Application of Somaclonal Variation
1. Somaclonal variation and gametoclonal variation represent useful source of introducing genetic variations that could be of value to plant breeders.
2. Single gene mutation in nuclear or organelle genome may give the best available variety in vitro that has a specific character.
3. Gametoclonal variation, induced mostly by meiotic recombination during the sexual cycle of F1 hybrid, results in trasngressive segregation to uncover unique gene combination.
4. Various cell lines selected in vitro may prove potentially applicable to agriculture and industry like resistance to herbicide, pathotoxin, salt or aluminium.
5. Variability in cell cultures has played a useful role in synthesis of secondary metabolites on a commercial scale.
6. Technique employed for Somaclonal and gametoclonal variation are relatively easier than recombinant DNA technique.
Somaclonal variants for agronomically desirable traits in several crop plants have been raised from tissue culture. Some examples of Somaclonal variation in crop plants as well as in some horticulturally important plants are given below:
Rice:
Significant improvements relative to parent were observed for seed weight, seed proteins percentage, tiller number, panicle length and time of flowering. At IRRI, mutants were observed for many characters such as panicle, grain, and leaf morphology and tiller arrangement.
Wheat:
Variations were manifested for gliadin proteins in seed, grain colour, plant height, heading date and yield.
Maize:
Plants regenerated from selected cell lines were resistant both to T-toxin and to infection to Drechslera maydis causing southern leaf blight. Cytoplasmic male sterile lines are very sensitive to the T-toxin produced by Drechslera maydis.
Potato:
Somaclonal variants were selected for resistance to Phytopthora infestans and to its multiple races and resistance to early blight.
Tomato:
Somaclones were isolated with variant phenotypes, such as recessive mutation for male sterility, resistance to Fusarium oxysporium, jointless pedicel , tangerine virescent leaf, flower and fruit colour.
Sugarcane:
Somaclonal variants have been isolated by different workers for cane yield, sugar yield and resistance to smut disease caused by Ustilago scitamini, downey mildew caused by Helminthosporium sacchari.
Geranium:
Skirvin and Jenick ( 1976) developed an improved scented geranium called ‘Velvet rose’ from Pelargonium species by isolating Somaclonal variant. The new cultivar has symmetrical flowers with large fertile stamens, five paired stigma and sets seed. The parential cultivar, on the contrary has asymmetrical flowers with reduced- sterile anthers, a two- paired stigma and never sets seeds.