Breeding is one of the most modern and promising sciences. Thanks to its achievements, new types of living organisms have already been created, which have brought many benefits to mankind. The subject of study, tasks and main directions of selection will be discussed in our article.
Subject and tasks of selection
What is the subject of selection? This is the science of improving existing and breeding new breeds of animals, plant varieties and strains of microorganisms. Its subject is the study and implementation in practice of the specific patterns of their evolution. The achievements of modern breeding include tens of thousands of organisms useful to humans. The theoretical basis of this direction is another science - genetics. It considers the features of heredity and variability of all living things.
The main tasks of breeding are breeding more productive plant varieties and fertile animal species. Moreover, scientists are trying to breed individuals that will be unpretentious to environmental conditions and their change in an unfavorable direction for them. Microorganisms are alsohigh requirements. This is resistance to mutation processes and the rate of division of beneficial bacterial cells.
Basic selection methods
What is the subject of selection, we found out. But since all the studied organisms differ significantly in structure and features, different groups of methods are applied to each of them. Since ancient times, still unconsciously, man has used selection. In selection, this is the main method. Along with it, hybridization and the action of mutagens are used. At the present stage of development, fundamentally new experimental methods are used - genetic and cell engineering.
Biotechnology
At present, biological processes and systems have gained the scale of industrial production. As a result, highly effective forms of microorganisms, cultures of cells and tissues of plants and animals have been obtained. Moreover, the achievements of modern selection make it possible to obtain a natural product with predetermined properties.
Features of plant breeding
So, the valuable original form is what serves as the subject of selection. However, the structural features of plants allow the use of only certain methods to create new traits based on the original ones. These are inbreeding, polyploidy, mutagenesis and hybridization. Among them are more traditional ones. These are various types of selection, as well as hybridization. In order to develop a new variety with the expected qualities, it is necessarydo difficult work. It consists in the selection of valuable initial forms and hybridization with subsequent selection. In this way, as a result of crossing apple trees with valuable taste and frost-resistant qualities, varieties were obtained that combine the valuable properties of hybrids.
Effective in plant breeding is the method of heterosis. To do this, you need to display independent rows of clean lines, and then cross them with each other. As a result, more productive varieties of many fruit and fodder crops are obtained.
The phenomenon of polyploidy is a multiple increase in the number of chromosomes. Initially, this occurred naturally in nature when plants were exposed to mutagens. At the present stage, breeders most often act on diploid cells with the alkaloid colchicine. The resulting forms have increased fertility compared to the original. And their genotype was changed to tetraploid.
Animal breeding
In animal breeding, slightly different methods are used, because they are not capable of vegetative reproduction. Scientists use mainly individual selection and two types of hybridization. With inbreeding, an increase in homozygosity is observed, leading to the degeneration of the species and the loss of its valuable qualities. To avoid this, breeders alternate between closely and unrelated crosses. Valuable individuals were obtained by scientists by crossing individuals of different species. Examples of such breeding achievements are the hybrid of a donkey and a horse - a mule, a yak and a cow - a khaynak. The problem is that most of the individualsobtained from such crossing are sterile and not capable of producing fertile offspring. The exceptions to this rule are the liger and tiger lion, whose females are capable of further reproduction.
Microorganisms and features of their selection
Now let's find out what is the subject of selection of microorganisms. These are all types of prokaryotic bacteria, protozoa, unicellular fungi and lower plants - algae. Many of them are sources of medicines, feed additives, fertilizers, used in winemaking, bread and dairy products. In order to transfer a valuable and productive strain to industrial production, it is necessary to go through several stages. The most stable cells are identified first. This selection is based on hereditary variability. Further, valuable strains are treated with mutagens. After that, it is necessary to identify the most productive cells with an already altered genotype. Selected clones are subjected to multiple subcultures on a new nutrient medium. And already selected strains are propagated on an industrial scale.
Prospects for the development of biotechnology
The achievements of modern breeding have already helped to solve many important problems. For example, newly developed, more productive plant and animal varieties are helping to provide food to areas of the planet that need it most.
The use of biohumus and fertilizers based on chemotrophs and earthworms provide accelerated growth of plant mass. When using these substances,obtained by breeders, the soil is more efficiently supplied with nitrogen and phytohormones.
In plant propagation, the method of tissue culture is increasingly being used, as a result of which it is possible to obtain planting material that is not infected with viruses. On the basis of microorganisms, breeders have recently created new feed proteins that are better absorbed by animals.
Breeding is also an important part of the modern pharmaceutical industry. Biosynthesis produces hormones, antibiotics and enzymes.
So, the subject of selection are methods that can increase the productivity of agriculture, food and pharmaceutical industries. At present, thanks to the achievements of modern science, varieties, breeds and microorganisms have been created, thanks to which many problems of mankind will be solved.
