Morphological, molecular and pathogenic characterization of Botryosphaeria dothidea causing leaf blight disease of Polygonatum cyrtonema in China

Polygonatum cyrtonema has been widely cultivated as a medicinal and edible plant in China, where it is considered to have substantial economic and human health benefits. However, several foliar diseases threaten P. cyrtonema production and can reduce its quality and yield. Between August and September 2022, severe symptoms of an unknown leaf blight disease were observed on P. cyrtonema in a planting in Hubei, China, with an incidence of 10%–20%. To determine the causal agent of the unknown disease, fungal isolates were collected, identified, and evaluated for pathogenicity to complete Koch's postulates and confirm the pathogen of leaf blight on P. cyrtonema. In this study, leaf samples with typical blight symptoms were collected and the pathogen was isolated and examined following Koch's postulates. The suspected pathogen was identified by both morphological features and DNA sequencing of the internal transcribed spacer region (ITS), beta-tubulin (TUB2), and transcription elongation factor 1 alpha (TEF-1α) gene. Finally, the pathogenicity tests were performed using in vitro and in vivo inoculations. The pathogen was identified as Botryosphaeria dothidea. To our knowledge, this is the first report of P. cyrtonema leaf blight in China. These discoveries will provide a basis for subsequent research to develop prevention and control measures of leaf blight disease in future. •The causal agent of leaf blight disease on Polygonatum cyrtonema was first isolated and identified.•The pathogen was identified as Botryosphaeria dothidea via Koch hypothesis.•Biological characteristics of B. dothidea were demonstrated under laboratory conditions.