Mutation breeding:
- Genetic variability is created by induced mutation. (By application of mutagen, chemical or physical).
- Screening and selection of the parent with desirable character used as a parental plant for breeding programme.
- In mung bean, resistance to yellow mosaic virus and powdery mildew were induced by mutation.
- Natural wild varieties of plant with disease resistant genes are available but low yield.
- These wild varieties are hybridized with high yield varieties to make them disease resistant and also high yielding variety.
- Resistance to yellow mosaic virus in bhindi (Abelmoschus esculentus) was transferred from a wild species and resulted a new variety of A.esculentus called Parbhani kranti.
Plant breeding for Developing Resistant to insect pest:
- Another major cause of large scale destruction of crop plants is the insect and pest infestation.
- Insect resistance in host crop is due to morphological, biochemical or physiological characteristics.
Characters that make the plant resistance to insect pest:
- 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 acid, low nitrogen and sugar content in maize make them resistant to stem borers.
- Steps for developing insect pest resistant variety of crop are same as others.
- The resistant variety selected either form the wild variety of from other available cultivars.
Plant breeding for Improved Food quality:
- Around three billion people suffer from micronutrient, protein and vitamin deficiencies called Hidden hunger.
- Diets lacking essential micronutrients particularly iron, vitamin A, iodine or zinc- increase the risk of diseases; reduce life span, reduce mental ability.
- Biofortification:-breeding crops with higher levels of vitamins and minerals or higher protein and healthier fats – is the most practical means to improve public health,
- Objectives of biofortification: is to improve
- Protein content and quality.
- Oil content and quality
- Vitamin content and
- Micronutrient and mineral content.
- Hybrid maize developed with twice the amount of amino acids lysine and tryptophan, compared with existing maize.
- Wheat variety Atlas 66, having high protein content has been used as donor for improving cultivated wheat.
- Iron fortified rice developed with five times more iron than existing variety.
- IARI New Delhi developed:
- Vitamin A enriched carrots, spinach pumpkin.
- Vitamin C enriched bitter gourd, bathua mustard tomato.
- Iron and Calcium enriched spinach and bathua
- Protein enriched beans- broad, lablab, French and garden peas.
SINGLE CELL PROTEIN (SCP):
- More that 25% of human population is suffering from hunger and malnutrition.
- One of the alternating sources of proteins for animal and human is SCP.
- Production of biomass (protein) in large scale using micro-organism and low cost raw material is called single cell proteins.
- Microbes like Spirulina grown on waste water from potato processing plants, straw, molasses, animal manure and even sewage, to produce large quantities of biomass with rich in protein, mineral, fats, carbohydrate and vitamins.
- It has been calculated that 250 kg cow produces 200gm of protein per day. In the same period 250gm of micro-organism like Methylophilus methylotophus, expected to produce 25 tones of protein.
- Another example is production of biomass like mushroom from straw.
TISSUE CULTURE:
- Potency or power or ability of a single cell/ explants to develop a whole plant is called totipotency.
- This property led the scientist able to develop whole plant from explants – any part of plant, cell grown in a test tube, under sterile condition in special nutrient medium.
- The nutrient medium provides a carbon source such as sucrose. Inorganic salts, vitamins amino acids and growth regulator like auxin, cytokinin.
- The method of production of thousands of plants through tissue culture is called micropropagation.
- Plants grown by micropropagation are genetically identical called somaclones.
Application of tissue culture:
- Production of large number of plant from small tissue or single cell.
- Production of genetically identical plants (somaclones)
- Recovery of healthy plants from diseased plants by meristem culture. Although the plant infected with virus, the meristem is free of virus.
Somatic hybridization:
- Isolation of single cells from the plants.
- Digestion of cell wall to get protoplast of different donor cells, by use of cellulase and pectinase.
- Two protoplast of two different plants with desirable character are fused to form hybrid protoplast, either by using electric field or by PEG (polyethylene glycol).
- These hybrids are called somatic hybrid and the process called somatic hybridization. E.g. production pomato plant from potato and tomato.
Abbreviation:
- ET : Embryo Transfer
- IARI : Indian Agricultural Research Institute
- IRRI : International Rice Research Institute
- ICAR : Indian Council of Agriculture Research
- MOET : Multiple Ovulation Embryo Transfer
- NDRI : National Dairy Research Institute
CBSE Biology (Chapter Wise) Class XII ( By Mr. Hare Krushna Giri )
Email Id : [email protected]
