掘氏疫霉同宗配合、异宗配合特性的研究

本文对掘氏疫霉的同宗配合、异宗配合特性进行了研究,发现新分离的掘氏疫霉A~2交配型菌株,不经过配对培养可以产生卵孢子;菌种在15℃下保存,自身可孕性能力逐渐减退。菌株通过接种黄瓜后,异宗配合特性可以恢复,同宗配合特性不能恢复。经过营养生长,无性繁殖,菌株后代的交配型不引起改变。通过对疫霉属有关种不同交配型与掘氏疫霉各菌株不同交配型配对培养,以及菌种不同保存时间、不同培养基、疫霉属有关种的种间和种内配对,讨论了掘氏疫霉同宗配合、异宗配合特性的影响因素。

HOMOTHALLIC AND HETEROTHALLIC BEHAVIOR OF PHYTOPHTHORA DERCHSLERI TUCKER

It was found that A~2 isolates of Phytophthora drechsleri freshly isolated from diseased plants showed the ability to form oospores without being paired with A~1 type isolates.This ability declined as the isolate was stocked at 15℃ for a long time.The hetero- thallic features of P.drechsleri was stable except three isolates lost the mating ability during a long time storage.The reinfection of pathogen seemed having no effect on the restoration of homothallic behavior of P.drechsleri but has effect on the restoration of heterothallic features of the isolates which lost mating ability. It was also found that the oospore quantity formed in mating depended on the mating type,medium,time,and so on,and substance like,β-sito-sterol can induce the oospore forma- tion of A~2 mating type isolates of P.drechsleri.These results are.considered possible evidence of physiological differences of sexuality between A~1 and A~2 mating type isolates. The possibility of chemical stimulation of sexual reproduction between compatible isola- tes of P.drechsleri was investigated by using filter membrane to separate compatible isolates in mating test.It was suggested that sexual behavior of Phytophthora was not an appropriate cri- terion for taxonomy.