Tissue Culture Technigues Of Catalpa Bungei

The different explants of Catalpa bungei C.A.Mey.were used to select proper explants for tissue culture.After a serial of studies,two tissue culture techniques,including direct organogenesis from stems with axillary buds and indirect organogenesis from callus,were established to provide a important methods for asexual propogation for Catalpa bungei. The results were as follows:1.Asepsis SowingFollowing the procedure:selecting healthy and plump seed→soaking in tap water for 48h→washing in gliding water for 3h→soaking in 70%alcohol soaking for 5 min→soaking in HgCl₂ for 8 min→culture.The aseptic plantlet rate could reach 68%.2.Direct organogenesis from stem with axillary budThe effective procedure of setting up asepsis shoots is follow:The explants were the oneyear stem with bud and them were cut to 1～2cm sect with one auxiliary bud each,then washing in tap water for 2h→cutting into 0.5cm growing points→soaking in 70%alcohol soaking for 30S→washing in sterile water for 4 times→soaking in 0.1%HgCl₂ for 6 min→washing in sterile water for 4 times→culture;The most suitable medium for primary culture was:N6+6-BA1.0mg/L+NAA0.01mg/L;The most suitable medium for sub culture was:N6+ 6-BA2.0mg/L+NAA0.1mg/L+Vc100mg/L+Lanthanide 2mg/L;The most suitable medium for rooting induction was N6+NAA1.0mg/L.3.Indirect organogenesis from callusOptimal explants for callus:Induce callus by using its leaves,petioles,terminal buds, stems and roots as the explants,the chosen explants:stems＞terminal bud＞roots＞leaves＞petioles;The most suitable medium for callus inducing was N6+6-BA3.0mg/L+NAA0.05mg/L; The most suitable medium for callus differentiation was N6+TDZ0.2mg/L+NAA0.01mg/L.4.Callus identification:Four kinds of callus were found in the callus.The primary conclusion was thatâ…¢type white callus andâ…£type brown callus were non-embryogenic callus,â… type green callus andâ…¡type purple callus were likely to be embryogenic callus after the macroscopic,scan electron microscopic and transmission electron microscopic observation of the four typical calluses.