摘要白粉病是橡胶树生产中最重要的病害之一，是由粉孢属病菌Oidium heveae Steinm.引起。目前，对该病原菌在寄主中侵染行为及其与寄主互作的组织细胞学尚缺乏系统研究。本文利用显微技术，结合多种染色方法，观察了橡胶树白粉菌侵染橡胶树叶组织的细胞学变化及寄主的抗性反应。O. heveae在寄主上发育要经历 5 个关键发育时间点，即分生孢子萌发高峰（4 hpi）、附着胞形成高峰（8 hpi）、侵入结构（初生吸器）形成高峰（15 hpi）、次生菌丝形成高峰（24 hpi）、分生孢子梗形成高峰（5 dpi）；分生孢子萌发侵入寄主前，其能量来自自身贮存的能量物质。在互作过程中，病原菌初生吸器形成之后，橡胶树叶组织开始出现明显的氧暴发、胼胝质和乳突等抗性反应，活性氧在橡胶树与病原菌互作中起到了重要的作用，当橡胶树叶片中活性氧积累较低时，有利于O. heveae的发育及入侵，活性氧积累较高时，则引发寄主氧暴发等以阻止病原菌进一步扩展。O. heveae在寄主上发育的 5 个关键发育时间点分别属于病原菌侵染前期、潜育期和侵染后期，橡胶树叶组织早期亲和互作与中后期非亲和互作保持了专性寄生菌与寄主间发育平衡的进化关系。
关键词橡胶树；橡胶树白粉菌；侵染；细胞学
中图分类号:Q 932文献标识码：ADOI：10.3969/j.issn.05291542.2014.03.005Cytological analysis of compatible interactions between rubber
tree and Oidium heveaeWan Sanlian,Liang Peng,Liu Wenbo,Zhang Yu,Miao Weiguo,Zheng Fucong(Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources/College of
Environmental and Plant Protection, Hainan University, Haikou570228, China)AbstractPowdery mildew, a disease caused by Oidium heveae Steinm. is one of the most important leaf diseases that affect rubber tree plantations. Yet, at present there is a lack of systematic cytological research on the infection process and hostpathogen interactions. This study used a combination of various staining techniques and microscopy to observe the O. heveae infection process and the cytological changes in the infected leaves associated with host resistance response. The infection of O. heveae in the host developed through 5 crucial time points: conidia germination peak at 4 hours post infection (hpi), appressoria formation peak (8 hpi), penetration structure (primary haustoria) formation peak (15 hpi), secondary hyphae formation peak (24 hpi) and conidiophore formation peak at 5 days post infection. Prior to haustorium penetration into the host cells, the energy for the process came from conidium’s own energy reserves. After the formation of pathogen’s primary haustoria, in response to pathogen penetration, the rubber tree leaves initiated resistance reactions, including reactive oxygen burst and formation of calluses and papillae. Reactive oxygen species played an important role in the rubber treepathogen interactions. Low ROS levels in the rubber tree leaves allowed the development and penetration of O. heveae. In contrast, high levels of ROS and resultant oxygen burst prevent further pathogen expansion. The development of O. heveae infection in the host proceeded through 5 crucial time points, including the initial period of pathogen infection, latent period and postinfection period. In the leaves of rubber tree, an early phase of compatible hostpathogen interactions and later phase of incompatible interactions preserve the balance in the evolution of obligatory hostpathogen relationships.
Key wordsrubber tree；Oidium heveae；infection；cytology 橡胶树是热带及亚热带的重要经济林木，橡胶树白粉菌（Oidium heveae Steinm.）是引起橡胶树白粉病的病原菌［1］。橡胶树白粉病最早1918年报道于印尼爪哇，自1951年中国首次报道在海南发现后，相继在中国的各植胶区都有发现［23］，目前已成为我国早春防治橡胶树“两病一虫”的重点［3］，该病在适宜条件下具有发病快危害重的特点，严重感病时还可能造成第二次落叶［2,45］，使干胶产量明显减少。橡胶树白粉菌是一种活体专性寄生菌，无法进行离体培养，国内外学者对橡胶树白粉病病原菌进行了一定的探索性研究，在病原生物学方面，对其在叶片上的入侵情况进行了初步的形态学方面的描述［69］。在寄主与病原菌互作方面，一些研究认为寄主角质层的厚度与抗病性存在一定正相关性［1011］，而原生质体大小仅在橡胶抗病品系的抗病性中可能具有重要作用，但研究者们未在橡胶品系中发现过敏性坏死反应，以及其他主动抗病反应，如胼胝体、木栓层等［11］。前人的研究结果多集中于橡胶树白粉病菌侵染中后期寄主的表现行为，以及对该病害防治措施的探讨，而对于病原菌在橡胶树叶片上的具体侵染行为、侵染时期及对病原菌与寄主互作尚缺乏详细的研究，尤其对于病原菌侵染前期或入侵早期的研究相对较少。橡胶树白粉病菌4~8 d就繁殖一代，病害发生快［5］，因此探究橡胶树白粉菌在寄主上的各发育关键性阶段，及侵染后寄主细胞做出的反应，有助于理解病原菌对寄主侵染行为及橡胶树感病的原因，对提前预警流行、及早采取防治对策阻止病害的传播与危害具有重要的理论意义和应用价值。