Pathogenicity and diversity of large-spored Alternaria associated with three solanaceous vegetables (Solanum tuberosum, S. lycopersicum and S. melongena) in China

Alternaria foliar diseases are important factors that pose a significant threat to yield in solanaceous crops. To clarify the diversity of large-spored Alternaria species in China, diseased leaves of three solanaceous vegetables (potato, tomato and eggplant) were collected and used for fungal isolation. In total, 67 strains representing six species in section Porri of Alternaria were isolated, based on morphological characterizations and multilocus phylogenetic analyses. There were three known species (A. blumeae, A. linariae and A. solani), one new record of A. argyroxiphii and two new species, A. melongenicola sp. nov. and A. yichangensis sp. nov. The sequence analyses encompassed the internal transcribed spacer region of rDNA (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), Alternaria major allergen (Alt a 1), translation elongation factor 1-alpha (TEF1) and RNA polymerase second largest subunit (RPB2). To confirm pathogenicity, 15 representative strains were evaluated for their virulence under greenhouse conditions. The results revealed that they were able to induce leaf spot symptoms on potato, tomato and eggplant plants with a range of aggressive abilities. The present study provides a basis for the recognition and management of Alternaria foliar diseases.