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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Mycology and Nematology Genetic Diversity and Biology Laboratory » Research » Publications at this Location » Publication #390819

Research Project: Enhancing Plant Protection through Fungal Systematics

Location: Mycology and Nematology Genetic Diversity and Biology Laboratory

Title: Two new species of plasmopara affecting wild grapes in the United States

item Salgado-Salazar, Catalina
item THINES, M - Goethe University

Submitted to: Mycological Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/3/2022
Publication Date: 6/27/2022
Citation: Salgado-Salazar, C., Thines, M. 2022. Two new species of plasmopara affecting wild grapes in the United States. Mycological Progress. 21:63.

Interpretive Summary: Fungi and fungus-like organisms cause a great many diseases on economically important plants, resulting in yield losses or outright death of the host. Grape downy mildew caused by Plasmopara viticola is one of the most severe and destructive diseases of grapes, impacting both the yield and the quality of the harvested fruits, making it a major constraint for the grape industry. This study uses DNA sequences and microscopy to describe two new species of Plasmopara on wild hosts related to grape. Although the potential impact the new species described have on the grape industry is still unknown, the results of this study have important implications for viticulture, including breeding for resistance and disease management. The information from this study will be useful to plant pathologists, regulatory officials and others involved in grape production.

Technical Abstract: Downy mildew species in the genus Plasmopara are obligate biotrophic pathogens responsible for destructive diseases of economically important cultivated and ornamental plants. During the late summer of 2020 and 2021, a downy mildew was observed on porcelain berry (Ampelopsis grandulosa var. brevipedunculata) in different locations in Maryland, U.S.A. A total of thirteen samples were collected from an equal number of diseased plants. Phylogenetic analyses of the cox2 mtDNA and LSU rDNA regions indicated that they constituted an undescribed species here described as Plasmopara ampelopsis. Concurrently, a second species on wild Vitis species was also found, among historical downy mildew specimens used in previous studies, and it is here described as Plasmopara carveri. These newly described species are closely related to P. viticola and P. muralis. Although molecular phylogenetic analyses strongly support the segregation of these species, diagnostic morphological characters for each species were not observed. Therefore, a list of specific substitutions in the cox2 region is provided as diagnostic characters. It remains unclear if these new species represent a threat to the grapevine industry.