Isolation and identification of Colletotrichum truncatum causing anthracnose disease of the Chinese medicinal herb Cynanchum paniculatum

Cynanchum paniculatum is a valuable medicinal herb used for the effective treatment of various human ailments. A severe anthracnose disease of C. paniculatum was recently observed in Tai'an, China, which caused considerable economic losses in this main herb-growing region of northern China. Infected plants had conspicuous symptoms consisting of circular brown lesions on the leaves and pods, as well as light brown cankers with dark spines on the stem surface. Fungi were isolated from diseased plant tissues, which exhibited radial colony morphology with dense white mycelial growth on potato dextrose agar. Through morphological observation and multigene sequencing analysis of the ITS region and actin, beta-tubulin and histone genes, the isolated fungi were identified as Colletotrichum truncatum. Pathogenicity tests were conducted resulting in symptoms on C. paniculatum similar to those seen in the field. Considering the fungal species in the genus Colletotrichum are major phytopathogens that can cause serious anthracnose diseases on numerous crop species, the pathogenicity of an isolate of C. truncatum was assessed on multiple plant species. This is the first report of C. truncatum causing anthracnose of the Chinese medicinal herb C. paniculatum.