Various branches of science engaged in breedingvarieties of cultivated plants, breeds of farm animals and strains of bacteria, use both traditional and the latest practical techniques and methods. They will depend primarily on the object of selection work. In other words, conducting experiments with plants, a scientist can use mass selection or the method of a mentor, while working with animals or microorganisms, such techniques are used to a limited extent, or not at all.
The purpose of this article is to clarify the issue ofwhether this form of breeding, such as the mentor method, is theoretically possible and practically feasible in creating new or improving existing breeds of cattle, pigs and poultry.
Peculiarities of animal breeding
The work of Ch., Widely known in scientific circles.Darwin's “Changes in domestic animals and cultivated plants under the influence of domestication,” written in the mid-19th century, still remains a reference book for a whole pleiad of modern scientists engaged in practical activities. It lists the main breeding methods: hybridization, heterosis and closely related crossing based on artificial selection.
In experiments with animals, avoid using it.mass form, as usually a pair of parental individuals gives a small number of hybrids, each of which has a certain value in material equivalent. Let's not forget that representatives of the classes of Birds and Mammals, who are mainly the main objects of breeding, are characterized only by sexual reproduction. This means that techniques based on vegetative forms (grafting, budding, vaccination) are not acceptable for animals. In order to deal with the question of whether the mentor method is used in animal breeding, it is logical to first find out the essence of this technique.
Teacher's method
Outstanding Russian scientist breeder I.V.Michurin, whose genius research became fundamental for world science, applied a purposeful vegetative approach of plants of two different varieties. As a result, both individuals began to acquire new features and properties. For example, the shape, size or color of fruits, as well as their taste qualities, changed. Conducting the grafting in the crown of the rootstock plant, I. V. Michurin was able to create such conditions under which the cutting began to receive nutrients from the maternal individual.
All this ultimately changed the course.metabolic reactions in cells and tissues of the graft, and, therefore, its phenotypic characteristics. The above grafting method has become known in plant breeding as a mentor method.
Examples of creating new varieties of fruit crops
One of the very first, received I.Michurin back in 1908, this is Belfleur-Kitayka apple variety. As a graft, the breeder took the stalk of the American Belfleur yellow variety with outstanding taste. The stock was a large-fruited Chinese seedling - a local variety, zoned in the territory of Central Russia. Its main advantages were frost resistance and resistance to the main diseases of apple trees - scab and powdery mildew. Applying the mentor method, the scientist, as a result of hybridization, obtained a new variety that was best adapted to the difficult climatic conditions of northern latitudes in combination with the high taste of the fruit. Apples michurinsky varieties have white flesh delicate sweet taste with a delicate aroma.
For over a hundred years, this culture has continuedgrown in household farms not only in Russia, but also in Ukraine, Armenia, the republics of the North Caucasus. Gardeners appreciate this variety also for consistently high yield and frost resistance. At breeding stations and in fruit nurseries, Belfleur-Kitayka saplings are also used as a stock in hybridization processes, due to which approximately 13 new varieties have been created.
Aims and objectives of receiving directional education of hybrid plants
Based on the above facts, it becomesthe immense importance of the experimental work of I. V. Michurin, which not only developed the mentor method, but also made it one of the leading in the development of new varieties of fruit and berry crops.
Experiments of the scientist's successors - E. S.Stroeva, E.N. Sedov and other employees of the All-Russian Research Institute for Fruit Plant Breeding generalized the goals achieved as a result of applying the techniques of directional education of hybrid seedlings.
К наиболее значимым из них относятся следующие:leveling of unfavorable phenotypic traits in hybrid individuals, as well as consolidation of desirable properties for humans in plants of the created variety. Summarizing the numerous results of plant breeding, the researchers came to an understanding of certain patterns that accompany the use of vaccinations in practice. Consider them in more detail.
Conditions for obtaining vegetative hybrids
Using the mentor method in animal breeding, the following rules must be taken into account:
- a plant from which a stalk or kidney (graft) is taken should be vegetatively young, not older than 1–2 years old, and the scion of a perennial tree should be used as a mentor;
- next to the vegetative grafting shoot, a large number of rootstock branches are necessarily preserved, which influence the phenotypic characteristics of the reared plant.
Благодаря вышеуказанным условиям селекционерам manages to form economically valuable properties in fruit and berry crops. Being one of the most popular and widespread methods of breeding new varieties of agricultural crops, this technique, unfortunately, still remains insufficiently studied by modern biochemists and cytologists.
Tissue engineering
On the question of whether animal breeding is usedmentor method or not, the answer will be negative. Interesting in this regard are studies on biotechnology relating to cloning, that is, synthesis of a complete copy of the organism by the matrix (one or several somatic cells). In this case, an analogy with the vegetative reproduction form of plant organisms can be traced, since the resulting clone of the animal consists of cells of uniform genotype. Experiments in the field of tissue and genetic engineering are carried out by the method of growing them in a nutrient medium. In the chromosomes of the nucleus, all hereditary information about the organism is stored, which means that an unlimited number of individuals — copies — can be obtained from just one cell.
Characteristics of animal breeding techniques
I.V.Michurin developed a mentor method exclusively for use in experiments with plant organisms, more specifically with fruit and berry crops. As we said earlier, animal studies have their own specifics. First of all, this is the absence of vegetative reproduction in higher vertebrates.
We must remember that their organisms are different.a high degree of integration of all organs and systems; therefore, a change in one attribute of a certain organ under the influence of a mentor will inevitably lead to serious disturbances in the functioning of the systems associated with it anatomically and physiologically. In practice, it will be expedient to introduce the following techniques into working with animals, namely: closely related crossing (inbreeding) and distant hybridization. The first is used to create clean lines and further obtain the effect of heterosis, and the second is used to breed new breeds of animals.
