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Abstract: AP2/EREBP transcription factors play an important role in plant development, hormone response, and responses to biotic and abiotic stress. OsASIE1, a member of the EREBP subfamily of AP2/EREBP transcription factors in rice (Oryza sativa L.), is determined to be involved in abiotic stress response. OsASIE1 expression was induced by drought and salt stresses. In addition, an electrophoresis mobility shift assay (EMSA) revealed that the AP2 domain of the OsASIE1 protein can bind to both DRE (dehydration-responsive element) and GCC box (ethylene response element, ERE) in vitro. All these results indicate that OsASIE1 may participate in abiotic stress response by regulating the expression of downstream genes with DRE and GCC box binding. Overexpression of OsASIE1 in transgenic rice plants might be used to improve tolerance to salt stress. [Copyright &y& Elsevier]

Abstract: The objectives of this study were to gain insight into the temporal and spatial expression patterns of two-component system (TCS) genes in rice (Oryza sativa L.) under drought stress and to understand the relationship between TCS gene expression and drought resistance. Using a whole rice genome microarray, the expression profiles of TCS genes of rice lines with different drought resistance were analyzed at various growth stages. The TCS genes showed greatly difference of expression pattern in various organs but in similar patterns in the same tissues at different stages. Genes for type-A response regulator (RR), a negative regulator of cytokinin (CK) signaling, were mostly repressed by drought stress, whereas, genes for type-B RR with an opposite role to type-A RR were mostly induced by drought stress. These changes were supposed to be related to the enhancement of CK signaling under drought stress. This supposition was confirmed by the down regulation of ethylene receptor genes and the cross-talk of hormones under drought condition. The His kinase genes (HK5 and HK3) that are homologous to CK receptor genes (AHK2, AHK3, and CRE1) in Arabidopsis were induced by drought stress. However, HK6 homologous to AHK5 (CK-independent 2, CKI2) was repressed when exposed to drought stress. These results provided further confirmations of the above supposition. In drought resistant introgression lines and IR64, no significant differences of TCS gene expression profiles were observed under drought stress. This result indicates that the TCS genes are probably in relation to drought responsiveness. [Copyright &y& Elsevier]