铝胁迫下大豆根尖柠檬酸分泌及SGA1基因的表达.docVIP

 铝胁迫下大豆根尖柠檬酸分泌及 SGA1 基因 的表达# 杨列耿1，杨曙1，张永先1，黎晓峰1,2** 5 10 15 20 25 30 35 40 （1. 广西大学农学院，南宁 530005； 2. 亚热带生物资源保护与利用国家重点实验室，南宁 530004） 摘要：为揭示铝诱导有机酸分泌的机制，对铝胁迫下大豆根尖分泌有机酸及根尖 SGA1 基因 的表达进行了研究。自行设计了根尖培养和根尖分泌物收集装置，成功地检测到铝诱导大豆 根尖分泌的柠檬酸。柠檬酸分泌随着铝处理浓度（25、50 μmol· L-1）和时间（2-12 h）的 增加而增加。大豆根尖以模式 II 分泌柠檬酸：处理后的前 4h，分泌速率很低，其后显著提 升。有机酸明显分泌的诱导期长达 6h。另一方面，在铝（50 μmol· L-1）溶液中添加 G 蛋 白抑制剂霍乱毒素(200 ng· ml-1)，柠檬酸分泌减少 38.7%。RT-PCR 分析结果显示，铝诱导 大豆根尖 SGA1 基因的表达，其表达水平随着铝处理时间（0.5-12h）的延长有提升的趋势， 而铝诱导的 SGA1 基因表达明显早于有机酸开始分泌时间（6 h）。这些结果暗示，铝诱导大 豆根尖分泌柠檬酸及 SGA1 基因的表达，G 蛋白可能参与有机酸分泌的调控。 关键词：植物营养学；大豆；柠檬酸；分泌；G 蛋白；基因 中图分类号：Q945.78 Secretion of Citrate from Root Apices and Expression of SGA1 in the Soybean under Al Stress Yang Liegeng1, YANG Shu1, ZHANG Yongxian1, LI Xiaofeng1,2 (1. College of Agriculture, Guangxi University, Nanning 530005; 2. State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Nanning 53004) Abstract: Abstract: In this paper the secretion of organic acids from root apices and the expression of SGAI gene in root tips under aluminum stress were investigated to elucidate the mechanisms for Al-induced secretion of organic acids. A mini-growth incubator for incubating root-apices and collecting root apex exudates was invented and Al-induced secretion of organic acids was detected successfully by means of this incubator. The secretion elevated with the increase of Al concentration and prolongation of treatment with Al. Citrate was secreted from root apices by pattern II in soybean. The secretion rate was very low within initial 4 h after Al treatment but remarkably elevated thereafter. A gap between the secretion and Al treatment reached to about 6 h. On the other hands, the addition of cholera toxin, an inhibitor of G-protein, to Al solution, the amount of citrate secreted decreased by 38.7%. RT-PCR analysis results indicated that SGA1 expression was resulted from Al treatment. In generally, the expression levels elevated with the prolongation of the treatm