Natural spread of Hypovirulence in Cryphonectria parasitica. A case study, Sergude - Minho – Portugal

Abstract

Chestnut (Castanea sativa) is a species of great economic and social importance in the Northern region of Portugal. One of the biggest barriers to increased nut production is related to the presence of biotic factors such as the old and familiar Ink Disease and more recently the Chestnut Blight that is causing high mortality in chestnut. In the absence of chemical fungicides capable of stopping the development of the Chestnut Blight and considering the reduced effectiveness of other mitigation measures, hypovirulence is the most advantageous way to control the disease in Europe. The method showed high ability to heal the cankers and promote the complete recovery of chestnut. The molecular mechanism of hypovirulence is associated with the presence of dsRNA virus of the genus Hypovirus. In Sergude (Minho) in a chestnut grove with all trees attacked by Cryphonectria parasitica in a period of 3-4 years occurred the natural remission of cankers leading to the recovery of diseased trees. Our objective was to understand the mechanisms involved in the expression of hypovirulence and factors associated with its natural dispersion. We studied the population structure of C. parasitica present in chestnut and associated epiphytic and endophytic mycoflora