Analysis Of Potassium Nutrient Efficiency In Cotton And Construction Of Bt SCry1A Gene

Transgenic plants have been widely applied in crop production. Indeed transgenic technology greatly contributes to improvement of cotton cultivar quality such as transgenic Bt cotton, which has been widely bred in the word since 1996 due to their perfect resistance to insects. Although Bt cotton play an important role in national economy, it brings some new problems in practical cotton production.Bt cotton is much sensitive to potassium deficiency. Source of potassium is very poor in china and potassium fertilizer has been applied much lower than nitrogen and phosphate fertilizer for long time. But Bt cotton requires high potassium and shows low utilization efficiency of potassium. Potassium deficiency leads to premature senility, yield reduction and quality decline for many Bt cotton varieties. So it's necessary to further study the nutritional characteristics of Bt cotton. Genetic engineering technology is an effective way of improving potassium absorption and utilization efficiency for Bt cotton.The efficiency of nutrient absorption and utilization of different species and different varieties from same species is various. In this study, four high-efficient varieties and five low-efficient varieties were screened from 20 cotton varieties. Efficiency of nutrient absorption and utilization evaluation system was improved and optimized. High affinity potassium transporter gene Atkup1 was cloned from Arabidopsis thaliana. We also constructed plant expression vector of Atkup1, which was transformed into cotton by pollen tube pass method. These results established the foundation for potassium gene exploitation and further improving potassium nutrition absorption of cotton varieties.Many Bt cotton verities exists the phenomena-the efficacy of Bt cotton is high at early developmental stage, and decrease thereafter. Some research reports that decrease of the whole Bt Cry1A mRNA results in decrease of insect-resistant protein. In order to prolong the Cry1A mRNA half-life and improve expression level of active protein, the number of Bt gene was increased and Bts Cry1A expression vector was constructed. Bts Cry1A expressed in Pichia.pastoris. 87.5% recombinants expressed Bt protein by elisa test strip assay and presented insecticidal effect by bioassay. Bts Cry1A and Bt Cry1A were transformed into tobacco respectively. Insecticidal test illuminated that 33.3% of Bts tobaccos showed high resistance, 58.3% showed moderate resistance and 8.3% was no resistance. One of three Bt tobaccos showed no resistance, and two of them showed moderate resistance. These results indicated the expression product of Bts Cry1A presented insecticidal activity.The potassium utilization efficiency investigation of Bt cotton not only guides the production of these varieties, but also provides a valuable germplasm. Potassium nutrition high-efficient and low-efficient varieties play great role in illuminating the molecular mechanism of cotton potassium nutrition absorption. Construction and expression research of dual- Bt Cry1A vector provide a basis for increasing active domain, improving resistance, prolonging mRNA half-life, and enhancing Bt protein expression.