Selection- a science that develops ways to create new and improve existing plant varieties, animal breeds and strains of microorganisms.

The creation of new varieties and breeds is based on such important properties of a living organism as heredity and variability. That is why genetics - the science of the variability and heredity of organisms - is the theoretical basis of selection.

Having its own tasks and methods, selection is firmly based on the laws of genetics, is an important area for the practical use of the patterns established by genetics. At the same time, selection is also based on the achievements of other sciences. To date, genetics has reached the level of purposeful design of organisms with the desired features and properties.

Variety, breed and strain- a stable group of 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 directions of selection:

• high productivity of plant varieties, fertility and productivity of animal breeds;
• improving the quality of products (for example, taste, appearance of fruits and vegetables, the chemical composition of the 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).

• breeding of stress-resistant breeds (for breeding in conditions of high crowding - in poultry farms, farms, etc.);
• fur farming;
• fish farming - breeding of fish in artificial reservoirs.

THE DIFFERENCE OF CULTURAL FORMS FROM WILD

cultural forms	wild forms
developed traits that are beneficial to humans and often harmful in natural conditions	the presence of signs that are inconvenient for a person (aggressiveness, pricklyness, etc.)
high productivity	low productivity (small fruits; low weight, egg production, milk yield)
less adaptable to changing environmental conditions	high adaptability
do not have means of protection against predators and pests (bitter or poisonous substances, thorns, thorns, etc.)	the presence of natural protective devices that increase vitality, but are inconvenient for humans

basic breeding methods

Main selection methods:

• selection of parent pairs
• selection
• hybridization
• artificial mutagenesis

Selection of parent pairs

This method is used primarily in animal breeding, because animals are characterized by sexual reproduction and a small number of offspring.

Breeding a new breed is a lengthy process that requires large material costs. It may be purposeful obtaining a certain exterior(a set of phenotypic traits), an increase in milk yield, milk fat content, meat quality, etc.

Breeding animals are evaluated not only by external signs, but also by origin and offspring quality. Therefore, it is necessary to know their pedigree well. In breeding farms, when selecting producers, a record of pedigrees is always kept, in which the exterior features and productivity of parental forms are evaluated over a number of generations.

works by I. V. Michurin

Selection work occupies a special place in the practice of improving fruit and berry crops. I. V. Michurina. He attached great importance to the selection of parent pairs for crossing. However, he did not use local wild varieties (since they had stable heredity, and the hybrid usually deviated towards the wild parent), but took plants from other, remote geographical locations and crossed them with each other.

An important link in Michurin's work was purposeful education hybrid seedlings: in a certain period of their development, conditions were created for the dominance of the traits of one of the parents and the suppression of the traits of the other, i.e., effective control of the dominance of traits (various methods of tillage, fertilization, grafting into the crown of another plant, etc.).

The mentor method- upbringing on the stock. As a scion, Michurin took both a young plant and buds from a mature fruit-bearing tree. With this method, it was possible to give the desired color to the fruits of the cherry-cherry hybrid called "Beauty of the North".

Michurin also used distant hybridization. He obtained a kind of hybrid of cherry and bird cherry - cerapadus, as well as a hybrid of blackthorn and plum, apple and pear, peach and apricot. All Michurin varieties are supported by vegetative propagation.

Selection

artificial selection- preservation for further reproduction of individuals with traits of interest to the breeder. Forms of selection: mass and individual.

• Intuitive (unconscious) selection- the most ancient form of selection used by ancient man: selection of individuals by phenotype, i.e. with the most useful feature combinations.
• Methodical selection- selection for reproduction of individuals with clearly defined characteristics, according to the goal and taking into account their phenotypes and genotypes.

• Mass selection- elimination from reproduction of individuals that do not have valuable traits or have undesirable traits (for example, aggressive ones).

Mass selection can be effective if qualitative, simply inherited and easily identifiable traits are selected. Mass selection is usually carried out among cross-pollinated plants. At the same time, breeders select plants according to the phenotype with the traits of interest to them. The disadvantage of mass selection is that the breeder cannot always determine the best genotype from the phenotype.

• Individual selection- selection of individual individuals with traits of interest to a person and obtaining offspring from them.

Individual selection is more effective in selecting individuals for quantitative, difficultly inherited traits. This type of selection makes it possible to accurately assess the genotype by analyzing the inheritance of traits in offspring. Individual selection is used in relation to self-pollinated plants (varieties of wheat, barley, peas, etc.).

Hybridization

In breeding work with animals, two methods of crossing are mainly used: inbreeding and outbreeding.

Inbreeding- crossbreeding of closely related forms: siblings or parents and offspring are used as initial forms.

Result: obtaining homozygous organisms → decomposition of the original form into a number of pure lines.

Cons: reduced viability (recessive homozygotes often carry hereditary diseases).

To a certain extent, such crossing is similar to self-pollination in plants, which also leads to an increase in homozygosity and, as a result, to the consolidation of economically valuable traits in descendants. At the same time, homozygotization for the genes that control the studied trait occurs the faster, the more closely related crossing is used for inbreeding. However, homozygotization during inbreeding, as in the case of plants, leads to the weakening of animals, reduces their resistance to environmental influences, and increases the incidence.

In breeding, inbreeding is usually only one step in improving a breed. This is followed by crossing different interline hybrids, as a result of which unwanted recessive alleles are transferred to a heterozygous state and the harmful effects of inbreeding are markedly reduced.

outbreeding- unrelated crossing between individuals of the same breed or different breeds of animals within the same species.

Result: obtaining a large number of heterozygous organisms → maintaining useful qualities and increasing their severity in the next generations.

Remote hybridization - obtaining interspecific and intergeneric hybrids.

Distant hybridization in animal breeding is used much less frequently than in plant breeding.

Interspecific and intergeneric hybrids of animals and plants are most often sterile, since meiosis is disturbed and gametogenesis does not occur. At the same time, the restoration of fertility in animals is a more difficult task, since it is impossible to obtain polyploids based on the multiplication of the number of chromosomes in them.

Overcoming the infertility of interspecific hybrids of plants was first achieved in the early 20s of the twentieth century by Soviet genetics G. D. Karpechenko when crossing radish and cabbage. This newly man-made plant looked neither like a radish nor like a cabbage. The pods occupied, as it were, an intermediate position and consisted of two halves, one of which resembled a cabbage pod, the other a radish. Each of the original forms had 9 chromosomes in the germ cells. In this case, the cells of the hybrid obtained from them had 18 chromosomes. But some eggs and pollen grains contained all 18 chromosomes (diploids), and when they were crossed, a plant with 36 chromosomes was created, which turned out to be fertile. Thus, the possibility of using a polyploid to overcome non-crossing and infertility during distant hybridization was proved.

It happens that individuals of only one sex are infertile. For example, in hybrids of a high-mountain bull, yak and cattle, (sterile) males and females are fertile (fertile).

