Putrescine enhances somatic embryogenesis and plant regeneration in upland cotton

Improvement in somatic embryogenesis has been achieved in several cotton lines (Gossypium hirsutum L.) from the Georgia and Pee Dee germplasm with culture media containing various Putrescine concentrations. The best results were obtained with the alpha-naphthalene acetic acid (NAA)-based treatments, S 15 g.05 NAA and EMMS2, as compared to the 2,4-dichlorophenoxyacetic acid (2,4-D)-based culture medium, EMMS4. Inclusion of 0.5 mg 1(-1) Putrescine improved somatic embryo (SE) induction for most treatments and lines tested. An 8-and 2-fold improvement was achieved in SE production on the EMMS2-0.5 Putrescine treatment as compared to EMMS2 alone for cotton lines PD 97019 and GA 98033, respectively. A significant increase in SE number (53-fold) was obtained with the addition of 0.5 mg 1(-1) Putrescine to EMMS2 for PD 97021, which was essentially recalcitrant without Putrescine treatment. Conversion of SEs into plants was both genotype- and culture medium-dependent.