Identification and characterization of Diaporthe eres causing leaf blight disease on the medicinal herb Polygonatum sibiricum

Abstract

The rhizome of Polygonatum sibiricum, known as huang-jing (黄精 in Chinese) in traditional Chinese medicine, is consumed to treat various diseases. During surveys in 2017, diseases reducing the productivity and longevity of the herb seedlings were observed on Mount Maoshan, China, including leaf blight caused by Diaporthe spp. This study aimed to identify the fungal species and evaluate the effectiveness of fungicides (prochloraz, tebuconazole, pyraclostrobin, and zhongshengmycin) against the pathogen in vitro. Based on morphological characteristics, pathogenicity tests, and phylogenetic analysis of the combined genes including the internal transcribed spacer (ITS)1-5.8S rRNA-ITS2 (rDNA-ITS), β-tubulin (TUB), translation elongation factor 1-α (EF1-α), and calmodulin (CAL) gene regions, the causal agent of the new disease was identified as Diaporthe eres. Among the tested fungicides, prochloraz, tebuconazole, and pyraclostrobin significantly inhibited the mycelial growth of D. eres on potato dextrose agar, whereas zhongshengmycin was less effective in inhibiting mycelial growth. The leaf blight caused by D. eres represents a potential threat to P. sibiricum nursery productivity and longevity in China, and its management should be further investigated in the field.