Breeding is one of the most modern and promising sciences. Thanks to her achievements, new types of living organisms have already been created that have brought many benefits to humanity. The subject of study, tasks and main directions of selection will be considered in our article.
The subject and objectives 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 laws of their evolution. Achievements of modern selection number tens of thousands of beneficial organisms for humans. The theoretical basis of this direction is another science - genetics. She considers the features of heredity and variability of all living things.
The main objectives of breeding is the breeding of more productive plant varieties and prolific species of animals. Moreover, scientists are trying to bring individuals that will be unpretentious to environmental conditions and their change in the unfavorable direction for them. High requirements are also imposed on microorganisms. 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 organisms studied differ significantly in structure and features, different groups of methods are applied to each of them. From ancient times, unknowingly people used selection. In breeding, 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 cellular engineering.
Biotechnology
Currently, biological processes and systems have gained the scale of industrial production. As a result, highly effective forms of microorganisms and cell and tissue cultures of plants and animals were obtained. Moreover, the achievements of modern selection make it possible to obtain a natural product with predetermined properties.
Features of plant breeding
So, a valuable initial form is what serves as the subject of selection. However, the structural features of plants allow only certain methods to be used to create new characters based on the original ones. This is inbreeding, polyploidy, mutagenesis and hybridization. Among them are more traditional. These are various types of selection, as well as hybridization. To develop a new variety with the expected qualities, it is necessary to carry out complex 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 combining the valuable properties of hybrids were obtained.
The heterosis method is also effective in plant breeding. To do this, it is necessary to derive independent rows of clean lines, and then cross them together. The result is more productive varieties of many fruit and feed crops.
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 colchicine alkaloid. The resulting forms have increased fertility compared to the original. And their genotype is changed to tetraploid.
Animal breeding
In animal breeding, slightly different methods are used because they are not capable of vegetative propagation. Scientists use mainly individual selection and two types of hybridization. When kinship is related, 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 closely and unrelated crosses. Valuable individuals were obtained by scientists by crossing individuals of different species. Examples of such selection achievements are a hybrid of a donkey and a horse - a mule, a yak and a cow - a haynak. The problem is that most individuals obtained from such crosses are sterile and unable to produce prolific offspring. An exception to this rule are ligers and tigers, females of which are capable of further breeding.
Microorganisms and features of their selection
And 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, are used in winemaking, the production of bread and dairy products. In order to transfer a valuable and productive strain to industrial production, it is necessary to go through several stages. First, the most stable cells are detected. At the heart of this selection is hereditary variation. 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 undergo repeated reseeding to a new nutrient medium. And already selected strains are propagated on an industrial scale.
Prospects for the development of biotechnology
Achievements of modern selection have already helped solve many important problems. For example, newly bred, more productive plant varieties and animal breeds help provide food to areas of the planet that are especially in need.
The use of vermicompost and fertilizers created on the basis of chemotrophs and earthworms provide an accelerated increase in plant mass. When using these substances obtained by breeders, the soil is more efficiently supplied with nitrogen and phytohormones.
In plant propagation , the tissue culture method is increasingly used , as a result of which planting material not infected with viruses can be obtained. Based on microorganisms, breeders have recently created new fodder proteins that are better absorbed by animals.
Breeding is also an important part of the modern pharmaceutical industry. Using biosynthesis, hormones, antibiotics and enzymes are obtained.
So, the subject of selection is the methods by which it is possible to increase the productivity of agriculture, food and pharmaceutical industries. Currently, thanks to the achievements of modern science, varieties, breeds and microorganisms have been created, thanks to which many problems of mankind will be solved.