High frequency induction of multiple shoots and plant regeneration from zygotic embryo axis explants of cotton cultivar L-604 (Gossypium hirsutum L.).

An efficient, robust regeneration protocol has been developed using zygotic embryo axis explants of an elite cultivar L-604 ( Gossypium hirsutum L.). Explants regenerated on MSB5 medium supplemented with 0.5 mg -l Thidiazuron, 0.1 mg -l Naphthalene acetic acid, 5.0 mg -l Silver nitrate and 1.0 g -l activated charcoal, was identified as the best combination for producing the maximum number (12.67) of multiple shoots per explant. In addition, the highest shoot elongation (5.30 cm) and maximum regeneration frequency (89.0%) was also recorded in the same hormonal combinations. In vitro shoots were successfully rooted on ½ MSB5 medium containing 1.5 mg -l IBA. Well rooted plants were subsequently transferred to polyhouse and greenhouse conditions for primary and secondary hardenings respectively and about 95% of the plants were established successfully. The conditions optimized in this study for inducing multiple shoots could be best suitable for development of transgenic L-604 variety for agronomically important traits.