Question

How can one do plant breeding for developing resistance to insect pests? Give a few examples to insect resistance characteristics. Also mention the source of pest resistance genes.

Answer 1

How can one do plant breeding for developing resistance to insect pests :-

1. Conventional Breeding:

Conventional plant breeding has been going on for hundreds of years, and is still commonly used today.

It is known as the breeding or planting, which uses chemical ways like chemical fertilisers or synthetic components. In conventional breeding, genetically modified foods or non-ecological foods are used in breeding animals.

It is carried out by following steps:

(a) Selection and screening of germplasm for the disease resistance.

(b) Hybridisation of selected plants.

(c) Selection and evaluation of hybrids.

(d) Testing and release of new varieties into the market.

2. Mutation Breeding:

Mutation is a process by which genetic variation is achieved through the changes in base sequences within genes. This creates a new character or trait absent in parental generation. Mutation breeding can be defined as the process of breeding by artificially inducing mutations using chemicals or radiations.

It is carried out by the following steps:

(a) Inducing mutations in plants by various means.

(b) Screening the plant by various means.

(c) Selecting the desirable plant for the multiplication for breeding.

In mung bean, resistance to yellow mosaic virus and powdery mildew were introduced by mutations.

Resistance to yellow mosaic virus in bhindi Abelmoschus esculentus was transferred from a wild species and resulted in a new variety of A. esculentus called Parbhani Kranti.

Currently, mutation heeding is being carried out for disease resistance, as there is limited availability of disease resistance genes in the crop plants and their wild relatives.

Plant Breeding for Developing Resistance to Insect Pests:

The insect resistance in host crop plants may be due to the morphological, biochemical or physiological characteristics.

The important characters that lead to pest resistance are:

(i) Hairy leaves in plants. For example, resistance to jassids in cotton and cereal leaf beetle in wheat.

(ii) Solid stem in wheat exhibits non-preference by stem sawfly.

(iii) In cotton, smooth leaf and absence of nectar repel bollworms.

(iv) In maize, high aspartic acid, low nitrogen and sugar content protect them from stem borers. Breeding methods for insect pest-resistance involve the same steps as those for any other agronomic trait.