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Home » Publications » Papers » 2008

VI International chesnut symposium
Miyun-Beijing (China) 25-28 september, 2008


Diversity of vegetative compatibility types, mating types and occurrence of hypovirulence in Cryphonectria parasitica populations in NW Spain

O. Aguín¹, D. Montenegro¹, M.J. Sainz², M. Hermida¹ and J.P. Mansilla¹

¹Estación Fitopatolóxica do Areeiro. Deputación de Pontevedra. Subida a la Robleda s/n, E-36153 Pontevedra, Spain.
²Departamento de Producción Vegetal. Universidad de Santiago de Compostela, Campus Universitario, E-27002 Lugo, Spain. E-mail:

ABSTRACT: Chestnut blight, caused by Cryphonectria parasitica, is widely spread in chestnut stands all over the world. At present, the most promising prospects to control the disease are based on the knowledge of its fungal populations in affected stands and the use of hypovirulent strains. A survey was carried out to study the biology of C. parasitica populations in chestnut stands in Lugo and Ourense provinces (NW Spain), determining the diversity of vegetative compatibility types (vc), mating type diversity and occurrence of hypovirulent strains. A total of 612 isolates were obtained, most showing a virulent phenotype. Only four isolates, from Lugo province, showed the presence of dsRNA, which was indicative of hypovirulence. Hypovirus molecular characterization of these isolates determined they belonged to subtype E of Cryphonectria hypovirus-1 (CHV1-E).The diversity of vegetative compatibility types was very low. Only 9 vc types were found, being five of them present in both provinces. Four vc types were compatible with the known European testers (EU1, EU9, EU66 and EU72), and the other five corresponded to types being only found so far in NW Spain, named E1-E5. The dominant vc types in both populations were E1, E2 and E3, being present in 97% of the isolates. Two hypovirulent strains were compatible with vc type E1, one with vc type E2 and one with vc type E3. The study of mating types showed that the idiomorph MAT-1 was predominant in both populations. Its mainly asexual reproduction, the low rate of diversity of compatibility types and the detection of hypovirulent strains compatible with dominant vc types are factors favouring the application of a biological control program in affected stands in NW Spain.

Key words: biological control, dsRNA virus, chestnut blight