Study on the diversity of rust pathogens from different hosts in Guizhou Province, China

Rust fungi are obligate plant pathogens that belong to Basidiomycota, Puccinomycetes, Pucciniales. Guizhou Province in Southwest China is rich in plant resources and has suitable climate conditions for plant disease development, but there are few studies on rust fungi. In this study over 300 plant samples with typical rust symptoms were collected from 33 counties in various regions of Guizhou Province. These samples come from 98 different host plants in 33 families. According to ITS -BLAST comparison results, the rust fungi belonged to 17 genera of 11 families in Chaconiaceae (Mikronegeria), Coleosporiaceae (Coleosporium), Gymnosporangiaceae (Gymnosporangium), Melampsoraceae (Melampsora), Phakopsoraceae (Phakopsora), Phragmidiaceae (Gerwasia, Hamapora, Phragmidium), Pileolariaceae (Pileolaria), Pucciniaceae (Endophylum, Macropyxis, Puccinia, Uromyces), Pucciniastraceae (Pucciniastram), Tranzscheliaceae (Tranzschelia), and Uredinineae incertae sedis (Nyssopsora, Peridiopsora). Phylogenetic analysis based on combined sequence data of ITS, LSU and tef1 alpha loci, coupled with morphological evidence, support the species identification. Ninety-three species of rust fungi were obtained, comprising 29 novel taxa and 61 known species. Most of the rust species belonged to Pucciniaceae (48.9%), while the most prevalent host family infected was Rosaceae (21.9%). The Rosaceae are particularly susceptible to Phragmidium spp.