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

Abstract

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‐α (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.

Alternaria diseases on potato and tomato

“…Alternaria crassa is reported on tomato and other hosts, but not potato (Bessadat et al., 2020 ; Peixoto et al., 2021 ), and an A. crassa isolate from another host was able to infect tomato (Peixoto et al., 2021 ). Alternaria argyroxiphii was reported on potato and even though it was not found on tomato plants, it was capable of infecting them under laboratory conditions (Zhao et al., 2023 ).…”

“…Affected leaves become yellow and senescent until they dry up or fall off (Agrios, 2005 ). In severe cases, this can cause complete defoliation (Zhao et al., 2023 ).…”

Four New Species of Small-Spored Alternaria Isolated from Solanum tuberosum and S. lycopersicum in China

“…Alternaria foliar disease caused by large-spored Alternaria species has been frequently reported from section (sect.) Porri comprising A. solani, A. blumeae, A. linariae, A. grandis and A. protenta infecting both potatoes and tomatoes [14,16]. Another type of Alternaria, small-spored Alternaria has been detected in a large number of the sampled leaves [17].…”

“…Especially for Alternaria spp., they are widely distributed with a great impact on economic returns of crops. When encountering favorable conditions, it can cause serious yield reduction or even no harvest [ 14 , 15 ]. Alternaria foliar disease caused by large-spored Alternaria species has been frequently reported from section (sect.)…”

“…grandis and A . protenta infecting both potatoes and tomatoes [ 14 , 16 ]. Another type of Alternaria , small-spored Alternaria has been detected in a large number of the sampled leaves [ 17 ].…”