DIVERSITY OF VEGETATIVE COMPATIBILITY GROUPS OF CRYPHONECTRIA PARASITICA IN EUROPE
U HEINIGER1, P CORTESI2, C COLINAS3, C PERLEROU4, D RIGLING1, C ROBIN5, K SOTIROVSKI6, M USCUPLIC7
1Swiss Federal Institute for Forest, Snow and Landscape Research, CH-8903 Birmensdorf, Switzerland; 2Istituto Patologia Vegetale, Universita, I-20133 Milano, Italy; 3University, SP-25198 Lleida, Spain; 4Forest Research Institute, NAGREF, GR-57006 Vassilika, Greece; 5INRA Pathologie végétale, BP 81, F-33 882 Villenave d'Ornon, France; 6Faculty of Forestry, RM-Skopje, Macedonia; 7 Faculty of Forestry, BH-Sarajevo, Bosnia-Herzegovina
Background and objectives
Materials and methods
Results and conclusions
A total of 33 vc types were identified. Twenty vc types were found in Italy, 28 in Switzerland, 28 in France, five in Macedonia, 17 in Bosnia, three in Greece, and 10 in Spain. Many vc types were rare. At all sites one or two vc types dominated. The diversity was greatest in northern Italy and southern Switzerland with a maximum of 16 vc types per site. In southern Italy, Macedonia, Greece, and Spain, only one to four vc types were identified per site. Vc types were not evenly distributed throughout Europe. EU-2 was the dominant vc type in northern Italy, Switzerland, and south-eastern France but was absent in southern Italy and Macedonia. EU-10 was not found in Switzerland and northern Italy. In contrast, it occurred at a frequency of about 25% in southern Italy, 0.3% in Macedonia and 2% in Greece. EU-12 accounted for 95% of the Macedonian isolates, 85% of the Greek isolates and for 86% of the isolates at a site in Sicily. In northern Italy and Switzerland, EU-12 never represented more than 8% of the isolates at the sites where it was present.
These results show that no equilibrium of vc types is established in Europe. This may be a consequence of multiple introductions, founder effects or restricted gene flow. Since the dissemination of hypovirulence is hampered by vc diversity, appropriate quarantine regulations are recommended to prevent the introduction of new vc types. Moreover, biological control must be carried out with hypovirulent strains belonging to the most common vc types at the site treated.