PB-Overexpression of OsZn15, a CCCH-tandem zinc finger protein, increases drought tolerance in rice

Zinc finger proteins constitute a large family which has been studied to have various functions in different organisms. Tandem CCCH zinc finger proteins (TZFs), members of the zinc finger protein family, are known to participate as post-transcriptional regulators of gene expression in eukaryotes. Here, we showed that the OsZn15, a gene for tandem CCCH zinc finger protein, is induced by abiotic stress and its overexpression in transgenic rice plants (PGD1:OsZn15) gains higher drought tolerance. Gene expression analysis of promoter:GFP plants revealed that OsZn15 is specifically expressed in anther and embryo, but not in vegetative organs. In-field evaluation, grain yield was higher in the PGD1:OsZn15 than nontransgenic plants under drought conditions. Interestingly, OsZn15 is shown to not only localize at nucleus but also co-localize with both processing bodies (PB) and stress granules (SG), two messenger ribo-nucleoprotein complexes which are known to activate by forming cytoplasmic foci under stress conditions. In sum, these results suggest that OsZn15 increases drought stress tolerance of rice probably by participating in RNA turnover in PB and SG.