than lu-thousand species of cultural races and a huge co -li-che-stvo varieties. By 1940, there were already 300 thousand specimens in the All-So-Uz-In-sti-tu-te races-te-ni-water-stva. At the present time, a collection of lectures is in a hundred-yan-but half-nya-is-sya and is used-for-lu-che-for new rubbish -tov on the os-but-ve already from-the-west. Exploring in a lu-chen-ny during ex-pe-di-tion ma-te-ri-al, N.I. Va-vi-lov came to the opening of the opre-de-len-noy for-co-no-mer-no-sti, someone-paradise and became a gene-not-ty-che-os -no-howl se-lecture. This za-ko-no-dimension in-lu-chi-la is called the “law of go-mo-lo-gi-che-series of inheritance”. For-mu-li-ditch-ka of this for-to-on, someone-ruyu suggested-lo-lived N.I. Va-vi-lov: “Ge-not-ti-che-ski close genera and species ha-rak-te-ri-zu-yut-sya similarity-us-mi row-yes-mi-heritage -noy from-men-chi-in-sti with such rightness that, knowing a number of forms in pre-de-lah of the same kind, you can foresee -the existence of parallel forms in other related species and genera. The closer the species and genera of si-ste-ma-ti-che-ski, the more complete the similarity in the ranks of their iz-men-chi-vo-sti.

This complex form-mu-li-ditch-ku can be pro-il-lu-stri-ro-vat, on the example of the family of evil-to-vyh (Fig. 4), which includes -dyat ho-ro-sho from-would you millet, rye, barley-men, rice, ku-ku-ru-za.

Rice. 4. Cereal family ()

This family has a number of signs, some traces in different species, from to this family. To such signs from-no-sat-sya on-whether winter forms, red color in grains, for example, red color meets -cha-et-sya and rye, and wheat-ni-tsy, and ku-ku-ru-zy. In the same way, winter forms are found in both wheat and rye. This is what served as the basis of the discovery of this for-to-on. The law of go-mo-lo-gi-che-series is true not only for races, but also for animals. So, for example, yav-le-niya al-bi-niz-ma na-blu-yes-yut-sya in both man-ve-ka and mammal-ko-pi-ta-yu -shchy, and even in birds (Fig. 5).

Rice. 5. The phenomenon of albinism ()

The law discovered by Vavilov has practical significance, it can be disassembled on a specific example: in a plant, lu-pi-na, the fruits contain a very large number of - protein content, and lupine (Fig. 6) could be a very valuable food crop, but its seeds contain dangerous poisonous al -ka-lo-id.

Rice. 6. Perennial lupine with poisonous alkaloid seeds ()

Therefore, it was impossible to use lupine as a food for my culture. One-of-a-know-but that other pre-hundred-vi-te-whether se-mei-stvo bo-bo-vy: peas, beans, alfalfa, soybeans - do not have that - which gene. So, it’s possible to predict that lu-pi-na-possibility-m-ta-tion is in such a non-al-ka-lo-id-form. And really-but, se-lek-qi-o-ne-ram managed to get-to-chit without-al-ka-lo-id-ny form of lu-pi-na, and now lupine is active but is used in agriculture as a beautiful fodder crop (Fig. 7).

Rice. 7. Feed varieties of lupine ()

We examined the history of the emergence of a new, in-the-res-noy, and most importantly, a very useful and practically significant science of selection, its main tasks. In the course of our next lessons, we will learn more in detail about the selection methods and works of N.I. Wa-wee-lo-wa.

Bibliography

Mamontov S.G., Zakharov V.B., Agafonova I.B., Sonin N.I. Biology. General patterns. - Bustard, 2009.
Ponomareva I.N., Kornilova O.A., Chernova N.M. Fundamentals of General Biology. Grade 9: A textbook for students in grade 9 educational institutions / Ed. prof. I.N. Ponomareva. - 2nd ed., revised. - M.: Ventana-Graf, 2005.
Pasechnik V.V., Kamensky A.A., Kriksunov E.A. Biology. An Introduction to General Biology and Ecology: A 9th Grade Textbook, 3rd ed., stereotype. - M.: Bustard, 2002.

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Homework

What is a selection?
What are the main tasks of co-time se-lec-tion?
What does the law of homologous series of heredity say?

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