MECHANISM OF GENE INDUCTION IN ETHYLENE BIOSYNTHETIC PATHWAY BY HERBICIDES

虽然生长素类除草剂被认为与天然生长素类除草剂作用相似，并且它们对乙烯生物合成的刺激被认为与除草剂的植物毒性作用有关，但它们的确切作用机制仍然是个谜。本研究旨在阐明生长素类除草剂二氯喹啉酸对敏感禾本科植物的作用方式和乙烯合成相关基因的诱导机制。根显著促进了乙烯的释放，特别是在光照下。此外，只有在光照下才能检测到叶片漂白和含水量下降。光照对二氯喹啉酸的植物毒性作用是唯一的，而其他生长素类除草剂如2，4-D则没有观察到这种作用。因此，该酶的诱导被认为是乙烯释放增加的主要因素。从诱导的模式，参与创伤诱导型ACC基因的除草剂在光的建议。诱导基因的研究正在进行中。

Although the auxin-type are considered to herbicides act like natural auxins in plants and their stimulation of ethylene biosynthesis is assumed to be involved in the phytotoxic action of the herbicides, their precise action mechanism is still enigma. The objectives of this study were to clarify the mode of action of auxin-type herbicide quinclorac on susceptible gramineous plants and the mechanisms of gene induction involved in ethylene synthesis.Quinclorac treatment to corn (Zea mays cv. Honey Bantam) roots significantly stimulated ethylene evolution from shoots especially under light irradiation. Moreover, bleaching of leaves and decrease of water content was detected only in the light. Involvement of light for the phytotoxic action was unique to quinclorac and not observed with other auxin-type herbicides such as 2,4-D.Ethylene evolution was also affected by ambient temperature during the herbicide treatment.In this research, we found that ACC synthase, one of key enzymes of ethylene synthesis was significantly induced by quinclorac only in the light. Therefore induction of this enzyme is considered to be main factor of increased ethylene evolution. From the pattern of the induction, involvement of wound-inducible type ACC gene by the herbicide in the light was suggested. Investigation on the induced gene is now in progress.