22.光発芽レタス種子におけるジベレリン生合成、不活性化酵素遺伝子、DELLA遺伝子の発現解析(口頭発表)

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Germination of lettuce (Lactuca sativa L. cv. Grand Rapids) seed is regulated by phytochrome. We have shown that endogenous levels of bioactive gibberellin (GA_1) increased after red light irradiation during germination of lettuce seeds. In order to investigate the molecular mechanism on control of endogenous GA_1 levels, we have isolated 11 cDNAs encoding GA metabolic enzymes (LsCPS, LsKS, LsKO1, 2, LsKAO, LsGA20ox1, 2, LsGA3ox1, 2, LsGA2ox1 and 2) and carried out expression analysis by semiquantitative RT-PCR. We reported previously that expression levels of LsGA3ox1 increased and these of LsGA2ox2 decreased after red light irradiation, and the effects of red light were partially cancelled by application of ABA. In this study, the functions of translated products of lettuce diterpene cyclases (LsCPS and LsKS) and P450 monooxygenases (LsKO1, 2 and LsKAO) were confirmed by in vitro assay using recombinant enzymes. And expression analysis of 11 GA metabolic enzyme genes will be performed by real time QRT-PCR. Recently, it was reported that the expressions of GAI and RGA encoding DELLA proteins, negative regulators for GA signaling, were down-regulated by phytochrome in Arabidopsis (Oh et al., 2007). Then, we successfully isolated two GAI/RGA homologue cDNA fragments from lettuce (LsGAI/RGA like1, 2), and will discuss regulation of these genes by phytochrome.
植物化学調節学会の論文
2007-10-05