Creating Low Gossypol Cotton Material By Genetic Engineering

Gossypol and other Protective terpenoids are secondary metabolites. They can increased susceptibility in the selfprotection system of plants against insect pests. It has been demonstrate that(+)-δ-cadinene synthase gene has a close relationship with gossypol synthesis process. Here we used a powerful RNA interference(RNAi) approach to interfere target gene. Two fragments(CAD1-a and CAD1-c) of(+)-δ-cadinene synthase gene were chosen for RNAi target sequence, and are driven by the Ca MV 35 S promoter. CAD1-a gene was also driven by the Cotton α-globulin promoter. We developed cotton material with gossypol in all the tissues except seeds. We detected the expression pattern of gossypol biosynthesis related genes in different transgenic cotton plants by q RT-PCR. our results demonstrated that;(1) FPS, P450 and d HG-6-OMT genes were highly expressed in root and leaf. The expression of CAD1-c gene was observed in cotton stem, leaf & sepal. However, CAD1-a gene was opposite.(2) RNA interference of CAD1-c gene, significantly increased the expression of CAD1-a gene. and the interference of CAD1-a gene, results in increased expression of CAD1-c gene. We observed that CAD1-c and CAD1-a gene play a complementary role in their function. However when the interference of CAD1-a gene was stronger, the expression level of CAD1-c also decreased. Our results concluded that CAD1-a may regulate the expression of CAD1-c gene.(3) The signal transduction mechanism of CAD1-c gene belongs to PAMP-triggered immunity(PTI), and the signal transduction mechanism of CAD1-a gene belongs to effector-triggered immunity(ETI). JA may inhibit the expression of WRKY1 gene, the WRKY1 gene regulate the expression of CAD1-a gene, and CAD1-a gene & CAD1-c regulate the expression of one another. CAD1-c gene may affect the pathway of ABA signaling, and is also involved in the process of plant hormone signal transduction and disease resistance.(4) Transcriptomic analysis of transgenic materials showed the increased expression of 122 genes of A-2(CAD1-a) strain and decreased expression of 58 genes. In C-15(CAD1-c) strain, the expression of 421 genes increased and 115 genes were decreased. Overall, 453 genes changed expression in C-15, 97 genes changed expression in A-2 and 83 genes have complex expression.(5) We used HPLC to determine the gossypol content from transgenic cottonseed. Interference of CAD1-a and CAD1-c two DNA sequence fragments of(+)-δ-cadinene synthase gene results in significant reduction of gossypol contents in transgenic cotton seeds, which have great value in equaculture and food processing industry.