| The structure characteristics, chemical compositions and cell inclusion contents ofburl development mechanism, with induced by Agrobacterium tumefaciens, were tested on1-year old Chinese white poplar seedling. The results obtained are showed as follows:With the micro-structure analysis, it demonstrates that the position induced by A.tumefaciens would make cell hyperplasia at the beginning around the wound, of which itestablished vessel differentiation at the fast developing part. The burl tissue is formingslowly with those of cell hyperplasia that extrudes some of host stem tissue to develop anapophysis on the skin of stem of Chinese white poplar, in which it would established newstructure-lignified. There are upgrowth vascular bundle that connect with host's vascularsystem in well-developed burl, of which its present shapes of tree-like and swirl. At thesame time, the more width rays are developing and the vessels diameter are increasingmarkedly below the position of inoculation as well as vessels diameter are decreasingsharply above the position.By the anatomical structure analysis, it show that all parameters but wall thickenss offiber decreased at the inoculation position of treatment trees, and the vessels where areabove the burl and just at the inoculation position are becoming smaller compare withother positions, whereas they, with the position that below the inoculation position, are assimilar as the control one. On the other hand, the parameters in the control tree are almostthe same. There is significantly difference (5%level) of the fiber and vessel element length,width among burls, in which it suggest that cell division in vivo are abnormity. To comparewith that of in xylem, the fiber and vessel are obviously smaller in burl.The analysis on wood chemical compositions,from different positions of the treatmenttree, present that cold water extractives, hot water extractives, 1%NaOH extractives andlignin increased, but the cellulose decreased to compare with the control one. Furthermore,the extractives saturated by three ways mentioned above in the burl increased the most,which they were 2.6～4.3times. 1.5～2.6times. and 1.1～1.8times but cellulose decreased51～99% than that of in xylem. The content of lignin at the position of inoculation of thexylem was 2.7times higher than that of in burls. Even so, the content of lignin in burl was slightly higher than of in other positions.By cell inclusion contents variation analysis, the results showed that in comparingwith control trees, the contents of soluble sugar, protein, potassium, calcium are decreasedin roots and leaves of treatment trees, but there were significant increase in xylem andphloem of treatment ones at inoculation position. Inclusion contents of bud existedvariation, but the trend was increasing during development of Chinese white poplar burl.We can believe that nutrition supply give priority to inoculation position and burl overother positions... |
