Characterizing Ectomycorrhizal Fungal Community Structure and Function of Two Varieties of Pinus clausa That Differ in Disturbance History

Megan A Rúa

doi:10.3390/f12020219

Abstract

Despite the immense amount of diversity present in the soil biota, the ecological and evolutionary processes that regulate species diversity and abundance of ectomycorrhizal (ECM) fungi across space and time remain elusive. In forest ecosystems, ECM fungal diversity may be maintained by periodic disturbances which operate at different time scales due to their effects on host genetic and phenotypic characteristics and the associated environment. To investigate the degree to which these factors shape ECM fungal community composition and function, I sampled 10 independent sites for a pine species indicative of an endangered ecosystem, the Florida scrub, where disturbance history has driven the divergence of a single species into two genetically distinct varieties (Pinus clausa var. immuginata and var. clausa). A total of 300 ECM fungal species were identified based on rDNA ITS sequences, but each variety harbors different ECM species composition and function. A follow-up greenhouse experiment, in which the seed from each variety was grown in its own soil (“home”) and in the soil of the other variety (“away”), suggests these communities differentially impact the growth of their host seedlings. While var. clausa seedlings had the same total biomass regardless of soil origin, var. immuginata had higher biomass in their own soil compared to var. clausa. This is likely due to an increased number of ECM colonized tips in the home soil compared to in away soil. Taken together, these results may suggest different evolutionary histories where structure host genetic and phenotypic characteristics may be important for structuring their dynamics with ECM fungi.

Highlights

The soil biota contains an enormous amount of global biodiversity; our ecological understanding of the processes that regulate the abundance and species diversity of soil microorganisms across space and time is limited [1,2]
Between 27 May and 3 June 2014, I haphazardly sampled five trees at each site that were similar in size as determined by diameter at breast height (DBH; Table 1)
Selection by the environment is one process suggested to be important for shaping soil microbial community composition [52,53]

Summary

Introduction

The soil biota contains an enormous amount of global biodiversity; our ecological understanding of the processes that regulate the abundance and species diversity of soil microorganisms across space and time is limited [1,2]. The extent to which host varieties dictated by a history of disturbance shape the composition and function of the ECM fungal community is investigated. ECM fungi and their plant hosts have a long ecological and evolutionary history important for understanding forest ecosystems. ECM fungi associate with woody species in boreal, temperate, and tropical forests where they affect host growth and water/nutrient absorption [6]. These relationships are important for conifer hosts, as they form obligate associations and play a pivotal role in both the survival and regeneration of their hosts [6,7]

Methods

Results

Discussion

Conclusion