Location, but not defensive genotype, determines ectomycorrhizal community composition in Scots pine (Pinus sylvestris L.) seedlings

1. For successful colonisation of host roots, ectomycorrhizal (EM) fungi must overcome host defence systems, and defensive phenotypes have previously been shown to affect the community composition of EM fungi associated with hosts. Secondary metabolites, such as terpenes, form a core part of these defence systems, but it is not yet understood whether variation in these constitutive defences can result in variation in colonisation of hosts by specific fungal species.

2. We planted seedlings from twelve maternal families of Scots pine (Pinus sylvestris) of known terpene genotype reciprocally in the field in each of six sites. After three months we characterised the mycorrhizal fungal community of each seedling using a combination of morphological categorisation and molecular barcoding, and assessed the terpene chemodiversity for a subset of the seedlings. We examined whether parental genotype or terpene chemodiversity affected the diversity or composition of a seedling’s mycorrhizal co...