54. 光発芽レタス種子におけるアブシジン酸代謝酵素遺伝子

概要

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Germination of lettuce (Lactuca sativa L. cv. Grand Rapids) seed is regulated by phytochrome. Endogenous levels of physiologically active gibberellin (GA) GA_1, increased and those of abscisic acid (ABA) decreased after red-light irradiation during germination of lettuce seeds. We have isolated and characterized cDNAs encoding biosynthetic and catabolic enzymes of GA and ABA to investigate the molecular mechanism on regulation of endogenous levels of the two phytohormones. In this study, we attempted to characterize LsABA8ox1-4 of which deduced amino acid sequences are highly homologus to that of Arabidopsis ABA 8'-oxidase (ABA8ox). ABA8ox is ABA catabolic enzyme belonging to P450 monooxygenase family. In vitro assay using recombinant proteins expressed in yeast indicated that translated products from LsABA8ox2, 3, 4 catalyze the step from ABA to phaseic acid. Analysis of tissue specific expression pattern of LsABA8ox3, of which transcript levels accumulated after red light irradiation, by in situ hybridization suggested that signals were detected at root apex and provasculature in germinating lettuce seeds.
植物化学調節学会の論文
2005-10-13