The soil biota is diverse, yet the ecological and evolutionary processes that regulate species diversity and abundance of soil microorganisms across space and time remains elusive. Phenotypic and genetic differences in host species may be one factor important for maintaining diversity in the soil biota. In forest ecosystems, ectomycorrhizal (ECM) fungi represent a key component of the soil biota, forming obligate relationships with many tree species and playing a pivotal role in nutrient cycling. To investigate the degree to which host genetic background shapes the ECM fungal community, we coupled field and greenhouse studies using the unique species Pinus clausa. This species has diverged into two genetically distinct varieties as a result of disturbance history (var. immuginata and var. clausa) and is indicative of an endangered ecosystem, the Florida scrub. We directly sampled ten populations of P. clausa (five of each variety) and characterized the fungal community composition based on ITS sequencing. We also performed a follow up greenhouse experiment in which seed from each variety was grown in its own soil (‘home’) and in the soil of the other variety (‘away’) and compared plant and fungal performance.
Results/Conclusions
Our field investigations confirmed 300 unique OTUs associated with ECM fungal species from a total of 39094 root tips. Multivariate analyses suggest each variety harbors different fungal communities both in terms of species composition and when fungi are grouped based on the nutrient exploration strategies. Specifically, ECM fungi with the medium distance fringe or contact exploration types were most common for var. immuginata sites while ECM fungi with the long distance exploration type were more prominent for var. clausa sites suggesting important functional differences in the ECM fungal communities of the two varieties. Data from the greenhouse experiment suggests these communities deferentially impact the growth of their host plants. While var. clausa plants had the same total biomass regardless of soil origin, var. immuginata had higher biomass in their own soil compared to var. clausa’s soil. This is likely due to an increased number of ECM colonized tips in the home soil compared to away soil. Taken together these results suggest different evolutionary histories which structure the genetic and phenotypic characteristics of the host that may be important for structuring their dynamics with ECM fungi.