Modified fiber qualities of the transgenic cotton expressing a silkworm fibroin gene

A silkworm gene for fibroin was introduced into the upland cotton WC line by Agrobacterium-mediated transformation. PCR detection for fibroin, nptII and gus genes, Kanamycin (Km)-resistance analysis and GUS-histochemical assay were conducted on 30 regenerated plants from 9 callus lines, and 17 positive plants were obtained by these 5 screening methods. By Km-resistance analysis and PCR for fibroin, 6 homozygous lines in T-3 were obtained. Southern blot and Northern bolt demonstrated that the fibroin gene was inserted into the genome of these 6 lines, stably inherited and expressed. Compared to the control, the surface structure of mature fiber in the 6 lines was significantly distorted and an increased number of convolution was observed by scanning electron microscopy (SEM). Fiber quality traits analysis indicated that fiber elongation of the 6 homozygous lines was all increased and fiber strength of 3 lines was enhanced. These results indicated that fibroin expression influenced cotton fiber structure and quality, suggesting that fibroin has great potential for improving cotton fiber quality by genetic engineering.