杨树受机械损伤与光肩星天牛危害的防御性反应

杨树是我国“三北”地区防护林建设的主栽树种,自20世纪70年代以来长期受到光肩星天牛的严重危害。北抗杨对光肩星天牛有一定的抗性,但产生抗性的生化机制尚不清楚。本研究采用试剂盒法与高效液相色谱法以未受害、机械损伤、虫害北抗杨为研究材料,对其树皮和木质部中的次生代谢产物和防御酶含量进行检测,以探索其抗性机制。结果表明,北抗杨受到机械损伤和光肩星天牛危害后其反应不同:1)次生代谢产物,北抗杨受到机械损伤后,树皮中的水杨苷和白杨甙含量显著上升,槲皮苷含量降低;而受光肩星天牛危害后,树皮中的水杨苷和槲皮苷含量显著上升,白杨甙含量无显著变化。机械损伤的北抗杨木质部总酚含量高于虫害与未受害木质部,后两者间无显著差异;光肩星天牛危害的北抗杨木质部白杨甙和亚麻木酚素含量高于机械损伤木质部与未受害木质部。遭受机械损伤与虫害后北抗杨木质部的总酚苷含量显著高于未受害木质部。2)防御酶活性分析表明,与未受害北抗杨树皮相比,受到机械损伤与虫害后的树皮苯丙氨酸解氨酶(PAL)活性显著升高,但两者间无差异;受到机械损伤与虫害后的树皮超氧化物歧化酶(SOD)活性高于未受害树皮,且机械损伤树皮高于虫害树皮;北抗杨受机械损伤与虫害后木质部中的过氧化物酶(POD)活性高于未受害木质部,但两者间无差异。3)与未受害北抗杨相比,北抗杨受机械损伤、虫害后部分次生代谢物和防御酶都有不同程度的增加,推测这些物质可能与北抗杨抗逆性反应有关。

Defensive responses of Populus deltoides cl. Beikang to mechanical injury and Anoplophora glabripennis infection

Poplar, as the main tree species of the protection forest in the “Three-North” area of China, has been seriously damaged by Anoplophora glabripennis since 1970s. Populus deltoides cl. Beikang (PDB) shows strong resistance to A. glabripennis, but the biochemical mechanism of resistance is unclear. In this study, the quantities of secondary metabolites and the activity of defense enzymes in bark and xylem from undamaged, mechanically damaged, and A. glabripennis infected PDB were detected by kit and HPLC techniques. The results showed different responses of PDB to mechanical damage and A. glabripennis infection. Secondary metabolites, the quantities of D-(-)-salicin and aspen significantly increased after mechanical injury compared with the undamaged materials, but the quantities of quercitrin decreased. The quantities of D-(-)-salicin and quercitrin significantly increased after insect infection, but without difference for aspen. There was no significant difference for the total quantities of phenolics between insect infected and uninjured xylem, but both were significantly lower than that in the mechanical damaged xylem. The quantities of aspen and flax lignans in the insect infected xylem was higher than those in the mechanical damaged xylem and uninjured xylem, while the quantities of total phenolic glycosides in the mechanical damaged xylem and the insect infected xylem were both significantly higher than that in the uninjured xylem. PAL activity was not different between mechanical damage and insect infection, whereas both were significantly higher than that of uninjured bark. SOD activity in mechanical damaged bark was significantly higher than that in insect infected bark, which were both higher than that of uninjured bark. POD activity had no significant difference between mechanical damage and insect infected xylem, but were higher than that of uninjured xylem. Compared with the uninjured PDB tree, the secondary metabolites and defense enzymes in the mechanical damaged and A. glabripennis infected PDB increased in varied degrees, which would be related with the resistance of PDB to external injury.