PLANT BREEDING Manipulation of plant species to create

PLANT BREEDING Manipulation of plant species to create desired plant types of better yield and disease resistance.

CHARACTERS INCORPORATED INTO CROP PLANTS BY BREEDERS • Increased crop yield • Improved quality • Increased tolerance to environmental stresses such as – Salinity – Extreme temperature – Drought • Resistance to pathogens (viruses, fungi, bacteria) • Increase tolerance to insect pests

STEPS INVOLVED IN PLANT BREEDING • 1. Collection of variability • Collection and preservation of different varieties which have genetic variability, species and relatives of cultivated species (example: germplasm collection of plants having all the diverse alleles for all genes in a given crop)

• 2. Evaluation and selection of parents • Plants with desirable combination of characters are identified and multiplied and used in the process of hybridization. Example: creation of pure lines • 3. Cross hybridization among the selected parents • Desired characters from the two different parents are combined by cross hybridizing the two parents (high protein quality of one parent combine with disease resistant variety of another parent) • ↓ • Hybrids that combine the desired characters in one plant are produced.

• DISADVANTAGES: • Time consuming processes • The hybrids may or may not combine the desired characters.

• 4. Selection and testing of superior recombinants: • Plants that have combination of desired character are selected (i. e. ) plants that are supported to both the parents. • These are self pollinated for many generations till they reach homozygosity.

• 5. Testing, release and commercialization of new cultivars: • Yields and disease resistance of newly selected lines are evaluated under crop management practices. • The materials are tested in farmer’s fields for three growing seasons at several agro climatic zones in the country. • Yield and other characters are compared with a reference cultivar

PLANT BREEDING FOR DISEASE RESISTANCE – Crops show high yield will be selected - disease resistant. • Ex. Semi dwarf varieties of wheat and rice (high yielding types) – sonalika and kalyan sona (wheat).

• IR 8, Taichum native (Taiwan dwarf varieties of rice) • Jaya and ratna (Indian semi-dwarf varieties of rice)

• Sugar cane: Saccharum barrberi (poor sugar content and yield grown in North India) crossed with saccharum officinarum (thick stem with high sugar content grows in south India) to get a variety which is of high yield, thick stem, high sugar and ability to grow in north INDIA.

• MILLETS: (Hybrid maize, jowar and bajra Advantage of Hybrid breeding • 1. Develop high yielding varieties resistant to water stress.

PLANT BREEDING FOR DISEASE RESISTANCE • Disease resistance cultivars enhance food production. • Reduce the dependence on fungicides and bactericides. • CRITERIA REQUIRED: • Knowledge on causative organism. • Mode of transmission:

TOBACCO VIRUS LATE BLIGHT OF POTATO • Ex. • (i) Fungi- rust of wheat, red rot of sugar cane, late blight of potato. • (ii) Bacteria – black rot of crucifers. • (iii) Viruses- tobacco mosaic, turnip mosaic etc.

• METHODS OF BREEDING FOR DISEASE RESISTANCE Conventional method: Hybridisation Selection 2. Mutation breeding

• STEPS: • 1. Screening germplasm for resistance resources. • 2. Hybridisation of related parents. • 3. Selection and evaluation of the hybrids. • 4. Testing and release of new varieties.

Crop varieties bred by hybridization and selection for Disease resistance to fungi, bacteria and viral diseases • MUTATION BREEDING: • 1. INDUCTION OF MUTATION • Chemical or radiations in plants to develop desirable characters. • These plants are selected and used as a source in breeding

• 2. Introduction of genes. • Transfer of resistant gene by sexual hybridization in the target &the source of the plant. • Introduction of resistant genes from wild relatives into the high yielding varieties. • Gene for resistance to yellow mosaic virus introduced in bhindi - Abelmoschus esculentus from hybrid species A. esculentus-parbhani kranti

Plant breeding for developing insect/pest resistant varieties: - • Morphological, physiological and biochemical characteristics are responsible for insect resistance in host crop plants. • Morphological characters • Eg: hairy leaves of plants – resistance to pest.

• resistance to Jassids------>cotton • resistance to cerealleaf beatle----->wheat • Solid stems in wheat -------> resistance to beetle sawfly • Smooth leaves and nectarless cotton ----- resistance to bollworms as them. do not attract bollworms.

• Biochemical characteristic: • • High aspartic acid } • Low N 2 } → resistant to stem borers • Low sugar content in maize }

PLANT BREEDING FOR IMPROVED FOOD QUALITY • • Diet lacking Micronutrients – iron Vitamin A 1. Increase risk for diseases Iodine 2. Reduces life span Zinc 3. Reduces mental abilities in human

• BIOFORTIFICATION • Breeding crops with higher levels of vitamins and minerals pr higher proteins and healthier fats. • OBJECTIVE: • 1. To improve public health • 2. Protein content and quality 3. Oil content and quality • 4. Vitamin content • 5. Micronutrient and mineral content

• Example • 1. MAIZE HYBRIDS : twice the amount of amino acids , lysine and tryptophan • 2. WHEAT VARIETY: Atlas 66 -High protein content. • 3. Vitamin A enriched carrots , spinach , pumpkin • 4. Vitamin C enriched bitter gourd mustard, bathua, tomato. • 5. Calcium enriched – spinach, bathua • 6. Protein enriched beans - broad lab, French and garden peas.

• SINGLE CELL PROTEIN : • Microbes grown on industrial scale as a source of protein for animals and human nutrition –single cell protein

• MICROBES AS FOOD • Example: Spirulina rich in protein , minerals, fats, carbohydrates and vitamins. • MUSHROOM - rich in proteins

• MATERIALS NEEDED FOR GROWTH OF SPIRULINA • 1. Waste water from potato processing plants (containing starch) • 2. Straw • 3. Molasses • 4. Animal manure • 5. Sewage

• TISSUE CULTURE: • Regeneration of whole plants from explants ( any part of a plant grown in a test tube) under sterile conditions in special nutrient media • TOTIPOTENCY: • The capacity to generate a whole plant from any cell / explant

• Components of nutrient medium for tissue culture: • Carbon source-sucrose • Inorganic salts • Vitamins • Amino acids • Growth regulators like auxins and cytokinins etc.

• APPLICATION OF TISSUE CULTURE: • 1. Micro propagation: Propagation of large no. of plants in very short durations through tissue culture. • SOMACLONES : Plants produced by a tissue culture method are identical to the original plant. • PLANTS PRODUCED BY THIS (SOMACLONE) METHOD : Somaclones of tomato, banana, apple etc.

• 2. Recovery of healthy plants from diseased plants by growing the meristem ( virus free) of infected plants in vitro to obtain virus free plants. • Ex. Meristems of banana, sugarcane, potato etc. • 3. Somatic hybridization: Protoplasts ( plant cell after digesting the cell wall).