异宗配合疫霉同宗配合形成卵孢子的诱导

菌株存放６～２４个月、菌丝损伤、土壤浸出液和绿色木霉（Ｔｒｉｃｈｏｄｅｒｍａｖｉｒｉｄｅ）可诱导槐生疫霉（Ｐｈｙｌｏｐｈｔｈｏｒａｒｏｂｉｎｉｃｏｌａ）、掘氏疫霉（Ｐ．ｄｒｅｃｈｓｌｅｒｉ）和烟草疫霉（Ｐ．ｎｉｃｏｌｉａｎａｅ）部分Ａ＿２交配型菌株产生卵孢子，表现同宗配合特性，而Ａ＿１交配型菌株一般较稳定。樟疫霉（Ｐ．ｃｉｎｎａｍｏｍｉ）仅在土壤浸出液和绿色木霉的刺激下，部分Ａ＿２交配型菌株才形成卵孢子。但是，根据Ｚｅｎｔｍｙｅｒ方法制备的刺槐和雪松的根浸液对上述４种疫霉的卵孢子产生均无诱导作用。     

苎麻疫霉生长速率菌落形态同宗配合性状的遗传研究

测定了引起中国棉花疫病病菌──苎麻疫霉（同宗配合种）菌株ＥＣＳＺＩ－８的生长速率、菌落形态、同宗配合等生物学性状在游动孢子和卵孢子后代的遗传。结果表明上述性状在无性和有性后代均可稳定地遗传，认为苎麻疫霉ＥＣＳＺＩ－８菌株控制上述生物学性状的遗传因子是纯合的。     

Homothallism in Pseudoperonospora humuli

The downy mildew pathogen, Pseudoperonospora humuli, forms oospores abundantly in diseased hop tissue. Diverse monosporangial isolates of P. humuli derived from samples collected in Japan, Germany and the USA readily formed oospores within hop leaves when inoculated singly, suggesting homothallism. Single zoospore isolates also readily formed oospores within hop leaves, further supporting the homothallic nature of this oomycete. The majority of oospores were deemed viable based on cytoplasm characteristics and plasmolysis assays. However, disease symptoms failed to develop when hop leaves were inoculated with newly formed oospores, even when oospore conditioning was attempted with treatment with potassium permanganate or β‐glucuronidase/arylsulphatase, brief exposure to freezing temperature, or passage through an earthworm. Oospores derived from a monosporangial isolate of P. humuli that overwintered outdoors in infested leaves buried in soil also failed to cause downy mildew. Pseudoperonospora humuli is homothallic and oospores of the organism appear to require as yet unknown conditions to stimulate their germination and/or infection.