In vitro Multiple Shoot Induction in Soybean

Abstract

Genetic transformation is a crucial tool for cultivar improvement; however, soybean is regarded as highly recalcitrant and the success of transformation is affected by the explant source and the rate of in vitro shoot regeneration. Multiple shoot induction on soybean (Glycine max L.) cultivar LS 677 was carried out using single and double coty-node explants from soybean seedlings derived from seeds germinated on Murashige and Skoog (MS) culture media containing different concentrations of N 6 -benzyladenine (BA) and BA in combination with kinetin (KIN). Seedlings obtained from cytokinin treatments (2-4 mg L -1 BA) were stronger with thick hypocotyls, reduced epicotyls and primary roots with few or no lateral root formation. These seedlings showed a better potential as a source for excision of explants than the thin, elongated control seedlings grown on MS medium without cytokinins. The highest number of multiple shoots, from both explant types, was obtained on MS media supplemented with 1.57 and 2.00 mg L -1 BA. The induced shoots were efficiently elongated and rooted on MS medium without plant growth regulators (PGRs). Rooted plantlets were acclimatised under controlled conditions with 70% success and produced viable seeds. The results of this study indicate that the soybean double coty-node explants derived from cytokinin treated seedlings could be a better explant source for in vitro shoot multiplication than the single coty-node explants.