Prokaryotic taxa play keystone roles in the soil microbiome associated with ornamental boxwood accessions at the U.S. National Arboretum

Authors: LEBLANC, NICHOLAS - Orise Fellow; Crouch, Jo Anne

Submitted to: Ecology and Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/8/2019
Publication Date: 8/27/2019
Citation: Leblanc, N., Crouch, J. 2019. Prokaryotic taxa play keystone roles in the soil microbiome associated with ornamental boxwood accessions at the U.S. National Arboretum. Ecology and Evolution. 9(19):11102-11111. https://doi.org/10.1002/ece3.5614.
DOI: https://doi.org/10.1002/ece3.5614

Interpretive Summary: Microbes such as fungi and bacteria are commonly found in soil, where they function collectively as a microbiome that influences plant health. In this research, we investigated the microbiome of soil surrounding the roots of mature, healthy boxwood plants using DNA profiling techniques. Our goal was to find out which fungi and bacteria are the most important soil microbes, and to learn whether or not different types of boxwood plants influence which ones are present. Bacteria were identified as the key members of the boxwood soil microbiome, which makes them possible targets for plant health management. The study showed that physical location and the presence of different types of boxwood did not affect the overall microbiome. But some boxwood types did form unique associations with rare bacterial types. The presence of high numbers of microbes that alter nitrogen compounds suggest that fertilizer regimes might be used to alter the composition of the boxwood microbiome. This information will be useful to plant pathologists, agronomists and other professionals seeking to use the resident microbes as the basis for new and environmentally friendly approaches to manage healthy boxwood soil microbiomes.

Technical Abstract: The microbiome associated with ornamental plants has largely been neglected, despite its potential for improving plant health. This work characterized the composition and diversity of the soil microbiome associated with species and cultivars of ornamental boxwood, a group of woody perennial shrubs commonly used in residential and historical landscapes. Soil was collected from 82 individual curated boxwood accessions at the U.S. National Arboretum National Boxwood Collection. Amplicon libraries targeting archaea, bacteria, and fungi were generated and sequenced using the Illumina MiSeq platform. The three microbial groups differed in diversity, bacteria represented by the most taxa, followed by fungi and then archaea. Co-association networks indicated that archaea and bacteria show greater evidence of being keystone taxa than fungi. Neither spatial distance among samples nor association with different types of boxwood were significant predictors of soil microbiome composition. However, bacterial diversity and the abundance of rare bacterial and fungal taxa were significantly different in soil from different types of boxwood. Overall, this work demonstrates the potential for targeting specific keystone taxa to shift the soil microbiome associated with these boxwood accessions and that planting different species or cultivars in the landscape may shift the abundance of rare microbial taxa and bacterial diversity.