Brassinosteroid biosynthesis

Brassinosteroids are a group of plant steroid hormones that regulate growth and development. More than fifty naturally occurring brassinosteroids have been identified in a wide range of plant species. The most abundant and widely occurring brassinosteroids are C28 steroids, and among them brassinolide (BL) is the most biologically active. Plants have multiple pathways for biosynthesis of BL, which are derived from the steroid biosynthetic pathway. Two pathways from campestanol to castasterone (CS), C6 oxidation and the late-C6 oxidation pathways, operate in many plants. Another branching pathway, the early-C22 oxidation pathway, was demonstrated using a brassinosteroid-deficient mutant of Arabidopsis thaliana. Recently, a new shortcut pathway from campesterol to 6-deoxotyphasterol was demonstrated by a functional analysis of cytochrome P450 monooxygenases responsible for brassinosteroid biosynthesis. Thus, at least four pathways are involved in the biosynthesis of CS, and CS is further metabolized to BL by lactonization of the B ring.

Metabolism; Metabolism of terpenoids and polyketides

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[Atarasii Syokubutuhorumon no Kagaku] (In Japanese)

Koudansya saientific:199-138 (2002)

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[Shinpan Syokubutuhorumon no Sigunarudentatu] (In Japanese)

Syujyunsya:165-186 (2004)

PMID:12529536

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Plant Physiol 131:287-97 (2003)

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Physiologia Plantarum 126:539-548 (2006)

PMID:17138693

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C-23 hydroxylation by Arabidopsis CYP90C1 and CYP90D1 reveals a novel shortcut in brassinosteroid biosynthesis.

Plant Cell 18:3275-88 (2006)

PMID:17693126

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Refining the plant steroid hormone biosynthesis pathway.

Trends Plant Sci 12:377-80 (2007)

PMID:15710611

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The last reaction producing brassinolide is catalyzed by cytochrome P-450s, CYP85A3 in tomato and CYP85A2 in Arabidopsis.

J Biol Chem 280:17873-9 (2005)

PMID:18685225

Katsumata T, Hasegawa A, Fujiwara T, Komatsu T, Notomi M, Abe H, Natsume M, Kawaide H

Arabidopsis CYP85A2 catalyzes lactonization reactions in the biosynthesis of 2-deoxy-7-oxalactone brassinosteroids.

Biosci Biotechnol Biochem 72:2110-7 (2008)

PMID:15705958

Tanabe S, Ashikari M, Fujioka S, Takatsuto S, Yoshida S, Yano M, Yoshimura A, Kitano H, Matsuoka M, Fujisawa Y, Kato H, Iwasaki Y

A novel cytochrome P450 is implicated in brassinosteroid biosynthesis via the characterization of a rice dwarf mutant, dwarf11, with reduced seed length.

Plant Cell 17:776-90 (2005)

PMID:14615594

Hong Z, Ueguchi-Tanaka M, Umemura K, Uozu S, Fujioka S, Takatsuto S, Yoshida S, Ashikari M, Kitano H, Matsuoka M

A rice brassinosteroid-deficient mutant, ebisu dwarf (d2), is caused by a loss of function of a new member of cytochrome P450.

Plant Cell 15:2900-10 (2003)