小麦胁迫相关基因TaLEAL3的克隆及分子特性分析

第3组LEA蛋白(late embryogenesis abundant protein)介导干旱、高温、高盐等非生物胁迫响应, 关于普通小麦LEA基因的研究鲜有报道。利用噬菌体原位杂交技术, 从小麦苗期干旱胁迫条件构建的cDNA文库中筛选出LEA蛋白基因TaLEAL3, 其全长750 bp, 编码区长501 bp, 编码166个氨基酸, 含有一个明显的核定位信号区。氨基酸同源性分析发现, TaLEAL3属于第3组LEA蛋白, 序列中含有由11个氨基酸组成的3个不完全重复的基序和α-螺旋的LEA结构。电子定位结果显示, TaLEAL3基因位于4BL、4DL和5AL染色体上, 主要在茎中表达, 而在根中几乎无表达。实时荧光定量PCR分析表明, 在干旱、低温和ABA诱导下, TaLEAL3基因表达量明显增加。在该基因上游1.7 kb序列处, 预测具有启动子的核心序列和增强子序列, 及与干旱和低温等多种逆境胁迫相关的调控序列。本研究为深入分析小麦LEA蛋白基因的功能, 初步解析LEA蛋白的作用机制提供了数据。

Isolation and Molecular Characterization of Stress-Related TaLEAL3 Gene in Wheat

Group 3 LEA proteins are proved to mediate plant responses to abiotic stresses such as drought, low temperature, and high salt. However, the LEA genes from common wheat (Triticum aestivum L.) have been rarely studied. We cloned a LEA gene, designated TaLEAL3, from the cDNA library of drought-treated wheat seedlings using phage hybridization in situ. The TaLEAL3 gene is 750 bp in full length and has a 501 bp open reading frame (ORF) encoding 166 amino acids. Based on multiple sequence alignment, TaLEAL3 was found to have the LEA structure characterized by α-helix and three incomplete repeat motifs comprising 11-mer amino acids. The result of electronic mapping showed that TaLEAL3 was located on chromosomes 4BL, 4DL, and 5AL. This gene was mainly expressed in stems but almost not in roots. Besides, the expression of TaLEAL3 was induced markedly by drought, low-temperature, and exogenous abscisic acid. Promoter analysis showed that the core promoter elements and cis-acting elements responding to drought and low-temperature stresses were found in the region of 1.7 kb upstream of TaLEAL3 gene. These results provided experimental data for further studying the function of LEA genes and the mechanism of LEA proteins.