Effects Of Tomato S-nitrosoglutathione Reductase Gene(SlGSNOR) Silencing On Heat Resistance In The Leaves Of Tomato

Yield reduction issues of greenhouse vegetable have become increasingly prominent due to global warming. The research of high temperature resistant mechanism for greenhouse vegetables is important for the improvement of cultivation practices and high temperature resistant breeding. Nitric oxide (NO) as a plant second messenger of disease-resistance/resistance response, complete the signal transduction by the S-protein nitrosylation. S-nitrosylation regulates the high temperature resistance of plants, but the specific mechanism is still not clear.In this study, TRV and tomato plants v(Solarium lycopersicum Mill.cv.Ailsa Craig) were used to construct the gene silencing vecor with the pragment of SIGSNOR, SIRBOH. The VIGS plants were used to investigate the effect of tomato SIGSNOR silencing under high temperature on the photo synthetic apparatus and high temperature resistance. Then we analysed the gene expression and hormone content, antioxidant system to study the the role of S-nitrosylation in plant resistant response particularly high temperature resistence, providing theoretical basis for improving cultivation practices under high temperature. The main conclusions are as follows:1The Effects of SIGSNOR gene silencing under high temperature on photo synthetic parameters, Rubisco activity and fluorescence parameters were investigated. Under high temperature stress, the pTRV-SlGSNOR silencing plants decreased photosynthetic rate compared with pTRV.The decrease of photosynthetic rate accompanied with the decrease of Gs and the increase of Ci. The Rubisco activity decreased in the pTRV-SIGSNOR silencing plants. In the gene silencing plants Fv/Fm、φPSⅡ、qP decreased significantly,and NPQ was inhibited.2We have studied GSNOR activity and the effect on the NO and SNOs under hith temperature stress. After high temperature treatment for3hours. GSNOR enzyme activity increase the most, both pTRV-SIGSNOR and pTRV have improved significantly, while the pTRV-SIGSNOR silencing plants showed significantly lower than pTRV.After heat sress, the SNOs of pTRV and pTRV-SIGSNOR plants were induced. As the increase of treatment time. pTRV-SlGSNOR was increased more than pTRV, and after high temperature treatment for24hours, the SNOs of silencing plants is1.5times of that of pTRV. At the same time, the NO contens of pTRV and pTRV-SlGSNOR increase gradually after the high temperature treatment, NO increase rate of silencing plants was significantly higher than that of pTRV. Therefore, because of SlGSNOR silencing, tomato endogenous SNOs and NO can not be timely cleared under high temperature.3The impacts of tomato SlGSNOR gene silencing on ROS under high temperature stress were examined. H2O2/NO is a second messenger involved in hormone response and stress response.After high temperature,tomato SlGSNOR gene silencing inhibited the induction of H2O2, so reactive oxygen species as a "early warning mechanism" can not start, resulted in an decrease of antioxidant enzyme activity、gene expression and glutathione content. The induction of MAPK cascade was inhibited.Thus led to a significant increase in the content of MDA. This indicates that the SlGSNOR play an important role in maintaining the balance of redox status and enhancing oxidative stress resistance.4The influences of SlGSNOR gene silencing on hormone under high temperature were studied. The effect of SlGSNOR gene silencing on heat resistance is related to ABA and SA.5The role of S-nitrosylation in the ROS and NO signals under high temperature. After high temperature treatment, in the pTRV-SlGSNOR silencing plants, H2O2induction was inhibited, which led to severe oxidative stress. Exogenously applied H2O2, the inhibition eased. The redox status improved, leading to increase the activity of antioxidase and antioxidant gene expression level. The pTRV-SlRBOH silencing plants could not induce the outbreak of ROS under high temperature, and the GSNOR enzyme activity was not induced, leading to SNOs accumulation. This showed a similar response as pTRV-SlGSNOR.Perhaps NO inhibited NADPH oxidase through S-nitrosylation, thereby blocking the ROS-MAPK-hormone-defense gene expression signal pathway.