Loblolly Pine Genetics Structure Its Mycorrhizal Community

Plant populations are constantly exposed to a multitude of biotic and abiotic environmental selection pressures. The ability of a population to persist in or adapt to its environment is heavily influenced by the genetic underpinnings of the traits involved. Thus, in order to understand patterns in current plant populations, and to predict future populations dynamics, an understanding of the genetic basis of adaptive traits is necessary. For example, genetic correlations between traits (driven by pleiotropy or linkage disequilibrium) could influence how species evolve under multiple, conflicting selection pressures, potentially either constraining or enhancing the adaptation of species to each other. The interaction between mycorrhizal fungi and their host trees is a useful system in which to advance the study of how the genetic architecture of traits affects the adaptation of populations. Mycorrhizal fungi are comsymbionts of most plants, deriving mineral nutrients from the soil and transferring them to the host, while the host provides carbohydrates to the fungi. Mycorrhizal fungi have also been shown to affect essential host traits such as drought tolerance, and to alter competitive interactions within and among plant species. In addition to symbiotic interactions belowground with EM fungi, loblolly pine populations are subject to aboveground antagonistic interactions in the form of insect pests and fungal pathogens. Through both laboratory and field experiments, the work presented here explores the degree to which mycorrhizal traits in loblolly pine are genetically determined by the genetics of the host plant, and the degree to which mycorrhizal traits are genetically correlated with other traits. This information will help us to understand how natural and artificial selection focused on one or a few traits of interest (e.g., to mitigate the effects of pests and pathogens) may be indirectly affecting other traits, such as compatibility with symbiotic species belowground, and to better understand how plants may evolve in response to complex suites of selective sources