The Forming And Defense Function Of Secretory Duct In The Stem Of Ailanthus Altissima

Ailanthus aliissima (Mill.) Swingle, is a large tree indigenous to world, and it was used extensively as a street tree. In the stem of Ailanthus altissima, constitute secretory ducts are present only in pitch normally, and traumatic secretory ducts develop in the secondary xylem after wounding. However, it is not clear about the ontogeny of normal and traumatic secretory ducts, the defense function of secretory ducts and there is no information for signal in the mechanisms of induction for traumatic ducts. The purpose of this study was to show the distribution, development, anatomy and defense function of secretory ducts with anatomical and cytochemical methods, and determine if ethylene directly induce the traumatic ducts formation by electrophoresis and western blot technology.Constitute secretory ducts are present in pitch normally, and traumatic ducts are arising under the stimulus of mechanical wounding, in the secondary xylem of stem. The constitute ducts are formed by the separation of epithelial cells from each other during development, and the traumatic duct are formed by the autolysis of epithelial cells. Secretory ducts develop schizogenously and traumatic ducts develop lysigenously.Cytochemical test reveals that the normal ducts and traumatic ducts consist of terpenoids, resins and polysaccharides. Cytohistological analyses indicated that constitutive dcuts and traumatic ducts are coordinated to provide an effective defense for plant.Exogenous applications of methyl jasmonate, methyl salicylate, and ethylene were used to assess inducible defense signaling mechanisms in Ailanthus altissima’s stems. Methyl jasmonate and ethylene but not methyl salicylate can caused traumatic secretory ducts appear. Wounding and applications of methyl jasmonate increase1-aminocyclopropane-l-carboxylic acid (ACC) oxidase protein. The ethylene antagonist,1-methylcyclopropene (1-MCP), have an effect of inhibition of traumatic ducts formation. These data show these traumatic ducts forming are mediated by ethylene. The results also indicate a central role of ethylene in induced traumatic ducts formation.