不同松材线虫虫株接种雪松等寄主后的组织病理学变化

用来自日本和中国的几个松材线虫虫株,分别对黑松、马尾松和雪松进行接种,接种后分离树体内的线虫,并观察树体的组织细胞变化。研究结果表明,2个日本虫株均能使黑松、马尾松和雪松发病并枯死,而中国线虫虫株仅能够使黑松和马尾松发病枯死,不能使雪松致病。接种后不同时间分离线虫,比较线虫在寄主体内的数量消长情况。发现凡接种发病死亡的,其体内线虫数量最多;发病但没有死亡的,其体内线虫数量也较多;中国虫株接种的雪松,一直没有表现任何症状,其体内也分离到了一定数量的线虫。接种后组织病理学变化表明,细胞和组织变化与线虫的移动和扩散有关。黑松和马尾松,接种日本和中国浙江松材线虫虫株后,72 h时皮层和韧皮部的薄壁细胞变形、死亡普遍存在,树脂道泌脂细胞和木射线细胞均遭到线虫破坏。144 h后,皮层、韧皮部、木质部和髓心大量细胞死亡,形成空洞,管胞中可见线虫活动。而对于雪松,接种日本松材线虫虫株后,皮层、韧皮部和形成层细胞死亡,树脂道泌脂细胞和木射线细胞死亡,有少量代谢物聚集。中国松材线虫虫株接种后,初期皮层、韧皮部细胞变形并破坏;但是,细胞的破坏只局限在小范围内。后期皮层、韧皮部细胞被破坏,但形成层完整,木射线和管胞基本完好。

Histopathological Changes of Cedrus deodara and Other Hosts Inoculated with Different Pine Wood Nematode Isolates

Three nematode isolates were collected from China and Japan and were inoculated in Pinus thunbergii,P.massoniana and Cedrus deodara.The nematodes were separated from infected trees,and the histopathological changes were observed.Results showed that P.thunbergii,P.massoniana and C.deodara wilted and died when inoculated with two nematode isolates from Japan.However C.deodara still kept healthy after inoculated with nematodes from China.Nematodes were re-isolated from the infected trees at different times,and the numbers of nematodes in the host were also compared.The number of nematodes isolated from dead trees was higher than that from the living trees infected with nematodes.However,a certain number of nematodes were also isolated from healthy trees of C.deodara.Histopathological changes showed that the changes in cells and tissues were related to the movement and spread of nematodes.The parenchyma cells of cortex and phloem tissues in P.thunbergii and P.massoniana were damaged 72 hours after inoculated nematodes from Japan and China.Cells of resin canals and wood rays were hurt by nematodes.The cells of cortex,phloem,xylem,and medulla were destroyed 144 hours after inoculated,and nematodes were observed in the tracheid.The cells of C.deodara inoculated with Japanese nematodes were also damaged,and the cells of cortex and phloem were damaged at the initial stage only in a small area,and the cells died at the later stage,but cambium was complete,wood ray and tracheid were still remain in good condition.