Differential activation of two ACC oxidase gene promoters from melon during plant development and in response to pathogen attack

作者：Lasserre E; Godard F; Bouquin T; Hernandez JA; Pech JC; Roby D; Balague C

来源：Molecular and General Genetics, 1997, 256(3): 211-222.

• ACC oxidase
• ethylene
• hypersensitive
• response
• senescence
• transcriptional activation

ACC (1-aminocyclopropane-1-carboxylate) oxidase genes are differentially expressed in melon during development and in response to various stresses. We investigated the molecular basis of their transcription by analysing the 5' untranslated regions of the ACC oxidase genes CM-AC01 and CM-AC03. In order to determine how their temporal and spatial expression patterns were established, we fused the promoter regions of CM-AC01 (726 bp) and CM-AC03 (2260 bp) to the beta-glucuronidase (GUS) reporter gene and examined their regulation in transgenic tobacco plants. The CM-AC01 promoter was able to drive GUS expression in response to wounding, and to treatment with ethylene or copper sulfate. It was also rapidly induced (8-12 h postinoculation) in tobacco leaves inoculated with the hypersensitive response (HR)-inducing bacterium Ralstonia solanacearum. Expression was also observed during compatible interactions but was delayed. In contrast, the CM-AC03 promoter was not expressed in response to infection, but was up-regulated during flower development. Both promoters were regulated during leaf senescence but in different patterns. The CM-AC01-driven GUS activity increased sharply concomitantly with the onset of chlorophyll breakdown, while the CM-AC03 promoter drove strong GUS expression in green, fully expanded leaves and this declined at the onset of senescence. This result is consistent with the expression patterns of these two genes in senescent melon leaves. These data suggest that the regulation of expression of CM-AC01 is related preferentially to stress responses, whereas CM-AC03 seems to be associated with developmental processes. The possible role of ethylene is discussed, particularly in the regulation of the CM-AC01 gene in response to stress and during senescence.

• 出版日期1997-10