Identification of abiotic stress-responsive genes: a genome-wide analysis of the cytokinin response regulator gene family in rice.

ABSTRACT

Response regulators (RRs) are implicated in various developmental processes as well as environmental responses by acting as either positive or negative regulators, and are crucial components of cytokinin signaling in plants. We characterized 36 RRs in rice (Oryza sativa L.; Os) using in silico analysis of publicly available data. A comprehensive analysis of OsRR family members covered their physicochemical properties, chromosomal distribution, subcellular localization, phylogeny, gene structure, distribution of conserved motifs and domains, and gene duplication events. Gene Ontology analysis indicated that 22 OsRR genes contribute mainly to the cytokinin response and signal transduction. Predicted cis-elements in RR promoter sequences related to phytohormones and abiotic stresses indicated that RRs are involved in hormonal and environmental responses, supporting previous studies. MicroRNA (miRNA) target analysis showed that 148 miRNAs target 29 OsRR genes. In some cases, multiple RRs are targets of the same miRNA group, and may be controlled by common stimulus responses. Based on the analysis of publicly available gene expression data, OsRR4, OsRR6, OsRR9, OsRR10, OsRR22, OsPRR73 and OsPRR95 were found to be involved in responses to abiotic stresses. Using quantitative reverse transcription polymerase chain reaction we confirmed that six of these RRs, namely OsRR4, OsRR6, OsRR9, OsRR10, OsRR22 and OsPRR73, are involved in the response to salinity, osmotic, alkaline and wounding stresses, and can potentially be used as models to understand molecular mechanisms underlying stress responsiveness.