Endogenous level of 28-Norcastasterone is strictly regulated in Plant Cells |
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Authors: | Tae-Wuk Kim Jung-Yun Hwang Se-Hwan Joo Hyeonsook Cheong Richard P. Pharis Seong-Ki Kim |
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Affiliation: | 1. Department of Life Science, Chung-Ang University, 156-756, Seoul, Korea 2. Department of Genetic Engineering, Chosun University, 501-759, Kwang-Ju, Korea 3. Department of Biological Sciences, University of Calgary, T2N IN4, Calgary, Canada
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Abstract: | 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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