Characterization And Functional Analysis Of The Vacuolar Na～+/H～+ Antiporter Gene In Agropyron Elongatum

Salt tolerance is one of the most important factors that affect productivity of crops in the world. To cope with salt stress, plants have developed a variety of adaptation mechanisms. One of them is the compartmentation of Na+ into the vacuoles by the vacuolar Na+/H+ antiporters. It is reported that overexpressing the vacuolar Na+/H+ antiporter gene can improve the salt tolerance of Arabidopsis and tomato. In this study, we islated a vacuolar Na+/H+ antiporter gene AeNHX1 from Agropyron elongatum, the functional analysis demonstrated that this gene plays an important role in plant salt tolerance. Overexpressing AeNHX1 can remarkably promote the salt tolerance of transgenic Arabidopsis and Festuca arundinacea plants. Our study suggests that AeNHX1 can be used to improve plant salt tolerance by genetic engineering. The main results of this study summarized below: According to the sequences of the vacuolar antiporter proteins in GenBank, we designed degenerate primers to isolate vacuolar antiporter gene. Two genes, which named AeNHX1 (Acession Numeber:AF507044)and AeNHX2 (Acession Numeber:AY371178) were isolated from root and leaf of Agropyron plants. Sequence analysis and phylogenetic tree shows that they belong to a vacuolar antiporter gene family.AeNHX1-GFP fusion protein was constructed and transiently expressed in onion epidermal cells. The green fluorescence was detected on the tonoplast, demonstrating that AeNHX1 subcellular localization on vacuolar membrane. Southern hybridization shows that there are at least seven copies of AeNHX1 in Agropyron genome. Northern hybridization shows that AeNHX1 is constitutively expressed in root tissues, and its expression is not induced by salt stress.Full-lengh cDNA of AeNHX1 was introduced into the yeast Na+/H+ antiporter mutant...