Gene cloning and expression of cytosolic glutathione reductase in rice (Oryza sativa L.)

We have isolated a cDNA (RGRC2) encoding glutathione reductase (GR) from ri ce (Oryza sativa L,), The comparison of deduced amino acid sequences from R GRC2 and other plant GR cDNAs indicated that RGRC2 encodes a putative cytos olic isoform, The recombinant RGRC2 protein had enzymatic properties compar able to those of GR from rice embryo. Subcellular fractionation showed that the RGRC2 protein is localized primarily in cytosol. mRNA and protein of R GRC2 were observed mainly in roots and calli but little in leaf tissues. So uthern blot analysis showed that the RGRC2 gene exists as a single copy gen e. Here, we have also isolated a genomic clone completely corresponding to RGRC2. The RGRC2 gene is split into 16 exons spread about 7.4 kb of chromos omal DNA, with ceding sequence beginning in the 2nd exon and ending in the 16th exon. From the presence of two ABA-responsive elements in the 5'-flank ing region of RGRC2, we examined the expression in rice seedlings treated w ith ABA and the ABA-related environmental stresses, chilling, drought and s alinity. The expression of RGRC2 was strongly induced by all these treatmen ts. We suggest that the expression of the rice cytosolic GR gene is regulat ed via ABA-mediated signal transduction pathway under environmental stresse s.