该文旨在初步探讨水杨酸的主要结合态——葡糖基水杨酸(salicylic acid 2-O-β-D-glucose, SAG), 是否参与了高温诱导的植物耐热性信号传递过程。采用水杨酸(salicylic acid, SA)生物合成抑制剂——多效唑(paclobutrazol, PAC), 预处理豌豆(Pisum sativum)叶片, 再加以高温诱导, 结果发现与未经PAC处理的对照相比, 豌豆叶片受高温诱导的耐热性降低。同时, PAC预处理导致高温锻炼过程中SAG信号峰值消失。利用同位素标记和蛋白免疫印迹分析发现, PAC所导致的SAG信号减弱, 不仅是由于SA生物合成受到抑制, 而且还归因于水杨酸糖苷转移酶(salicylic acid glucosyltransferase, SAGT)蛋白合成和活性降低所引起的自由态SA向SAG转化的减缓。以上结果表明, SAG表现出了与自由态SA相似的信号功能, 并参与了高温锻炼诱导植物耐热性的信号传递过程。

To investigate whether conjugated salicylic acid (SA)—SA 2-O-β-D-glucose (SAG) involves thermotolerance of pea leaves induced by heat acclimation, we used the inhibitor of SA biosynthesis (i.e., paclobutrazol; PAC) to evaluate the role of SAG, and found that PAC treatment reduced the thermotolerance of pea leaves induced by heat acclimation. Our further analyses indicated that PAC pretreatment led to an abrupt decrease in SAG during heat acclimation, which might be not only due to the inhibition of SA biosynthesis but also to the conversion retarding of free SA to SAG catalyzed by glucosyltransferase (SAGT). These results suggest that SAG may act as a signal molecule as SA does, to involve thermotolerance induced by heat acclimation.