Efficient shoot regeneration from double cotyledonary node explants of green gram [Vigna radiata L. (Wilczek)]

Abstract

An efficient shoot regeneration protocol has been developed yielding up to 27 shoots using double cotyledonary node explants of cultivar ML 267 of green gram [Vigna radiata (L.) Wilczek]. The explants were derived from 3-d-old seedlings germinated on Murashige and Skoog (MS) and Gamborg’s medium (B5) containing (2.0 mg/L) 6-benzyl aminopurine (BAP). They were initially cultured onto MS B5 medium augmented with different concentrations of BAP and very low concentrations of different auxins (NAA, IAA & IBA) and cytokinin (Kn) for shoot bud induction. The explants showing multiple shoot bud initials were transferred to MS B5 media containing reduced concentrations of BAP for shoot proliferation. Among the different auxins and cytokinins tested, presence of BAP+NAA in shoot bud induction and low BAP in shoot proliferation medium gave the best regeneration response. Profuse rooting was achieved in 90% of explants on ½ MS B5 medium devoid of any hormones. Over 90% of the rooted plants grew well and were fertile after transfer to glass house and set seeds normally. Histological examination of 4-d-old explants confirmed direct organogenesis through axillary shoot regeneration. Protocol so developed is currently being utilized for genetic enhancement of green gram using Agrobacterium mediated transformation.