But sometimes gametogenesis in distant hybrids proceeds normally, which made it possible to obtain new valuable breeds of animals. An example is the archa-merinos, which, like argali (mountain sheep), can graze high in the mountains, and as merinos give good wool. Prolific hybrids have been obtained from crossing local (Indian) cattle with zebu. When crossing beluga and sterlet, a fertile hybrid was obtained - bester, ferret and mink - honorik, a hybrid between carp and crucian carp is productive.

In nature, there are hybrids of a zebra and a horse (zebroid), a bison and a bison (bison), a black grouse and a partridge (mezhnyak), a hare and a white hare (cuff), a sable and a fox (kidus), as well as a tiger and a lion (ligr ).

Examples of intergeneric hybrids of plants include a hybrid of wheat and rye (triticale), a wheat-couch grass hybrid, a hybrid of currant and gooseberry (yoshta), a hybrid of swede and fodder cabbage (kuuzika), hybrids of winter rye and wheatgrass, grassy and tree-like tomatoes, etc. .

heterosis- the phenomenon of increased viability, productivity, fertility of hybrids of the first generation, exceeding both parents in these parameters.

Already from the second generation, the heterotic effect fades. Apparently, this is due to a decrease in the number of heterozygous organisms and an increase in the proportion of homozygotes.

Classical examples of the manifestation of heterosis are the mule (a hybrid of a mare and a donkey) and a hinny (a hybrid of a horse and a donkey) (Fig. 1.2). These are strong, hardy animals that can be used in much more difficult conditions than parental forms.

Rice. 1. Mule Fig. 2. Loshak

Their life expectancy is much higher than that of the parent species.

A hinny is smaller than a mule and a shrew, therefore it is less convenient for use in human economic activities.

Heterosis is widely used in industrial poultry farming, for example - broiler chickens, which are characterized by very fast growth. Broiler chicken is the final hybrid obtained by crossing several lines of different breeds of chickens (meat parental forms), tested for compatibility. Initially, Cornish (as the paternal form) and White Plymouthrock (as the maternal form) were used for such crossing.

artificial mutagenesis

Artificial mutagenesis is most commonly used as a plant breeding method. It is based on the use of physical and chemical mutagens to obtain plant forms with pronounced mutations. Such forms are further used for hybridization or selection.

Widely used in plant breeding polyploidy.

polyploidy- an increase in the number of sets of chromosomes in the cells of the body, a multiple of the haploid (single) number of chromosomes; type of genomic mutation.

Sex cells of most organisms are haploid (contain one set of chromosomes - n), somatic - diploid (2n). Organisms whose cells contain more than two sets of chromosomes are called polyploids, three sets are triploids (3n), four are tetraploids (4n), etc. The most common organisms with a multiple of two chromosome sets are tetraploids, hexaploids (6n ) etc.

Polyploids with an odd number of sets of chromosomes (triploids, pentaploids, etc.) usually do not produce offspring (sterile), because the germ cells they form contain an incomplete set of chromosomes - not a multiple of the haploid one.

appearance of polyploidy

Polyploidy occurs when chromosomes do not separate during meiosis. In this case, the germ cell receives a complete (non-reduced) set of somatic cell chromosomes (2n). When such a gamete fuses with a normal one (n), a triploid zygote (3n) is formed, from which a triploid develops. If both gametes carry a diploid set, a tetraploid is produced. Polyploid cells can arise in the body during incomplete mitosis: after doubling the chromosomes, cell division may not occur, and two sets of chromosomes appear in it. In plants, tetraploid cells can give rise to tetraploid shoots whose flowers produce diploid gametes instead of haploid ones. When self-pollinated, a tetraploid can occur, when pollinated with a normal gamete, a triploid. During vegetative propagation of plants, the ploidy of the original organ or tissue is preserved.

Thanks to polyploidy, high-yielding polyploid varieties of sugar beet, cotton, buckwheat, etc. have been bred. Polyploid plants are often more viable and prolific than normal diploids. Their greater resistance to cold is evidenced by the increase in the number of polyploid species in high latitudes and high mountains.

Since polyploid forms often have valuable economic traits, artificial polyploidization is used in crop production to obtain initial breeding material.

Obtaining polyploids in the experiment is closely related to artificial mutagenesis. For this purpose, special mutagens are used (for example, the alkaloid colchicine), which disrupt the divergence of chromosomes in mitosis and meiosis.

Productive polyploids of rye, buckwheat, sugar beet and other cultivated plants have been obtained; sterile triploids of watermelon, grapes, banana are popular due to seedless fruits.

The use of distant hybridization in combination with artificial polyploidization allowed domestic scientists to obtain fertile polyploid hybrids of plants (G. D. Karpechenko, a tetraploid hybrid of radish and cabbage) and animals (B. L. Astaurov, silkworm tetraploid hybrid).

Silkworms of Astaurov

Cases of natural polyploidy in animals are very rare. However, Academician B. L. Astaurov developed a method for the artificial production of polyploids from an interspecific hybrid of silkworms Bombyx mori and B. mandarina. Both of these species have n = 28 chromosomes.

When synthesizing the tetraploid, the method of artificial parthenogenesis was used. Initially, parthenogenetic polyploids of B. mori were obtained - 4 n, 6 n. All obtained individuals were fertile (prolific) females.

Then the parthenogenetic females of B. mori (4n) were crossed with males of another species B. mandarina (2n). Triploid females 2n B. mori + 1 n B. mandarina appeared in the progeny from such crossing.

These females, sterile under normal conditions, reproduced by parthenogenesis. At the same time, 6n females sometimes appeared parthenogenetically (4n B. mori + 2n B. mandarina).

In the offspring from crossing these females with 2n B. mandarina males, 4n forms of both sexes were selected with a double set of chromosomes of each species (2n B. mori + 2n B. mandarina).

If the hybrid 1n B. mori + 1n B. mandarina was sterile, then the tetraploid (4n) turned out to be fertile and, when bred, gave fertile offspring. With the help of polyploidy, thus, it was possible to synthesize a new form of silkworm.

biotechnology

Biotechnology- a science that studies the possibility of modifying biological organisms to meet human needs.

Application of biotechnology (Fig. 3):

• production of medicines, fertilizers, biological plant protection products;
• biological wastewater treatment;
• recovery of valuable metals from sea water;
• correction and correction of genetic pathologies.

Rice. 3. Possibilities of biotechnology

For example, the inclusion in the genome of E. coli of the gene responsible for the formation of insulin in humans made it possible to establish the industrial production of this hormone (Fig. 4).

Rice. 4. Biotechnology for the production of insulin

In biotechnology, methods of genetic and cell engineering are successfully applied.

GENE AND CELL ENGINEERING

Genetic Engineering- artificial, purposeful change in the genotype of microorganisms in order to obtain cultures with predetermined properties.

Research in the field of genetic engineering extends not only to microorganisms, but also to humans. They are especially relevant in the treatment of diseases associated with disorders in the immune system, in the blood coagulation system, in oncology.

The main method of genetic engineering: the selection of the necessary genes, their cloning and introduction into a new genetic environment. For example, the introduction of certain genes with the help of a plasmid into the body of a bacterium for the synthesis of a certain protein by it (Fig. 5).

