In the present study, a series of experiment were carried out to investigate the influence of explant type and media combination on the induction of embryogenic callus, plant regeneration and suitable explant for DNA microinjection. The size of explant played major role in the plant regeneration. Mortality rate was high when smaller size explant was used. The plants developed through meristem culture did not undergo any type of malformation because the meristems are highly organized tissues and showed no variation for the phenotypic characters in these studies. With the increase in kinetin concentration up to 2 mg L-1, shoot formation was enhanced and callus initiation and proliferation was observed which was maximum at 6 mg L-1 concentration. Best media for callus induction, shoot and root regeneration was MS medium supplemented with 2 mg L-1 K and 1.5 mg L-1 IAA. All varieties showed higher degree of root formation except FH-900 and CIM-446 that showed least rooting. The MS medium without growth regulators produced moderate shoot and root formation while medium containing different levels of phytohormones effected significantly in shoot and root formation. Charcoal had positive effect on callus induction and browning was reduced. It is concluded that cotyledon and root from the local genotypes are not suitable explants for callus induction and proliferation. Ovules and hypocotyls are the best for callus induction. The efforts are underway to develop plant regeneration procedure for gene transfer leading to rapid introduction of leaf curl virus resistance into the higher yielding cotton genotypes and vice versa.
Muhammad Aslam , Nadia Iqbal , M. Mohsin Iqbal , M.A. Haq and Y. Zafar , 2005. Optimization/Standardization of Tissue Culture Technology Suitable for Inducing Genetic Transformations through Microinjection in the Locally Adopted Cotton Genotypes. Asian Journal of Plant Sciences, 4: 249-254.