C2H2-type zinc finger OsZFP15 accelerates seed germination and confers salinity and drought tolerance of rice seedling through ABA catabolism

Environmental factors and plant hormones are major players in seed germination. Abscisic acid (ABA) not only delays seed germination but also acts as a central regulator in plant growth, development and response to stress conditions. In this study, a rice C2H2-type zinc finger protein, OsZFP15, was screened by microarray and characterized. RT-qPCR and GUS staining assays revealed that OsZFP15 was significantly induced by ABA and multiple abiotic stresses. Subcellular localization assay indicated that OsZFP15 protein was located in the nucleus of rice protoplast. Overexpression of OsZFP15 reduced the sensitivity to ABA and down-regulated transcript levels of ABA-responsive genes including LEA3 and LIP9, but increased transcript level of OsABA8ox2, suggesting that OsZFP15 is a positive regulator of ABA catabolism. Additionally, overexpression of OsZFP15 in rice enhanced ABA catabolism and thus accelerated seed germination. We further investigated the role of OsZFP15 in abiotic stress response. Overexpression of OsZFP15 promoted reactive oxygen species (ROS) production and accordingly reduced the tolerance to oxidative stress. Conversely, improvements in salinity and drought tolerance were observed in OsZFP15 overexpression plants.