Internal Resistance in Winter Oilseed Rape Inhibits Systemic Spread of the Vascular Pathogen Verticillium longisporum
Internal Resistance in Winter Oilseed Rape Inhibits Systemic Spread of the Vascular Pathogen Verticillium longisporum
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DOI：
10.1094/phyto-99-7-0802
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发表时间：
2009-07-01
期刊：
影响因子：
3.2
通讯作者：
von Tiedemann, A.
中科院分区：
文献类型：
--
作者：
Eynck, C.;Koopmann, B.;von Tiedemann, A.
黄萎病是危害欧洲油菜生产的一种维管真菌病原菌。对甘蓝型油菜的感病品种(猎鹰)和抗性品种(SEM05-500256)进行了系统传播和维管反应的研究。在根浸渍接种和定量聚合酶链式反应后，两种基因型的定植仅在根渗透和下胚轴定植的初始阶段显示出相似之处，而只有在‘猎鹰’中才记录到对地上部的大量侵染。结论是，SEM05-500256中所代表的抗性类型不能阻止植物基地的入侵，因为它在植物基地的根渗透和定殖之后很好地在内部表达。用组织化学方法，结合生化分析，研究了下胚轴组织侵染后产生的屏障的形态和生化性质。组织化学研究表明，血管闭塞的建立和通过细胞壁上结合的酚类和木质素的沉积加强了管状分子。此外，还观察到了可溶性酚类物质的积累。虽然在两种类型的血管组织中都发现了这些反应，但在抗性类型中发生的强度明显更高，并与疾病表型相对应。在抗性品种中，酚类物质以时间依赖的方式差异表达，在侵染早期，预先形成的可溶性酚类物质和细胞壁结合的酚类物质，在侵染后期重新形成木质素和类木质素聚合物。这是首次发现苯酚代谢在甘蓝型油菜对长孢霉的内部防御中的重要作用，并定位了植物下胚轴中的关键防御反应。
Verticillium longisporum is a vascular fungal pathogen presently threatening oilseed rape production in Europe. Systemic spread and vascular responses were studied in a susceptible ('Falcon') and a resistant genotype (SEM 05-500256) of Brassica napus. Colonization of both genotypes after dip-inoculation of the roots followed by quantitative polymerase chain reaction revealed similarities only in the initial stages of root penetration and colonization of the hypocotyl, while a substantial invasion of the shoot was only recorded in 'Falcon'. It is concluded that the type of resistance represented in SEM 05-500256 does not prevent the plant base from being invaded as it is internally expressed well after root penetration and colonization of the plant base. The morphological and biochemical nature of barriers induced in the hypocotyl tissue upon infection was studied with histochemical methods accompanied by biochemical analyses. Histochemical studies revealed the build-up of vascular occlusions and the reinforcement of tracheary elements through the deposition of cell wall-bound phenolics and lignin. Furthermore, the accumulation of soluble phenolics was observed. Although these responses were found in vascular tissues of both genotypes, they occurred with a significantly higher intensity in the resistant genotype and corresponded with the disease phenotype. In the resistant genotype phenols were differentially expressed in a time-dependent manner with preformed soluble and cell wall-bound phenolics at earlier time points and de novo formation of lignin and lignin-like polymers at later stages of infection. This is the first study identifying a crucial role of phenol metabolism in internal defense of B. napus against V. longisporum and locating the crucial defense responses in the plant hypocotyl.