Plant omics: genome-wide analysis of ABA repressor1 (ABR1) related genes in rice during abiotic stress and development.

Rice is one of the world's most important food crops. Approximately 50% of rice production is affected by drought, an abiotic stress greatly impacting crop quality and yield. Agrigenomics research now offers the promise of understanding the drought stress impacts at a systems level. ABA repressor 1 (ABR1) is a member of the ethylene-responsive element-binding factor (ERF/AP2) superfamily of ERF transcription factors. We report here a global expression analysis of the rice ABR1-related genes where we identified the expression pattern of each Oryza sativa ERF (OsERF) during various developmental stages and abiotic stress treatments. The group X OsERFs, closely related genes orthologous to ABR1, exhibited significant differential expression profiles during certain stages of development and in response to abiotic stresses. We selected a subset of these genes and validated their observed expression profiles in response to abiotic stresses using quantitative RT-PCR. Moreover, we discovered that pairs of recently duplicated group X OsERFs display highly distinct expression profiles from one another. We determined the subcellular localization of two group X OsERF genes and observed localization to the nucleolus. To the best of our knowledge, this is the first report of localization of rice ERF protein to the nucleolus. This study also points out an overlap of expression under abiotic stress and reproductive developmental stages, indicating cross talk among different signaling pathways. This genome-wide expression analysis of rice ABR1 homologs paves the way for future functional analyses, with the goal to develop strategies to improve rice abiotic stress tolerance.