DEVELOPMENTAL REGULATION OF 2 TOMATO LIPOXYGENASE PROMOTERS IN TRANSGENIC TOBACCO AND TOMATO

Two lipoxygenase (LOX) genes (tomloxA and tomloxB) are expressed in ri pening tomato fruit, and tomloxA is also expressed in germinating seed lings [12]. The 5'-upstream regions of these genes were isolated to st udy the regulatory elements involved in coordinating tomlox gene expre ssion. Sequence analysis of the promoters did not reveal any previousl y characterized regulatory elements except for TATA and CAAT boxes. Ho wever, the sequence motif GATAcAnnAAtnTGATG was found in both promoter s. Chimeric gene fusions of each tomlox promoter with the beta-glucuro nidase reporter gene (gus) were introduced into tobacco and tomato pla nts via Agrobacterium-mediated transformation. GUS activity in tomloxA -gus plants during seed germination peaked at day 5 and was enhanced b y methyl jasmonate (MeJa) treatment. No GUS activity was detected in t omloxB-gus seedlings. Neither wounding nor abscisic acid (ABA) treatme nt of transgenic seedlings modified the activity of either promoter. D uring fruit development, GUS expression in tomloxA-gus tobacco fruit i ncreased 5 days after anthesis (DAA) and peaked at 20 DAA. In tomloxB- gus tobacco fruit, GUS activity increased at 10 DAA and peaked at 20 D AA. In transgenic tomato fruit, tomloxA-gus expression was localized t o the outer pericarp during fruit ripening, while tomloxB-gus expressi on was localized in the outer pericarp and columella. These data demon strate that the promoter regions used in these experiments contain cis -acting regulatory elements required for proper regulation of tomlox e xpression during development and for MeJa-responsiveness.