MORPHOLOGICAL ANALYSIS OF SPORES FROM DIFFERENT ALLIUM RUST POPULATIONS

The morphology of uredinia and urediniospores in seven rust isolates from Allium porrum (leek) at different locations in the U.K., three from A. schoenoprasum, one from A. babingtonii and one from A. scorodoprasum was compared. Although the urediniospores from the latter two hosts were orange compared with the orange brown colour of those from the first two, there were no clear-cut qualitative differences at optical microscope or SEM levels. Statistical analysis of individual quantitative characters showed that all samples from leek had significantly lower spine densities on the urediniospore walls than those from the other Allium spp. and that the samples from A. babingtonii and A. scorodoprasum had a significantly larger number of germ pores per urediniospore than the samples from other host species. Using principal components analysis and cluster analysis with six quantitative characters the samples were split into leek and non-leek groups. The samples from A. schoenoprasum were separated less clearly from the rest of the non-leek group. Telia of fresh and herbarium specimens from twelve different Allium spp. differed in the occurrence of fused paraphyses and the occurrence and frequency of one- and two-celled teliospores. The telial and uredinial characters separated the same three species independently. It is suggested that the following names be used: Puccinia allii (DC.) Rud. for the rust on A. porrum, Puccinia mixta Fuckel for the rust on A. schoenoprasum and Uromyces ambiguus (DC.) Lév. for the rust on A. babingtonii. © 1990, British Mycological Society. All rights reserved.