小麦脂质转运蛋白基因TaLTP克隆及功能分析

Cloning and Functional Analysis of Lipid Transfer Protein Gene TaLTP in Wheat

脂质转运蛋白(lipid transfer protein,LTP)是广泛存在于植物中的一类小分子蛋白,因其能在植物细胞膜间运输脂类物质而得名,在植物角质层合成和适应多种环境胁迫中起重要作用。本研究利用同源克隆方法得到Ta LTP-s的c DNA全长序列510 bp,开放阅读框为339 bp,编码112个氨基酸。利用RIL群体将Ta LTP-s定位在染色体1A上,距离两侧标记WMC449和WMC93的遗传距离分别为2.1 c M和5.9 c M。通过原生质体亚细胞定位显示Ta LTP-s定位于细胞膜和细胞质中。小麦开花期Ta LTP-s在小花中表达量较高,尤其是在花药中的表达量远高于在根和叶中。在ABA、PEG、Na Cl及4℃低温胁迫诱导下,小麦Ta LTP-s均上调表达,可能与抗逆性调节相关。在高盐胁迫处理下,转基因拟南芥幼苗的细胞膜稳定性和存活率显著高于野生型。研究结果为利用小麦脂质转运蛋白基因改良作物抗逆性奠定了基础。

Lipid transfer protein（LTP） is a kind of small molecular protein, which name stands for its ability to transfer lipid between cell membranes in plant. LTP plays a key role in cuticle synthesis and adaptation to abiotic stress. We cloned a full-length c DNA sequence of Ta LTP gene encoding a lipid transfer protein from wheat（Triticum aestivum L.）, which length is 510 bp with a 339 bp open reading frame. The c DNA sequence contains 112 amino acids with a N-terminal signal peptide within the first 25 amino acids. This gene contains eight cysteine residues conserved in amino acid sequences. Ta LTP-s was detected to be located between markers WMC449 and WMC93 on chromosome 1A in wheat, with genetic distances of 2.1 c M and 5.9 c M, respectively. The result of subcellular localization exhibited that Ta LTP-s is located in the cell membrane and cytoplasm. Ta LTP-s was expressed in all tissues at flowering stage, including leaf, root, floret, anther and pistil, and mature seeds of wheat. The highest expression level was identified in the floret, especially in the anther. Ta LTP-s was up-regulated by ABA, PEG, Na Cl, and 4oC treatments which indicates that Ta LTP-s is involved in different signal pathways responding to abiotic stress. Arabidopsis thaliana overexpressing Ta LTP-s showed higher cell membrane stability and survival rate than the controls under salinity stress. These results provide a candidate gene for wheat improvement in response to salt and other abiotic stresses.