Germinability and infective ability of urediniospores produced in axenic cultures of five Melampsora species, as affected by the artificial media on which the cultures grew.

Abstract

Urediniospores produced in the axenic cultures of five isolates, Mca-1A, Mco-1A, Mep-1A, Met-1A and Mhu-2B which were derived from the uredinial stage of five Melampsora species parasitic on willows, were examined for their germinability and infective ability. The urediniospores produced in the isolates grown on QMS-7 medium, except for isolate Mca-1A, neither germinated nor infected the respective host plants. In contrast, urediniospores produced on HOR medium (isolates Mco-1A, Mep-1A and Met-1A) and on OR medium (isolate Mhu-2B) germinated and infected the respective host plants. By using isolate Mhu-2B, effects of vitamins and agar added to media on which the colonies grew on the germinability and the infective ability of urediniospores produced in the colonies were defined. Kinds of agar added to the media affected the germinability and infective ability of urediniospores, while vitamins had no effect. It is suggested that water-soluble substance(s) contained in Difco Bacto-agar promote or enhance the germinability of urediniospores produced in the colonies.