Isolation And Characterization Of Stress-inducible Promoters And A Low-Temperature-Responsive Gene OsLCL3 In Rice

Rice is one of the most important grain crops in the world. Drought, high salt, high or low temperature and other abiotic stresses seriously restrict the distribution and yield of rice, and as a consequence agr icultural produc tivity wou ld be affec ted. Research on the mechanism of how p lants respond to ab iotic s tresses cou ld promo te the deve lopment of life science. Meanwhile, some key genes or promoters involved in abiotic stresses response may be used to gene tically improve crops. And the gra in y ield of our coun try and even of the world would be increased.This study is comprised of two parts. The first part is the isolation of stress inducible promoters. PC1 and PD1 strongly induced by low temperature and drought respectively, were identified through the charac terization of severa l cand idate promo ters. The second part is the isolation and characterization of a low temperature responsive gene, Os LCL3. This gene played an important role in response and resistance to low temperature in rice. The main results are as follows:1. Rea l-time PCR ana lysis of f ive cand idate promo ters was conduc ted, and four of them were induced by corresponding stress, and three of them were strongly induced;2. GUS staining of the above four candidate promoters’ transgenic plants was carried out and it was found that two promoters showed difference in activity after stress compared to those of unstressed plants;3. GUS activities o f transgenic p lants o f the above two p romoters w ere analyzed under different stresses, and their activity w ere induced by corresponding stress. The promoter that was strongly induced by low temperature was PC1, while the promoter that was strongly induced by drought was PD1.4. S equence analysis of PC1 and PD1 w as conducted, low temperature response element LTRE and o ther ab iotic c is-acting e lements we re found in PC1 wh ile d rought response element DRE and other abiotic cis-acting elements were found in PD1;5. The gene Os LCL3 corresponding to PC1 promoter was isolated. BLAST analysis of O s LCL3 protein sequence w as conducted and it w as found to belong to DU F761 superfamily. P hylogenetic tree analysis indicated O s LCL3 is very conserved in herbal monocot plants;6. The subcellular localization of Os LCL3 protein was conducted in rice protoplast transient expression system, and its localization was preliminarily determined to be in the nucleus and cytoplasm;7. Os LCL3 was over-expressed in rice and low temperature treatment of over-expressed lines w ere conducted. It w as found that the electrical conductivity of over-expressed lines after low temperature stress was significantly lower than that of wild type plants, and the survival rate of over-expressed lines after low temperature stress was significantly h igher than that of w ild type p lants. I t indicated that Os LCL3 may p lay an important role in low temperature stress response and resistance in rice.