大豆菌核病菌丝侵染茎叶过程扫描电镜观察研究

Study of Scanning Electron Microscopic Observation on the Mycelium Infection Process of Soybean Sclerotinia sclerotirum on Leaf and Stem

为充分了解大豆菌核病菌丝侵染过程,促进大豆菌核病耐性品种筛选及致病机理研究,本研究以感病品种合丰25和耐病品种Mapple Arrow为材料,对离体叶片和茎秆菌丝接种后,采用扫描电镜对菌丝特性、茎叶组织变化、侵染特征等进行系统观察。结果表明:不同耐性品种菌丝侵染速度及组织病斑大小表现出明显差异。接种后菌丝迅速进行分枝繁殖,分枝的尖端形成椭圆形膨大,类似"侵染胞"的结构,接种后5 d菌丝缺乏营养来源,生长活力下降,组织干瘪,侵染能力降低。菌丝接种后第3天,感病品种合丰25,叶片表层物质几乎全部消失,叶肉细胞出现明显皱缩,耐病品种Mapple Arrow叶片表层物质基本完整保留,除个别细胞出现凹陷皱缩,其余细胞形状仍较为完好;茎秆在第3天表现与叶片相似,感病品种表层物质消失,耐病品种仍基本保留。叶片和茎秆侵染过程中,气孔为直接侵入通道,菌丝也可以侵入组织细胞内部。

In order to fully understand the mycelium infection process of soybean Sclerotinia sclerotirum and promote the selection of resistant varieties and the pathogenicity mechanism study,this study used the susceptible variety Hefeng 25 and the partial resistant variety Mapple Arrow as materials to systematically observe the characteristics of mycelium,the changes of stem and leaf tissue,and the infection characteristics after inoculating mycelium on the leaves and stem in vitro.The results showed that there were significant differences in the infection speed of mycelium and the size of tissue lesion among different resistant varieties.After inoculation,the mycelium produced branching and propagation rapidly,the tip shape of the branch grew elliptic and expanded,similar to the structure of‘infection cell’.Five days after inoculation,the mycelium lacked nutrition source,the growth vigor decreased,the tissue dried up,and the infection ability decreased.On the third day after inoculation of mycelium,Hefeng 25,a susceptible variety,the surface materials of leaves almost disappeared,and the mesophyll cells shruncked obviously.The surface materials of the leaves of Mapple Arrow,a partial resistant variety,were basically intact,except for some cells which were sunken and shrunk,the shape of the rest cells were still relatively intact.On the third day,the observation performance of culms was similar to that of leaves,the surface materials of susceptible varieties disappeared,and that of resistant varieties was still basically reserved.In the process of leaf and stem infection,stomata invade the passage directly,and the mycelium could also invade the inside of tissue cells.