Isolation of a novel abscisic acid stress ripening (OsASR) gene from rice and analysis of the response of this gene to abiotic stresses

Abiotic stresses constitute a serious threat to agricultural production, which often develops into major crop production reducing factors around the world. Molecular biology technology has, however, emerged as a promising vehicle improving crop tolerance. A cold-, drought- and heat-inducible gene designated Oryza sativa L. abscisic acid stress-ripening ( OsASR ) gene, GenBank accession: AK318549.1 was identified in rice Pei’ai64s ( O. sativa L. ssp. Indica cv.) using the GeneChip rice genome array (Affymetrix) representing 51, 279 transcripts from two rice subspecies japonica and indica . The expression profile of OsASR obtained by the microarray analysis was confirmed by quantitative real-time reverse transcription polymerase chain reaction (RT-PCR) analysis of the gene. The two sets of data matched very well, suggesting that OsASR is a multiple stresses responsive gene in rice. Based on the sequence, PCR primers were designed. The cDNA with the whole open reading frame (ORF) was amplified by PCR and cloned. Sequence analysis showed that the cDNA encodes a protein of 284 amino acid residues with M.W. ≈ 11.7 kD and pI ≈ 10.4. The gene encodes a protein with several conserved domains. Comparison of protein sequences indicates that OsASR encodes a putative abscisic acid stress-ripening protein. Analysis of the putative promoter region for candidate cis-regulatory elements using PlantCARE software identified seven kinds of cis-elements related to stress responses. Based on the aforementioned analyses and results obtained, we propose that OsASR is a novel candidate gene involved in stress tolerance in rice. Keywords: Rice, microarray, abiotic stress, reverse transcription polymerase chain reaction (RT-PCR), abscisic acid stress ripening