铝胁迫下黑麦和小麦根尖分泌有机酸的研究

Secretion of organic acids from root apices under Al stress in rye and wheat

关键词:  铝  根尖  有机酸  分泌

Key words:  Aluminum  root apex  organic acids  secretion

摘要:

通过建立的活体根培养及微量根尖分泌物收集系统,对铝胁迫下黑麦和小麦根尖分泌的有机酸进行研究。结果表明:50、100、200、300 μmol·L^-1 AlCl₃处理后黑麦根尖分泌柠檬酸和苹果酸,而铝仅诱导小麦根尖分泌苹果酸。铝处理3 h后,根尖分泌的苹果酸显著增加,并在9 h内维持较高的分泌速率。铝诱导黑麦根尖分泌柠檬酸有明显的迟缓期,Al(300 μmol·L^-1)处理后的最初3 h,根尖分泌的柠檬酸并不显著增加。在铝溶液中添加的阴离子通道抑制剂A-9-C(20、60、100 μmol·L^-1)显著抑制根尖分泌有机酸。然而,将黑麦根尖浸泡于含异三聚体G蛋白激活剂霍乱毒素(50 ng·mL^-1)后,根尖分泌的有机酸显著增加。说明建立的微量根尖分泌物收集系统适合于铝诱导根尖分泌有机酸的研究,小麦和黑麦根尖在铝胁迫下以不同模式通过阴离子通道分泌有机酸,而异三聚体G蛋白可能介导根尖分泌有机酸。

Abstract:

Secretion of organic acids from roots apices in rye and wheat were investigated by a system for in vivo root apex culture and micro-exudates collection,to elucidate the mechanisms for Al-induced secretion of organic acids. The results showed that Al(50,100,200,300 μmol·L^-1 AlCl₃)induced secretion of citrate and malate from rye root apices,while wheat root apices secreted malate alone in response to Al treatment. Malate was significantly secreted from root apices of rye and wheat after the treatment with Al for 3 h,and malate was secreted with a high secretion rate within 9 h treatment. There was a lag between the secretion of citrate and Al treatment in rye. At initial 3 h,Al failed to induce significantly secretion of citrate. On the other hand,the addiction of anion channel inhibitor A-9-C(20、60、100 μmol·L^-1)to Al solution,the secretion of organic acids was significantly inhibited. However,the amount of organic acids secreted elevated significantly after the exposure of root apices to Al solution with heterotrimeric G-protein agonist cholera toxin(50 ng·mL^-1). These results suggested that our system for in vivo root apex culture and micro-exudates collection was a available tool for the studies on Al-induced secretion of organic acids,and organic acids were secreted from root apices of rye and wheat by anion channels in different patterns,while heterotrimeric G-protein may mediate the secretion of organic acids from root apices.