Phylogeny and taxonomy of <i>Podosphaera filipendulae</i> (<i>Erysiphaceae</i>) revisited

Abstract

The genus Filipendula comprises about 15 species of perennial herbs distributed in the temperate zone of the Northern Hemisphere (Schanzer, 1994). In the past, Filipendula was treated as a part of the genus Spiraea until its reintroduction as separate genus by Maximowicz (1879). Spiraea is a larger genus of about 80 to 100 deciduous shrub species distributed in the temperate Northern Hemisphere, with a few species in subtropical regions. The highest diversity of Spiraea occurs in Asia, most notably in China (Drábková, Pospíšková, & Businský, 2017). Numerous species are used as popular ornamental shrubs worldwide. Filipendula and Spiraea pertain to the family Rosaceae, but they are not closely allied. Filipendula is a part of the subfamily Rosoideae, but with an isolated position in phylogenetic multilocus analyses, i.e., it does not belong to any tribe (Potter et al., 2007). Spiraea is the type genus of tribe Spiraeeae, which belongs to the subfamily Amygdaloideae (previously Spiraeoideae, Porter et al., 2007;Drábková et al., 2017). Powdery mildews (Erysiphaceae) are common detrimental pathogens on numerous rosaceous host plants. Salmon (1900) assigned powdery mildew on Filipendula vulgaris (as Spiraea filipendula) to Sphaerotheca humuli, followed by Homma (1937), who included Japanese powdery mildews on Filipendula spp. and Spiraea spp. under Sph. humuli. Sawada (1951) described Sph. spiraeae on Spi. thunbergii from Japan. Based on Chinese type material on F. ulmaria, Zhao (1981) introduced the new species Sph. filipendulae. The two species on Filipendula and Spiraea spp. are barely distinguishable morphologically with regard to their asexual or sexual morphs. Therefore, Braun (1987) merged the two species. Later, Braun and Takamatsu (2000) reallocated Sph. spiraeae to Podosphaera. The first comprehensive phylogenetic analysis of powdery mildews on rosaceous hosts suggested that Podosphaera on Filipendula and on Spiraea, although barely distinguishable morphologically, belong to two different clades (Takamatsu, Niinomi, Harada, & Havrylenko, 2010). Based on these results, Braun and Liu (in Liu, 2010) proposed the combination P. filipendulae. A new powdery mildew species, P. filipendulensis, has recently been described from India on F. vestita . The authors compared results of sequence analyses with sequences from P. ferruginea, P. macularis and P. spiraeae, but unfortunately without inclusion of sequences retrieved from P. filipendulae. To clarify the phylogeny, taxonomy, distribution and host range of P. filipendulae, a new

Secondary DNA Barcodes (CAM, GAPDH, GS, and RpB2) to Characterize Species Complexes and Strengthen the Powdery Mildew Phylogeny

“…Qiu et al (2020) used five genes (ITS, LSU, IGS, TUB2, and CHS1) to increase resolution in the Golovinomyces ambrosiae complex. Using solely GAPDH (Figure 6) we were able to delimit taxa of this complex, consistent with Qiu et al (2020). Liu S. Y. et al (2021 used four genes (ITS, CHS1, and fragments of two unnamed orthologous genes) to split the Blumeria graminis complex into eight separate species.…”