Reference "A rice WRKY gene encodes a transcriptional repressor of the gibberellin signaling pathway in aleurone cells"

Reference ID

11288

Title

A rice WRKY gene encodes a transcriptional repressor of the gibberellin signaling pathway in aleurone cells

Source

Plant physiology, 2004, vol. 134, pp. 1500-1513

Authors (6)

Zhang-Z-L	Xie-Z
Zou-X	Casaretto-J
Ho-T-H	Shen-Q-J

Abstract

The molecular mechanism by which GA regulates plant growth and development has
been a subject of active research. Analyses of the rice (Oryza sativa) genomic
sequences identified 77 WRKY genes, among which OsWRKY71 is highly expressed in
aleurone cells. Transient expression of OsWRKY71 by particle bombardment
specifically represses GA-induced Amy32b alpha-amylase promoter but not abscisic
acid-induced HVA22 or HVA1 promoter activity in aleurone cells. Moreover,
OsWRKY71 blocks the activation of the Amy32b promoter by the GA-inducible
transcriptional activator OsGAMYB. Consistent with its role as a transcriptional
repressor, OsWRKY71 is localized to nuclei of aleurone cells and binds
specifically to functionally defined TGAC-containing W boxes of the Amy32b
promoter in vitro. Mutation of the two W boxes prevents the binding of OsWRKY71
to the mutated promoter, and releases the suppression of the OsGAMYB-activated
Amy32b expression by OsWRKY71, suggesting that OsWRKY71 blocks GA signaling by
functionally interfering with OsGAMYB. Exogenous GA treatment decreases the steady-
state mRNA level of OsWRKY71 and destabilizes the GFP:OsWRKY71 fusion protein.
These findings suggest that OsWRKY71 encodes a transcriptional repressor of GA
signaling in aleurone cells.