Chen Xianyang, Bao Hexigeduleng, Guo Jie, Jia Weitao, Li Yinxin
a Key Laboratory of Plant Molecular Physiology; Institute of Botany ; Chinese Academy of Sciences ; Beijing , PR China.
Plant Signal Behav. 2015;10(4):e993240. doi: 10.4161/15592324.2014.993240.
Recently, we found NHX1, the gene encoding a Na(+)/H(+) exchanger, participated in plant disease defense. Although NHX1 has been confirmed to be involved in plant salt tolerance, whether the NHX1 transgenic plants exhibit both salt tolerance and disease resistance has not been investigated. The T1 progenies of Nicotiana tabacum L. lines expressing SeNHX1 (from Salicornia europaea) were generated for the present study. Compared with PBI-type control plants, SeNHX1 transgenic tobaccos exhibited more biomass, longer root length, and higher K(+)/Na(+) ratio at post germination or seedling stage under NaCl treatment, indicating enhanced salt tolerance. The vacuolar H(+) efflux in SeNHX1 transgenic tobacco was increased after treatment of NaCl with different concentration. Meanwhile, the SeNHX1 transgenic tobaccos showed smaller wilted spot area, less H2O2 accumulation in leaves after infection of Phytophthora parasitica var. nicotianae. Further investigation demonstrated a larger NAD(P)(H) pool in SeNHX1 transgenic tobacco. These evidences revealed that overexpression of SeNHX1 intensified the compartmentation of Na(+) into vacuole under salt stress and improved the ability of eliminating ROS after pathogen attack, which then enhanced salt tolerance and disease resistance simultaneously in tobacco. Our findings indicate NHX1 has potential value in creating crops with both improved salt tolerance and disease resistance.
最近，我们发现编码Na(+)/H(+)交换蛋白的基因NHX1参与了植物的病害防御。尽管NHX1已被证实参与植物的耐盐性，但尚未研究过NHX1转基因植物是否同时具有耐盐性和抗病性。本研究培育了表达SeNHX1（来自欧洲海蓬子）的烟草品系的T1代后代。与PBI型对照植株相比，SeNHX1转基因烟草在NaCl处理后的萌发后或幼苗期表现出更多的生物量、更长的根长以及更高的K(+)/Na(+)比值，表明其耐盐性增强。用不同浓度的NaCl处理后，SeNHX1转基因烟草的液泡H(+)外流增加。同时，SeNHX1转基因烟草在感染烟草疫霉后，萎蔫斑面积更小，叶片中H2O2积累更少。进一步研究表明，SeNHX1转基因烟草中NAD(P)(H)库更大。这些证据表明，SeNHX1的过表达在盐胁迫下增强了Na(+)向液泡的区室化，并提高了病原体攻击后清除活性氧的能力，从而同时增强了烟草的耐盐性和抗病性。我们的研究结果表明，NHX1在培育具有改良耐盐性和抗病性的作物方面具有潜在价值。
