Phylogeny and taxonomy of grass rusts with aecia on Ranunculus and Ficaria

Abstract

This study is focused on macrocyclic, heteroecious grass rusts (Pucciniales) with the aecial stage on Ranunculus spp. and Ficaria verna. Our aim is to study their phylogeny and host range, and evaluate differentiating morphological and molecular markers. Phylogenetic analyses of ITS-LSU rDNA recognised Puccinia perplexans, P. magnusiana, Uromyces dactylidis, U. poae, and three other lineages of uncertain taxonomic classification (U. cf. festucae and Uromyces species having aecia on Ranunculus). We showed that U. poae complex is a sister to U. dactylidis and belongs to the single clade with P. perplexans, phylogenetically distant from P. magnusiana. Of the PCR fingerprinting methods tested for species differentiation, only ISSR-PCR was found to be suitable. The analysis supported classical morphology-based taxonomic concepts of the species. Ficaria verna and Ranunculus acris were found to be the exclusive hosts of U. poae and P. perplexans, respectively. Ranunculus repens hosted U. dactylidis, P. magnusiana and an unidentified taxon from the U. poae clade. No specific differential features were found in aeciospore ornamentation, and only Uromyces cf. festucae can be distinguished based on specific aecial morphology. Based on aeciospore dimensions, only two species, U. dactylidis and P. perplexans, cannot be distinguished. All other species, including sister species U. poae and U. dactylidis, showed statistically significant differences. Because of overlapping morphological features of aecia and aeciospores, the molecular characters are necessary for their determination.