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γ-谷氨酰半胱氨酸合成酶(γGCS)是植物细胞内谷胱甘肽(GSH)生物合成的限速酶,在植物许多的生理过程中具有重要作用。从刚毛柽柳转录组数据库中分析并获得1条刚毛柽柳γGCS基因全长c DNA序列,命名为ThγGCS。该基因全长2 121 bp,开放阅读框为1 536 bp,编码511个氨基酸。生物信息学分析结果表明,ThγGCS推导的氨基酸序列分别与苜蓿、大豆以及橡胶树等具有很高的同源性;进化分析结果表明ThγGCS属双子叶植物γGCS亚类,同橡胶树,芥菜等γGCS分为一组,与单子叶植物的亲缘关系较远。该蛋白质无跨膜结构域,但具有1个保守的GCS2结构域,并被定位于叶绿体中,说明ThγGCS蛋白质较稳定,并属于谷氨酰半胱氨酸连接酶家族。为了研究该基因在不同非生物胁迫下的应答情况,利用实时定量RT-PCR技术,分析ThγGCS在NaCl和PEG胁迫处理后不同时间、不同组织中基因的表达。结果表明,ThγGCS受NaCl、PEG诱导上调表达,推测其可能在刚毛柽柳抗旱耐盐过程中发挥重要作用。
Gamma-glutamylcysteine synthetase (γGCS) is a rate-limiting enzyme in the biosynthesis of glutathione (GSH) in plant cells and plays an important role in many physiological processes in plants. A full-length c DNA sequence of γGCS gene from Tamarix ramosissima was obtained from the Tamarix ramosissima transcriptome database and named as ThγGCS. The full length of this gene was 2 121 bp, with an open reading frame of 1 536 bp encoding 511 amino acids. The results of bioinformatics analysis showed that the deduced amino acid sequence of ThγGCS had high homology with that of Medicago sativa, soybean and rubber tree respectively. The phylogenetic analysis showed that ThγGCS belongs to the dicotyledonous γGCS subclass, Group, and monocotyledons distant genetic relationship. This protein has no transmembrane domain but a conserved GCS2 domain and is localized in the chloroplast, indicating that the ThyGCS protein is more stable and belongs to the glutamylcysteine ligase family. In order to investigate the response of this gene under different abiotic stresses, the gene expression of ThγGCS in different tissues and tissues at different time points after NaCl and PEG stress was analyzed by real-time quantitative RT-PCR. The results showed that ThγGCS was up-regulated by NaCl and PEG, suggesting that ThγGCS might play an important role in the drought tolerance and salt tolerance of Salix babylonica.