SEQUENTIAL EXPRESSION OF 2 1-AMINOCYCLOPROPANE-1-CARBOXYLATE SYNTHASEGENES IN RESPONSE TO BIOTIC AND ABIOTIC STRESSES IN POTATO (SOLANUM-TUBEROSUM L.) LEAVES

Plants produce ethylene in response to many biotic and abiotic stresse s. In response to ozone the foliage of potato plants sequentially expr essed two ACC synthase genes (ST-ACS4, ST-ACS5). The same expression p attern of the two genes also occurred in response to Cu2+ and infectio n with Alternaria solani. ST-ACS5 expression increases very rapidly re aching a maximum earlier than ST-ACS4 transcripts, after which ST-ACS5 expression declines. ST-ACS4 expression increases at a slower rate an d reaches its maximum after ST-ACS5. The sequential nature of expressi on argues that the two genes have different signal transduction and ge ne regulatory mechanisms.