Some Factors Affecting Vitrification in Brassica napus Transformation Mediated by Agrobacterium tumefaciens

To this day,Agrobacterium-mediated transformation is the most widely used method in plant gene engineering,its mechanism is best understood and its effects are most satisfactory.In tissue culture for transformation of Brassica napus mediated by A.tumefaciens,vitrification of the regenerated plantlets often occurs,which normally reduces the frequency of gene transformation.The experiment reported in this paper showed that many factors affected vitrification,including phytohormone concentration,sucrose concentration,agar concentration and inoculum density.The concentration of 6-BA and ZT had significant influence on budding rate and vitrification rate.Vitrification rate increased with their concentration.6-BA 1 mg/L plus ZT 2 mg/L gave quite satisfactory results.Sucrose concentration and agar concentrations also had significant influence on vitrification rate.Vitrification and budding rate decreased with increasing sucrose and agar concentration.Sucrose 50 g/L plus agar 10 g/L was advisable.Meanwhile,inoculum density had significant influence on the occurrence of vitrification.Vitrification tended to be more serious with higher inoculum density,but budding rate was little influenced by it.A density of 20-30 inocula per dish was appropriate.