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KMID : 0368420050480040483
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Journal of Plant Biology
2005 Volume.48 No. 4 p.483 ~ p.486
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Endogenous level of 28-Norcastasterone is strictly regulated in Plant Cells
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Kim Tae-Wuk
Hwang Jung-Yun
Joo Se-Hwan
Cheong Hyeon-Sook
Pharis Richard P.
Kim Seong-Ki
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Abstract
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A cell-free enzyme solution prepared from cultured cells ofPhaseolus vulgaris mediated C-24 methylation of 28-nor-castasterone to castasterone with the aid of S-adenosylmethionine as a co-substrate in the presence of the NADPH cofactor. This enzyme solution also catalyzed conversion of 28-norcastasterone to a demethylated 28-norcastasterone, most likely 26,28-didemethyl-castasterone, when S-adenosylmethionine was not added to the enzyme solution. Furthermore, gene expression ofArabidopsis CYP85A1 andCYP85A2 mediating the conversion of 6-deoxo-28-norcastast-erone to 28-norcastasterone was strongly inhibited by treatment of 28-norcastasterone. These results suggest that 28-norcastasterone, along with castasterone and brassinolide, is an important brassinosteroid whose endogenous level should be strictly controlled to express brassinosteroid activities in plants.
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KEYWORD
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Arabidopsis, brassinosteroid, homeostatic regulation, 28-norcastasterone, Phaseolus vulgaris
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