Diversity and Distribution of Calonectria Species in Soils from Eucalyptus urophylla × E . grandis , Pinus massoniana , and Cunninghamia lanceolata Plantations in Four Provinces in Southern China.

The species of include many notorious plant pathogens and are widely distributed around the world. Leaf blight caused by species is considered one of the most prominent diseases in plantations in China. Some species isolated from soils in plantations are highly pathogenic to inoculated genotypes. In southern China, the plantation trees , spp., and are always adjacently planted, especially in FuJian, GuangDong, GuangXi, and YunNan Provinces. The aim of this study was to understand the diversity and distribution of in soils from plantations of different tree species in different geographic regions. Soil samples were collected from 12 sampling sites in × . , . , and . plantations in FuJian, GuangDong, GuangXi, and YunNan Provinces. Approximately 250 soil samples were collected from each sampling site, and a total of 2991 soil samples were obtained. A total of 1270 isolates were obtained from 1270 soil samples. The 1270 isolates were identified based on DNA sequence comparisons of the partial gene regions of , , , , , and . These isolates were identified as 11 species: (69.50%), . (13.10%), . (10.80%), . (2.50%), . (2.36%), . (0.31%), . (0.24%), . (0.24%), . (0.16%), and . (0.08%) in the . species complex and . (0.71%) in the . species complex. The three dominant species, . , . , and . , were widely distributed. The richness of (percentage of soil samples that yielded ) in soils in the eastern regions (relatively humid regions) was higher than that in the western regions. The richness of . × . , . , and . plantations decreased gradually. For each of the three dominant species, its richness in the eastern regions was generally higher than that in the western regions; the species richness was highest in . × . plantations for . , while for each of . and . its species richness was highest in . plantations. The genetic variation in . , . , and . was more greatly affected by geographic region than by plantation tree species. This study expanded our understanding of the richness, species diversity, and distribution characteristics of in soils from the plantations of different tree species in different geographic regions in southern China. Results in this study enhanced our understanding of the influencing characteristics of geographic region and tree species on the species and genetic diversity of soilborne fungi.