Pandurangaiah Merum, Lokanadha Rao G, Sudhakarbabu O, Nareshkumar A, Kiranmai K, Lokesh U, Thapa Ganesh, Sudhakar Chinta
Department of Botany, Sri Krishnadevaraya University, Anantapuram, 515003, India.
Mol Biotechnol. 2014 Aug;56(8):758-69. doi: 10.1007/s12033-014-9754-0.
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.
NAC家族是最大的植物特异性转录因子家族，在植物发育过程中的各种重要生理过程中发挥作用。已知NAC蛋白在赋予植物对干旱和盐度等非生物胁迫的耐受性方面至关重要，但它们中大多数的功能仍不清楚。在本研究中，我们首次报道了来自豆科植物（Macrotyloma uniflorum）的NAC转录因子成员MuNAC4的表达赋予了耐旱性。通过重组MuNAC4二元载体转化方法培育了花生（Arachis hypogaea）转基因植株。对这些转基因株系的分子分析证实了MuNAC4基因的稳定整合和表达。与野生型相比，12个T5代株系对干旱胁迫的耐受性显著增强，侧根生长增多。经长期干燥胁迫试验的转基因植株显示侧根增多且生长呈绿色。生理参数分析还表明，MuNAC4的过表达在提高转基因花生的水分胁迫耐受性、减少对膜结构的损伤以及增强胁迫下的渗透调节和抗氧化酶调节方面发挥了重要作用。本研究证实MuNAC4是未来用于作物耐旱性植物工程方法的重要候选基因。
