Dark septate endophyte improves salt-tolerance of native and invasive lineages of Phragmites australis

Authors: GONZALEZ MATEU, MARTINA - University Of Maryland; BALDWIN, ANDREW - University Of Maryland; Maul, Jude; YARWOOD, STEPHANIE - University Of Maryland

Submitted to: The ISME Journal: Multidisciplinary Journal of Microbial Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/2/2020
Publication Date: 4/27/2020
Citation: Gonzalez Mateu, M., Baldwin, A.H., Maul, J.E., Yarwood, S.A. 2020. Dark septate endophyte improves salt-tolerance of native and invasive lineages of Phragmites australis. The ISME Journal: Multidisciplinary Journal of Microbial Ecology. https://doi.org/10.1038/s41396-020-0654-y.
DOI: https://doi.org/10.1038/s41396-020-0654-y

Interpretive Summary: Fungal endophytes establish mutualistic associations with most plant species and can play a major role in plant ecology and community structure. These endophytes can improve host nutrient uptake, improve host defense against pathogens, modify trophic interactions, and improve host tolerance to abiotic stress. We conducted experiments targeting a better understanding of plant-microbe interactions which can help improve various aspects of invasive species management as well as improve our understanding of salt tolerance in crop plants grown in sub-par or inundated soils. In this study we characterized the fungal endophyte communities of contiguous stands of native and invasive P. australis across a salinity gradient. We used next generation sequencing and microscopy to address the role of lineage and salinity in structuring root fungal communities over a growing season. In pursuing this objective, we identified salinity-driven colonization patterns and found fungal endophytes improved salt-tolerance of P. australis. We also found that mutualists played a role in stress tolerance of the invasive P. australis lineage, and used laboratory and greenhouse assays to test this prediction. This type of plant-fungal association may be important in integrated management strategies of both invasive and crop species of plants and informs efforts to combat the loss of agricultural lands due to encroaching saltwater and rising sea levels.

Technical Abstract: Fungal endophytes are fungi that live within the plant but act in a non-pathogenic manner in most cases. Fungal endophytes can improve plant tolerance to abiotic stress. However, the role of these plant-fungal interactions in invasive species ecology and their management implications remain unclear. This study characterized the fungal endophyte communities of native and invasive lineages of Phragmites australis and assessed the role of dark septate endophytes (DSE) in salt tolerance of this species. We used Illumina DNA sequencing to characterize root fungal endophytes of contiguous stands of native and invasive P. australis along a salinity gradient. DSE colonization was assessed throughout the growing season in the field, and their role in salinity tolerance was investigated using laboratory and greenhouse studies. Native and invasive lineages had distinct fungal endophyte communities that shifted across the salinity gradient. DSE colonization was greater in the invasive lineage and increased with salinity. Laboratory studies showed that DSE inoculation increased P. australis seedling survival under salt stress; and a greenhouse assay revealed that the invasive lineage had greater aboveground biomass under mesohaline conditions when inoculated with a DSE. We observed that P. australis can establish mutualistic associations with DSE when subjected to salt stress. This type of plant-fungal association may be important in integrated management strategies of both invasive and crop species of plants, and informs efforts to combat the loss of agricultural lands due to encroaching saltwater and rising sea levels.