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Subcellular Localization Analysis and Overexpression Verification of Transcription Factor HB-12 from Sunflower (Helianthus annuus L.)
Sun Ruifen, Zhang Yanfang, Guo Shuchun, Li Suping, Yu Haifeng, Nie Hui, Niu Suqing, Qiao Huilei, An Yulin*
Inner Mongolia Academy of Agriculture and Animal Husbandry Sciences, Huhhot 010031, China
Abstract: Transcription factor HB-12 from sunflower belongs to HD-Zip I transcription factor family and plays an important role in plant stress response. Subcellular localization analysis showed that HB-12 protein was located in the nucleus. At the same time， the plant superexpression vector of HB-12 was constructed and tobacco leaves were transformed by Agrobacterium-mediated transformation and transgenic plants were obtained. The salt tolerance of transgenic tobacco was tested， the physiological and biochemical indexes were determined and the expression of stress related genes were analyzed under NaCl stress. The results showed that under NaCl stress， the degree of discoloration in transgenic tobacco leaves was lighter than that of in wild type leaves， and the differentiation of transgenic tobacco was better than that of wild type， the growth rate and rooting rate of transgenic tobacco plants were higher compaired to that of wild type tobacco; The contents of chlorophyll and proline and the activities of POD and SOD were higher than wild type tobacco. The relative gene expression level of transgenic tobacco were significantly higher than those of wild tobacco. These indicated that overexpression of HB-12 in tobacco enhanced its NaCl tolerance， which would set the foundation for further study on the mechanism of salt tolerance in plants and the improvement of salt-tolerant traits in crops. The overexpression of HB-12 from sunflower in transgenic tobacco could inhibit the activity of chlorophyll degrading enzyme and decrease the decomposition of chlorophyll. The proline synthase gene P5CS and the antioxidant related gene POD， MnSOD and GuZnSOD were induced to up-regulated expression， promoting the biosynthesis of praline and enhancing the activities of POD and SOD， improving the ability of tobacco to resist salt damage. The results set the foundation for further study in the mechanism of salt tolerance in plants and the improvement of salt-tolerant traits in crops.
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