Fungal species associated with grapevine trunk diseases in Washington wine grapes and California table grapes, with novelties in the genera Cadophora, Cytospora, and Sporocadus

Authors: TRAVADON, RENAUD - University Of California, Davis; LAWRENCE, DANIEL - University Of California, Davis; MOYER, MICHELLE - Washington State University; Fujiyoshi, Phillip; Baumgartner, Kendra

Submitted to: Frontiers in Fungal Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/9/2022
Publication Date: 10/7/2022
Citation: Travadon, R., Lawrence, D.P., Moyer, M.M., Fujiyoshi, P.T., Baumgartner, K. 2022. Fungal species associated with grapevine trunk diseases in Washington wine grapes and California table grapes, with novelties in the genera Cadophora, Cytospora, and Sporocadus. Frontiers in Fungal Biology. 3. Article 1018140. https://doi.org/10.3389/ffunb.2022.1018140.
DOI: https://doi.org/10.3389/ffunb.2022.1018140

Interpretive Summary: Grapevine trunk diseases cause serious economic losses to grape growers worldwide. Identification of the microscopic fungi that cause these diseases is a critical first step to learn how they spread and, subsequently, how to prevent disease. We isolated in culture and then identified fungi from grapevines with trunk diseases in two regions with contrasted climates: wine-grapes in southeastern Washington and table-grapes in the southern San Joaquin Valley of California. Species identification was confirmed through comparisons with the DNA of known species. We identified 36 species from 112 isolates, with a combination of species that are new to science, are known causal fungi of grapevine trunk diseases, or are known causal fungi of diseases of other woody plants. The novel species Cadophora columbiana, Cytospora macropycnidia, Cytospora yakimana, and Sporocadus incarnatus are formally described, four species are newly reported from North America, and grape is reported as a new host for three species. Six species were shared between the two regions: Cytospora viticola, Diatrype stigma, Diplodia seriata, Kalmusia variispora, Phaeoacremonium minimum, and Phaeomoniella chlamydospora. Dominating the species community in Washington wine-grape vineyards were species in the fungal families Diatrypaceae, Cytosporaceae and Sporocadaceae, whereas in California table-grape vineyards, the dominant species were in the families Diatrypaceae, Togniniaceae, Phaeomoniellaceae and Hymenochaetaceae. Pathogenicity tests demonstrated that 10 isolates cause wood discoloration similar in appearance to the symptomatic wood they were originally isolated from. Growth rates at temperatures from 5 to 35°C of 10 isolates per region, pathogenicity test, suggest that adaptation to local climate might explain their contrasted distributions.

Technical Abstract: Grapevine trunk diseases cause serious economic losses to grape growers worldwide. The identification of the causal fungi is critical to implement appropriate management strategies. Through a culture-based approach, we identified the species composition associated with symptomatic grapevines in two regions with contrasted climates, with samples from wine-grapes in southeastern Washington and table-grapes in the southern San Joaquin Valley of California. Species identification was confirmed through molecular identification, sequencing two to six gene regions per isolate, and multilocus phylogenetic analyses were used to identify novel species. We identified 36 species from 112 isolates, with a combination of species that are new to science, are known causal fungi of grapevine trunk diseases, or are known causal fungi of diseases of other woody plants. The novel species Cadophora columbiana, Cytospora macropycnidia, Cytospora yakimana, and Sporocadus incarnatus are formally described, four species are newly reported from North America, and grape is reported as a new host for three species. Six species were shared between the two regions: Cytospora viticola, Diatrype stigma, Diplodia seriata, Kalmusia variispora, Phaeoacremonium minimum, and Phaeomoniella chlamydospora. Dominating the species community in Washington wine-grape vineyards were species in the fungal families Diatrypaceae, Cytosporaceae and Sporocadaceae, whereas in California table-grape vineyards, the dominant species were in the families Diatrypaceae, Togniniaceae, Phaeomoniellaceae and Hymenochaetaceae. Pathogenicity tests demonstrated that 10 isolates cause wood discoloration similar to symptomatic wood they were isolated from originally. Growth rates at temperatures from 5 to 35°C of 10 isolates per region, pathogenicity test, suggest that adaptation to local climate might explain their contrasted distributions.