Axenic cultures from basidiospores of Cronartium ribicola

Abstract

Axenic colonies of Cronartium ribicola were routinely established directly from basidiospores. The methods permit axenic spore collection from field-grown Ribes plants. The colonies grew to a maximum 5-mm diameter in 5–6 weeks, after which the size remained stable. The mononucleate hyphae remained virulent for at least 24 months without media change. Yeast extract, peptone, and bovine serum albumin supplements were required in the medium, but bovine serum albumin may be replaced by nucleic acids or a trace-element solution. Germinal hyphae, but not vegetative hyphae, exhibit both sensitivity to light and negative geotropism. These have noteworthy implications regarding the general pattern of tree infection within forest stands.