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

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 (B 5) containing (2.0 mg/L) 6-benzyl aminopurine (BAP). They were initially cultured onto MS B 5 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 B 5 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 B 5 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.