In Vitro Plant Regeneration in Cotton by Multiple Shoot Induction

A rapid and simple multiple shoot induction protocol has been developed from cotyledonary node explant. The cotyledonary node explant consists of lower 0.5 mm portion of hypocotyl and cotyledonary node without any cotyledons attached. Murashige and Skoog (1962) medium supplemented with B5 vitamins and growth regulators such as 6-Benzylaminopurine and Kinetin (2:1 mg/L) resulted into the formation of mass of uncountable shoot buds. The induction of shoot buds was direct and without callus formation. Shoot buds were allowed to grow into well-defined shoots in shoot growth medium. The elongated shoots were separated and rooted in modified MS medium supplemented with NAA. Explants of several genotypes formed multiple shoots, which could be harvested on repeated sub-culture in three to four successive cycles. Statistical analysis (LSD) showed that there was no significant difference among cultivars in the number of shoot produced per explant. The frequency of shoot number per explant was in the range of 9.0 to 18.3. Plants of seven varieties were established in the soil. The plants grow normally with zero branching habit, produce flowers, set bolls and seeds. These plants are being evaluated in R1 generation for variation, if any. This protocol is considered more suitable for micropropagation, germplasm preservation and genetic transformation experiments.