Species identification and pathogenicity study of Alternaria fungi causing pear black spot disease in Anhui Province

Black spot disease is a significant disease during the growth period of pear trees. The species and pathogenicity of Alternaria fungi causing black spot disease in Anhui Province are still unclear.

In this study, through phylogenetic analysis of multi-gene tandem sequences, pathogens causing pear black spot disease (PBS) in Anhui Province were identified, primarily Alternaria alternata, Alternaria gaisen and Alternaria tenuissima, with A. alternata being the dominant species (41.18%). The single nucleotide polymorphism (SNP) density of Alt a1 was much higher than that of other genes, and the codon bias was affected by both natural selection and mutation. The codon bias and the amino acid ratio of Alt a1 in A. alternata and A. gaisen were highly consistent, and A. tenuissima was quite different from them. The pathogenicity of A. alternata was significantly negatively correlated with the daily mycelia growth rate, dry weight of mycelia and alternariol production, and significantly positively correlated with tenuazonic acid (TeA) and tentoxin production. TeA might be the main virulence factor in the pathogenic process of A. alternata.

This study presents novel ideas for classifying Alternaria fungi and provides a theoretical basis for establishing prevention and control technologies for PBS control and toxin reduction. © 2026 Society of Chemical Industry.