Evaluation of different carbon sources for high frequency callus culture with reduced phenolic secretion in cotton (Gossypium hirsutum L.) cv. SVPR-2

• We have evaluated the role of carbon sources in controlling excessive phenolic secretion from callus culture of cotton.
• Maltose was found to control phenolic secretion when it is used as a sole carbon source.
• Efficient protocol was developed for high frequency callus induction and proliferation for SVPR-2 cotton cultivar using different plant growth regulators.
• Adjustment of carbon source concentrations was found to play an important role in cotton callus culture.
• The present work will be helpful for establishing callus culture and getting regeneration to carry out genetic transformation studies in SVPR-2 cotton cultivar.

An efficient protocol was developed to control excessive phenolic compound secretion during callus culture of cotton. As cotton is naturally rich in phenolic compounds factors influencing the phenolic compound secretion, callus induction and proliferation were optimized for getting high frequency callus culture. Different carbon sources such as fructose, glucose, sucrose and maltose were tested at various concentrations to control phenolic secretion in callus culture. Among them, 3% maltose was found to be the best carbon source for effectively controlling phenolic secretion in callus induction medium. High frequency of callus induction was obtained on MSB5 medium supplemented with 3% Maltose, 2,4-D (0.90 μM) and Kinetin (4.60 μM) from both cotyledon and hypocotyl explants. The best result of callus induction was obtained with hypocotyl explant (94.90%) followed by cotyledon explant (85.20%). MSB5 medium supplemented with 2,4-D (0.45 μM) along with 2iP (2.95 μM) gave tremendous proliferation of callus with high percentage of response. Varying degrees of colors and textures of callus were observed under different hormone treatments. The present study offers a solution for controlling phenolic secretion in cotton callus culture by adjusting carbon sources without adding any additives and evaluates the manipulation of plant growth regulators for efficient callus culture of SVPR-2 cotton cultivar.