the arabidopsis ear-motif-containing protein rap2.1 functions as an active transcriptional repressor to keep stress responses under tight control拟南芥ear-motif-containing蛋白rap2.1函数作为一个活跃的转录抑制因子使应激反应得到严格控制.pdf

Dong and Liu BMC Plant Biology 2010, 10:47 /1471-2229/10/47 RESEARCH ARTICLE Open Access The Arabidopsis EAR-motif-containing protein RAP2.1 functions as an active transcriptional repressor to keep stress responses under tight control * Chun-Juan Dong, Jin-Yuan Liu Abstract Background: Plants respond to abiotic stress through complex regulation of transcription, including both transcriptional activation and repression. Dehydration-responsive-element binding protein (DREB)-type transcription factors are well known to play important roles in adaptation to abiotic stress. The mechanisms by which DREB-type transcription factors activate stress-induced gene expression have been relatively well studied. However, little is known about how DREB-type transcriptional repressors modulate plant stress responses. In this study, we report the functional analysis of RAP2.1, a DREB-type transcriptional repressor. Results: RAP2.1 possesses an APETALA2 (AP2) domain that binds to dehydration-responsive elements (DREs) and an ERF-associated amphiphilic repression (EAR) motif, as the repression domain located at the C-terminus of the protein. Expression of RAP2.1 is strongly induced by drought and cold stress via an ABA-independent pathway. Arabidopsis plants overexpressing RAP2.1 show enhanced sensitivity to cold and drought stresses, while rap2.1-1 and rap2.1-2 T-DNA insertion alleles result in reduced sensitivity to these stresses. The reduced stress sensitivity of the plant containing the rap2.1 allele can be genetically complemented by the expression of RAP2.1, but not by the expression of EAR-motif-mutated RAP2.1. Furthermore, chromatin immunoprecipitation (ChIP) analysis has identified Responsive to desiccation/Cold-regulated (RD/COR) genes as downstream targets of RAP2.1 in vivo. Stress-