Whole Genome Analysis of the OsGRF Gene Family Encoding Plant-Specific Putative Transcription Activators in Rice (Oryza sativa L.)

Abstract

OsGRF1 (Oryza sativa GROWTH-REGULATING FACTOR1) is a rice gene encoding a putative novel transcriptional regulator. We identified and characterized eleven homologs of OsGRF1 in the rice genome. All twelve OsGRF proteins have two highly conserved regions, the QLQ (Gln, Leu, Gln) and WRC (Trp, Arg, Cys) domains, and sequences reminiscent of transcription factors. OsGRF genes were preferentially expressed in young and growing tissues, and applied gibberellic acid (GA3) enhanced the expression of seven OsGRF genes. In situ hybridization showed high levels of OsGRF1 transcripts in the shoot apical meristem and in cells surrounding the vasculature of the intercalary meristem. In a GAL4-based yeast assay, the C-terminal region of OsGRF1 was found to have transactivation activity. These results indicate that OsGRF1 acts as a transcriptional activator. Based on the in situ expression pattern of OsGRF1, we postulate that it may be involved in regulating vegetative growth in rice.

Arabidopsis GROWTH-REGULATING FACTOR7 Functions as a Transcriptional Repressor of Abscisic Acid– and Osmotic Stress–Responsive Genes, Including DREB2A

“…Previous works suggest that several GRF proteins have transactivation activity in yeast, and the C-terminal region was suggested to be responsible for this activity (Choi et al, 2004;Kim and Kende, 2004). This is in contrast with our hypothesis that GRF7 can function as a transcriptional repressor.…”

“…The distances between proteins were calculated by the neighbor-joining method with 1000 bootstrap trials, and Poisson correction was used to correct multiple substitutions at the same site. The nomenclature of the GRF family members from Arabidopsis and rice (Oryza sativa) is according to that used in previous reports (Kim et al, 2003;Choi et al, 2004).…”

A transcriptional coactivator, AtGIF1, is involved in regulating leaf growth and morphology in Arabidopsis

“…rowth-regulating factor (GRF) genes occur in the genomes of all seed plants thus far examined (1)(2)(3). The deduced protein products of GRF genes contain, in their N-terminal region, the conserved QLQ and WRC domains, which define the GRF protein family.…”

“…The QLQ domain shows similarity to the N-terminal part of the yeast SWI2͞SNF2 protein (1)(2)(3). Because the N-terminal region of SWI2͞SNF2 mediates the interaction with another component of the SWI2͞SNF2 chromatinremodeling complex in yeast (4), the QLQ domain of GRF may also function in protein-protein interactions (1)(2)(3). The WRC domain contains a functional nuclear localization signal and a DNA-binding motif consisting of the conserved spacing of three Cys and one His residues (1, 2).…”

“…The C-terminal regions of GRF proteins diverge in length and amino acid sequence from each other but nevertheless have common features that are reminiscent of transcription factors. We suggested that the GRF proteins may be a previously undescribed class of transcription regulators (1)(2)(3).…”