Study On The Response Characteristics Of Transgenic Bt Cotton To Salt Stress

With the rapid rise of transgenic Bt cotton accounted in the proportion of cotton area planted in China as well as the increasing severity of soil salinization, the study of genetically modified cotton’s response mechanism to a variety of salt stress is markedly important for the safe and sustainable cultivation of genetically modified cotton. In the paper, through pot experiment, transgenic cotton91Bt,507Bt, Z30and their non-transgenic control97,507, Z16were used to study the response characteristics, such as photosynthetic water gas exchange parameters, the reflectance spectrum and its characteristic parameters, photosynthetic proteins and metabolite profile, at different salt concentrations (0,50,200mmol·L-1) and duration (7d,15d,21d), respectively.The results show that salt stress can significantly affect the photosynthetic water gas exchange parameters, the reflectance spectral curves and photosynthetic pigment and protein content of the tested cotton, and the more serious salt stress is, the more obvious changes are. The response differences of photosynthetic water gas exchange parameters and reflectance spectra curves to salt stress between transgenic Bt cottons and their non-transgenic controls depend on the varieties. Among them, compared to their non-transgenic controls (97,507), the transgenic cottons’(97Bt,507Bt) water gas exchange parameters of photosynthesis and spectral reflectance in the visible light region are more sensitive to salt stress, while the transgenic cotton Z30and its non-transgenic control Z16do not show significant differences in the response to salt stress. There are no significant differences in the spectral reflectance characteristics index (NDVI, RRed/RGreen, NIRR800, PRI, γRE) responsing to salt stress between the transgenic cottons and their non-transgenic controls. The principal component analysis of the H1NMR shows the metabolite profiles of all the tested cotton under non-salt and severe salt stress have apparent classification in the level of the principal component2. The difference is mainly focused on the cell membrane-related metabolites, sugar, osmo-regulation metabolites, transaminase products, the shikimate pathway metabolites; There are no apparent classification on the response of the metabolite profiles to salt stress between all the transgenic Bt cottons and their non-transgenic controls. Heatmap analysis indicates that the highest concentrations of metabolites are membrane-related metabolites and osmo-regulation metabolites, while the overall level of amino acid metabolites is lower. Sugars, only the concentration of fructose is higher, the others show the change trends that related to the cotton varivties and the degree of salt stress. One-way ANOVA shows that the changes of10kinds of metabolites, such as sucrose, fructose, and nositol, which play a major contribution to the principal component analysis are significantly different between the transgenic cotton97Bt,501Bt, Z30and their non-transgenic control97,507and Z16, and the differences in response to salt stress depend on cotton varieties. In generally, genetically modified cottons response more sensitive to salt stress than their non-transgenic controls.