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Regulation of castasterone level in primary roots of maize, Zea mays
Author(s) -
Kim YoungSoo,
Kim TaeWuk,
Chang Soo Chul,
Pharis Richard P.,
Lee June Seung,
Han TaeJin,
Takatsuto Suguru,
Cheong Hyeonsook,
Kim SeongKi
Publication year - 2006
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.2006.00650.x
Subject(s) - brassinosteroid , brassinolide , biosynthesis , enzyme , chemistry , enzyme assay , demethylation , biochemistry , methionine , elongation , zea mays , stereochemistry , botany , biology , gene expression , plant growth , materials science , amino acid , arabidopsis , ultimate tensile strength , mutant , metallurgy , dna methylation , gene , agronomy
Gas chromatography–mass spectrometry analysis revealed that primary roots of maize contain 28‐norcastasterone (28‐norCS) and its biosynthetic precursors, cholesterol, and cholestanol, which suggests that the C 27 ‐brassinosteroid (C 27 ‐BR) biosynthetic pathway to generate 28‐norCS is operative in the roots. A cell‐free enzyme solution prepared from maize roots successfully mediated C24‐methylation of 28‐norCS to produce castasterone (CS) with the aid of S‐adenosyl‐ l ‐methionine, which indicates that CS can be generated through C 27 ‐BR biosynthesis, as well as C 28 ‐BR biosynthesis, in maize roots. Enzymatic conversion study using the cell‐free enzyme solution demonstrated that CS is converted into 26‐norCS in the enzyme solution. Exogenously applied 28‐norCS and 26‐norCS showed less activity than CS in the activation of gravitropic curvature and inhibition of root elongation. Taken together, a steady‐state level of CS, the active BR in maize roots, seems to be strictly controlled by complicated processes such as C 28 ‐ and C 27 ‐BR biosynthesis and biodegradation by C26‐demethylation to exert its biological activity.