Overexpression of a New Zinc Finger Protein Transcription Factor OsCTZFP8 Improves Cold Tolerance in Rice

Abstract

Cold stress is one of the most important abiotic stresses in rice. C 2 H 2 zinc finger proteins play important roles in response to abiotic stresses in plants. In the present study, we isolated and functionally characterized a new C 2 H 2 zinc finger protein transcription factor OsCTZFP8 in rice. OsCTZFP8 encodes a C 2 H 2 zinc finger protein, which contains a typical zinc finger motif, as well as a potential nuclear localization signal (NLS) and a leucine-rich region (L-box). Expression of OsCTZFP8 was differentially induced by several abiotic stresses and was strongly induced by cold stress. Subcellular localization assay and yeast one-hybrid analysis revealed that OsCTZFP8 was a nuclear protein and has transactivation activity. To characterize the function of OsCTZFP8 in rice, the full-length cDNA of OsCTZFP8 was isolated and transgenic rice with overexpression of OsCTZFP8 driven by the maize ubiquitin promoter was generated using Agrobacterium-mediated transformation. Among 46 independent transgenic lines, 6 single-copy homozygous overexpressing lines were selected by Southern blot analysis and Basta resistance segregation assay in both T 1 and T 2 generations. Transgenic rice overexpressing OsCTZFP8 exhibited cold tolerant phenotypes with significantly higher pollen fertilities and seed setting rates than nontransgenic control plants. In addition, yield per plant of OsCTZFP8-expressing lines was significantly (p<0.01) higher than that of nontransgenic control plants under cold treatments. These results demonstrate that OsCTZFP8 was a C 2 H 2 zinc finger transcription factor that plays an important role in cold tolerance in rice.