- Conventional breeding is often constrained by the availability of limited number of disease resistance genes that are present and identified in various crop varieties or wild relatives.
- Inducing mutations in plants through diverse means and then screening the plant materials for resistance sometimes leads to desirable genes being identified.
- Mutation is the process by which genetic variations are created through changes in the base sequence within genes resulting in the creation of a new character or trait not found in the parental type.
- Inducing mutations artificially through use of chemicals or radiations, and selecting and using the plants that have the desirable character as a source in breeding – this process is called mutation breeding.
Example- i) In mung bean, resistance to yellow mosaic virus and powdery mildew were induced by mutation. ii) Resistance to yellow mosaic virus in bhindi (Abelmoschusesculentus ) was transferred from a wild species and resulted a new variety of esculentus and Parbhanikranti.
Fig, mutated mung bean resistant to yellow mosaic virus
Plant breeding for developing resistant to insect pest
Insect resistance in host crop is due to morphological, biochemical or physiological characteristics.
Some characters make the plans resistance to insect are-
- Hairy leaves in several plants make them resistant to insect pest.
- Solid stem in wheat lead to non-preference by stem sawfly.
- Smooth leaves and nectar-less cotton variety do not attract bollworms.
- High aspartic acids, low nitrogen and sugar content in maize make them resistant to stem borers.
- Pusagaurav, a variety of Brassica is resistant to Aphids.
- Pusa sem-2 and pusasem 3 varities of flat bean are resistant to jassids, aphids and fruit borer.
Fig. flat beans
- Pusasawani and pusa A-4 of Okra (bhindi) are resistant to shoot and fruit borer.
Plant breeding for improved food quality
- Around three billion people in the world suffer from deficiency of micronutrient, protein and vitamin which is called hidden hunger which can lead to increase the risk of diseases, reduce life span, reduce mental ability etc.
- Food production should be increases qualitatively and quantitatively.
- Biofortification is the process of breeding crops which produce higher levels of nutrients like vitamins, minerals, protein and healthier fats to improve public health.
Biofortification is done to improve-
- Protein content and quality.
- Oil content and quality.
- Vitamin content.
- Micronutrient and mineral content.
i) Hybrid maize developed with twice the amount of amino acids lysine and tryptophan compared with existing maize.
ii) Wheat variety atlas 66 having high protein content has been used as donor for improving cultivated wheat.
iii) Iron fortified rice developed with five times more iron content than existing variety.
Indian agricultural research institute (IARI) has developed following plants
- Vitamin A enriched carrots, spinach and pumpkin.
- Vitamin C enriched bitter gourd, bathua, mustard, tomato.
- Iron and calcium enriched spinach and bathua.
- Protein enriched beans like broad, lablab, French and garden peas.
Fig. garden pea