Identification of Fuscohypha expansa Associated With Rot of Gastrodia elata Tubers in Hunan Province, China

ABSTRACT Gastrodia elata , a traditional medicinal plant used for over 2000 years, is highly susceptible to fungal diseases, and tuber rot has recently caused severe yield losses in Hongjiang, Hunan Province, China. Diseased tubers exhibited black surface lesions, with the underlying tissues softened into a pulpy mass, accompanied by mucilage that adheres to soil particles and a strong foul odour. The causal pathogen was isolated in pure culture and identified as Fuscohypha expansa based on detailed morphological characteristics and multilocus phylogenetic analyses of ITS, LSU and RPB2 sequences. Pathogenicity tests fulfilling Koch's postulates confirmed its ability to reproduce typical symptoms on G. elata tubers. To our knowledge, this study provides the first report of the genus Fuscohypha in China and its first evidence as a plant pathogen, offering new insights into disease aetiology and a foundation for future management strategies.