Canadian Journal of Botany - Revue Canadienne de Botanique (1992) 70, 334-339

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T.J. Gulya, T.P. Freeman and D.E. Mayhew (1992)
Ultrastructure of virus-like particles in Plasmopara halstedii
Canadian Journal of Botany - Revue Canadienne de Botanique 70 (2), 334-339
Abstract: Virus-like particles were observed in five North Dakota isolates of Plasmopara halstedii race 2, the causal agent of sunflower downy mildew. Virus-like particles were observed in fungal mycelium within sunflower seedlings showing typical symptoms of systemic infection as well as from seedlings displaying 'twisted leaf syndrome'. Virus-like particles were never observed in sunflower cells. The particles were isometric in shape and measured 23-26 nm in thin sections and 32 nm after phosphotungstic acid staining. Virus-like particles occurred dispersed throughout the cytoplasm and in membrane-bound organelles. Both crystalline and noncrystalline arrays were common. The particles were observed in haustoria, intercellular hypha, sporangiophores, zoosporangia, and oospores. Four species of double-stranded RNA were detected in sunflower tissue infected with P. halstedii; none were detected in healthy sunflower tissue. This is only the second report of an isometric, virus-like particle occurring in a member of the Peronosporales.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Thomas J. Gulya

Research topic(s) for pests/diseases/weeds:
general biology - morphology - evolution
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
general biology - morphology - evolution

Pest and/or beneficial records:

Beneficial Pest/Disease/Weed Crop/Product Country Quarant.

Plasmopara halstedii Sunflower (Helianthus annuus) U.S.A. (mid N)
Plasmopara halstedii mycoviruses (antagonist) Plasmopara halstedii