Genetic diversity and population structure of Valdensinia heterodoxa, a potential biocontrol agent for salal in coastal British Columbia

Abstract

Valdensinia heterodoxa is an ascomycete fungus currently being considered as a potential biocontrol agent against salal (Gaultheria shallon). To assess its effectiveness and risks as a biocontrol agent, we investigated its population structure in three geographically separate populations on Vancouver Island and in coastal mainland, British Columbia. Valdensinia heterodoxa was cultured from infected salal leaves, and single-spore cultures were obtained prior to DNA isolation. Amplified fragment length polymorphisms (AFLPs) were used to generate individual DNA fingerprints for each V. heterodoxa isolate. We found low genetic diversity, with just 30 of the 214 loci being polymorphic. There were many shared haplotypes within each population, and analysis of pairwise kinship coefficients showed that as spatial distance increased, genetic similarity decreased. Analysis of molecular variance among populations revealed significant genetic differentiation, with an F _ST of 0.182, suggesting limited gene flow. The findings suggest that with low diversity and high population differentiation, the effectiveness of V. heterodoxa as a biocontrol agent to manage salal in forested areas may be limited to localized salal populations or to use in combination with other control methods.

Keywords:

• Valdensinia heterodoxa
• amplified fragment length polymorphism
• genetic diversity
• population structure
• biocontrol
• Gaultheria shallon
• salal