The ZxNHX Gene Encoding Vacuolar Na+/H + Antiporter from the Xerophyte Zygophyllum xanthoxylum Plays Important Roles in Response to Drought

摘要

Sodium (Na+) has been found to play important roles in adaptation of xerophytic species to drought conditions. The vacuolar Na+/H+antiporter is involved in the compartmentation of Na+into vacuoles from cytosol. In this study, a gene (ZxNHX) encoding vacuolar Na+/H+antipoiter was isolated and characterized from Zygophyllum xanthoxylum, a succulent xerophyte growing in desert areas of northwest China. The results revealed that ZxNHX consisted of 532 amino acid residues with a conserved binding domain (TM LFFIYLLPPI87) for amiloride and shared higher similarity (73-81%) with the known vacuolar Na+/H+antiporters. Semi -quantitative RT -PCR analysis showed that the transcript abundance of ZxNHX in Z. Xanthoxylum subjected to drought (50 -15% of FWC -field water capacity) was 2.3 -4.4 times of that in plants grown under 70% of FWC. Leaf Na+concentration in plants treated with drought was 1.5 -2.2 times of that in control plants. It is clear that there is a positive relationship between the up -regulation of ZxNHX and Na+accumulation in Z. Xanthoxylum exposed to drought. These results suggest that ZxNHX plays important roles in response of Z. Xanthoxylum to drought.