LAUSR

Zygophyllum xanthoxylum, a succulent xerophyte, possesses excellent salt tolerance which is closely associated with vacuolar Na+ compartmentation via ZxNHX1. RNA interference (RNAi)-mediated ZxNHX1 silencing impaired the characteristics of Na+ accumulation and thus inhibited normal growth of Z. xanthoxylum. To explore the molecular mechanisms underlying the changed phenotype, here we compared the different expression of salt-responsive genes between ZxNHX1-RNAi line and wild type at transcriptome level. The result showed that vast genes were differently expressed in leaves or roots between ZxNHX1-RNAi line and wild type under control condition or salt treatment. Among them, 142 unigenes were differently expressed in both roots and leaves under 50 mM NaCl for 6 h and 24 h between ZxNHX1-RNAi line and WT. These differentially expressed genes (DEGs) were related to transmembrane transportation based on Gene Ontology (GO) annotations. In terms of ion transport, 49 DEGs were identified, in which some genes associated with Na+ and K+ homeostasis were down-regulated; meanwhile, silencing of ZxNHX1 triggered the differential expression of several genes involved in the transport of important nutrient elements including N, P, Ca, and Mg. Besides, silencing of ZxNHX1 affected the expression level of 18 and 26 genes related to photosynthesis and ROS scavenging, respectively. This study provided strong evidences to indicate the dominant role of ZxNHX1 in maintaining the characteristics of salt accumulation and regulating the salt tolerance of Z. xanthoxylum.