13. ヤエナリおよびシロイヌナズナにおけるカスタステロンとブラシノライドの配糖化機構

概要

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We have examined the metabolism of brassinolide (BL) and its biosynthetic precursor castasterone (CS) in mung bean explants and Arabidopsis seedlings by using LC/MS/MS. In mung bean explants, CS and BL were converted to several glucosides, and conjugation with glucose occurred at C-2, C-3, C-22 or C-23 of CS and BL. In contrast, in Arabidopsis seedlings, conjugation occurred only at C-2 or C-23. BL-23G was a major BR glucoside in both plant species, however conversion ratio from BL to BL-23G in Arabidopsis seedlings (0.7%) was 35 times less than that of mung bean explants (24.9%). We examined natural occurrence of these BR glucosides (BR-Gs), but we could not identify them from seedlings nor seeds of mung bean and Arabidopsis. The phenotypic recovery and hydrolysis of BR-Gs were observed in the metabolism of BR-Gs in Arabidopsis det2 mutant. Free BRs and their glucosides seem to be interconvertible in Arabidopsis. Our results indicate that glucosylation at C-23 hydroxyl group of BL is an important process in plants, but profile of BR glucosylation varies with plant species.
植物化学調節学会の論文
2004-10-13