Identifying and characterizing Stagonosporopsis cucurbitacearum causing spot blight on Pinellia ternata in China

Background: Pinellia ternata (Thunb.), a perennial herbal plant in the Araceae family, has great medicinal value and market demand. In August 2020, an outbreak of severe leaf spot blight disease resulted in a huge yield loss of P. ternata. It is necessary to isolate and identify the pathogens that cause spot blight on P. ternata. Methods: In this study, we isolated and identified the pathogens by fulfilling Koch's postulates. Disease samples with typical spot blight symptoms were collected and pathogens were isolated from the diseased tissues. The pathogen was identified based on its biological characteristics and molecular analysis of internal transcribed (rDNA-ITS) and large subunit (LSU) sequences. Phylogenetic tree were constructed using MEGA7 software and pathogenicity tests were performed using in vivo inoculation. Finally, the pathogen was recovered and identified from the inoculated plants. Results: Based on Koch's postulates, we identified the pathogen causing spot blight on P. ternata as Stagonosporopsis cucurbitacearum. To our knowledge, this is the first study to explore spot blight on P. ternata caused by S. cucurbitacearum in China.