中文摘要：

本文利用电子显微镜技术研究了内吸性杀菌剂甲霜灵（Metalaxyl）对大豆疫霉Phytophthoras ojae野生菌株和突变菌株的形态学及超微结构的影响。结果表明：不同浓度甲霜灵处理后可导致野生菌株和突变菌株发生一系列不同的变化。低浓度（1μg/mL）处理后,野生菌株在培养基上的生长即可受到抑制,菌丝呈现不规则的肿胀、过度分枝;菌丝细胞壁不规则加厚,菌丝细胞内液泡增加,脂肪粒累积,细胞器排列紊乱,原生质最终坏死。随浓度的升高,野生菌株立即停止生长,菌丝干瘪坏死。而突变菌株只在高浓度（10μg/mL）甲霜灵处理后顶端菌丝出现少量较小的分枝,菌丝细胞壁无增厚现象,但细胞内脂肪粒大量积累,明显高于敏感性菌株;突变菌株在高浓度甲霜灵压力下仍继续生长。

英文摘要：

The effects of metalaxyl, an acylalanine phenylamide fungicide exhibiting systemic properties, on morphology and ultrastructure of the wild-type isolate and the metalaxyl-resistant mutant ofPhytophthora sojae in vitro were examined by means of electron microscopy techniques. Ultrastructral observations on the wild-type isolate revealed marked alterations at a low concentration of metalaxyl （1μg/mL）, such as uneven growth of hyphae, excessive branching of hyphal tips, cessation of hyphal growth and bulb-like swelling of hyphal tips; mitochondria lost their distinct structures, number and size of vesicles increased, cell walls became thickened and hyphal cytoplasm was seriously degenerated in presence of a high concentration of metalaxyl （10μg/mL） While, hyphae of the metalaxyl-resistant mutant displayed little morphological changes after treatment with the high concentration of metalaxyl （10μg/mL）. Observations indicated hyphal tips just appeared little excessive branching, hyphal cell contained a high number of lipid bodies, but fungal cell walls did not thicken. Hyphae maintained their growth and get across the filter treated with 10μg/mL metalaxyl.