玉米液泡膜焦磷酸酶基因ZmVPP1的克隆及逆境下的表达分析

采用同源克隆的方法在玉米中得到一个与拟南芥耐盐基因AVP1类似的基因.BLAST分析表明,该基因编码蛋白属于质子泵焦磷酸酶家族(H_PPase superfamily)中的Ⅰ型VPP,将其命名为ZmVPP1.ZmVPP1包舍一个2301bp的开放阅读框,编码766个氨基酸残基.蛋白比对结果表明,该蛋白在不同植物中相当保守.实时荧光定量PCR检测发现,ZmVPP1基因在成熟叶片中高丰度表达,在生殖器官中表达量较少.脱水、高盐、低温等逆境胁迫条件和ABA处理下的表达分析表明,ZmVPP1基因受逆境的诱导表达,属于不依赖于ABA的途径.由此推断,ZmVPP1可能参与玉米对Na+的隔离,从而起到耐盐的作用.

Cloning and Expression Analysis of ZmVPP1 under Stresses in Maize (Zea mays L.)

Understanding molecular mechanisms of salt tolerance is beneficial to molecular breeding for salt tolerance in Maize. Previous studies on Arabidopsis revealed that the Na+/H+ antiporter conferring salt tolerance depends on the proton gradients established by proton pumps. H+-ATPase and H+-pyrophosphatase pump cytoplasmic H+ across the vacuolar membrane into the vacuole, generate the H+ gradient, and power secondary active transporters of inorganic ions and organic acids. Therefore, in this study a gene from maize based on AVP1 of Arabidopsis by the homology-based cloning was cloning. Blast searches indicated that this gene encodes a vacuolar membrane pyrophosphatase (VPP)-like protein belonging to the H_PPase superfamily, therefore named as ZmVPP1. The cDNA contains an uninterrupted open reading frame of 2301 bp, coding for a polypeptide of 766 amino acids. Multiple sequences alignment revealed that the protein is highly conserved in the plants. Real-time quantitative PCR was used to analyze expression patterns of ZmVPP1 in different organs and under different stresses. We found that ZmVPP1 was mainly expressed in mature leaves but lower in reproductive organs such as young ear, indicating that ZmVPP1 may play some roles in sequestration of Na+ in the vacuole of mature leaves and protect young tissues. Expression under dehydration, PEG, NaCl, cold and ABA showed that ZmVPP1 was response to the stresses rather than ABA. The results suggest that ZmVPP1 is involved in salt tolerance.