向日葵霜霉菌吸器和孢囊梗发育的电镜观察

电镜观察发现,在菌丝产生的入侵栓穿透寄主细胞壁之前,寄主细胞已在壁与质膜间分泌有大量的胼胝质。入侵栓壁由两层构成,分别与菌丝细胞壁相连接,当入侵栓穿透寄主细胞壁后,迅速扩张,膨大成吸器,吸器卵球形,吸器壁由染色深的外层和染色浅的内层构成。随吸器进一步发育吸器外间质明显增宽,其中分布有大量染色较深的物质。在孢囊梗产生时,首先由位于气孔下方的菌丝产生多个孢囊梗原基,原基伸出气孔后,迅速膨大,并产生多个突起,突起经不断延伸而形成孢囊梗。

Electron Microscopy Observation of Development of Haustorium and Sporangiophore in Sunflower Downy Mildew

The development of haustorium and sporangiophore in sunflower downy mildew was examined with transmission and scanning electron microscopy. The result from observation showed that there was a collar formed between host cell wall and plas-malemma before a penetration peg formed on intercellular hyphae penetrated host cell wall, and the penetration peg wall was formed with two layers and continouos in connection with the hyphal wall. Once a penetration peg penetrated into host cell, it expanded rapidly and became a haustorium in the shape of oval-sphere. The wall of the haustorium consisted of a denesly stained outer layer and a lighly stained inner layer. With further development, extrahaustrial matrix enlarged and contained a lot of densely stained material. During formation of sporangiophore, several sporangiphore primordia were produced on the hyphae located in substomatal cavity. The primordia became narrow for going through host stoma and expanded at outer surface of leaves, then the primordia could produce one to several protrusions at the outer surface, and the protrusions finally became sporangiphores by continuous expanding and extending.