How many common breeding methods are there in high school biology in the new curriculum standard?

There are cross breeding, mutation breeding, haploid breeding, polyploid breeding, genetic engineering breeding, cell engineering breeding and so on.

Hybrid breeding:

Principle: Gene recombination.

2. Common methods: hybridization-selfing-screening-selfing.

3. Advantages: Excellent traits located in different individuals are concentrated in one individual.

4. Disadvantages: the breeding time is long and the process is complicated.

5. For example: hybrid rice, China Holstein cattle.

Mutation breeding:

Principle: gene mutation.

2. Common methods: physical methods: X-ray, γ-ray, ultraviolet ray, laser, etc.

Chemical methods: nitrous acid, diethyl sulfate, colchicine, etc.

3. Advantages: the mutation frequency is increased, and excellent varieties can be obtained in a short time.

4. Disadvantages: There are few favorable mutations, and a lot of materials must be disposed of.

5. Examples: mutation of soybean, cultivation of high-yield penicillin strain, space wheat, space pepper.

polyploid breeding

1. Principle: Chromosome variation

2. Common methods: colchicine treatment of germinated seeds or seedlings.

3. Advantages: the fruits and seeds are large and nutritious.

4. Disadvantages: stunted growth; It's hard to spread it on animals.

5. For example: triploid seedless watermelon

Haploid breeding:

1. Principle: Chromosome variation

2. Common methods: anthers are cultured in vitro to form haploids, and then treated with colchicine.

3. Advantages: the breeding cycle is obviously shortened.

4. Disadvantages: the method is complicated and the survival rate is low.

5. Example: Wheat anther culture in vitro

Genetic engineering breeding

Principle: Gene recombination (or heterologous DNA recombination).

Methods: The target gene was extracted → loaded into vector → introduced into recipient cells → gene expression → screened out new varieties that met the requirements.

Advantages: it is not limited by species and can be carried out purposefully according to human needs.

Disadvantages: it may cause ecological crisis and is technically difficult.

Application of cell engineering in breeding

Principle: Cell totipotency