Rice. 5. Application of genetic engineering

The main stages of solving the genetic engineering problem are as follows:

1. Obtaining an isolated gene.
2. Introduction of a gene into a vector (plasmid) for transfer into the body.
3. Transfer of a vector with a gene (recombinant plasmid) into a modified organism.
4. Transformation of body cells.
5. Selection of genetically modified organisms and elimination of those that have not been successfully modified.

Cell engineering- this is a direction in science and breeding practice that studies methods of hybridization of somatic cells belonging to different species, the possibility of cloning tissues or whole organisms from individual cells.

It includes cultivation and cloning of cells on specially selected media, cell hybridization, transplantation of cell nuclei and other microsurgical operations for the "disassembly" and "assembly" (reconstruction) of viable cells from individual fragments.

At the moment, it has been possible to obtain hybrids between the cells of animals that are distant in their systematic position, for example, mice and chickens. Somatic hybrids have found wide application both in scientific research and in biotechnology.

Hybrid cells derived from human and mouse and human and Chinese hamster cells were involved in the decoding of the human genome.

Hybrids between tumor cells and lymphocytes have the properties of both parental cell lines: they divide indefinitely and can produce certain antibodies. Such antibodies are used for therapeutic and diagnostic purposes in medicine.

In embryology, organisms are used to study the processes of differentiation of cells and tissues during ontogenesis. chimeras, made up of cells with different genotypes. They are created by connecting the cells of different embryos at the early stages of their development.

Animal cloning- another method of cell engineering: the nucleus of a somatic cell is transplanted into an egg cell devoid of a nucleus, followed by the cultivation of the embryo into an adult organism.

The advantage of cell engineering is that it allows experimentation on cells rather than entire organisms.

Cell engineering methods are often used in combination with genetic engineering.

works by N. I. Vavilov

Nikolai Ivanovich Vavilov - Russian geneticist, plant grower, geographer.

1. N. I. Vavilov organized 180 expeditions (20-30 years of the twentieth century) to the most inaccessible and often dangerous regions of the globe in order to study the diversity and geographical distribution of cultivated plants.
2. He collected a unique, the world's largest collection of cultivated plants (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 breeders as the starting material for creating new varieties of grain, fruit, vegetable, industrial, medicinal and other crops.
3. Created the doctrine of plant immunity.

   N. I. Vavilov subdivided plant immunity into structural (mechanical) and chemical. The mechanical immunity of plants is due to the morphological features of the host plant, in particular, the presence of protective devices that prevent the penetration of pathogens into the plant body. Chemical immunity depends on the chemical characteristics of plants.

4. The law of homologous series of hereditary variability: genetically close species and genera have genes that give similar characteristics. Thus, it is possible to predict the presence of characters in other species of a known genus.
5. He established that the greatest variety of forms of the species is concentrated in those areas where this species arose. N. I. Vavilov singled out 8 centers of origin of cultivated plants.

Centers of origin of cultivated plants

Centers of origin of cultivated plants- geographical areas that are home to the wild ancestors of cultivated plants.

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 centers of domestication (centers domestication) found in domestic animals.

Eight centers of origin of cultivated plants were identified (Fig. 6):

1. Mediterranean (asparagus, olives, cabbage, onions, clover, poppy, beets, carrots).

2. Anterior Asian (figs, almonds, grapes, pomegranate, alfalfa, rye, melon, rose).

3. Central Asian (chickpea, apricot, pea, pear, lentil, flax, garlic, soft wheat).

4. Indo-Malay (citrus, breadfruit, cucumber, mango, black pepper, coconut, banana, eggplant).

5. Chinese (millet, radish, cherry, apple, buckwheat, plum, soy, persimmon).

6. Central American (pumpkin, beans, cocoa, avocado, shag, corn, sweet potato, cotton).

7. South American (tobacco, pineapple, tomato, potato).

8. Abyssinian Center (banana, coffee, sorghum, durum wheat).

In the later works of N. I. Vavilov, the Western Asian and Central Asian centers are combined into the South-West Asian center.

Rice. 6. Centers of origin of cultivated plants

Currently, 12 primary centers of origin of cultivated plants are distinguished.

Quite often, non-specialists are suspicious of hybrid plants, unaware that many of the crops they grow in their own garden plots are the result of long labors of breeders.

• Crossbreed development
• Benefits of crossing

What is plant crossing

Hybridization or crossing of plants is one of the main methods of plant breeding. The essence of the method is contained in the crossing of two plants of different varieties, species or genera.

The result, which depends on the selection of parent plants, is the production of species and new varieties.

For example, few people know that in nature there were no such crops as plum or garden strawberries. Plum was taken by the method of cherry plum and blackthorn crossing, and garden strawberries, or as they are incorrectly called strawberries, are the result of crossing wild types of strawberries - Virginia and Chilean.

Crossbreed development

The development of crossbreeding is contained in the unnatural or natural transfer of pollen from a plant of one variety or species to another, carried out under careful control.

At this time, it is fundamentally important to isolate the flowers in order to exclude the ingress of foreign pollen.

Crossing method:

1. Choose two plants of different varieties or species.
2. Choose the most comfortably arranged flowers on the mother plant.
3. Unblown (one day before blooming) buds carefully open.
4. Carefully remove all stamens with pollen with tweezers.
5. Wrap flowers with stamens removed with a white narrow cloth so that there is no unplanned pollination.
6. The day before the removal of stamens from one plant from the second (paternal) from buds planning to bloom, collect pollen in a glass jar.
7. The jar is closed with gauze or a bright transparent cloth and placed in a dry place.

A day after the removal of the stamens from the mother plant, fertilization is performed:

• The best result is the first good half of the day until twelve o'clock.
• Shake the dust can.
• The pollen that has settled on the walls of the jar is carefully applied with a cotton swab or a second improvised tool (perhaps also with a finger) on the stigma of the pestle of the mother plant.
• Cover the fertilized flower again with a bright narrow cloth or gauze.
• Fertilization is repeated for 3 days.

Fertilized flowers must be covered for the entire growth period until fruit ripening. Extra flowers are recommended to be removed. At the end of the collection of ripe fruits, they should be aged from several weeks to several months, depending on the time of storage and ripening of the culture.

Seeds of stone fruit plants are sown immediately on the ridges, pome seeds of summer ripening after three days of drying are sown in the sand on the beds in the autumn. Seeds of plants that ripen in autumn are harvested at a time when the fruits are already beginning to deteriorate, but no later than April. After drying and harvesting, they are sown in prepared containers.

Spatial and temporal isolation during crossing

When crossing cross-pollinated crops, it is possible to use spatial isolation: plants are grown in different areas remote from plants of this variety. These crops include carrots, cabbage, beets, etc.

In dioecious plants, such as spinach, when grown in the same area, one of the varieties must be removed male plants.

Crossing cross-pollinated crops in isolated areas greatly minimizes labor costs: pollination occurs naturally - by wind or insects. In addition, in one isolated area, it is possible to spread a couple of plants of the same variety, thus increasing the number of hybrid seeds taken. A significant shortcoming for the method lies in the impracticability of completely eliminating the ingress of foreign pollen.

