Shifts in Symbiotic Endophyte Communities of a Foundational Salt Marsh Grass following Oil Exposure from the Deepwater Horizon Oil Spill

Abstract

Symbiotic associations can be disrupted by disturbance or by changing environmental conditions. Endophytes are fungal and bacterial symbionts of plants that can affect performance. As in more widely known symbioses, acute or chronic stressor exposure might trigger disassociation of endophytes from host plants. We tested this hypothesis by examining the effects of oil exposure following the Deepwater Horizon (DWH) oil spill on endophyte diversity and abundance in Spartina alterniflora – the foundational plant in northern Gulf coast salt marshes affected by the spill. We compared bacterial and fungal endophytes isolated from plants in reference areas to isolates from plants collected in areas with residual oil that has persisted for more than three years after the DWH spill. DNA sequence-based estimates showed that oil exposure shifted endophyte diversity and community structure. Plants from oiled areas exhibited near total loss of leaf fungal endophytes. Root fungal endophytes exhibited a more modest decline and little change was observed in endophytic bacterial diversity or abundance, though a shift towards hydrocarbon metabolizers was found in plants from oiled sites. These results show that plant-endophyte symbioses can be disrupted by stressor exposure, and indicate that symbiont community disassembly in marsh plants is an enduring outcome of the DWH spill.

Foliar fungal endophyte communities are structured by environment but not host ecotype in Panicum virgatum (switchgrass)

“…Deciphering the importance of specific mechanisms driving FFE community structure at the local site level is complex. Previous research has shown that local plant community diversity can drive differences in soil microbial communities (Bakker et al 2014) and leaf bacterial communities (Laforest-Lapointe et al 2017), and disturbance regimes can impact FFE community assembly (Kandalepas et al 2015). The low FFE diversity at the Madison site might therefore be related to relatively low plant community diversity in the immediate vicinity of our experimental site (personal observation) and high level of disturbance due to water-level fluctuations along the Ohio River.…”

“…), and disturbance regimes can impact FFE community assembly (Kandalepas et al. ). The low FFE diversity at the Madison site might therefore be related to relatively low plant community diversity in the immediate vicinity of our experimental site ( personal observation ) and high level of disturbance due to water‐level fluctuations along the Ohio River.…”

Microbiomes: unifying animal and plant systems through the lens of community ecology theory

“…Other recent research shows startlingly long-term effects of physical disturbance for plant EF communities following the 2010 Deepwater Horizon Oil spill in the Gulf of Mexico. Characterization of these EF communities in smooth cordgrass showed near total loss of leaf EF, even 3 years after the original oil spill occurred ( Kandalepas et al, 2015 ). In both of these situations, however, the functional consequences of reduced microbiome diversity remain unknown.…”

Endophytic root bacteria associated with the natural vegetation growing at the hydrocarbon-contaminated Bitumount Provincial Historic site

“…Hydrocarbon content is documented to both increase and decrease root-associated bacterial abundance (Kostka et al 2011;Kandalepas et al 2015). Peng et al (2013) studied the abundance of endophytic root bacteria in 2 different plant species, Alopecurus aequalis Sobol and Oxalis corniculata L., from PAH-contaminated soils.…”