The Research On Agrobacterium Tumefaciens-mediated Transformation Of Expansin Gene Into Tabacco

Expansin is the only special cell wall protein which can induce hot passivation cell wall in vitro to extend found in recent years so far. Expansin can can regulate expansion of cell wall and control the growth of plant cell. It can cause decline in pH and activate related hydrolysis enzyme and cause degradation of some hemi - cellulose such as wooden glucosan or β- glucosan and break hydrogen bond between hemi -cellulose and micro filament silk and change cell wall loading network through hormone regulation,then accelerate growth.If Expansin gene is transformed into poplar trees,eucalyptus and other important vegetations, it can enhance tree growth rate and have great application prospects. Tobacco was the first model plant which applied to molecular biology and genetic engineering research.The Expansin gene carried in the T-DNAs of binary vectors which contain npt 11 gene ,were used to transform the explants of tabacco via Agrobacterium transformation. Through stringent selection of the infected explants on the medium added with Kanamycin and following assays,the transgenic tabacco plants were regenerated from the Kanamycin resistant explants.The following is the results of experiments: I Construction of high capacity and fast regeneration system of explants (1) Inducement of shootAfter compare, 14-18 days old seeds were confirmed to supply explants which have the strongest capacity of regeneration. Based on the MS medium, a series of medium were devised and selected by effect.The medium of inducing differentiation of explants is MS+ 6-BA 0.5mg/L. Shoots came out in about 7 days and the average number of adventitious bud is 8.7; (2) Redication of shootBased on the 1/2MS medium,a series of medium were devised and selected by effect. The medium of inducing rootage of sprouts is 1/2MS+ IAA 0.1mg/L. The rootage rate reached 100%.The root system was developed and looked radical.