Phytopathology. 1998 Nov;88(11):1141-8. doi: 10.1094/PHYTO.1998.88.11.1141.
ABSTRACT The burrowing nematode Radopholus similis is one of the most damaging pathogens on banana plantations. The role of phenolics in plant defense responses to the nematode was histochemically and ultrastructurally investigated in susceptible and partially resistant cultivars. Histochemical observations of healthy roots revealed that high levels of lignin, flavonoids, dopamine, cafeic esters, and ferulic acids were associated with a very low rate of nematode root penetration in the resistant cultivar. The presence of lignified and suberized layers in endodermal cells contributed to limit invasion of the vascular bundle by the pathogen. After infection, flavonoids were seen to accumulate early in walls of cells close to the nematode-migrating channel in both cultivars and in all tissues of the infected resistant roots including the vascular tissues. The labeling pattern obtained with the gold-complexed laccase and with anti-pectin monoclonal antibodies showed that phenolics were distributed in a loosened pectin-rich material surrounding the nematode. This study provides indications that constitutive phenolics in banana roots are associated with the limitation of host penetration and colonization by R. similis. Accumulation of flavonoids in response to infection was detected in the vascular tissues of susceptible plants and in all root tissues in the partially resistant plants.
摘要 钻蛀线虫 Radopholus similis 是香蕉种植园最具破坏性的病原体之一。本研究从组织化学和超微结构水平，研究了酚类物质在感病和部分感病品种植物对线虫防御反应中的作用。健康根系的组织化学观察表明，木质素、类黄酮、多巴胺、咖啡酸酯和阿魏酸水平较高的品种，其线虫根穿透率非常低。内皮层细胞中木质化和木栓化层的存在有助于限制病原体侵入维管束。感染后，两种品种中，靠近线虫迁移通道的细胞壁以及感病抗性根的所有组织（包括维管束组织）中，类黄酮都被观察到早期积累。用金复合漆酶和抗果胶单克隆抗体获得的标记模式表明，酚类物质分布在围绕线虫的疏松果胶丰富物质中。本研究表明，香蕉根中的组成性酚类物质与限制 R. similis 对宿主的穿透和定殖有关。在易感植物的维管束组织和部分抗性植物的所有根组织中，都检测到了对线虫侵染的黄酮类物质的积累。
