European Journal of Plant Pathology (2017) 148, 65-73

P. Zamora, A. González Casas, M. Dueñas, R. San Martin and J.J. Diez (2017)
Factors influencing growth, sporulation and virus transfer in Cryphonectria parasitica isolates from Castilla and León (Spain)
European Journal of Plant Pathology 148 (1), 65-73
Abstract: Biological control with Cryphonectria hypovirus CHV1 of the chestnut blight, caused by the fungus Cryphonectria parasitica, has reduced the impact of the disease in Europe. The virus reduces the virulence of the fungus so that it causes non-lethal cankers, thus enabling the chestnut trees to overcome the disease. The virus can be transmitted horizontally by hyphal anastomosis or vertically to the conidia. In this study, we investigated growth and sporulation of the fungus as well as rates of horizontal transmission of the virus at different temperatures. We used fungal isolates of the vegetative compatibility types (vc types) that are most prevalent in Castilla and León (central northern Spain) to evaluate the effects of fungal strain on the parameters tested. In addition, we infected four isolates of C. parasitica with hypovirus subtypes CHV1-F1 and CHV1-I, to determine the influence of virus subtype on growth, sporulation and virus transfer. We assessed growth of fungal colonies and horizontal transmission of the virus at 15 °C and 25 °C. Colony growth was affected by an interaction between fungal isolates included in vc type EU1 or EU11 and virus at both 15 °C and 25 °C. However, horizontal transmission of the virus was only influenced by the fungal genotype of isolates included in vc type EU1 or EU11, and spore production was only affected by the virus subtype. Vertical transmission was also influenced by the fungal isolate and virus subtype. Growth of the fungal isolates varied depending on the virus subtype with which they were infected. This supports the theory that fungal host and virus subtype influence transmission and dissemination of hypovirulence. The fungal genotype affects colony growth and horizontal transmission of the virus. It is common to expect a good dissemination of the hypovirus with a low vc type diversity but the selection of the best combination of hypovirus and fungal isolate is crucial for the success of biological control not only for small areas but in larger chestnut populations as well.
(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): Paula Zamora, Julio Diez

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

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Cryphonectria parasitica	Chestnut (Castanea)	Spain (continental)
Cryphonectria parasitica hypoviruses (antagonist)	Cryphonectria parasitica	Chestnut (Castanea)	Spain (continental)