Optimization of shoot apex based cotton regeneration system

Cotton (Gossypium spp.) belonging to the genus Gossypium in the family Malvaceae. Cotton is an important fibre crop of global importance. It is grown in tropical and subtropical regions of more than 80 countries with an annual production of 20 million tonnes. It is an important source of oil and high quality protein meal and plays a significant role in the national economy. Among the cotton producing countries, India has the distinction of having the largest cotton growing area in the world with all four cultivated species under cultivation. The recalcitrance of cotton to regeneration through somatic embryogenesis has slowed down the development of transgenic cottons. Hence alternate strategies to obtain transgenic cotton via organogenesis in some varieties have been taken up. A direct shoot regeneration protocol was optimized for three cultivars of cotton Coker310, MCU-5, SVPR-2. Shoot apex from vigorous seedlings were placed in six different shoot apex media composition for shoot development. The efficiency of shoot development was higher when the shoot apices were cultured on SAM1 (MS+ 0.1 mg/l kinetin) irrespective of the genotypes. The nine day-old explants had a significant effect on shoot development. Among the different Regeneration media tried, the best rooting response was observed on RM2 (MS+ 0.1 mg/l GA3 + 1.0 mg/l IAA). Key Words-Cotton, Direct organogenesis, Shoot apex