VIEW ARTICLE

A New Perspective of the Axenic Culture of Puccinia graminis f. sp. tritici from Uredospores. P. G. Williams, Research Fellow (Wheat Industry Research Council), Department of Agricultural Botany, The University of Sydney, Sydney 2006, Australia; Phytopathology 61:994-1002. Accepted for publication 20 March 1971. DOI: 10.1094/Phyto-61-994.

Applying the Giemsa stain to nutrient agar cultures of Puccinia graminis f. sp. tritici shows that dikaryotic mycelia are formed only by uredospores which differentiate an infection structure. Saprophytic cultures also contain monokaryotic haploid mycelia. These mycelia originate from germ tubes which fail to differentiate. The mode of origin of haploid mycelia suggests that in normal differentiation the substomatal vesicle is the site of derepression of nuclear functions concerned with the metabolism of vegetative cells. Experiments demonstrate that the formation of infection structures in culture is affected by nutrients, heat shock, the time of collecting the inoculum, and genetic constitution. The results are discussed in relation to the new perspective they provide of the theory and practice of axenic rust culture.