Catalogue of fungi in China 6: Rhytismataceae on twigs of Rhododendron

Rhytismatales M.E. Barr ex Minter (Leotiomycetes, Ascomycota) is an order mostly consists of plant-associated ascomycetes, some of its members are plant pathogens that can cause significant economic losses, while others are important in biological control, ecological cycles, and pharmaceutical production. Numerous studies have shown that Rhytismatales species have distinct host specificity, among which Rhododendron is one of the most preferred hosts of Rhytismatales species, and it has an extremely high species diversity in China, accounting for about 60% of the global Rhododendron species. The diversity of host plants often breeds a high degree of fungal diversity.

In this research, a sum of 46 specimens were collected from the twigs of Rhododendron species in China. Subsequently, based on multi-gene phylogenetic analyses using molecular sequence data from the internal transcribed spacer (ITS) region, the large subunit of the ribosomal RNA gene (nrLSU), and the mitochondrial small subunit (mtSSU), and morphological characteristics, three new genera were proposed (Neolophodermium, Truncomyces, and Virgamyces), and 21 species residing in 11 genera of Rhytismataceae were delimited, which include 18 new species and three new combinations. This study complements the diversity of Rhytismataceae on twigs of Rhododendron. An integrated taxonomic approach includes the evidence for morphological characteristics, the ecological data, and the phylogenetic analyses based on multiple loci, were demonstrated that can be defined a natural classification of Rhytismataceae on the genus level.

The morphological and molecular characterization of Rhytismataceae on Rhododendron spp. is further systematic in this study. The results of this investigation showed the ecological, morphological, and taxonomic variety of Rhytismataceae linked to several Rhododendron species in China. In addition to broadening our understanding of the hosts and genetic diversity of Rhytismataceae on Rhododendron, it offered vital information for comprehending the ecology of the Rhytismataceae linked to Rhododendron.

The study solved some polyphyletic problems and provided a basis for the establishment of a natural classification system of Rhytismatales in the future. It also offers a significant theoretical basis for the prevention and control of major forest tree diseases caused by Rhytismatales species and for the breeding of disease-resistant forest trees.

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Catalogue of fungi in China 6: Rhytismataceae on twigs of Rhododendron