Premium
HvMCB1, a R1MYB transcription factor from barley with antagonistic regulatory functions during seed development and germination
Author(s) -
RubioSomoza Ignacio,
Martinez Manuel,
Diaz Isabel,
Carbonero Pilar
Publication year - 2006
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2005.02596.x
Subject(s) - aleurone , promoter , endosperm , biology , repressor , transcription (linguistics) , gene , microbiology and biotechnology , transcription factor , gene expression , northern blot , regulation of gene expression , genetics , linguistics , philosophy
Summary The functional analysis of hydrolase gene promoters induced by gibberellin (GA) in barley aleurone cells upon germination has identified a tripartite GA‐response complex (GARC) containing a 5′‐ TATC CAC‐3′ box as well as the GA‐responsive element (GARE) recognized by GAMYB and the pyrimidine box interacting with the DOF transcription factors BPBF and SAD. We show here that the MCB1 gene encoding a R1MYB protein binds to the 5′‐ TATC CAC‐3′ (GATA core) box in vitro and is a transcriptional repressor of a GA‐induced amylase ( Amy6.4 ) promoter in bombarded aleurone layers. Northern blot and mRNA in situ hybridization analyses showed that the MCB1 transcripts accumulate in the aleurone cells upon germination, as well as in endosperm tissues during seed development. The HvMCB1 protein expressed in bacteria binds in a specific manner to a 27‐mer oligonucleotide containing the 5′‐TATCCAC‐3′ sequence, derived from the promoter region of the Amy6.4 gene. Accumulation of the MCB1 transcript diminished in response to external GA incubation in aleurone cells, and in transient expression experiments HvMCB1 repressed transcription of the Amy6.4 promoter in GA‐treated aleurone layers and reversed the GAMYB‐mediated activation of this amylase promoter. In contrast, during endosperm maturation HvMCB1 acted as a transcription activator of the seed‐specific Itr1 gene promoter through binding to a 5′‐GATAAGATA‐3′ box.