The trophic mutant type is taken as an example to illustrate the process and principle of mutagenesi

The basic principle of mutation breeding is genetic mutation, which mainly includes chromosomal aberrations and genetic mutations.

1. Advantages of mutagenesis breeding:

1. There are many types of mutations, the time is short, and the smile is muted;

2. Expanding the mutation spectrum is more effective for improving individual single traits, and at the same time, it is more difficult to improve the single traits such as maturity, lodging resistance, dwarf stalk, and disease resistance of multi-Chan slow containing traits.

3. The induced variation is easy to stabilize, and most of the variations induced by shortening the breeding period are changes in a major gene, which is stable and relatively fast, and is generally basically stable after 3 or 4 generations.

2. Disadvantages of mutagenesis breeding:

1. It is easy to cause harm to the human body, and most of the chemical mutagens are toxic substances, and the safety is not high, so it is difficult to determine the direction of mutagenesis. low frequency of beneficial mutants produced by mutagenesis;

2. It is difficult to effectively control the direction and nature of variation;

3. Difficult to operate.

In breeding, mutant is a commonly used method that refers to the modification of the genes of a plant or animal to form a new variety or individual. Mutants have a lot of variability and therefore have a lot of potential for innovation. The following are the uses and methods of mutant foci in breeding:

1.Produce new varieties: Mutants can cause changes in the traits of plants or animals, resulting in new varieties. For example, through mutants, rice plants can be made more drought-tolerant, disease-resistant, etc.

2.Screening of excellent genes: Through the screening of mutants, some excellent genes can be found, and then the influence of these genes on traits can be studied, so as to achieve the purpose of screening out better varieties.

3.Improving the tolerance of the species: By insidious collapse and inducing mutants, plants or animals can be more resilient to the adverse conditions of the environment, thereby improving the tolerance of the species.

4.Improves photosynthesis efficiency: By making mutants, during photosynthesis, it can be stimulated to produce species with higher photosynthetic efficiency.

5.Improved plant or animal yields: After multiple screenings, mutants can be reverse-bred or cross-bred to produce high-yielding high-quality varieties.

The above are some of the uses and methods of mutants in breeding. Of course, it is necessary to be careful when using mutants for breeding, because the mutant degree is large and may have adverse effects on the species, so sufficient evaluation and experimentation are required to determine the feasibility of using mutants, as well as to accurately determine the mutation site.

Summary. The mutagenesis breeding steps mainly include mutagenesis and screening, in which the mutagenesis process includes: selection of the starting strain, preparation of single spore or single cell suspension, selection of mutagenesis and mutagenesis dose, mutagenesis treatment, etc.

Mutation breeding uses physical, chemical and other factors to induce mutations in organisms under artificial conditions, and selects them to breed new varieties of plants, animals and microorganisms.

The selection process of mutagenic offspring is briefly described.

The mutagenesis breeding steps mainly include mutagenesis and screening, in which the mutagenesis process includes: selection of starting strains, preparation of single spore or single cell suspension, selection of mutagenesis and mutagenesis dose, mutagenesis treatment, etc. Mutation breeding is the use of physical, chemical and other factors under artificial conditions to induce mutations of organisms, select from them, and breed new varieties of plants, animals and microorganisms.

The mutagenic generation resulting from mutagenesis treatment, denoted as m1. Due to the inhibition and damage of mutagenic factors such as radiation, the germination rate, emergence rate, adult plant rate, seed setting and skill rate of M1 are generally low, the development is delayed, the plant is dwarf or deformed, and the severant chimera appears. But these changes are generally not passed on to future generations.

Most of the genetic variations caused by mutagenesis are recessive, so M1 is generally not selected and harvested as a single plant, single spike or treatment.

The second generation of mutagenesis (M2) is the generation with the largest mutagenesis, and it is also the key period of selection. Most of the variations are unfavorable, but beneficial variations such as precocious maturity, short in the pole, disease resistance, stress resistance, and good quality can also occur, and the frequency of variation is about.

After the three generations of mutagenesis (M3), with the increase of generations, the separation of traits decreased, and some traits could be quickly stabilized once obtained. After several generations of selection, stable and excellent mutant lines can be obtained, and new varieties can be further experimented with. Mutant lines with certain prominent traits can also be used as hybrid initiation parents.

Ways to overcome the incompatibility of distant hybridization.