Biology subjects

Morrison, E. W.

Publications and source records attributed to Morrison, E. W..

3 recordsLinked to original sources

bioRxiv2024

Microbial trait multifunctionality drives soil organic matter formation potential

Soil microbes are a major source of organic residues that accumulate as soil organic matter (SOM), the largest terrestrial reservoir of carbon on Earth. As such, there is growing interest in determining the microbial traits that drive SOM formation and stabilization; however, whether certain microbial traits consistently predict SOM accumulation across different functional pools (e.g., total vs. stable SOM) is unresolved. To address these uncertainties, we incubated individual species of fungi in SOM-free model soils, allowing us to directly relate the physiological, morphological, and biochemical traits of fungi to their SOM formation potentials. We find that the formation of different SOM functional pools is associated with distinct fungal traits, and that multifunctional species with intermediate investment across this key grouping of traits (namely, carbon use efficiency, growth rate, turnover rate, and biomass protein and phenol contents) promote SOM formation, functional complexity, and stability. Our results highlight the limitations of categorical trait-based frameworks that describe binary (high/low) trade-offs between microbial traits, instead emphasizing the importance of synergies among microbial traits for the formation of functionally complex SOM.

ecology↗

bioRxiv2021

Pathogen and endophyte assemblages co-vary with beech bark disease progression, tree decline, and regional climate

Plant-pathogen interactions are often considered in a pairwise manner with minimal consideration of the impacts of the broader endophytic community on disease progression and/or outcomes for disease agents and hosts. Community interactions may be especially relevant in the context of disease complexes (i.e, interacting or functionally redundant causal agents) and decline diseases (where saprobes and weak pathogens synergize the effects of primary infections and hasten host mortality). Here we describe the bark endophyte communities associated with a widespread decline disease of American beech, beech bark disease (BBD), caused by an invasive scale insect (Cryptococcus fagisuga) and two fungal pathogens, Neonectria faginata and N. ditissima. We show that the two primary fungal disease agents co-occur more broadly than previously understood (35.5% of infected trees), including within the same 1-cm diameter phloem samples. The two species appear to have contrasting associations with climate and stages of tree decline, wherein N. faginata was associated with warmer and N. ditissima with cooler temperatures. Neonectria ditissima showed a positive association with tree crown dieback - no such association was observed for N. faginata. Further, we identify fungal endophytes that may modulate disease progression as entomopathogens, mycoparasites, saprotrophs and/or additional pathogens, including Clonostachys rosea and Fusarium babinda. These fungi may alter the trajectory of disease via feedbacks with the primary disease agents or by altering symptom expression or rates of tree decline across the range of BBD.

ecology↗

bioRxiv2020

Characterization of mating type genes in heterothallic Neonectria species with emphasis on N. coccinea, N. ditissima, and N. faginata

Neonectria ditissima and N. faginata are canker pathogens involved in an insect-fungus disease complex of American beech (Fagus grandifolia) commonly known as beech bark disease (BBD). In Europe, both N. ditissima and N. coccinea are involved in BBD on European beech (Fagus sylvatica). Field observations across the range of BBD indicate that new infections occur primarily via ascospores. Both heterothallic (self-sterile) and homothallic (self-fertile) mating strategies have been reported for Neonectria fungi. As such, investigations into mating strategy are important for understanding both the disease cycle and population genetics of Neonectria. This is particularly important in the U.S. given that over time N. faginata dominates the BBD pathosystem despite high densities of non-beech hosts for N. ditissima. This study utilized whole-genome sequences of BBD-associated Neonectria spp. along with other publicly available Neonectria and Corinectria genomes and in vitro mating assays to characterize mating type (MAT) loci and confirm thallism for select members of Neonectria and Corinectria. MAT gene-specific primer pairs were developed to efficiently characterize the mating types of additional single ascospore strains of N. ditissima, N. faginata, and N. coccinea and several other related species lacking genomic data. In vitro mating assays were used in combination with molecular results to confirm thallism. These assays also comfirmed the sexual compatibility among N. ditissima strains from different plant hosts. Maximum likelihood phylogenetic analysis of both MAT1-1-1 and MAT1-2-1 sequences recovered trees with similar topology to previously published phylogenies of Neonectria and Corinectria. The results of this study indicate that all Neonectria and Corinectria tested are heterothallic based on our limited sampling and, as such, thallism cannot help explain the inevitable dominance of N. faginata in the BBD pathosystem.

microbiology↗