Mechanisms For ZFP252-Mediated Stress Tolerance And Expression Analysis Of OsGLP1

Rice (Oryza sativa L.) is one of the essential food crops in the whole world, the growth and crop productivity of which are largely affected by environmental issues such as drought, salt and temperature. Thus, understanding the molecular mechanisms for plant responsiveness to environmental stresses has the values of practical application. Several TFⅢA-type zinc finger proteins are involved in the network of response to abiotic stresses in rice and ZFP252is one of them. In our previous study, we have confirmed ZFP252transgenic lines conferred drought and salt tolerance, while the molecular mechanism is still elusive. In this research, we aimed to clarify the molecular mechanisms of ZFP252-mediated stress tolerance by different ways. We also detected the expression of stress responsive gene OsGLPl. Novelties achieved in this study are as follows:1. Overexpression of ZFP252reduced the size of stoma, which is the important factor affecting various physiological characters including photo synthetic and transporation rate, water lose rate, etc.2. ZFP252was localized in the nucleus. The transcriptional activation assay in yeast showed that ZFP252had no transcriptional activation activity, while this protein functioned as a transcriptional repressor confirmed by transient expression assay in rice protoplast cells.3. The ZFP252transgenic rice exhibited the reactive oxygen species (ROS)-scavenging ability. Our data showed that ZFP252increased superoxide dismutase (SOD) and catalase (CAT) activities in rice seedling under stress.4. Ten differentially expressed metabolites were identified by Gas Chromatograph-Mass Spectrometer-computer (GC-MS), four of them were up-regulated while six were down-regulated. Metabonomics results showed that L-Aspartic acid may be a potential biomarker for ZFP252transgenic lines, and this compound was involved in various metabolic pathways, including biosynthesis of plant hormone ethylene and carbon fixation in photosynthetic organisms. Two other identified metabolites, pentaric acid and uracil, also affect L-Aspartic acid biosynthesis. It is possible that the molecular mechanism of ZFP252mediated stress tolerance may be related to ethylene. Three metabolites related to ethylene biosynthesis were detected through GC-MS, which were pentaric acid, L-aspartic acid and butanedioic acid. In addition, expression of ZFP252was repressed when treated with ETH (ethrel).5. The OsGLPl encoding a germin-like protein was cloned and analyzed for its expression profiles. Tissue-specific expression assay indicated that OsGLPl was expressed mainly in leaf, stem and panicle. OsGLP1was down-regulated when seedlings were treated with salt, PEG6000, heat and cold, while induced by H2O2and ABA. Many positively co-expressed genes with OsGLPl were related with cellular secretion, indicating a correlation between OsGLPl function and cell wall.