In addition, with natural cross-pollination, about a good half of the plants are found to be fertilized with pollen of their own variety.

In regions with a warm climate, where the growing season is quite long, it is possible to use isolation in time intervals for plants with fast flowering flowers: different combinations of crossing are carried out in the same area. Various flowering periods exclude unplanned cross-pollination.

In breeding practice, in the absence of sufficient space for organizing individual plots, insulating structures are used:

• The design is made in the form of a frame, which is covered with a light transparent fabric.
• To isolate individual shoots or inflorescences, small houses are made of parchment paper or gauze, which are wrapped around a wire frame.

For plants pollinated by insects, when constructing insulators, it is better to use materials such as cambric or gauze, for wind-pollinated crops - parchment paper.

Benefits of crossing

The process of hybridization - crossing plants - is aimed at obtaining plant varieties that have the advantageous features of parental varieties, such as:

• High yield
• disease resistance
• Frost resistance
• drought tolerance
• Short maturation time

For example, if the paternal and mother plants have resistance to various diseases, then the resulting hybrid will inherit resistance to both diseases.

Hybrid varieties of plants have better viability, they are less susceptible to changes in temperature, humidity, and changes in climatic conditions than their non-hybrid counterparts.

Pure grades!!! or hybrids! what to choose?

Fascinating notes:

Selected by important queries, relevant articles:

Cucumbers have always been an integral part of the diet of every person. Their breeding is considered one of the most basic tasks of the gardener. Summer salad is unthinkable...

There is a water leak in the kitchen, a drain in the bathroom is clogged, you need to install a toilet, sink and more? All these issues require urgent solutions. Professional plumbing services to help you! Calling a plumber at home in Moscow from our company means getting quality plumbing services at an affordable price and on time.

Don't know how to call a plumber to your house? Call us! A plumber on call will come to you in 30 minutes for free. Leave a request and wait for the plumber.

How to solve plumbing problems?

There are three options for solving a plumbing problem: do it yourself, contact the housing office or call a plumber at your place of residence from our company. The first, of course, is the most budget option. But he requires you to understand this area, have free time, as well as the availability of special tools and spare parts. The second option involves a lot of inconvenience. A utility worker can only come to you during business hours, which may not coincide with yours. And if you have a force majeure event in the evening, at night, on a weekend or a holiday? For example, did a drainpipe break, a sewer clogged, a toilet flush tank not working, and more? There is a way out - contact us and order plumbing services urgently! We work around the clock, without breaks and weekends, and within a short time our specialist will be at your door. Plumbing services are provided with careful observance of the relevant regulatory documentation. Calling a plumber to your home in Moscow with a guarantee for the work performed. Urgent repair, installation and dismantling of plumbing from market leaders!

We are a team of professionals, we have been working in the plumbing services market for many years. Our staff consists of qualified specialists who thoroughly understand both the plumbing and sewer systems, and the latest generation of plumbing. Our masters are equipped with everything necessary, which allows them to provide speedy service, diagnostics and repair of plumbing equipment. Our Moscow emergency service of plumbers promptly visits you and solves plumbing problems efficiently around the clock.

We provide plumbing services not only to owners of apartment buildings, but also to owners of the private sector. The arrangement of an autonomous heating system is also our profile. Taking into account the individual features of the structure, we are ready to offer different solutions for the problem of rational heating of housing.

Services we offer:

• laying / replacement / cleaning of sewer pipes;
• installation of a water heater, boiler and heating radiators;
• installation of a filter system and pumping equipment;
• wiring of plastic and metal-plastic pipes;
• replacement of the siphon, fine or coarse filters;
• installation of hot and cold water meters;
• connection of household appliances to water supply and sewerage;
• dismantling of plumbing equipment and more.

Plumbing services from us - the best solution for you!

Plumbing services - the work of professionals

Any plumbing work requires a professional approach. As practice shows, amateurish actions can only aggravate the situation. It is not necessary to equip, for example, a water heater on your own. We install boilers and boilers in accordance with the rules for the safety and operation of this equipment.

Do you need to conduct collector wiring of polypropylene water supply pipes or change the battery at the height of the heating season? Not a problem, call us! With the help of a pipe freezer, we will quickly and efficiently, without draining the water, perform all the work.

We also install hot tubs and jacuzzis. These activities are usually associated with dismantling, connection to sewerage and water supply. Our experienced craftsmen, taking into account knowledge, new technologies and modern tools, will always find the most practical solution for your situation. The appearance of a blockage in the pipeline is a reason to call a plumber to your house.

5 reasons why you should choose us:

• we provide a full range of plumbing services;
• guarantee the quality and efficiency of work;
• fulfill our obligations;
• issue a guarantee and documentary reporting;
• We approach each order individually.

Often, non-specialists are suspicious of hybrid plants, unaware that many of the crops they grow in their garden plots are the result of many years of work by breeders.

In dioecious plants, such as spinach, when grown in the same area, one of the varieties needs to remove the male plants.

Crossing cross-pollinated crops in isolated areas greatly minimizes labor costs: pollination occurs naturally - by wind or insects. In addition, it is possible to spread several plants of the same variety in one isolated area, thus increasing the number of hybrid seeds obtained. A significant drawback of this method is the impossibility of completely eliminating the ingress of foreign pollen. In addition, with natural cross, about half of the plants are fertilized with the pollen of their own variety.

In regions with a warm climate, where the growing season is quite long, for plants with fast-flowering flowers, isolation in time intervals can be used: different combinations of crossing are carried out in the same area. Different flowering periods exclude unplanned cross-pollination.

In breeding practice, in the absence of sufficient space for the organization of individual plots, insulating structures are used:

• The design is made in the form of a frame, which is covered with a light transparent fabric.
• To isolate individual shoots or inflorescences, small "houses" are made of parchment paper or gauze, which are covered with a wire frame.

For plants pollinated by insects, when constructing insulators, it is better to use materials such as cambric or gauze, for wind-pollinated crops - parchment paper.

The process of hybridization - crossing plants - is aimed at obtaining plant varieties that have the advantageous properties of parental varieties, such as:

• High yield
• Resistance to
• Frost resistance
• drought tolerance
• Short maturation time

For example, if the paternal and mother plants have resistance to different diseases, then the resulting hybrid will inherit resistance to both diseases.

Hybrid varieties of plants have better viability, they are less susceptible to changes in temperature, humidity, and changes in climatic conditions than their non-hybrid counterparts.

More information can be found in the video.

It is called sexual crossing of two individuals that differ from each other by more or less signs. They may belong to two varieties, races, varieties of the same species, two species of the same genus, or different genera of the same family. In most cases, the closer the crossed individuals are to each other, the more likely it is to get viable and fertile offspring.

Sexual hybridization is of great importance and application in practical crop production. Very many of our cultivated plants, as has already been pointed out, are sexual hybrids, partly obtained naturally in nature and taken from there into culture, partly bred by artificial crosses.

