Abstract: To understand mechanism(s) underlying stress responses and discover new stress-tolerance genes in rice (Oryza sativa L.), we analyzed a global genome expression profiling of the indica cultivar Pei’ai 64S subjected to cold, drought, or heat stresses. Expression profiles were obtained for leaf and panicle tissues at seedling, booting and heading stages from plants under no stress, or cold, drought or heat stresses using the GeneChip Rice Genome Array (Affymetrix) representing 51 279 transcripts from ja-ponica and indica rice. We identified a large number of genes highly up regulated or down regulated under the stresses. One of these genes, OsMsr1 (Oryza sativa L. Multiple Stresses Responsive Gene 1, GenBank accession: EU284112), was highly induced in leaf and panicle at all the developmental stages, in response to all stresses. The expression profile of OsMsr1 obtained by the microarray analysis was confirmed by quantitative real-time RT-PCR analysis of the gene. The two sets of data matched very well, suggesting that OsMsr1 is a multiple stresses responsive gene in rice. In order to study its function in stress tolerance, we cloned the cDNA of the gene through amplification by RT-PCR. Sequence analysis showed that the cDNA encodes a protein of 89 amino acid residues with M.W. ≈ 10 kD and pI ≈ 5. Searching sequence databases failed to find similarity to any gene of known function, and/or gene/protein domain. Analysis of the putative promoter region for candidate cis-regulatory elements using PlantCARE software (http://bioinformatics.psb.ugent.be/webtools/plantcare/html/) identified 5 matches to cis-elements related to stress re-sponses. Based on the above analyses and results obtained, we propose that OsMsr1 is a novel candidate gene involved in stress tolerance in rice. Further study on the function of the gene is in progress.

Key words: Oryza sativa L., Stress, Microarray, Real-time PCR, Gene cloning