Diversity of Diaporthe species associated with post-harvest decay on kiwifruit in China.

China is one of the largest kiwifruit-growing countries in the world. In recent years, post-harvest decay of kiwifruit has occurred widely in major cultivation areas, severely affecting the development of Chinese kiwifruit industry. Our previous study indicated that Diaporthe species were one of the dominant pathogens of the decay in China. In this study, further research was conducted on the diversity and pathogenicity of pathogens within the genus. Based on ITS sequences, 40 representative isolates were selected from 325 Diaporthe fungal isolates. Through the combination of multi-locus phylogenetic analysis and morphological observations, the 40 isolates were identified as 8 species, including four known pathogenic species: Diaporthe eres, Diaporthe sojae, Diaporthe hongkongensis, and Diaporthe passiflorae and four new host species: Diaporthe arecae, Diaporthe amygdali, Diaporthe tulliensis, and Diaporthe apiculata. Among the 325 isolates, D. eres had the highest abundance (58.9%) and the widest distribution (Jiangxi, Hubei, Shaanxi, Sichuan, and Shandong provinces). D. hongkongensis followed with a percentage of 3.7% and was distributed in Jiangxi, Hubei, and Shaanxi provinces. Pathogenicity tests showed all eight species infected both kiwifruit (Hayward) and apple (Tiaohong), with D. amygdali and D. hongkongensis exhititing the highest virulence on kiwifruit and D. arecae and D. hongkongensis on apple. Six species cross-infected citrus (Satsuma mandarin), notably D. tulliensis and D. arecae. Additionally, the eight species also exhibited varying degrees of pathogenicity on kiwifruit shoots. This study not only contributes to the understanding of the etiology of kiwifruit decay in China but also enriches the knowledge of fungal diversity within the Diaporthe genus, providing crucial insights for developing integrated management strategies against these cross-infectious pathogens.