In this study, strawberry plants (Fragaria × ananassa Duchesne ex Rozier) grown via elevated cultivation in a greenhouse were heavily infested with powdery mildew. We isolated the powdery mildew fungus from strawberry leaves and identified the isolate as Podosphaera aphanis (Wallroth) U. Braun & S. Takamatsu var. aphanis KSP-7 N, based on its morphological characteristics and sequencing of the ribosomal DNA internal transcribed spacer region. The host range of KSP-7 N was assessed by inoculating 17 plant families comprising 49 species (a total of 110 cultivars) with conidia. The fungus caused severe powdery mildew on the tested strawberry plants (commercial, wild, and false strawberries), produced scattered conidia on conidiophores, and formed completely catenated conidia within approximately 27 h from conidiophore erection to the first release of mature conidia. Six conidia were produced on each conidiophore; only those at the apex reached maturity. The cycles of conidial release were repeated 17 to 21 times at intervals of approximately 6 h, during gradual upward elongation of the conidiophores. At the final stage, conidia were released without growth or septation of the generative cells. Conidiophores produced an average of 38 conidia during a 96-h period. These results will help to clarify the modes of conidiogenesis, the lifetime of conidiophores, and the production of conidia on a conidiophore among powdery mildew pathogens isolated from strawberry leaves.

在这项研究中，通过在温室中高架栽培而生长的草莓植物（草莓属（Fragaria  ×  ananassa Duchesne ex Rozier））受到白粉病的严重侵害。我们从草莓叶片中分离出白粉病真菌，并将其鉴定为Podosphaera aphanis（Wallroth）U. Braun＆S. Takamatsu var。孤儿KSP-7 N基于其形态特征和核糖体DNA内部转录间隔区的测序。通过用分生孢子接种包括49种（共110个品种）的17个植物科来评估KSP-7 N的寄主范围。真菌在受试草莓植物（商业草莓，野草莓和假草莓）上引起严重的白粉病，在分生孢子体上产生散生的分生孢子，并在分生孢子体到成熟分生孢子的第一次释放之间约27小时内形成完全呈链状的分生孢子。每个分生孢子产生六个分生孢子。只有那些在顶点的才达到成熟。在分生孢子逐渐向上延长的过程中，分生孢子释放的周期以大约6 h的间隔重复17到21次。在最后阶段 分生孢子被释放而没有生殖细胞的生长或分离。分生孢子在96小时内平均产生38个分生孢子。这些结果将有助于阐明从草莓叶片分离出的白粉病病原体中分生孢子的模式，分生孢子的寿命以及在分生孢子上的分生孢子的产生。