Virulence of oomycete pathogens from <i>Phragmites australis</i>‐invaded and noninvaded soils to seedlings of wetland plant species

Crocker, Ellen; Karp, Mary Ann; Nelson, Eric B.

doi:10.1002/ece3.1468

Cited by 28 publications

(30 citation statements)

References 92 publications

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“…Importantly, richness reveals very little about pathogen load or pressure and it is still possible that the two lineages are experiencing different levels of pathogen pressure given differences in pathogen virulence on each plant lineage or surrounding plants (Crocker et al. , Allen et al. ).…”

Section: Discussionmentioning

confidence: 99%

“…We know that some oomycetes have lineage‐specific virulence in Phragmites (Crocker et al. ), and that the roles of many endophytic fungi and bacteria are plant and genotype specific (Schulz and Boyle , Hardoim et al. ).…”

Section: Discussionmentioning

confidence: 99%

“…), characterized and compared soil oomycete communities (Nelson and Karp , Crocker et al. , Cerri et al. ), and compared soil bacterial (Bowen et al.…”

Section: Introductionmentioning

confidence: 99%

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Root endophytes and invasiveness: no difference between native and non‐native Phragmites in the Great Lakes Region

et al. 2018

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Microbial interactions could play an important role in plant invasions. If invasive plants associate with relatively more mutualists or fewer pathogens than their native counterparts, then microbial communities could foster plant invasiveness. Studies examining the effects of microbes on invasive plants commonly focus on a single microbial group (e.g., bacteria) or measure only plant response to microbes, not documenting the specific taxa associating with invaders. We surveyed root microbial communities associated with co‐occurring native and non‐native lineages of Phragmites australis, across Michigan, USA. Our aim was to determine whether (1) plant lineage was a stronger predictor of root microbial community composition than environmental variables and (2) the non‐native lineage associated with more mutualistic and/or fewer pathogenic microbes than the native lineage. We used microscopy and culture‐independent molecular methods to examine fungal colonization rate and community composition in three major microbial groups (bacteria, fungi, and oomycetes) within roots. We also used microbial functional databases to assess putative functions of the observed microbial taxa. While fungal colonization of roots was significantly higher in non‐native Phragmites than the native lineage, we found no differences in root microbial community composition or potential function between the two Phragmites lineages. Community composition did differ significantly by site, with soil saturation playing a significant role in structuring communities in all three microbial groups. The relative abundance of some specific bacterial taxa did differ between Phragmites lineages at the phylum and genus level (e.g., Proteobacteria, Firmicutes). Purported function of root fungi and respiratory mode of root bacteria also did not differ between native and non‐native Phragmites. We found no evidence that native and non‐native Phragmites harbored distinct root microbial communities; nor did those communities differ functionally. Therefore, if the trends revealed at our sites are widespread, it is unlikely that total root microbial communities are driving invasion by non‐native Phragmites plants.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Root endophytes and invasiveness: no difference between native and non‐native Phragmites in the Great Lakes Region

et al. 2018

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“…Recent studies with P. australis have described distinct oomycete, archaea, and bacteria communities from rhizosphere soil of native and European P. australis lineages in North America (Nelson and Karp , Crocker et al. , Yarwood et al. , Bowen et al.…”

Section: Methodsmentioning

confidence: 99%

“…(, ), which demonstrated that various Pythium oomycetes differed in their virulence to seedlings of several wetland plant species based on the P. australis lineage they were isolated from (Crocker et al. ), whereas the impact of bulk soil did not differ between lineages (Crocker et al. ).…”

Section: Methodsmentioning

confidence: 99%

Intraspecific variation in indirect plant–soil feedbacks influences a wetland plant invasion

