铅胁迫下景天属和花生属植物根系有机酸分泌特性分析

在溶液培养条件下,铅（Pb）处理15 min后景天属植物就开始大量分泌有机酸,而花生属植物在4h后才开始分泌,总有机酸在12 h后达到最大值,且野生种类的分泌强度要明显超过栽培种类.蛋白质合成抑制剂环己亚酰胺（CHM）不影响景天属植物根系有机酸的分泌,但明显抑制了花生属植物有机酸的分泌,表明后者的分泌过程必须有新蛋白质的诱导合成.阴离子通道抑制剂苯甲酰甲醛（PG）和蒽-9-羧酸（A-9-C）均明显抑制Pb诱导下景天属和花生属植物根系有机酸的分泌,显示出两者的有机酸分泌是与膜系统上的阴离子通道密切相关,且能被Pb所诱导或激活.景天属植物和花生属植物根系有机酸的分泌受到抑制后,其叶片的相对电导率、丙二醛（MDA）含量都明显升高,显示植物抗逆境能力与根系有机酸的分泌强度存在一定联系.

Influence of Lead Stress on Root Organic Acid Exudates of Sedum and Arachis Plants

The organic acids secretion （OAS） in Sedum species roots occurred within 15 min of Pb exposure,while that in Arachis species roots was induced after at least 4 h.A protein-synthesis inhibitor cycloheximide （CHM） had no obvious effect on the Pb induced OAS in Sedum species,but strongly inhibited the OAS in Arachis species roots.This suggested that novel protein synthesis was not involved in the Pb induced oxalate secretion in Sedum species,but was essential in Arachis species.The OAS in Sedum species was sensitive to anion channel blocker phenylglyoxal （PG） and the citrate secretion in Arachis species was sensitive to anthrancene-9-carboxylic acid （A-9-C）,indicating anion channels were involved in OAS of both pattern plants.In accompanying with the inhibition of OAS by protein-synthesis inhibitor cycloheximide （CHM）,anion channel blocker PG and A-9-C,the level of cell relative conductivity and the contents of malondialdehyde （MDA） of Sedum and Arachis species under lead treatment were sharply improved.This indicated that there was a possible link between the capacity of plant stress resistance to heavy metal and the intensity of the organic acids and other chemical ecological metabolites exuded from roots.