| [Object]: Xinjiang has the climatic characteristics of abundant light and heat resources and large temperature difference between day and night.In order to keep the best growth rate and production rate of plants,the effects of insufficient and excessive light intensity or temperature stress on photosynthesis must be overcome in the light environment with highly varying light intensity.In recent years,it has been found that PsbS gene plays a key role in non-photochemical quenching(NPQ).Energy-dependent fluorescence quenching(q E)is the component of the fastest non-photochemical quenching(NPQ).In higher plants,q E activation depends on PsbS protein.In this thesis,the characteristics of PsbS gene family in upland cotton,the evolutionary relationship of PsbS gene among different species and the response mechanism of GhPsbS transgenic tobacco to different light and temperature conditions were explored,in order to know the physiological adaptability and action characteristics of this gene under excessive light energy and temperature stress in more detail.[Methods]: In this study,four members of PsbS gene family were identified from cotton database by bioinformatics method,and all members of PsbS gene family in upland cotton were analyzed by gene structure,physical and chemical properties,chromosome position,and gene sequence.Then,T4 transgenic over-expressed tobacco plants and wild-type tobacco plants transformed by our research group were selected as materials,and the differences of gene expression and the changes of photosynthetic characteristics and chlorophyll fluorescence characteristics of tobacco under different light and temperature treatments were measured and the changes of biomass under different light were also analyzed and determined.[Results]:(1)The results showed that four PsbS protein sequences were highly conserved.Phylogenetic tree analysis showed that four PsbS genes were identified in upland cotton and clustered into four branches.(2)The relative expression of GhPsbS gene under different light treatments was analyzed by real-time fluorescence quantitative PCR and it was found that constant low light and natural light negatively regulated the relative expression of GhPsbS gene.By studying the changes of relative expression of GhPsbS gene at 4℃,25℃,and 35℃,it was found that the gene was sensitive to temperature.(3)The analysis of photosynthetic results showed that the Pn,Gs and Tr of transgenic GhPsbS tobacco leaves were significantly higher than those of wild type,which indicated that transgenic tobacco had higher photosynthetic efficiency.The results of fluorescence parameter analysis showed that the NPQ of transgenic plants under natural light treatment was significantly higher than that of wild-type plants,and that of transgenic plants with constant high light was significantly lower than wild-type plants at the five-leaf stage.At the seven-leaf stage,the NPQ of transgenic plants was significantly higher than wild plants under natural light,and constant high light,but there was no significant difference under low light.Compared with the actual photochemical efficiency(ΦPSII)analysis results,it can be seen that the ΦPSII of transgenic plants growing to the five-leaf stage was significantly higher than wild-type plants after 8hours of constant high light treatment,while the ΦPSII of transgenic plants growing to the seven-leaf stage was significantly lower than wild-type plants.(4)The specific leaf weight,leaf area,and dry and fresh weight of transgenic tobacco and wild tobacco plants were measured under the conditions of constant light and natural light growth.Therefore,GhPsbS gene can promote the growth of tobacco.[Conclusions]: In this experiment,the members of PsbS gene family in upland cotton were analyzed,the evolutionary relationship of GhPsbS gene was known,and the background source of experimental plants was defined.Secondly,constant low light and natural light negatively regulate the relative expression of GhPsbS gene.High temperature may inhibit the relative expression of GhPsbS gene.At the same time,it was found in photosynthetic physiology that the heat dissipation ability and light capture ability of transgenic tobacco plants in different growth stages were different.GhPsbS gene can promote the growth of tobacco. |
PDF Full Text Request