Multiple Shoot Regeneration from Detached Embryonic Axis in Greengram (Vigna radiata) cv.SML 668

Background: Under prevailing regime of climate change and dynamic pest-crop interactions, greengram genetic improvement requires a speedier and precise tool such as genetic transformation to develop improved lines. In this context, an in vitro multiple shoot regeneration system via organogenesis was demonstrated in mungbean cv. SML668, a parent cultivar used in crop improvement programs, using double cotyledonary node (DCN) and detached embryonic axis (EA) explants with 1.0 mg l-1 BAP.Methods: While both the explants responded to in vitro regeneration, number of shoots regenerated was higher with EA (4.02 +/- 0.19) than with DCN (3.1 +/- 0.08). 6-benzyl aminopurine (BAP) was found to be most effective for inducing and regenerating multiple shoots, in comparison to all other phytohormones (NAA, IAA and TDZ) and supplements (amino acids) tested. Sub culturing twice on BAP supplemented media followed by two subcultures on basal media was optimal for multiple shoot regeneration. Rhizogenesis was obtained on basal media devoid of any phytohormones in EA explants and in 1.0 mg l-1 IAA for DCN explants. The in vitro regenerated plantlets were successfully hardened in a mixture of soil, sand and vermiculite that flowered, produced pods and viable seeds on maturity.Result: The study revealed that detached embryonic axis was a potential explant for in vitro regeneration in SML668, a cultivar not tested for its in vitro regeneration ability before.

Automated summary

A rapid and precise genetic transformation tool, in vitro multiple shoot regeneration system, was successfully demonstrated in greengram using detached embryonic axis (EA) and double cotyledonary node (DCN) as explants. BAP was found to be the most effective hormone for inducing and regenerating multiple shoots. Rhizogenesis was achieved in EA explants on basal media without phytohormones and in DCN explants with 1.0 mg l-1 IAA. In vitro regenerated plantlets were hardened and produced flowers, pods, and viable seeds. This study revealed the potential of EA as an explant for in vitro regeneration in the cultivar SML668.