Allen

Meyerson

Flick

et al. 2018

Ecology

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Plant-soil feedbacks (PSFs) influence plant competition via direct interactions with pathogens and mutualists or indirectly via apparent competition/mutualisms (i.e., spillover to co-occurring plants) and soil legacy effects. It is currently unknown how intraspecific variation in PSFs interacts with the environment (e.g., nutrient availability) to influence competition between native and invasive plants. We conducted a fully crossed multi-factor greenhouse experiment to determine the effects of Phragmites australis rhizosphere soil biota, interspecific competition, and nutrient availability on biomass of replicate populations from one native and two invasive lineages of common reed (P. australis) and a single lineage of native smooth cordgrass (Spartina alterniflora). Harmful soil biota consistently dominated PSFs involving all three P. australis lineages, reducing biomass by 10%. Indirect PSFs (i.e., soil biota spillover) from the two invasive P. australis lineages reduced S. alterniflora biomass by 7%, whereas PSFs from the native P. australis lineage increased S. alterniflora biomass by 6%. Interestingly, interspecific competition and PSFs interacted to weaken their respective impacts on S. alterniflora, whereas they exerted synergistic negative effects on P. australis. Phragmites australis soil biota decreased S. alterniflora biomass when grown alone (i.e., a soil legacy), but increased S. alterniflora biomass when grown with P. australis, suggesting that P. australis recruits harmful generalist soil biota or facilitates S. alterniflora via spillover (i.e., apparent mutualism). Soil biota also reduced interspecific competition impacts on S. alterniflora, although it remained competitively inferior to P. australis across all treatments. Competitive interactions and responses to nutrients did not differ among P. australis lineages, indicating that interspecific competition and nutrient deposition may not be key drivers of P. australis invasion in North America. Although soil biota, interspecific competition, and nutrient availability appear to have no direct impact on the success of invasive P. australis lineages in North America, intraspecific lineage variation in indirect spillover and soil legacies from P. australis occur and may have important implications for co-occurring native species and restoration of invaded habitats. Our study integrates multiple factors linked to plant invasions, highlighting that indirect interactions are likely commonplace in influencing plant community dynamics and invasion success and impacts.

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Plant effects on and response to soil microbes in native and non‐nativePhragmites australis

Bickford

Goldberg

Zak

et al. 2022

Ecological Applications

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Plant–soil feedbacks (PSFs) mediate plant community dynamics and may plausibly facilitate plant invasions. Microbially mediated PSFs are defined by plant effects on soil microbes and subsequent changes in plant performance (responses), both positive and negative. For microbial interactions to benefit invasive plants disproportionately, native and invasive plants must either (1) have different effects on and responses to soil microbial communities or (2) only respond differently to similar microbial communities. In other words, invasive plants do not need to cultivate different microbial communities than natives if they respond differently to them. However, effects and responses are not often explored separately, making it difficult to determine the underlying causes of performance differences. We performed a reciprocal‐transplant PSF experiment with multiple microbial inhibition treatments to determine how native and non‐native lineages of Phragmites australis affect and respond to soil bacteria, fungi, and oomycetes. Non‐native Phragmites is a large, fast‐growing, cosmopolitan invasive plant, whereas the North American native variety is comparatively smaller, slower growing, and typically considered a desirable wetland plant. We identified the effects of each plant lineage on soil microbes using DNA meta‐barcoding and linked plant responses to microbial communities. Both Phragmites lineages displayed equally weak, insignificant PSFs. We found evidence of slight differential effects on microbial community composition, but no significant differential plant responses. Soils conditioned by each lineage differed only slightly in bacterial community composition, but not in fungal composition. Additionally, native and non‐native Phragmites lineages did not significantly differ in their response to similar soil microbial communities. Neither lineage appreciably differed when plant biomass was compared between those grown in sterile and live soils. Targeted microbial inhibitor treatments revealed both lineages were negatively impacted by soil bacteria, but the negative response was stronger in non‐native Phragmites. These observations were opposite of expectations from invasion theory and imply that the success of non‐native Phragmites, relative to the native lineage, does not result from its interaction with soil microorganisms. More broadly, quantifying plant effects on, and responses to soil microbes separately provides detailed and nuanced insight into plant‐microbial interactions and their role in invasions, which could inform management outcomes for invasive plants.

show abstract

Virulence of oomycete pathogens from Phragmites australis‐invaded and noninvaded soils to seedlings of wetland plant species

Cited by 28 publications

References 92 publications

Root endophytes and invasiveness: no difference between native and non‐native Phragmites in the Great Lakes Region

Root endophytes and invasiveness: no difference between native and non‐native Phragmites in the Great Lakes Region

Intraspecific variation in indirect plant–soil feedbacks influences a wetland plant invasion

Plant effects on and response to soil microbes in native and non‐nativePhragmites australis

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