巴西橡胶树割胶树皮伤口的组织学和组织化学的变化

Histological and Histochemical Studies of Tapping Cut of the Tapped Rubber Tree (Heave Brasiliensis)

用光学显微镜技术和组织化学方法研究了巴西橡胶树(HeveabrasiliensisMuell.Arg.)割胶树皮伤口的变化,并测定了乳管中重要的防卫蛋白质几丁质酶在树皮伤口的积累和消失。结果表明,割胶诱导割口树皮组织产生伤害反应使割口得到保护。割口树皮依次出现3种防卫机制:⑴乳管预先形成的物理和化学防卫物质(橡胶粒子和包括几丁质酶在内的防卫蛋白质)在树皮伤口表面和乳管伤口末端的积累;⑵伤口周围的组织形成的化学防卫物质单宁、木质素和木栓质等;⑶在较长时间停止割胶(如冬季停割)时形成防卫结构创伤周皮。前两种防卫机制的作用是暂时的,只有最后创伤周形成时,树皮伤口才能得到充分有效的保护。

Tapping cut of tapped rubber tree （Hevea brasiliensis Muell. Arg.） was observed by using light microscopy and histochemistry. By assaying the activities of the cut, chitinase, an important defense protein in the laticifer, was traced after bark wounding. The results showed that wound response of the bark tissues around the tapping cut was induced by tapping to protect the cut. Three defense mechanisms appeared successively after tapping around the tapping cut： accumulation of the preformed physical and chemical defense materials, rubber particles and defense proteins including chitinase, in the cut surface and at the end of the cut of the laticifers; the defense materials e.g. tannins, lignin and suberin, that were formed after tapping; and wound periderm formed after long period rest of tapping, such as in the rest period of tapping in winter. The former two mechanisms gave only temporary protection to the tapping cut and the cut could not be protected completely and efficiently until the wound periderm was finally formed.