Expression Analysis Of OsHKs Gene Induced By Abscisic Acid And Their Relationships With H₂O₂in Rice Leaves

Abscisic acid (ABA), an important signaling molecule, can regulate a variety of physiological and molecular responses for plants against stresses, including drought, chilling and salt. Previous studies showed that one model of ABA action are related to plant oxidative stress signaling. ABA could induce the generation of hydrogen peroxide (H2O2) and enhance the capacity of antioxidant defense systems. H2O2is an important signaling molecule in the signal transduction induced by ABA. Recently, researches related to the ABA-induced antioxidant defense systems are increasingly in-depth and the ones about ABA receptor are becoming extensive.The two-component system (TCS), which works on the principle of histidine kinase (HK) phosphorelay signaling, is known to play an important role in diverse physiological processes in lower organisms and has recently emerged as an important signaling system in plants. But the relationship between ABA-induced oxidative stress signaling pathways and HKs gene is not clear reported. So an effort was made to elucidate the relationship between OsHKs genes and ABA, H2O2in semi-quantitative PCR by using rice as model material and bioinformatics methods combine with molecular biology methods in this study and finally find out two ABA-regulated OsHKs of the six known genes. The results are as follows:In this study, the transcript level of OsHKs gene was analyzed by semi RT-PCR. The4h time-course analysis of OsHK3gene expressions showed that the transcript level of OsHK3reached a maximum values during90min to120min of PEG treatment.100μmol·L-1ABA treatment resulted in an enhancement in the transcript level of OsHK3gene and reached its maximum value during60min to90min.10mmol·L-1H2O2treatment also resulted in an analogical enhancement in the transcript level of OsHK3gene and reached its maximum value during30min to60min. Again, with RT-PCR methods, the4h time-course analysis of OsHK5gene expressions showed that the transcript level of OsHK5reached a maximum values during60min to90min of PEG treatment.100μmol·L-1ABA treatment resulted in an enhancement in the transcript level of OsHK5gene and reached its maximum value during30min to60min.10mmol·L-1H2O2treatment also resulted in an analogical enhancement in the transcript level of OsHK5gene and reached its maximum value during30min to60min. These responses were alleviated by the pretreatment with the ABA biosynthetic inhibitor fluridone, but that could be recovered by ABA treatment.Pretreatments with H2O2scavenger and inhibitor DMTU and DPI suppressed the increases of gene expression within4h of ABA treatment. These suggested that H2O2is required for the ABA-induced up-regulation expressions of OsHKs gene in rice leaves. A new evidence was provided to ABA-induced signal transduction in plant cell antioxidant protection system.As mentioned above, we clarified that during the ABA-induced signal transduction, OsHKs played important roles as signal receptors to H2O2. This study provides new evidence to the relationships among ABA, H2O2and OsHKs so as to affluent the ABA-induced signal transduction in plant cell antioxidant protection system.