Multi-host species of Cercospora are associated with Cercospora leaf blight and purple seed stain of soybean

Abstract

Many Cercospora spp. are multi-host pathogens. The versatility of Cercospora newly associated with Cercospora leaf blight (CLB) and purple seed stain (PSS) in soybean seems to have been historically underestimated. Herein, we assembled multilocus sequence data (seven nuclear gene regions) with sequences from 36 fungal isolates sampled from non-soybean host species from Brazil (15 species) and United States (six species), in addition to 13 isolates from soybean. Phylogenetic tools explored relationships among isolates of Cercospora obtained from either soybeans or non-soybean hosts. Cercosporin production was determined to confirm whether the isolates belong to cercosporin-producing species of Cercospora. Among the five genealogical lineages, Lineage 1 showed C. kikuchii as the only member; this species is known to infect only soybean. The remaining four lineages were multi-host Cercospora which infected soybean along with ornamental and weed species. Genealogical placements were unrelated to host association and isolates clustered according to geography. Multi-host species of cercosporin-producing Cercospora are associated with CLB and PSS of soybean.