The ability for sexual hybridization in some families or individual genera and species turns out to be greater, in others less. Sometimes hybridization between morphologically closely related species fails, while it succeeds between more distant ones.

Sexual hybridization is most easily carried out between varieties and varieties belonging to the same species. Hybrids between species are obtained for the most part small in number, not very viable and infertile in the future; hybrids between genera are obtained much less frequently and in the future in most cases are sterile.

Research by I. V. Michurin showed that the sterility of hybrids in many cases is temporary.

Often, when crossing, the first generation of hybrids is characterized by extremely powerful development, exceeding the parental forms by several times in size. This phenomenon is called heterosis. In the offspring of hybrids obtained sexually, plants usually return to the previous size of their progenitors. But if such giant hybrids can reproduce vegetatively, then the resulting gigantism will also appear in vegetatively bred offspring. In this way, large varieties of root and tuber crops, ornamental trees and herbaceous plants with very large flowers, etc., can be bred. Annual new breeding of annual heterotic plants is also possible to increase their production, for example, in Tobacco, tomatoes, corn, etc.

In some cases of infertility of hybrids, it is possible, with the help of systematic subsequent crossings, to restore their fertility.

When crossing sexual hybrids of different species with each other, it was possible to obtain forms that are hybrids between 3, 4 or more species.

The issue of dominance - the predominance in the hybrid of certain traits of the parents or their ancestors - is the most important issue in breeding, in breeding new varieties.

I. V. Michurin believed that the hybrid does not represent something in between the producers. The heredity of a hybrid is composed only of those traits of producing plants and their ancestors, which in the early

stages of development of the hybrid are favored by external conditions. The dominance of certain traits also depends on the unequal power of producers in the sense of transmitting their traits to offspring. To a greater extent, the signs are transmitted: 1) species growing in the wild; 2) an older variety by origin; 3) an older individual plant; 4) older flowers in the crown. The mother plant, other things being equal, will transfer its properties more fully than the father plant, but if the conditions for growing hybrids are more favorable for the father plant, then its characteristics may dominate.

Plants weakened by drought or cold spring have a weaker power to transmit their hereditary properties.

To overcome the non-crossing of distant systematic species, I. V. Michurin developed a number of effective and very interesting methods from a general biological point of view.

The mediator method is that if any two species do not interbreed with each other, then one of them is crossed with some third, with which both of these species can be crossed. The resulting hybrid - "intermediary" - has a greater ability to cross, and it can be successfully crossed with the second of those species that were planned for crossing. I. V. Michurin used this method when crossing wild almond (Amygdalus nana) with peach; the intermediary here was a hybrid obtained from crossing the wild almond with the North American David peach ( prunus davidiana). Further studies have shown that such complex hybrid forms have a wide ability to interbreed with those species with which their original parent forms do not interbreed.

The method of "vegetative convergence", used by I. V. Michurin to overcome non-crossing, consists in the fact that a young seedling of one of the plants to be crossed is grafted into the crown of another, adult plant, with which it is desirable to cross. This seedling, unstable as an unformed organism, gradually changes until the time of flowering under the influence of a more powerful rootstock, approaches it in properties and crosses with it in the future better than the original form without grafting. I. V. Michurin used this method, for example, when hybridizing an apple tree and a mountain ash with a pear.

A method of using a pollen mixture, which also facilitates crossbreeding, is to mix a small amount of the pollen of the mother (pollinated) plant with the pollen of the pollinating plant. Presumably, pollen from one's own species makes the stigma more susceptible to pollination by foreign pollen. These methods are now widely used in breeding work with a variety of plants. It is also used to mix pollen of a third type or variety, which can also stimulate pollination by pollen, without this method it does not give results.

An important role in the works of I. V. Michurin was played by the education of young hybrid seedlings with unstable heredity. Distant hybridization without further directed education often does not give the desired results. A targeted effect on hybrids is achieved by various methods, including by grafting, or by the mentor method, in which the hybrid is repeatedly caused to enhance certain properties. The mentor method is based on the mutual influence of rootstock and scion. It was used by I. V. Michurin in two versions. With the so-called

cuttings of a young hybrid seedling are grafted into the crown of one of its adult producers, the quality of which (for example, frost resistance) is desirable to enhance in the hybrid. The grafted hybrid, under the powerful influence of the rootstock (stand mentor), acquires to a greater extent the property desired by the hybridizer (in this example, frost resistance). Or, for example, from a seedling, a hybrid between green renklod plum and sloe, the eyes were taken and grafted: one on the renklod, the other on the sloe. In the first case, in the future, a plant with signs of renklod (Renklod thorn) was obtained, in the second case with signs of thorn (Turn sweet). The reverse effect of the scion on the stock is reflected in the so-called grafting mentor, when, for example, by grafting several cuttings of an old variety (grafting mentor), which is characterized by abundant fruiting, into the crown of a young seedling, it is possible to speed up and improve the fruiting of the stock; with other combinations of grafted plants, this method, on the contrary, succeeded in delaying the ripening of fruits, lengthening their ability to remain in bed, etc.

These new principles and methods of work, discovered by IV Michurin, are of great importance. The selection of pairs during hybridization by preliminary biological analysis of the parents, the directed cultivation of hybrids, and the acceleration of the breeding of new varieties—all this is now widely used in the breeding of new varieties of cultivated plants.

By crossing hard wheats ( Triticum durum) with soft ( Triticum vulgare) obtained some new valuable varieties of wheat. Rye-wheat hybrids have been obtained, which are of interest both by themselves and for further crosses again with wheat in order to obtain hybrids with high grain quality of wheat and cold resistance of rye. Work is underway to cross wheat with wild couch grass (N. V. Tsitsin), with perennial wild rye. By crossing potatoes with its wild relatives, varieties of potatoes were obtained that are resistant to damage by a fungus dangerous for potatoes - late blight. Work is underway to cross annual sunflowers with perennials, sugarcane, which has a very long growing season, with its wild relatives with a shorter growing season, farmed watermelons with drought-resistant wild relatives, etc. Planned management of the development of plants (and animals) and the creation of new their forms, based on a deep study of complex biological relationships and the discovery of the patterns of life, constitute the theoretical basis of Soviet breeding.

We will tell you how to cross between two varieties of the same plant species - this method is called hybridization. Let it be plants of different colors or differing in the shape of petals, leaves. Or perhaps they will differ in terms of flowering or requirements for external conditions?

Choose plants that bloom quickly to speed up the experiment. It is also better to start with unpretentious flowers - for example, foxgloves, marigolds or delphiniums.

The course of the experiment and the diary of observations

First, formulate your goals - what do you want to get from the experiment. What are the desired traits for new varieties?

Keep a notebook-diary where you write down the goals and record the progress of the experiment from beginning to end.

Do not forget to describe in detail the original plants, and then the resulting hybrids. Here are the most important points: plant health, growth intensity, size, color, aroma, flowering time.

flower structure

In our article, a flower will be considered as an example, you can see it in the diagram and in the photographs.

