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通过随机克隆测序的方法从香蕉根系c DNA文库中获得海藻糖合成酶基因,命名为Ma TPS3。Ma TPS3扩增获得的c DNA序列全长为2 874 bp,包含一个完整的开放阅读框1 971 bp,编码蛋白含656个氨基酸。其氨基酸理化性质分析表明,Ma TPS3蛋白属于不稳定、疏水性蛋白蛋白,等电点p I6.26,具有两个结构域TPS和TPP;序列预测分析表明,Ma TPS3蛋白定位于细胞质中,该蛋白含一个跨膜区域,不存在信号肽。通过与已知植物的TPS氨基酸同源序列比对,相似性为67.31%;其中与印度水稻、蒺藜状苜蓿TPS氨基酸的进化关系较近,同源性分别为55.13%、54.71%。器官特异性分析表明,Ma TPS3在香蕉植株的根、球茎、假茎、叶、花、果实各器官中均有表达,在叶片和花中表达量较多。q PCR分析表明,盐胁迫下Ma TPS3表达量增加,于24 h时达到最高;在冷胁迫处理下,Ma TPS3表达量较0 h时则明显下调;ACC胁迫处理下,Ma TPS3表达量逐渐增加,在24 h表达量为0 h时4倍。巴拿马病菌4号生理小种(Foc4)侵染后,Ma TPS3在根系中下调表达,在24 h时表达量显著低于0 h时。因此,Ma TPS3可能参与调控香蕉抗盐胁迫机制,从而提高香蕉耐盐性,并参与调控植物激素生物合成。
The trehalose synthase gene was obtained from banana root cDNA library by random cloning sequencing and named Ma TPS3. The total length of c DNA sequence obtained from Ma TPS3 amplification was 2 874 bp, including a complete open reading frame of 1 971 bp and encoded protein of 656 amino acids. The amino acid physical and chemical properties of Ma TPS3 protein showed that Ma TPS3 protein is an unstable, hydrophobic protein protein with isoelectric point p I6.26, which has two domains of TPS and TPP. Sequence prediction analysis showed that Ma TPS3 protein localized in the cytoplasm. The protein contains a transmembrane region and no signal peptide is present. The similarity to the TPS amino acid sequence of the known plants was 67.31%. Among them, the phylogenetic relationship was close to TPS amino acid in Indian alfalfa and Medicago truncatula, and the homologies were 55.13% and 54.71% respectively. Organ-specific analysis showed that Ma TPS3 was expressed in all organs of banana plant roots, bulbs, pseudostems, leaves, flowers and fruits, and more in leaves and flowers. qPCR analysis showed that Ma TPS3 expression increased under salt stress and reached its peak at 24 h. Under cold stress, the expression of Ma TPS3 was significantly down-regulated compared with that at 0 h. Under the stress of ACC, the expression of Ma TPS3 gradually increased , 4-fold at 0 h at 24 h. Ma TPS3 was down-regulated in root system after infection with Foc4 panama virus, and its expression was significantly lower than that at 0 h at 24 h. Therefore, Ma TPS3 may be involved in the regulation of banana salt stress mechanism, thereby enhancing the salt tolerance of bananas and participating in the regulation of plant hormone biosynthesis.