Influence of in vitro mutagenesis on ovule culture and plant regeneration in cotton (Gossypium hirsutum L.)

The effects of gamma rays, ethyl methanesulphonate (EMS) and sodium azide (SA) on ovule culture, growth rate of ovular callus and percentage of seedling regeneration were investigated. Based on preliminary experiments, 15 day-post-anthesis (dpa) ovules were exposed to 10-50 Gy dose of gamma irradiation and treated with 1-5 mM EMS and SA. After gamma irradiation and treatment with the EMS and SA, the ovules were cultured on Murashige and Skoog's medium with 3 % sucrose, 0.8 % agar and 2,4-dichloro phenoxy acetic acid/indole-3-acetic acid (1.5 mg dm^-3) with kinetin (0.5 mg dm ^-3) for seedling regeneration from ovules. Attempts were made to standardize the protocol for seedling regeneration from mutated ovules and the seedlings were transferred to field conditions after hardening. Plants with irregular leaf morphology and reduced growth with chlorophyll deficiency were observed during the development of the seedlings. Stimulation on responses of irradiated/treated ovules, growth rate and percent seedling regeneration was noted at lower dose/concentration of mutagens. The results of the present study suggest that lower dose/concentration of mutagens may not induce irreversible genotypic changes but can stimulate callus induction and plant regeneration and agronomically important variants/mutants would be generated by in vitro culture techniques prompted us to combine mutagens to obtain regenerants with variations in yield components.