Identification and pathogenicity of Aspergillus species associated with vine canker in Mexico

Fungi associated with Aspergillus Vine Canker (AVC) infect vigorous new shoots and canes during plant training, entering through wounds. Recently, grapevines exhibiting symptoms resembling AVC have been observed in Mexico. Thus, this study aimed to investigate these diseased plants. Woody samples from symptomatic plants were surface sterilized with alcohol and fire and then placed onto Potato Dextrose Agar (PDA) medium. Seventeen isolates displaying morphology similar to the genus Aspergillus were characterized. Colony and microscopic characteristics were observed on Czapek Yeast Extract Agar (CYA) and Malt Extract Agar (MEA). Phylogenetic analysis using calmodulin (CaM) and β-tubulin (BenA) gene markers, revealed the presence of Aspergillus niger, A. tubingensis, and A. welwitschiae species. Notably, Aspergillus isolates have an optimal growth temperature range of 35–37 °C but some exhibited thermotolerance, growing even at 50 °C. In pathogenicity assays, A. niger A10SMX, A. niger A8SMX, and A. tubingensis A13SMX exhibited the highest virulence in cultivar ‘Merlot’, resulting in lesions up to 2 cm in length after 50 days of inoculation. In addition to necrotic lesions, mycelia, and black conidia were observed on the leaves. Finally, a pathogenicity assay on table grape cultivars revealed the cultivar ‘Cotton Candy’ as the most susceptible to Aspergillus spp., and ‘Prime Seedless’ as the least susceptible. This study represents the first report of Aspergillus species associated with AVC in Mexican vineyards.