Somatic embryogenesis and in vitro plant regeneration in moth bean [Vigna aconitifolia (Jacq.) Marechal]: a recalcitrant grain legume

An efficient in vitro regeneration protocol for moth bean [Vigna aconitifolia (Jacq.) Marechal] via somatic embryogenesis has been developed. Embryogenic callus cultures were established from the cotyledonary node as explant on semi-solid Murashige and Skoog (MS) medium supplemented with $0.75mg\;1^{-1}$ 2,4-dichlorophenoxyacetic acid (2,4-D) and $1.5mg\;1^{-1}$ 6-benzylaminopurine (BA) and with various additives ($50mg\;1^{-1}$ ascorbic acid and $25mg\;1^{-1}$ each of adenine sulphate, citric acid and $_L-arginine$). Numerous somatic embryos differentiated on MS basal nutrient medium supplemented with $0.25mg\;1^{-1}$ 2,4-D and $0.5mg\;1^{-1}$ of kinetin (Kin). Sustained cell division resulted in the formation of cell aggregates, which progressed to the globular- and heart-shaped somatic embryos and then, if they differentiated properly, to the torpedo shape and cotyledonary stages. The transfer of embryos onto fresh MS basal medium containing $0.2mg\;1^{-1}$ BA and $2.0mg\;1^{-1}$ gibberellic acid enabled the embryos to achieve complete maturation and germination. More than 80% of somatic embryos were converted into true-to-type fertile plants. In vitro-regenerated plantlets with well-developed roots were successfully hardened in a greenhouse and established in soil.