The appearance of flowers in different plants can vary significantly, but basically the same.

flower pollination

1. Start by choosing two plants. One will pollinator, and the other seed plant. Choose healthy and strong plants.

2. Keep a close eye on the seed plant. Choose an unblown bud with which you will carry out all manipulations, mark it. In addition, it will have to isolate before opening- tying it in a linen light bag. As soon as the flower begins to open, cut off all the stamens from it to avoid accidental pollination.

3. Once the flower of the seed plant is fully opened, put pollen on it from a pollinator plant. Pollen can be transferred with a cotton swab, a brush, or by tearing out the stamens of the pollinating flower and bringing them directly to the seed. Apply the pollen to the stigma of the flower of the seed plant.

4.Put on the flower of the seed plant linen bag. Do not forget to make the necessary notes in the diary of observations - about the time of pollination.

5. To be safe, repeat the operation with pollination after a while - for example, after a couple of days (depending on the timing of flowering).

Choose two flowers - one will serve as a pollinator, the other plant will become a seed.	Immediately, as soon as the flower of the seed plant blooms, cut off all the stamens from it.
Apply the pollen taken from the pollinating flower to the pistil of the flower of the seed plant.	A pollinated flower should definitely be marked.

Obtaining hybrids

1. If pollination went well, then soon the flower will begin to fade, and the ovary will increase. Do not remove the bag from the plant until the seeds are ripe.

2. Plant the resulting seeds as seedlings. When will you receive young hybrid plants, then give them a separate place in the garden or transplant them into boxes.

3. Now wait for the hybrids to bloom. Don't forget to write down all your observations in your diary. Among the first, and even the second generation, there may be flowers that exactly repeat the parental properties without changes. Such copies are rejected immediately. Check in with your goals and select among the received new plants those that best fit the desired characteristics. You can also pollinate them by hand, or isolate them.

If you decide to seriously engage in breeding new varieties, then you will need the advice of a specialist breeder. The fact is that you will need to find out whether you really have bred a new variety or are you following the path already beaten by someone. Competition in the field of creating new varieties is very high.

For those who decide to experiment with hybridization as a home hobby, we wish to get a lot of pleasure from this activity, make many joyful discoveries and finally give all our gardening friends a new variety of some wonderful flower named after itself.

In the 30s. of the last century N.I. Vavilov noted that the problem of creating disease-resistant crop varieties can be solved in two ways: by selection in the narrow sense of the word (selection of resistant plants among existing forms) and by hybridization (crossing different plants with each other). Plant breeding methods for immunity to pathogenic organisms are not specific. They are modifications of conventional breeding methods. The main difficulties in creating immune varieties are the need to simultaneously take into account the characteristics of plants and harmful organisms that damage them. At the moment, in breeding for resistance, all generally accepted modern methods of breeding work are used: hybridization, selection, as well as polyploidy, experimental mutagenesis, biotechnology and genetic engineering.

One of the main difficulties in plant breeding for immunity is the genetic linkage of plant traits that reflect their phylogenetic history in natural ecosystems. In the process of spontaneous domestication and the formation of highly productive and high-quality forms of plants, their immune system was weakened. In those cases where selection is carried out without attention to immunity, the weakening of the latter takes place in our time.

The most important task of breeding, genetics, and molecular biology is to find ways to combine high productivity and other economically valuable properties of plants with signs of their immunity. It is desirable that the basis of immunity be polygenic.

The simplest solution is when it is possible to isolate plants from the population of an existing variety that are highly immune to one particular pathogen. For such selection, different selection methods and analytical methods can be used, which take into account the heterosis of the variety population.

When drawing up breeding programs, the type of pollination of a plant population is very important (cross-pollination, self-pollination or the population belongs to an intermediate group). Breeding work for immunity to a pathogen should be carried out taking into account the following factors: in the population of plants of the first group, the unit of analysis is an individual plant, the other unit is the population (variety or line).

Traditional breeding methods in creating genotypes resistant to diseases and pests

Selection. Both in nature in general and in human breeding activities, selection is the main process of obtaining new forms (the formation of species and varieties, the creation of breeds, varieties). Selection is most effective when working with self-pollinating crops, as well as plants that reproduce vegetatively (clonal selection).

In breeding for resistance, selection is effectively used both by itself (it is the main method when working with necrotrophic pathogens), and as a component of the breeding process, without which it is generally impossible to do with any breeding methods. In practical selection for resistance, two types of selection are used: mass and individual.

Mass selection is the oldest breeding method, thanks to which varieties of the so-called folk selection were created, and is still a valuable source material for modern breeders. This is a type of selection in which a large number of plants are selected from the initial population in the field that meet the requirements for the future variety, immediately evaluating a set of traits (including resistance to certain diseases). The harvest of all selected plants is combined and sown in the next year in the form of one plot. The result of mass selection is the offspring of the total mass of the best plants selected for a certain trait (s).

The main advantages of mass selection are its simplicity and the ability to quickly improve a large amount of material. The disadvantages include the fact that the material selected by mass selection cannot be checked with offspring and determine its genetic value, and therefore, it is impossible to isolate varieties or hybrids that are valuable in breeding terms from the population and use them for further work.

Individual selection (pedigree) - one of the most effective modern methods of breeding for resistance. Hybridization, artificial mutagenesis, biotechnology and genetic engineering are primarily suppliers of material for individual selection - the next stage of selection work extracts the most valuable from the provided material.

The essence of the method lies in the fact that individual resistant plants are selected from the initial population, the offspring of each of which are subsequently propagated and studied separately.

Both individual and mass selection can be one-time and reusable.

One-time selection mainly used in the selection of self-pollinating crops. One-time individual selection provides for a consistent study in all links of the selection process, selected once for a certain plant trait. One-time mass selection is more often and most effectively used to improve the variety in seed production practice. Therefore, it is also called healing.

Multiple selections are more suitable and effective in the selection of cross-pollinated crops, their effectiveness is determined primarily by the degree of heterozygosity of the source material. Through repeated mass selection, resistance to necrotrophs is maintained - pathogens such as fusarium, gray and white rot, etc. Using this method, highly resistant to and.

Hybridization. Currently, one of the most used methods in breeding for resistance is hybridization - crossing genotypes with different hereditary abilities and obtaining hybrids that combine the properties of parental forms.

In breeding for disease resistance, hybridization is expedient and effective if at least one parental form is a carrier of hereditary factors that can provide genetic protection for the future variety or hybrid from potentially dangerous strains and races of the pathogen.

As noted earlier, such hereditary factors (effective resistance genes) were formed in the centers of related evolution of host plants and their pathogens. Many of them have already been transferred to cultivated plants from their wild relatives through distant hybridization. These are now known as crop resistance genes.

But the indisputable fact is that today most of these genes are widely used in breeding and have mostly lost their effectiveness, overcome as a result of the variability of pathogens. So intraspecific hybridization (between plants of the same species) in the creation of disease-resistant varieties or hybrids in some cases is unpromising. In order to obtain positive results, the breeder, involving in crossings one or another parental form, must be sure of the high efficiency of their resistance genes to the population of the pathogen in the place of future cultivation of the variety (hybrid).

