Overexpression of horsegram (Macrotyloma uniflorum Lam.Verdc.) NAC transcriptional factor (MuNAC4) in groundnut confers enhanced drought tolerance.

The NAC family being the largest plant-specific transcription factors functions in diverse and vital physiological processes during development. NAC proteins are known to be crucial in imparting tolerance to plants against abiotic stresses, such as drought and salinity, but the functions of most of them are still elusive. In this study, we report for the first time expression of the MuNAC4, a member of NAC transcription factor from horsegram (Macrotyloma uniflorum) conferring drought tolerance. The groundnut (Arachis hypogaea) transgenics were generated using recombinant MuNAC4 binary vector transformation approach. Molecular analysis of these transgenic lines confirmed the stable gene integration and expression of the MuNAC4 gene. Twelve lines of T5 generation exhibited significantly enhanced tolerance to drought stress with proliferated lateral root growth as compared to wild types. Transgenics exposed to long-term desiccation stress assays showed increased lateral roots and greenish growth. The physiological parameters analysis also suggests that overexpression of MuNAC4 plays a significant role in improving the water stress tolerance of transgenic groundnut, reducing the damage to membrane structures and enhancing osmotic adjustment and antioxidative enzyme regulation under stress. This study validates MuNAC4 as an important candidate gene for future phytoengineering approaches for drought tolerance in crop plants.