Optimization of Shoot Tip-Based in Vitro Plant Regeneration in Cotton (Gossypium spp.)

摘要

An in vitro regeneration system in cotton has been optimized from explants comprising pre-existing shoot apices of aseptically grown seedlings. This system has been found to be useful with a variety of genotypes (arborium and hirsutum). Shoot regeneration among genotypes on different media ranged from 69 to 80%. The age of explants showed a significant effect on shoot tip regeneration. On an average, 5 day-old shoot tips recorded highest regeneration of 76% as compared to 3 or 9 day old seedlings onA MS medium + 6% sucrose. The genotypic differences for regeneration rate were significant, indicating that the regeneration of shoot tips was genotype-dependent. Rooting efficiency between genotypes ranged from 60 to 67% was not significantly differentindicated that rooting efficiency is genotype independent under in vitro conditions. However, root induction was greatly influenced by media composition as it varied from 55 to 72%. Half MS + 0.05 mg/1 a-naphthalene acetic acid medium recorded the highest percentage of root induction (72%) closely followed by half MS (68%). Root and shoot formation was observed in all genotypes. After plantlet formation, in vitro-raised plantlets were shifted to test tubes containing a little cotton soaked with a smallamount of water for two weeks and the water from these tubes was changed daily. The hardened plantlets were then transferred to small polythene bags filled with sand: soil mixture in the greenhouse and finally transferred to earthen pots in glasshouse. These plants grew into healthy green plants and reached maturity.