Stress signaling molecules involved in defense and protein phosphatase 2A inhibitors modulate OsCATC expression in rice (Oryza sativa) seedlings

Rice catalase gene(s) remain poorly characterized against stress regulators, and thus we investigated expression of a yet uncharacterized rice catalase (CAT) gene, OsCATC, against global signaling molecules and protein phosphatase (PP) 2A inhibitors. Amino acid alignments among related CAT genes from plants revealed that functionally important amino acids at active center and heme-binding sites, including the peroxisomal targeting signals were highly conserved in OsCATC protein. OsCATC constitutively expressed in the leaf, and was down regulated by jasmonic acid (JA), salicylic acid (SA), ethylene (using the ethylene generator, ethephon), hydrogen peroxide, and PP2A inhibitors, cantharidin and endothall, with time till 12 h, followed by recovery at 24 h under continuous light. However, OsCATC down regulation by abscisic acid till 12 h, did not recover until 72 h; all these results suggested an effect of these signaling molecules and PP2A inhibitors on OsCATC expression. Based on present results, it is thought that OsCATC might be potentially important in rice defense/stress response(s), and could serve as a marker gene.