In vitro florigenesis: an efficient regeneration system avoiding time consuming vegetative phase in popular Indian soybean variety JS-335

Abstract

Soybean (Glycine max L.) is a major legume crop cultivated principally as protein rich bean. Improving quality and yield received considerable attention from researchers. Here, we explored molecular approaches to improve soybean quality and yield. In spite of recalcitrance, soybean plants successfully regenerated through complex and time consuming in vitro regeneration protocols via organogenesis and/or somatic embryogenesis and being used for transgenic development. Transformation efficiency is highly dependent on the regeneration as not all the cells transformed lead to the recovery of viable plant regeneration. Consequently, efficient in vitro regeneration found to be directly associated with the recovery of transformants. In the present study, we standardized the in vitro florigenesis using cotyledonary node with axillary bud as explant of soybean variety JS-335. Flower buds were directly induced from proximal end of the explant on Murashige-Skoog (MS) medium augmented with thidiazuron (TDZ) and α naphthalene acetic acid (NAA). TDZ proved a potential growth regulator to induce in vitro florigenesis. As a result of in vitro fertilization, pods were developed from flowers and matured within 40-45 days on hormone-free medium. Pods and seed set under in vitro conditions resemble pods and seeds produced under in vivo conditions. This pathway of in vitro florigenesis showed great potential for successful induction of in vitro flowering, which in turn can be explored in producing transgenic soybean seeds in popular Indian soybean genotype without escaping transgene.