Bao Ai-Ke, Wang Yan-Wen, Xi Jie-Jun, Liu Chen, Zhang Jin-Lin, Wang Suo-Min
State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, PR China.
Funct Plant Biol. 2014 Feb;41(2):203-214. doi: 10.1071/FP13106.
Lotus corniculatus L. is an important legume for forage, but is sensitive to salinity and drought. To develop salt- and drought-resistant L. corniculatus, ZxNHX and ZxVP1-1 genes encoding tonoplast Na+/H+ antiporter and H+-pyrophosphatase (H+-PPase) from a succulent xerophyte Zygophyllum xanthoxylum L., which is well adapted to arid environments through accumulating Na+ in its leaves, were transferred into this forage. We obtained the transgenic lines co-expressing ZxNHX and ZxVP1-1 genes (VX) as well as expressing ZxVP1-1 gene alone (VP). Compared with wild-type, both VX and VP transgenic lines grew better at 200mM NaCl, and also exhibited higher tolerance and faster recovery from water-deficit stress: these performances were associated with more Na+, K+ and Ca2+ accumulation in their leaves and roots, which caused lower leaf solute potential and thus retained more water. Moreover, the transgenic lines maintained lower relative membrane permeability and higher net photosynthesis rate under salt or water-deficit stress. These results indicate that expression of tonoplast Na+/H+ antiporter and H+-PPase genes from xerophyte enhanced salt and drought tolerance of L. corniculatus. Furthermore, compared with VP, VX showed higher shoot biomass, more cations accumulation, higher water retention, lesser cell membrane damage and higher photosynthesis capacity under salt or water-deficit condition, suggesting that co-expression of ZxVP1-1 and ZxNHX confers even greater performance to transgenic L. corniculatus than expression of the single ZxVP1-1.
百脉根是一种重要的豆科牧草，但对盐和干旱敏感。为培育耐盐耐旱的百脉根，将来自肉质旱生植物骆驼蓬（通过在叶片中积累钠离子很好地适应干旱环境）的编码液泡膜Na⁺/H⁺反向转运蛋白和H⁺焦磷酸酶（H⁺-PPase）的ZxNHX和ZxVP1-1基因转入这种牧草。我们获得了共表达ZxNHX和ZxVP1-1基因的转基因株系（VX）以及单独表达ZxVP1-1基因的转基因株系（VP）。与野生型相比，VX和VP转基因株系在200mM NaCl条件下生长更好，并且在水分亏缺胁迫下也表现出更高的耐受性和更快的恢复能力：这些表现与它们叶片和根中更多的Na⁺、K⁺和Ca²⁺积累有关，这导致较低的叶片溶质势，从而保留更多水分。此外，转基因株系在盐或水分亏缺胁迫下保持较低的相对膜透性和较高的净光合速率。这些结果表明，旱生植物液泡膜Na⁺/H⁺反向转运蛋白和H⁺-PPase基因的表达增强了百脉根的耐盐性和耐旱性。此外，与VP相比，VX在盐或水分亏缺条件下表现出更高的地上部生物量、更多的阳离子积累、更高的保水能力、更小的细胞膜损伤和更高光合作用能力，表明ZxVP1-1和ZxNHX共表达赋予转基因百脉根比单一ZxVP1-1表达更好的性能。
