西北地区小麦根部瓶梗霉新致病类型的形态学研究

Etiology of Phialophora new pathogenic species from wheat roots in Northwestern China

1993～1999年对西北麦区一种病原菌未知的根病依据柯赫氏证病律进行了病原学研究.结果由来自陕西、甘肃和宁夏等省区麦田的病根标样发现了23个瓶梗霉 Phialophora 分离菌株.经诱导不能产生子囊壳.在PDA培养基上菌落为灰色至浅褐色,气生菌丝致密,灰色.产孢细胞为瓶梗状,长10～20μm,宽3～4μm,无色至浅褐色,顶端有领环颈口.分生孢子无色,有两种,一种长卵圆形,单胞,稍弯曲,6～17μm×1.5～6μm;另一种新月形,单胞,4～8μm×1～1.5μm.附着枝浅褐色,筒形,端部呈钩状,1～2细胞,10～14μm×5～8μm.分离菌株接种小麦,引起根部皮层组织变褐,茎基叶鞘变褐,基叶褪绿,严重发病植株矮化,基叶枯死.该菌与已有瓶梗霉不同,暂定为瓶梗霉小麦致病类型.

The wheat roots caused by an unknowing pathogen was found in the northwestern wheat planting zones since 1993 .The etiological study following Koch's postulates was conducted in 1994～1996. Twenty-three isolates were gained from infected wheat roots collected from Shaanxi, Ningxia and Gansu provinces in Northwestern China. All isolates could not produce perithecia in artificial media and formed the grey to pale brown colonies with the pale aerial mycelium in PDA media. Conidiogenous cell is hyaline or pale brown, phialide with flared collarete at its apex, and length 10～20 μm, width 3～4 μm. It can produced two hyaline phialopore conidia, one is ovate to cylindrical, slightly curved, 6～17 μm×1.5～6 μm; another is lunate, 4～8 μm×1～1.5 μm. The hyphopodia is pale brown, cylindrical or slightly curve at apex, 10～14 μm×5～8 μm, made of 1～2 cell. Wheat roots inoculated with the isolates, the cortex tissue became brown, sheath in basic stem became dark, the down leaves turned chlorosis, some plants have dwarf and the leaves necrosis. The isolates is different from the Phialophora spp. Described in morphore and pathogenicity, we described it as wheat-pathogenic Phialophora group.