Morphological analyses of urediniospores and teliospores in seven Phragmidium species parasitic on ornamental roses

Abstract

Ornamental roses worldwide harbor 10 Phragmidium species. Among these, P. americanum, P. fusiforrne, P. montivagum, P. mucronaturn, P. rosae-pimpinellifoliae, P. rosae-rugosae and P. tuberculatum are frequently reported; however, these species are morphologically similar and difficult to distinguish. For better circumscription and correct identification of the species, this study examined morphological features in urediniospores and teliospores of the seven Phragmidium species collected on ornamental rose cultivars and wild species. The results indicated that some host-specific groups could be well circumscribed by the morphological properties of urediniospores and teliospores. However, without the precise identification of hosts, these morphological properties were not effective key characters for the identification of the species.

Two new Phragmidium species identified on Rosa plants native to China

“…Phragmidium fusiforme is one of the most widespread Phragmidium species in the northern hemisphere; it is characterized by multiple-celled (mostly greater than 10-celled) and fusiform teliospore with long papilla up to 15 μm at the spore apex, which is obviously different from that of the present species (Wei 1988, Hiratsuka et al 1992, Wahyuno 2001, Zhuang et al 2012. Phragmidium zhouquensis also differed from Ph.…”

“…mucronatum has papilla at the top of the teliospore (up to 13.5 μm long), which are clearly longer than those of Ph. longissima (Wei 1988, Hiratsuka et al 1992, Wahyuno 2001, Zhuang et al 2012. According to the consensus results of morphological and phylogenetic analyses, Ph.…”

“…Phragmidium americanum was similar to Ph. longissima with respect to teliospore size and cell number, but was distinct in that teliospores were sometimes slightly narrowed above and the pedicel length averaged 1−1.5 times the spore length (Cummins 1931, Wahyuno 2001. Phragmidium longissima resembled Ph.…”

“…rosae-californicae are distributed primarily in North America and have never been recorded in China (Cummins 1931). Phragmidium longissima was the first Phragmidium species reported on Rosa lichiangensis, which obviously differed from all the previously described Phragmidium species by the uredinial and telial host range (Wei 1988, Hiratsuka et al 1992, Wahyuno 2001, Tykhonenko 2007, Zhuang & Wei 2009, Zhuang et al 2012. …”

“…Wahyuno et al (2001) described seven Phragmidium species by analysing the morphological characteristics of a maximum of four spore stages from ten previously recorded species. These authors determined that the length, width, degree of tapering toward both ends, and apiculus length were sufficient to determine gross teliospore morphology, and these have been considered as important taxonomic characters.…”