[Objective] To clarify the species of Altenaria fungi causing black spot in the main pear producing areas of our country and their pathogenicity, and to provide a theoretical basis for formulating effective control measures. [Methods] Tissue isolation was collected from the main pear producing areas of our country, and the species identification and pathogenicity verification of the obtained strains were identified by combining morphology and molecular biology. [Result] A total of 405 Alternaria strains were obtained by tissue isolation and purification from pear producing areas in 14 provinces, autonomous regions and municipalities directly under the Central Government our country. Morphological observations and phylogenetic analysis of polygenes (ITS, GAP-DH, Alt al, TEF 1, endoPG, and His 3) showed that they belonged to six species of the genus Alternaria (4lternaria). Among them, there were 267 strains of Alternaria tenuissima, 115 strains of A. alternata, 14 strains of A. arborescens, 6 strains of A. gaisen, 2 strains of A. gossypina, and 1 strain of A. longipes. The results of inoculating the representative strains of these six species on the isolated leaves of P. emerald showed that they were all pathogenic, but there were differences between their pathogenicity. The results of inoculation on the isolated leaves of peach (Prunuspersica), kiwifruit (Actinidial chinensis) and citrus (Citrus reticutate) showed that these representative strains were pathogenic to peach and kiwifruit, but none of them could cause citrus disease. [Conclusion] There are six species of Alternaria fungi that cause pear black spot in our country, including A. tenuissinma, A. alternata, A. arborescens, A. gaisen, A. gossypina and A. longipes, among which A. tenuissima and A. alternata are the dominant species. They accounted for 65.9% and 28.4% of the total number of isolated strains, respectively. This study is the first report on the systematic identification of Ahernaria fungal species causing black spot in the main pear producing areas of our country.
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