Response to salinity stress and the corresponding physiological mechanism in Bt transgenic cotton seedlings | 幼苗期转Bt基因抗虫棉对盐胁迫的反应及耐盐机理研究

chinois. 研究转Bt基因抗虫棉对盐胁迫的反应，旨在揭示棉花的耐盐机理。以转Bt基因抗虫棉“鲁棉研16”为材料，在棉花幼苗长到3片真叶时进行盐处理（NaCl含量分别为0(CK)，2.6，4.2 g/kg），测定盐胁迫下转Bt基因抗虫棉的各种生理生化指标。盐胁迫使转Bt基因抗虫棉幼苗叶片光合速率（Pn）呈先下降后上升再下降的趋势，蒸腾速率（Tr）、气孔导度（Gs）均呈先上升后下降的趋势，胞间CO2浓度呈先上升后下降再上升的趋势。与对照相比，盐胁迫处理叶绿素a、叶绿素b、叶绿素a+b含量升高，叶绿素a/b降低。脯氨酸和可溶性糖含量在盐胁迫初期升高，后期下降。盐胁迫处理MDA和类胡萝卜素含量增加，POD活性升高。随着NaCl含量的增加，不同组织中Na+含量的变化趋势不同，K+含量变化趋势相同。盐胁迫条件下，棉花耐盐的主要机理是通过提高POD活性和类胡萝卜素含量抵抗过氧化，通过合成和积累脯氨酸、可溶性糖等有机物质抗拒脱水。在组织水平上未发现有利于提高棉花耐盐性的离子区域化分布。

anglais. The study on responses of seedling growth of Bt transgenic cotton plants to NaCl stress was conducted to reveal mechanism of salt tolerance with “SCRC16” as the material. Seedlings of 3 true leaves were watered with salt treatment (concentration of 0(CK), 2.6, 4.2 g/kg) and physiological and biochemical indicators of transgenic Bt cotton were measured. The results showed that: photosynthetic rate (Pn) had the tendency of declining first and then rising and then declining, transpiration rate (Tr) and stomatal conductance (Gs) in seedling leaves had the tendency of first rising and then declining. CO2 contents between cells had the tendency of first rising and then declining and then rising than the control. The contents of chlorophyll a, chlorophyll b and chlorophyll a+b were all higher, but chlorophyll a/b value was lower than the control. Proline and soluble sugar contents of cotton seedling were rising under salinity stress in early period of time, but declining to the original level thereafter. POD activity and MDA and carotenoid contents were all higher than the control in salinity stress. Change tendency of Na+ content from different tissues was different and change tendency of K+ content was the same. Results showed that the main mechanism of salt tolerance of cotton under salt stress are improvement of POD activity and carotenoids of cotton plants against peroxidation and synthesis and accumulation of proline, soluble sugar and other organic material to resist dehydration. Regional distribution of ions helping to improve salinity tolerance of cotton wasn’t found at the tissue level, which was very different from previous reports.