Against this background, the increasing importance in breeding for resistance is becoming distant hybridization (between plants from different botanical taxa). After all, plants of wild and primitive species are characterized by the most pronounced immunity. The genomes of wild relatives of cultivated plants have been and remain the main natural source of resistance genes, including complex immunity. Crossing cultivated plants of existing varieties with wild species usually allows you to increase the immunogenetic properties. And if earlier the use of distant hybridization was not very popular due to the difficulties associated with the imbalance of the genomes of parental forms, the linkage of resistance with economically undesirable traits, now methods have been developed to resolve problematic issues.

Remote hybridization makes it possible to transfer ecological plasticity, resistance to adverse environmental factors, diseases and other valuable properties and qualities from wild-growing plants to cultivated ones. Varieties and new forms of grain, vegetable, industrial and other crops have been created on the basis of distant hybridization. For example, the source of wheat immunity genes to, and is endemic to the Transcaucasus Triticum dicoccoides Korn.

As world practice shows, a very effective type of hybridization in the selection of self-pollinating crops for resistance is backcrosses (backcrosses) when a hybrid is crossed with one of the parent forms. This method is also called the method of "repair" of varieties, since it allows you to improve a certain variety for a particular trait that it lacks (in particular, resistance to a particular disease). But it should be borne in mind that the use of this method does not allow exceeding the productivity of a variety that is “repaired” (and according to the requirements of the State Service for the Protection of Rights to Plant Varieties of Ukraine, a variety cannot be registered if it does not exceed the standard in terms of productivity).

As a rule, in backcrossing, a disease resistance donor variety is used as the mother form, and an unstable but highly productive variety (resistance recipient) is used as the parent form. As a result of their crossing, hybrids are obtained, which are re-crossed with the parent form (backcrossing). A prerequisite is that the mother forms for each next backcross are selected from resistant hybrid plants of the previous crossing, found against an infectious background. The offspring are selected according to the phenotype of the recipient variety. Backcrosses are carried out until the genotype and phenotype of the recipient is almost completely restored, while acquiring resistance to the disease characteristic of the donor.

An increase in the efficiency of plant breeding for immunity to pests can be achieved by using previously created so-called immunity synthetics (known, for example, for corn). Mentioned synthetics are created on the basis of crossing 8-10 immune lines, characterized by different ecological plasticity and composition of immunity factors. Many of the synthetics are good sources for creating immune lines for the further development of single and double interline hybrids.

Mutagenesis. In contrast to hybridization methods, they are quite laborious and require many years of work to achieve the final result, experimental (artificial) mutagenesis makes it possible to increase plant variability in a short period and obtain resistance mutations that are not found in nature.

The method of experimental (artificial) mutagenesis is based on the directed action on plants of various physical and chemical mutagens (ionizing, ultraviolet, laser radiation, chemicals), as a result of which gene mutations occur in plant organisms (changes in the molecular structure of the gene), chromosomal mutations (changes in structures of chromosomes) or genomic (changes in sets of chromosomes).

The most valuable gene mutations in terms of breeding, which, unlike chromosomal ones, do not lead to sterility of pollen, infertility or inconsistency of mutant lines. Resistance gene mutations are most often associated with either a base change in a certain region of the chromosome DNA, or its loss, addition, or displacement. As a result, there is a change in the genetic code and, accordingly, a change in the physiological and biochemical mechanisms of the cell, which leads to inhibition of the growth, development and reproduction of the pathogen.

The method of artificial mutagenesis in breeding for disease resistance is used in many countries, but it cannot be considered the main method for obtaining resistant forms of plants. This method is most effectively used when working on resistance with crops that propagate vegetatively, since their propagation by seeds entails complex segregation in the offspring due to the high degree of heterozygosity.

It is, apparently, the further improvement of existing crops grown on already developed lands. Hybrids are something that can play a key role in food security. After all, most of the areas suitable for agriculture are already occupied. At the same time, increasing the amount of water, fertilizers and other chemicals used on them is not economically feasible in many places. That is why the improvement of existing crops is of exceptional importance. And hybrids are plants obtained just as a result of such an improvement.

The goal is not only to increase yields, but also to increase the content of protein and other nutrients. For a person, it is also very important the quality of proteins in edible (including people) should receive from food the right amount of all essential (i.e., those that they are not able to synthesize themselves) amino acids. Eight of the 20 amino acids a person needs come from food. The remaining 12 can be developed by him. However, plants with an improved protein composition as a result of selection inevitably require more nitrogen and other nutrients than the original forms, therefore, they cannot always be grown on infertile lands, where the need for such crops is especially great.

New Properties

Quality includes not only yield, composition and quantity of proteins. Varieties are being created that are more resistant to diseases and pests, due to the fruits they contain, more attractive in shape or color of fruits (for example, bright red apples), better able to withstand transportation and storage (for example, tomato hybrids of increased keeping quality), and also have other significant properties for a given culture.

The activities of breeders

Breeders carefully analyze the available genetic diversity. Over the course of several decades, they have developed thousands of improved lines of the most important agricultural plants. As a rule, thousands of hybrids have to be obtained and evaluated in order to select those few that will actually outperform those already widely bred. For example, in the United States from the 1930s to the 1980s. increased by almost eight times, although only a small part of the genetic diversity of this crop was used by breeders. There are more and more new hybrids. This allows more efficient use of cultivated areas.

hybrid corn

The increase in maize productivity was made possible mainly by the use of hybrid seeds. The inbred lines of this culture (hybrid in origin) were used as parental forms. From seeds obtained as a result of crossing between them, very powerful hybrids of corn develop. Crossed lines are sown in alternating rows, and panicles (male inflorescences) are manually cut from the plants of one of them. Therefore, all seeds on these specimens are hybrid. And they have very useful properties for humans. By careful selection of inbred lines, powerful hybrids can be obtained. These are plants that will be suitable for growing in any required area. Since the characteristics of hybrid plants are the same, they are easier to harvest. And the yield of each of them is much higher than that of unimproved specimens. In 1935, corn hybrids accounted for less than 1% of all this crop grown in the United States, and now virtually all. Now, obtaining significantly higher yields of this crop is much less laborious than before.

Successes of international breeding centers

Over the past few decades, a lot of effort has been made to increase the yield of wheat and other grains, especially in warm climate zones. Impressive success has been achieved in international breeding centers located in the subtropics. When new hybrids of wheat, corn and rice bred in them began to be grown in Mexico, India and Pakistan, this led to a sharp increase in agricultural productivity, called the Green Revolution.

Green revolution

Fertilizers and irrigation developed during it have been used in many developing countries. Each crop requires optimal growing conditions to obtain high yields. Fertilization, mechanization and irrigation are essential components of the Green Revolution. Due to the peculiarities of the distribution of credits, only relatively wealthy landowners were able to grow new plant hybrids (cereals). In many regions, the Green Revolution accelerated the concentration of land in the hands of a few of the wealthiest owners. This redistribution of wealth does not necessarily provide jobs or food for the majority of the population in these regions.

