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γ-谷氨酰半胱氨酸合成酶(γGCS)是细胞内谷胱甘肽(GSH)生物合成的限速酶,GSH在植物许多生理过程中发挥重要作用。本研究采用简并PCR和RACE技术获得巴西橡胶树γGCS基因全长cDNA序列,命名为HbγGCS(GenBank登录号:GU997638)。该基因全长2187bp,最长开放阅读框为1572bp,编码523个氨基酸。进化分析结果表明HbγGCS属双子叶植物γGCS亚类,同葡萄γGCS分为一组,与单子叶植物的亲缘关系较远。半定量RT-PCR结果表明HbγGCS基因在胶乳、叶片、树皮、花中均有表达,以花中表达量最大。健康橡胶树胶乳中HbγGCS表达量高于死皮树。HbγGCS表达受乙烯、茉莉酸、过氧化氢、机械伤害、干旱、低温和高盐调控。
Gamma-glutamylcysteine synthase (γGCS) is the rate-limiting enzyme in intracellular glutathione (GSH) biosynthesis and GSH plays an important role in many physiological processes in plants. In this study, the degenerate PCR and RACE techniques were used to obtain the full-length cDNA sequence of γGCS gene from Hevea brasiliensis (HbγGCS) (GenBank accession number: GU997638). The full length of this gene is 2187bp and the longest open reading frame is 1572bp, encoding 523 amino acids. Phylogenetic analysis showed that HbγGCS belongs to the dicotyledonous γGCS subclass, which is divided into a group with grapevine γGCS, which is more distantly related to monocotyledons. The results of semi-quantitative RT-PCR showed that the HbγGCS gene was expressed in latex, leaves, bark and flower, and the expression was the highest in flowers. The expression level of HbγGCS in healthy rubber latex was higher than that of dead skin. HbγGCS expression is regulated by ethylene, jasmonic acid, hydrogen peroxide, mechanical injury, drought, hypothermia and high salt.