玉米小分子热激蛋白ZmHSP17.7基因的克隆与功能分析

摘要

植物热激蛋白是一类代表性高温响应蛋白。以玉米种质POB21为材料,克隆了一个CDS序列长度为477 bp的小分子热激蛋白基因。该基因编码的蛋白含158个氨基酸,具有HSP20蛋白典型的ACD结构域,预测的等电点为5.36,分子量为17.746 kD,被命名为ZmHSP17.7。在水稻、拟南芥等植物基因组中都有其同源基因,进化和亚细胞定位分析表明,此基因属CI类小分子热激蛋白家族成员。Northern杂交分析表明,高温快速诱导ZmHSP17.7基因表达,15%PEG模拟干旱胁迫不诱导该基因表达,但在复合胁迫下干旱增强了高温的诱导效果。外源ABA也不影响该基因的表达。与野生型拟南芥相比,超表达ZmHSP17.7的转基因拟南芥在种子萌发和植株生长过程中表现出更强的高温和干旱耐受性,说明该基因可以在植物防御高温、干旱及复合胁迫中发挥一定作用。%Heat shock proteins are typical proteins responding to high temperature. Maize germplasm POB21 was used to isolate a small heat-shock protein gene with a 477 bp CDS sequence. This gene, designatedZmHSP17.7, encodes a protein of 158 amino acids, which contains the typical ACD domain of HSP20 proteins. The predicted isoelectronic point and molecular weight of ZmHSP17.7 protein are 5.36 and 17.746 kD, respectively. The ZmHSP17.7 homologues were found in diverse plants, such as Arabidopsis and rice. According to the phylogenetic and subcellular localization analyses, ZmHSP17.7 is considered as a member of CI class of small heat shock protein family. The Northern blotting assay indicated that the expression ofZmHSP17.7was quickly induced by high temperature. Drought stress simulated by 15% PEG did not regulate the gene expression independently, but enhanced the heat-induced gene expression under combined stress of high temperature and drought. Exogenous ABA had no influence onZmHSP17.7 expression. Overexpression ofZmHSP17.7 inArabidopsis during seed germination and plant growth enhanced tolerance to high temperature and drought stresses. Our results indicate thatZmHSP17.7 may play a certain role in pro-tecting plant from high temperature, drought and their combination.