Variation of mycelial morphology between species and formae spéciales of rust fungi of cereals and grasses

Abstract

The morphology of the infection structures (substomatal vesicles, primary infection hyphae, and haustorial mother cells) was described for 23 isolates comprising nine rust species of cereals and grasses. Interspecific differences in morphology were very large. The results indicate that it should be possible to identify single sporelings at least to species level. Between samples of the same rust species collected from different host species, no qualitative differences were found in some cases (Puccinia coronata); in other cases the differences between samples were as large as between species (P. recondita, P. brachypodii). Because primary infection structures develop on virtually any graminaceous plant, all observations were done using barley or Triticum dicoccum seedlings as substrate. The results indicate that inclusion of mycelial morphology in description of rust taxa may be helpful in taxonomic studies. The differences in mycelial morphology may also be exploited in certain phytopathological studies.