Fundación Ciencia & Vida, Zañartu 1482, Ñuñoa, Santiago, Chile.
Biochem Biophys Res Commun. 2013 Jan 11;430(2):535-40. doi: 10.1016/j.bbrc.2012.11.118. Epub 2012 Dec 8.
Environmental stress factors such as salt, drought and heat are known to affect plant productivity. However, high salinity is spreading throughout the world, currently affecting more than 45 millionha. One of the mechanisms that allow plants to withstand salt stress consists on vacuolar sequestration of Na(+), through a Na(+)/H(+) antiporter. We isolated a new vacuolar Na(+)/H(+) antiporter from Eucalyptus globulus from a cDNA library. The cDNA had a 1626 bp open reading frame encoding a predicted protein of 542 amino acids with a deduced molecular weight of 59.1 KDa. Phylogenetic and bioinformatic analyses indicated that EgNHX1 localized in the vacuole. To assess its role in Na(+) exchange, we performed complementation studies using the Na(+) sensitive yeast mutant strain Δnhx1. The results showed that EgNHX1 partially restored the salt sensitive phenotype of the yeast Δnhx1 strain. However, its overexpression in transgenic Arabidopsis confers tolerance in the presence of increasing NaCl concentrations while the wild type plants exhibited growth retardation. Expression profiles of Eucalyptus seedlings subjected to salt, drought, heat and ABA treatment were established. The results revealed that Egnhx1 was induced significantly only by drought. Together, these results suggest that the product of Egnhx1 from E. globulus is a functional vacuolar Na(+)/H(+) antiporter.
环境应激因子，如盐、干旱和热，已知会影响植物的生产力。然而，高盐度正在世界各地蔓延，目前影响超过 4500 万公顷。使植物能够耐受盐胁迫的机制之一是通过液泡 Na(+)/H(+)反向转运蛋白将 Na(+)隔离在液泡内。我们从桉树 cDNA 文库中分离到一种新的液泡 Na(+)/H(+)反向转运蛋白。该 cDNA 具有 1626bp 的开放阅读框，编码一个预测的 542 个氨基酸的蛋白质，推断分子量为 59.1 kDa。系统发育和生物信息学分析表明，EgNHX1 定位于液泡中。为了评估其在 Na(+)交换中的作用，我们使用 Na(+)敏感的酵母突变株 Δnhx1 进行了互补研究。结果表明，EgNHX1 部分恢复了酵母 Δnhx1 菌株的盐敏感表型。然而，其在转基因拟南芥中的过表达赋予了在 NaCl 浓度增加时的耐受性，而野生型植物则表现出生长迟缓。建立了受盐、干旱、热和 ABA 处理的桉树幼苗的表达谱。结果表明，Egnhx1 仅在干旱条件下显著诱导。综上所述，这些结果表明，来自桉树的 Egnhx1 的产物是一种功能性的液泡 Na(+)/H(+)反向转运蛋白。
