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

Reference ID

11418

Title

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

Source

The Plant cell, 2005, vol. 17, pp. 776-790

Authors (12)

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

Abstract

We have characterized a rice (Oryza sativa) dwarf mutant, dwarf11 (d11), that
bears seeds of reduced length. To understand the mechanism by which seed length
is regulated, the D11 gene was isolated by a map-based cloning method. The gene
was found to encode a novel cytochrome P450 (CYP724B1), which showed homology
to enzymes involved in brassinosteroid (BR) biosynthesis. The dwarf phenotype
of d11 mutants was restored by the application of the brassinolide (BL).
Compared with wild-type plants, the aberrant D11 mRNA accumulated at higher
levels in d11 mutants and was dramatically reduced by treatment with BL,
implying that the gene is feedback-regulated by BL. Precise determination of
the defective step(s) in BR synthesis in d11 mutants proved intractable because
of tissue specificity and the complex control of BR accumulation in plants.
However, 6-deoxotyphasterol (6-DeoxoTY) and typhasterol (TY), but not any
upstream intermediates before these compounds, effectively restored BR response
in d11 mutants in a lamina joint bending assay. Multiple lines of evidence
together suggest that the D11/CYP724B1 gene plays a role in BR synthesis and
may be involved in the supply of 6-DeoxoTY and TY in the BR biosynthesis
network in rice.