Analyses of multi-locus sequences and morphological features reveal Ilyonectria species associated with black rot disease of Gastrodia elata

Black rot is a common disease of Gastrodia elata, causing serious threats to G. elata production. In this study, a total of 17 cylindrocarpon-like strains were isolated from black rot G. elata tissues. Multi-locus sequence analyses based on ITS, HIS, TEF and TUB combined with morphological characterizations were employed to identify six Ilyonectria species, including four new species, I. longispora, I. sinensis, I. xiaocaobaensis and I. yunnanensis spp. nov., and two known species, I. changbaiensis and I. robusta. The pathogenicity of 11 isolates comprising type strains of the four new species and representative isolates from each of the six species was tested on healthy tissues of G. elata. All isolates were pathogenic to G. elata tissues, and symptoms were identical to black rot disease, confirming that our isolates were the causal agents of black rot disease of G. elata.