Triticale

Traditional breeding methods can sometimes lead to surprising results. For example, a hybrid of wheat (Triticum) and rye (Secale) triticale (scientific name Triticosecale) is gaining importance in many areas and appears to be very promising. It was obtained by doubling the number of chromosomes in a sterile hybrid of wheat and rye in the mid-1950s. J. O'Mara at the University of Iowa with colchicine, a substance that prevents cell plate formation. Triticale combines the high yield of wheat with the ruggedness of rye. The hybrid is relatively resistant to line rust, a fungal disease that is one of the main wheat yields. Further crosses and selection have produced improved triticale lines for specific areas. In the mid 1980s. This crop, thanks to its high yield, resistance to climatic factors and the excellent straw that remains after harvest, quickly gained popularity in France, the largest grain producer within the EEC. The role of triticale in the human diet is growing rapidly.

Conservation and use of crop genetic diversity

Intensive crossbreeding and selection programs lead to a narrowing of the genetic diversity of cultivated plants for all their traits. For obvious reasons, it is mainly aimed at increasing productivity, and among the very homogeneous offspring of specimens selected strictly on this basis, resistance to diseases is sometimes lost. Within a culture, plants become more and more uniform, as certain of their characters are more pronounced than others; therefore crops as a whole are more vulnerable to pathogens and pests. For example, in 1970, helminthosporiasis, a fungal disease of corn caused by the Helminthosporium maydis species (pictured above), destroyed approximately 15% of the crop in the United States, causing a loss of approximately $1 billion. These losses appear to be due to the emergence of a new race of the fungus, which is very dangerous for some of the main lines of corn that were widely used in the production of hybrid seeds. In many commercially valuable lines of this plant, the cytoplasm was identical, since the same pistil plants are repeatedly used in the production of hybrid corn.

To prevent such damage, it is necessary to grow in isolation and conserve different lines of critical crops that, even if the sum of their traits is not of economic interest, may contain genes useful in ongoing pest and disease control.

Tomato hybrids

Tomato breeders have been remarkably successful in increasing genetic diversity by attracting wild varieties. The creation of a collection of lines of this culture, carried out by Charles Rick and his collaborators at the University of California at Davis, made it possible to effectively fight many of its serious diseases, in particular those caused by imperfect Fusarium and Verticillum fungi, as well as some viruses. The nutritional value of tomatoes has been significantly increased. In addition, plant hybrids have become more resistant to salinity and other adverse conditions. This was mainly due to the systematic collection, analysis and use of wild tomato lines for breeding.

As you can see, interspecific hybrids are very promising in agriculture. Thanks to them, you can improve the yield and quality of plants. It should be noted that crossbreeding is used not only in agriculture, but also in animal husbandry. As a result of it, for example, a mule appeared (its photo is presented above). This is also a hybrid, a cross between a donkey and a mare.

Asks Oleg
Answered by Elena Titova, 12/01/2013

Oleg asks: "Hello, Elena! Tell me, please, is the crossbreeding of various types of plants, vegetables and fruits by scientists not an interference in God's creation and a sin? Do such successful crosses jeopardize Creationism? After all, if it was possible to cross different plants, then with In time, it will be possible to cross different animals, for example, a cat and a dog. So there is a possibility that from one simpler living creature a more complex one appeared, and so on until the appearance of a person?

Greetings, Oleg!

Scientists-breeders mainly carry out intraspecific crossings (hybridization) for the appearance of desirable traits (for humans, of course) in animals, plants and microorganisms, thereby achieving the creation of new or improved breeds, varieties, strains.

Within a species, crossing of individuals is relatively easy due to the similarity of their genetic material and anatomical and physiological features. Although this is not always the case, for example, in natural conditions it is impossible to cross a tiny Chihuahua dog and a huge mastiff.

But already on the way of crossing individuals of different species (and even more so different genera) there are molecular genetic barriers that prevent the development of full-fledged organisms. And they are expressed the stronger, the further the crossed species and genera are separated from each other. Due to the significantly different genomes of the parents, unbalanced sets of chromosomes, unfavorable combinations of genes can occur in hybrids, the processes of cell division and the formation of gametes (sex cells) can be disrupted, the death of the zygote (fertilized egg), etc. can occur. Hybrids can be partially or completely sterile (sterile ), with reduced viability up to lethality (although in some cases in the first generation there is a sharp increase in viability - heterosis), developmental anomalies may appear, in particular, reproductive organs, or the so-called chimeric tissues (genetically heterogeneous), etc. Apparently, therefore, the Lord warned His people: "... do not bring your livestock with a different breed; do not sow your field with two kinds [of seeds]" ().

Under natural conditions, cases of interspecific crossing are extremely rare.

There are examples of artificial distant hybridization: mule (horse + donkey), bester (beluga + sterlet), liger (lion + tigress), taigon (tiger + lioness), leopon (lion + female leopard), plum cat (plum + apricot), clementine (orange + tangerine), etc. In some cases, scientists manage to remove the negative consequences of distant hybridization, for example, fertile hybrids of wheat and rye (triticale), radish and cabbage (rafanobrassica) have been obtained.

And now your questions. Is artificial hybridization an interference with God's creation? In a certain sense, yes, if a person creates a version that is different from natural, which can be compared, say, with the use of decorative cosmetics by women to improve their appearance. Is artificial hybridization a sin? Is eating meat a sin? The Lord, out of our hardness of heart, allows the killing of living beings for the sake of food. Probably, also due to our hardness of heart, he also allows selective experimentation in order to improve the consumer properties of products that people need. In the same row - and the creation of drugs (in this case, laboratory animals are used and killed). Sadly, all this is the reality of a society where sin reigns and the “prince of this world” rules.

Do successful crosses put creationism at risk? In no way. Against.

You know that everything multiplies "after its kind." The biblical "kind" is not the biological species of modern taxonomy. After all, a rich diversity of species appeared after the Flood due to the variability of the characteristics of terrestrial organisms from Noah's Ark and aquatic inhabitants that survived outside the Ark, while adapting them to new environmental conditions. It is difficult to outline the biblical “kind”, the genetic potential of which is significant and was originally set at creation. It may include modern taxa such as species and genus, but probably not above a (sub)family. It is possible, for example, that large cats from modern systematic genera of the feline family go back to one original “genus”, and small felines to one or two others. It is clear that the species and genera that emerged from the biblical "genus" include their own, to some extent, depleted and altered (in relation to the original) genetic material. The combination of these not quite complementary parts (in interspecific and intergeneric crossings) encounters obstacles at the molecular-genetic level, which means that it does not allow giving rise to a full-fledged organism, although in rare cases this can happen within the biblical “kind”.

What does it say? The fact that there can be no crosses between “cat and dog” and “up to a person” in principle.

Another moment. Compare 580 thousand bp, 482 genes in the DNA of a single-celled mycoplasma and 3.2 billion bp, about 30 thousand genes in human DNA. If you imagine a hypothetical path "from amoeba to man", think about where the new genetic information came from? There is nowhere for it to come naturally. We know that information only comes from an intelligent source. So who is the Author of amoeba and man?

God's blessings!