Gametoclonal Variation

Gametoclonal variation in Plant tissue culture - Variation in gametes clones # Origin # Production # Application of Gametoclonal Variation in plants with their examples.

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1. Dr. Divya S harma Assistant Professor GAMETOCLONAL VARIATION

2. GAMETOCLONAL VARIATION Gameto ----  Gametic cells Clones ---- Generations GAMETOCLONAL VARIATION ----  GAMETOCLONES (variation in gametes clones)

3. The variations observed while culturing the gametic cells are regarded as gametoclonal variations. This is in contrast to the somaclonal variations detected in the cultures of somatic tissues. The term Gametoclones (in place of somaclones) is used for the products of Gametoclonal variations . By mitosis, somatic cells are divide, the genetic material is equally distributed to the daughter cells. In contrast, the gametes, being the products of meiosis, possess only half of the parent cell genetic material. Origin of Gametoclonal Variation

4. Gametoclonal Variation If the somatic-issue derived variants have a gametophytic origin such as pollen or egg cell, then its known as “ Gametophytic variation ”. It introduced for variation observed among plants regenerated from cultured gametic cells. It can be developed by culturing male and female gametic cell (anther culture).

5. The Gametoclonal variations differ from somaclonal variations by three distinct features: Mutants obtained from gametoclonal variations give rise to haploid plants since a single set of chromosomes are present. Meiotic crossing over is the recombination process observed in gametoclonal variations. The gametoclones can be stabilized by doubling the chromosome number.

6. Production of Gametoclones Gametoclones can be developed by culturing male or female gametic cells. The cultures of anthers or isolated microspores are widely used. Improvements have been made in several plant species through development of gametoclones. Eg ., Rice , Wheat , and Tobacco .

7. Crop Common name Characteristics Oryza sativa Rice Plant height; time of flowering; seed size and protein content; level of tillering ; waxy mutant; chloroplast content Nicotiana tabacum Tobacco Plant size; leaf shape; number of leaves; alkaloid content; virus resistance; time of flowering Brassica napus Rapeseed Leaf shape and color; time to flower; type of flower; glucinolate content; pod size and shape Hordeum vulgare Barley Plant height; days to maturity; grain yield; fertility Selected list of plants regenerated from Gametoclonal variations

8. Applications of Gametoclonal Variations Suitable for breeding Crop improvement Disease, herbicides, toxin resistance Abiotic resistance (cold, high temperature, ph) Biotic resistance (insect, bacteria etc)

9. Sources of Genetic Variations in the Gametoclones Cell culture technique may induce genetic variations. Variations may be induced while doubling the haploid chromosomes. Genetic variations may occur due to heterozygosity of the diploids.

10. Gametoclonal variations differ from somaclonal variations Somaclonal Variation Gametoclonal Variation Somaclonal variation involves fusion of somatic cells. Gametoclonal variation involves fusion of male and female gamete. It involves the production of allotetraploid plants happens. It results on production of the diploid plant. In Somaclonal variation, there is equal contribution of cytoplasm from both the plants. Cytoplasm contribution is more from female parent. Segregation does not occurs  in Somaclonal variation. Leads to occurrence of segregation. Wide crosses can be made easily Wide crosses are associated with sexual problem.

11. Sharma’s Classes - Dr. Divya Sharma Thank-you