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Clonal selection degeneration
- 1. Welcome
- 2. University of Agricultural Sciences, Dharwad College of Agriculture, Vijaypur Properties of asexually propagated crops, Clonal selection and Clonal degeneration Submitted to: Submitted by: Dr. M B Boranayak Brahmesh Reddy B R Dept. of genetics & Plant Breeding III yr A sec B1 batch College of Agriculture,Vijayapur College of Agriculture, Vijayapur
- 3. Asexual reproduction Multiplication of plants without the fusion of male and female gametes is known asexual reproduction. Asexual reproduction can occur either 1. By vegetative plant parts or 2. By vegetative embryo which develop without sexual fusion.
- 4. Rhizome : Turmeric (Curcuma domestica) Ginger(Zingiber officinale) Bulb : Garlic (Allium sativum), Onion (A. cepa)
- 5. Corm :Bunda (Colocasia antiquorum) Arvi (Colocasia esculenta) Tuber : Potato (Solanum tuberosum)
- 6. Significance Asexual reproduction has several advantages. 1. It leads to continuity of same genotype with great precision, because all the progeny have similar genotype and phenotype. 2. Useful in obtain large number of genetically identical individuals. 3. Promising genotype can be maintained. 4. It makes use of desirable bud mutations. Mutants can be directly released as varieties.
- 7. Clone Progeny of a single plant obtained by asexual reproduction is called a clone. Crop which are propagated asexually or by vegetative means clonal crops.
- 8. Features of Clones Homogeneous constitution :- The progeny of clone is genetically identical and have same genetic constitution. Thus clones are homologous. No genetic variation within a clone. Heterozygosity :-Asexually propagated crops are heterozygous so clone is also heterozygous. Progeny looks similar phenotypically but is heterozygous.
- 9. Vigorous growth Clones have hybrid vigour which is conserved due to sexual reproduction. Most of the varieties of sugarcane and potato are hybrids Source of variation There are three sources of variation in a clone. Viz. bud mutations, mechanical mixture, and occasional sexual reproduction.
- 10. Segregation in F1 When hybridization is done between different clones, segregation occurs in F1generation. Each F1 plant is potentially a new variety, therefore, selection is practised in F1. Wider adaptation: Clones are more adaptable to environmental conditions
- 11. Origin of Genetic variation within Clones. 1. Somatic mutation 2. Mechanical mixture 3. Sexual reproduction 4. Segregation in F1
- 12. Comparison among Clones, Purelines and Inbreds Particulars Clone Pureline Inbred Mode of pollination Cross pollination Self pollination Cross Pollination Natural mode of reproduction Asexual Sexual Sexual Genetic makeup of plant population Heterozygous Homozygous Hetrozygous Obtain through Asexual reproduction from a single plant Natural S.P.from a single homozygous plant Artificial self pollination and selection for several generation Maintained through Asexual reproduction Natural self pollination Artificial self pollination or Close Inbreeding Used as a variety Yes Yes No (Used for Hybrid and synthetic Hybrid development) Genetic makeup of plant with in an entity Heterozygous Homozygous Almost Homozygous
- 13. Method of improvement • A single outstanding plant select from a population forms the basis of a new variety. • The breeding behaviour of genotype of this plant is not important since there would be no further sexual reproduction. • An improved variety that has becomes variable, or from a population produces by crossing two or more clones.
- 14. Clonal selections Improvement of asexually propagated crops by selecting superior clones is known as clonal selection. Superior clones can be isolated from three types of materials 1. Local variety 2. Introduced variety 3. Inter crossed population
- 15. Breeding procedure of clonal selection It involves a minimum of 7 years for complete selection of the best superior and desired clones
- 16. SECOND YEAR:- Clones from the selected plants grown separately. a) Desirable clones selected
- 17. THIRD YEAR :- Preliminary yield trials with standard checks. a) Selection for quality, disease resistance etc. Disease nurseries may be planted. b) Few outstanding clone selected.
- 18. FOURTH-SIXTH YEAR :- Multilocation yield trials with standard checks. a) Best clone identified for release as a new variety.
- 19. SEVENTH YEAR :- The best clone release as a new variety. a) Seed multiplication for distribution begins.
- 22. Merits 1. Variety evolved by this method retains all the characters of the parental clones for several years. 2. Varieties are highly uniform like pure lines. They are highly stable because there is no risk of deterioration due to segregation and recombination 3. Effective method for genetic improvement of asexually propagated crops.
- 23. Merits (contd..) 4.Useful in isolation the best genotype from a mixed population of asexually propagated crops. 5.The selection scheme is useful for maintaining the purity of clone.
- 24. Demerits:- 1. selection method utilizes the variability already present in the population, and it has not been devised to generate variability. 2. Genetic makeup cannot be improved by this method without hybridization. 3. Varieties developed by clonal selection are highly prone to new of a disease.
- 26. Clonal Degeneration The loss in vigour and productivity of clone with time is known as clonal degeneration. Clonal degeneration= Degeneration is inherented in the clone. Degeneration may result from 1) Mutation 2) Viral diseases 3) Bacterial diseases
- 27. • Pidi Monthan is a clonal selection from Monthan. • High Gate is a clonal selection from Mitchel. • Kurfi Red Potato is a clonal selection from Darjeeling Red Round. It was propagated from a single disease free plant. • Kurfi Safed is a clonal selection from potato variety Phulwa. • Bombay Green Banana is a bud selection from Dwarf Cavendish. Major achievements
- 28. Achievements in clonal selection:- Crop Mango:- . Grapes:- Guava:- Sapota:- Clonal variety – Dasehari-51, Niranjan, Cardoz mankurad, Payur-1 – Pusa seedless, Thomson seedless, Perlet, Tas –e- ganesh, Sonaka, Rao sahebi, dilkhus. – L-49 Jyoti, Alandi, S-1, Arka mridula, – Cricket ball, Kirthi bharti, Badami, Baramasi, Guthi, Thagarampudi.
- 29. Papaya:- Pineapple:- Litchi:- Aonla:- Bael:- – CO-1, CO-2, CO-5, CO-6, Pusa giant, Pusa dwarf. – Singapore Spanish, MasmerahPuerto Rico – glorff,Saharanpur sel, swarna roopa. – NA-4, NA-5, NA-6, NA-7,NA-8,NA-10 – NB-1,NB-5, NB-6 crop Clonal variety