A Study On The Cloning And Gene Transformation Of A PtEXP1 Gene From Populus Tomentosa Carr.

Wood formation is a complex process composing many biological events that occur during the growth and differentiation of the vascular cambium. To improve the growth in trees and modify the wood quality, it is important to understand the molecular mechanisms of development of the xylem, that is to identify the key genes on wood formation as the targets for manipulation through genetic engineering.Expansin is a protein responsible for the extension of cell walls leading to the enlargement of the plant cells. The study of the function, expression of expansin during wood formation will provide the basis for improving wood quality by genetic engineering. The main results in this study are summarized as the followings:1. The PtEXP1 cDNA was amplified from the cambium zone of Populus tomentosa Carr. through the RT-PCR technique. This protein may involve in cell elongation during the xylem develpment.2. Approximately 776 bp fragement of PtEXP1 cDNA was inserted behind CaMV35S promoter of vector PBI121 in a sense orientation to generate the binary vector PBI121-PtEXP1. The binary vector was successfully mobilized into A.tumefaciens strain GV3101 .3. The transformed cells were screened by growing on the root-inducing-media with Kanamycin, which were transformed using the efficient leaf disc transformation sestem optimized for P.alba×P.glandulossa 84K.4. The transgene from 12 transformed plants were successfully amplified by PCR, of which9 transgenic plants were further confirmed by sounthern blotting. The results will help studing the function, expression of expansin during wood formation and will provide the basis and gene resource for improving wood quality by genetic engineering.