香蕉海藻糖合成酶基因(MaTPS5)生物学及表达特性分析

Biology and Expression Characteristics of Trehalose-6-Phosphate Synthase Gene from Banana

通过研究香蕉Ma TPS5基因的生物学功能,探讨海藻糖合成酶基因在香蕉植株抗逆反应中的作用。利用随机克隆测序法从香蕉根系转录组中获得海藻糖合成酶基因,命名为Ma TPS5。生物信息学分析表明,Ma TPS5全长c DNA序列3 081 bp,完整开放阅读框2 559 bp,编码852个氨基酸;Ma TPS5蛋白属于不稳定、疏水性蛋白,等电点p I6.52,有两个结构域GT1-TPS和TPP,定位于细胞质中,含2个跨膜区域,不存在信号肽;与已知植物TPS氨基酸序列同源性达到77.31%;进化分析表明,香蕉Ma TPS5氨基酸序列与野蕉TPS氨基酸序列聚为一类,说明二者亲缘关系较近,具有共同的祖先。组织特异性表达研究表明Ma TPS5在球茎、叶、花中表达量较高,在根中表达量最低。q RT-PCR分析表明,Ma TPS5响应激素ACC和盐的处理,表达量在24 h均达到极显著水平。在Foc TR4病原菌处理后,表达量升高,并在3个时段保持一致。结果表明,Ma TPS5可能依赖乙烯信号传导途径诱导自身表达,合成海藻糖,参与香蕉抗逆反应。

Our aim is to explore the role of trehalose-6-phosphate synthase gene in the stress tolerance of banana plant by studying its biological function. A gene from banana rhizome＇s transcriptome, designated as MaTPS5, was reaped using the method of random cloning and sequencing. Bioinformatics analysis showed the full length of MaTPS5 cDNA sequence Was 3 081 bp, containing a complete open reading frame of 2 559 bp, encoding 852 amino acids. Protein MaTPS5 was an unstable and hydrophobic protein with iso-electric point of 6.52,..in which there were two structure domains of GT1-TPS and TPP. It was located in cytoplasm and had two trans-membrane regions but no signal peptide. Comparing MaTPS5 protein sequence to the known plant TPS amino acid sequence, the＇ homology level was 77.31%. Phylogenetic analysis showed MaTPS5 protein sequence was clustered on a common branch with the TPS protein sequence of wi｜d banana, indicating that they were the close relatives and had a common ancestor. Tissue-specific analysis indicated MaTPS5 expression level was high in corm, leaves, and flowers, but the lowest in the roots, qRT-PCR analysis showed MaTPS5 expression increased when banana plantlets were treated with ACC and salt, and peaked at 24 h. After treating banana plantlets with Foc TR4 pathogen, the MaTPS5 expression level rose and was constant in three hours. The results showed MaTPS5 may depend upon the ethylene signaling transduction pathways to induce itself expression, and synthesize trehalose, and therefore participate in stress tolerance of banana plants.