Alternaria species in section Alternaria associated with Iris plants in China.

Plants of the Iris genus have been widely cultivated because of their medicinal, ornamental, and economic values. It commonly suffers from Alternaria leaf spot or blight disease leading to considerable losses for their commercial values. During an investigation of 14 provinces or municipalities of China from 2014 to 2022, a total of 122 Alternaria strains in section Alternaria were obtained from diseased leaves of Iris spp.. Among them, 12 representative strains were selected and identified based on morphological characterization and multi-locus phylogenetic analysis, which encompassed the internal transcribed spacer of rDNA region (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), translation elongation factor 1 alpha (TEF1), RNA polymerase second largest subunit (RPB2), Alternaria major allergen gene (Alt a 1), an anonymous gene region (OPA10-2), and endopolygalacturonase gene (EndoPG). The strains comprised two known species of A. alternata and A. iridicola, and two new species of A. setosae and A. tectorum, which were described and illustrated here. Their pathogenicity evaluated on Iris setosa indicated that all the strains could induce typical Alternaria leaf spot or blight symptoms. The results showed that the virulence was variable among those four species, from which A. tectorum sp. nov. was the most virulent one, followed by A. setosae sp. nov., A. iridicola and A. alternata.

Morphological and molecular identification of two new Alternaria species (Ascomycota, Pleosporaceae) in section Radicina from China.

The fungal genus Alternaria was distributed widely and found in different habitats such as plant or indoor environment. During an investigation into this genus in China, two new Alternaria species, Alternaria vulgarae and A. divaricatae were respectively isolated from diseased leaves of Foeniculum vulgare and Saposhnikovia divaricata, which both belonged to Umbelliferae. Phylogenetically, they were determined as new species belonging in the section Radicina of Alternaria based on the combined four gene fragments of ITS, TEF1, GAPDH and RPB2. Morphologically, the two species were illustrated and compared with other relevant Alternaria species in section Radicina.