Reference "OsBLE3, a brassinolide-enhanced gene, is involved in the growth of rice"

Reference ID

11427

Title

OsBLE3, a brassinolide-enhanced gene, is involved in the growth of rice

Source

Phytochemistry, 2006, vol. 67, pp. 1442-1454

Authors (5)

Yang-G	Nakamura-H
Ichikawa-H	Kitano-H
Komatsu-S

Abstract

Brassinosteroids (BRs) are a group of plant hormones involved in a wide range of
plant growth and developmental processes. To investigate the mechanism of BR
action in monocots, a brassinolide (BL) upregulated gene designated OsBLE3 was
identified, cloned and characterized in rice. It was mainly expressed in roots
and leaf sheaths with levels of expression directly dependent on the dose of BL.
In situ hybridization detected OsBLE3 mRNA in the shoot apical meristem, organ
primordia and vascular tissue. Furthermore, its expression was enhanced by co-
treatment with BL and low concentrations of IAA. These results, and the
existence of auxin response elements in the 5'-flanking region of the OsBLE3
gene, indicate that OsBLE3 expression is under control of both BR and auxin. The
GUS reporter gene driven by a 2277 bp OsBLE3 putative promoter was mainly
expressed in vascular tissues, branch root primordia and was responsive to
exogenous BL treatment. OsBLE3 transcript levels were greatly reduced in brd1
plants, a BL deficient mutant, compared to the wild type control. In OsBRI1
antisense transgenic rice and OsBLE3, the BR-insensitive mutant expression of
OsBLE3 in response to exogenous BL treatment was significantly lower compared to
that in control plants transformed with a vacant vector. Reduced OsBLE3
expression and growth retardation was also observed in OsBLE3 antisense
transgenic rice plants. Internode cell length of the OsBLE3 antisense transgenic
lines was about 70% of that in the vacant vector transformed control lines.
These results suggest that OsBLE3 is involved in cell elongation in rice through
dual regulation by BL and IAA.