Morphological characterization and pathogenicity of Diaporthe eres , D. spinosa and D. eugeniae causing leaf spot on Photinia × fraseri Dress in Jiangsu, China

Photinia fraseri is an evergreen shrub that plays a vital role in the development of urban landscapes. The development of P. fraseri is severely hampered by leaf spot, which has a major impact on the enhancement of urban landscape ecosystems. Uncertainty surrounds the Diaporthe species linked to P. fraseri leaf spot disease. In three parks in Jiangsu, China, diseased P. fraseri leaves with characteristic symptoms were gathered for this study. Three species morphotypes were found among the 60 isolates, and they were determined by morphological traits and multilocus phylogenetic analysis to be D. spinosa, D. eugeniae and D. eres. Phylogenetic analyses confirmed robust species delimitation, with all isolates forming distinct monophyletic clades with high bootstrap support (≥97%) and Bayesian posterior probability (≥0.97). The three species displayed differing levels of pathogenicity on P. fraseri, according to pathogenicity assays. In P. fraseri, wounding promoted the pathogenicity of D. spinosa, D. eugeniae and D. eres through conidial suspensions inoculation. The first report of D. spinosa and D. eugeniae causing leaf spot on P. fraseri globally and in China is provided by this study. The findings showed that they could cause a variety of aggressive leaf spot symptoms in P. fraseri plants. Diaporthe foliar diseases may now be recognized and managed with the help of this study.