Effects of signaling molecules, protein phosphatase inhibitors and blast pathogen (Magnaporthe grisea) on the mRNA level of a rice (Oryza sativa L.) phospholipid hydroperoxide glutathione peroxidase (OsPHGPX) gene in seedling leaves.

With a specific focus on rice self-defense response(s), the effects of global signaling molecules, jasmonic acid (JA), salicylic acid (SA), abscisic acid (ABA), and ethylene (using the ethylene generator, ethephon), and protein phosphatase (PP) inhibitors, cantharidin and endothall on expression of a rice phospholipid hydroperoxide glutathione peroxidase (OsPHGPX) gene in rice seedling leaves were investigated. We provide first evidence for a potent up-regulation of the OsPHGPX mRNA accumulation by these signaling molecules and PP inhibitors that strongly suggest its potential role in defense/stress. The OsPHGPX gene also showed a weak constitutive expression and responsiveness to cut. These inductions were influenced by light signal(s), and did not show a requirement for de novo synthesized protein factor(s). A potential interaction amongst these signaling molecules, especially JA, SA, ABA and kinetin, in modulating the OsPHGPX expression was found. The blast pathogen, Magnaporthe grisea also elicited the accumulation of OsPHGPX mRNA in leaves. This is a first systematic report in rice (and in plants) demonstrating the inducible nature (and expression) of the OsPHGPX gene by a variety of defense/stress-related stimuli, and modulation by the PPs of the kinase-signaling cascade(s).