木薯MeTPS7基因克隆及其在非生物胁迫下的表达分析

Cloning of MeTPS7 Gene in Cassava and Expression Analysis of It under Abiotic Stress

海藻糖-6-磷酸合成酶(trehalose-6-phosphate synthase,TPS)是海藻糖生物合成途径中的关键酶,提高TPS基因的表达可以增强植物在干旱、低温等非生物胁迫条件下的抗逆性。为了研究TPS基因在热带作物木薯抗逆中的功能,本研究通过RT-PCR的方法从木薯叶片中克隆了一个TPS基因,命名为Me TPS7。该基因含有一个2 562 bp的开放阅读框,编码853个氨基酸,含有TPS家族保守结构域,属于TPS第Ⅱ家族成员。系统进化树分析表明,Me TPS7与杞柳和杨树中同源基因的亲缘关系较近,序列相似性分别达到90.2%和90.3%。启动子元件分析表明,Me TPS7含有干旱诱导(MBS)、低温和干旱响应(C-repeat/DRE)、热胁迫响应(HSE)、ABA响应(ABRE)、以及光响应(ACE,G-Box,BoxⅠ,Box 4)等元件。实时荧光定量PCR分析表明,Me TPS7在须根中表达最高,叶片和储藏根中表达最低,其表达量仅为须根的34%和38%。而且,Me TPS7基因的表达能被干旱、低温、遮荫和ABA处理显著诱导。这些结果表明Me TPS7可能在转录水平参与ABA介导的木薯干旱、低温和遮荫胁迫响应,可作为候选基因进一步研究其在木薯抗逆中的功能。

Trehalose-6-phosphate synthase （TPS） is a key enzyme in the biosynthetic pathway of trehalose. Improving the expression of TPS gene can enhance the stress tolerance of plants under abiotic stress, such as drought and cold. In order to reveal the function of TPS gene in abiotic stress tolerance of tropical plant cassava, a TPS gene named MeTPS7 was cloned from cassava leaves by RT-PCR method in this study. This gene had a 2 562 bp open reading frame encoding 853 amino acids with conserved TPS domain, which belonged to the class II members of TPS gene family. Phylogenetic tree analysis showed that Me TPS7 had close genetic relationship with its homologous gene from Salix purpurea and Populus trichocarpa, and their sequence similarities were up to 90.2% and 90.3%, respectively. Promoter element analysis revealed that MeTPS7 contained drought-induced motif （MBS）, cold and drought responsive motif （C-repeat/DRE）, heat-responsive motif （HSE）, ABA responsive motif （ABRE）, and several light-responsive motifs including ACE, G-Box, Box I, Box 4. qRT-PCR analysis indicated that Me TPS7 had the highest expression in fibrous root, but the lowest in leaves and storage root, and their expressions were only 34% and 38% of that in fibrous roots. In addition, the expression of MeTPS7 could besignificantly induced by drought, cold, shading, and also ABA treatment. These results suggested that MeTPS7 might be transcriptionally involved in the ABA-mediated abiotic stress of drought, cold, and shading in cassava, which could be used as a candidate gene to further study its function in stress resistance of cassava.