Chestnut blight in the Minho region. Population structure and genetic variability of Cryphonectria parasitica

Abstract

Cryphonectria parasitica, the causal agent of chestnut blight, was considered one of the main factors of mortality of Castanea sativa. Introduced in Portugal in the 1990s, and with epidemic development, the disease has manifested high aggressiveness and a rapid dispersion. Currently it has a widespread distribution in the chestnut production regions.

Chemical, physical and cultural control means are not effective to control Chestnut Blight and only biological control by hypovirulence has shown to be effective in Europe.

The spread of the hypovirus is directly linked to the vegetative compatibility types (VCType) of the fungal populations, so there is a need to study the population structure of C. parasitica and identify the VCTypes present in each subpopulation. The incidence of Chestnut Blight was assessed in three chestnut groves in the Minho region, and the C. parasitica isolates obtained were further characterized. Each isolate was allocated to a VCType by matching with reference isolates, and the genetic variability of selected isolates was evaluated by BOX-PCR. The isolates obtained were functionally diverse comprising over five VCType, with EU-11 (62%), followed by EU-2 (20%), EU-1 e EU- 66 (5,5%) and EU-12 (7%). Banding patterns obtained by box-PCR fingerprinting did not reflect geographical origin or the VCType of the isolate.