Wound-induced expression of a gene for 1-aminocyclopropane-1-carboxylate synthase and ethylene production are regulated by both reactive oxygen species and jasmonic acid in Cucurbita maxima

Expression of the CM-ACS1 gene, which encodes for 1-aminocyclopropane-1-carboxylate synthase (EC 4.4.1.14), is induced in response to mechanical wounding followed by production of ethylene in mesocarp of winter squash (Cucurbita maxima). We examined the relationship between reactive oxygen species (ROS) and jasmonic acid (JA) in the accumulation of the CM-ACS1 transcript. The JA content increased within 2 h after wounding and its level was increased by about 5-fold at 3 h as compared to that of intact tissue disks. Diphenylene iodonium (DPI), an inhibitor of the superoxide-generating enzyme NAD(P)H oxidase, had no effect on the increase in JA content. However, DPI inhibited the accumulation of the CM-ACS1 transcript within I and 2 h after wounding. Acetylsalicylic acid, an inhibitor of the synthesis of JA, did not inhibit the accumulation of the transcript within 1 h but did inhibit accumulation within 2 and 3 h after wounding. These results suggest that the expression of CM-ACS1 is induced initially by ROS that are generated in disks upon wounding and then by JA, the level of which increases at a later time after wounding. (C) 2001 Editions scientifiques et medicales Elsevier SAS.