An official website of the United States government
Abstract Arbuscular mycorrhizal (AM) fungi are root symbionts that can facilitate plant growth and influence plant communities by altering plant interactions with herbivores. Therefore, AM fungi could be critical for the conservation of certain rare plants and herbivores. For example, North American milkweed species are crucial hosts for monarch butterflies (Danaus plexippus). Understanding how mycorrhizal composition affects milkweeds will have direct impacts on the conservation and restoration of both increasingly threatened guilds. We present data from three studies on the effect of AM fungal composition on milkweed growth, latex production, and establishment. First, we grew seven milkweed species with and without a mixture of native mycorrhizal fungi. We assessed how important fungal composition is to milkweed growth and latex production by growing four milkweed species with seven fungal compositions, as single‐species inoculations with four native fungi, a mixture of native fungi, a single commercial fungus of presumably non‐native origin, and noninoculated controls. Finally, we assessed the field establishment of two milkweed species with and without native mycorrhizal inoculation. Milkweed species grew 98% larger and produced 82% more latex after inoculation with native mycorrhizae. Milkweeds were strongly affected by fungal composition; milkweeds were inhibited by commercial fungi (average of −14% growth) and showed variable but positive responses to native fungal species (average of +3% to +38% biomass). Finally, we found that restoration establishment was dependent on inoculation with native fungi and milkweed species. Overall, our findings indicate that some milkweed species (i.e.,Asclepias syriacaandA. incarnata) are not responsive to mycorrhizal fungal presence or sensitive to mycorrhizal composition while others are, including endangered species (A. meadii) and species of high conservation value (A. tuberosa). We conclude that the reintroduction of native AM fungi could improve the establishment of desirable milkweed species and should be considered within strategies for plantings for monarch conservation.
more »
« less
Origin matters: mycorrhizal growth response and induced resistance to pathogens depend on mycorrhizal and pathogen source
Summary Arbuscular mycorrhizal fungi (AMF) are critical to native plant community ecology and influence plant invasions. Research has focused on nutritional benefits of AMF, although evidence shows that they may also confer pathogen resistance. However, most such work has focused on agriculturally relevant plant species. Therefore, whether AMF confer pathogen resistance tonative(wild) plant species, and impact of novel plant–microbial relationships on this benefit, remains understudied.We conducted a series of experiments measuring mycorrhizal‐induced resistance (MIR) to pathogens in native prairie plant species. We tested for pathogenicity across 69 field‐isolated fungi and oomycetes across five plant species. We then conducted experiments assessing growth response to native and non‐native AMF and pathogens in three plant species from native populations and milkweed (Asclepias syriaca) from native and postagricultural populations.We found evidence of MIR in milkweed. Moreover, we identified differential effects of AMF depending on plant species, with milkweed from native populations showing benefits from AMF. Finally, growth response was mediated by local adaptation, with matching AMF–pathogen origin strengthening responses.This work illustrates the importance of locally sourced AMF and plants to native plant ecology and suggests that pathogen resistance may be an important dimension of AMF benefit.
more »
« less
- Award ID(s):
- 2027458
- PAR ID:
- 10635784
- Publisher / Repository:
- New Phytologist
- Date Published:
- Journal Name:
- New Phytologist
- ISSN:
- 0028-646X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Many of the disturbance‐sensitive, late successional plant species in grasslands respond to arbuscular mycorrhizal (AM) fungi more positively via growth and establishment than plants that readily establish in disturbed areas (i.e. early successional species). Inoculation with AM fungi can therefore aid the establishment of late successional species in disturbed areas. If the differential benefit of AM fungi to late versus early successional plants is context‐dependent, however, this advantage could be diminished in high phosphorus (P) post‐agricultural soils or in future climates with altered precipitation.In this greenhouse experiment, we tested if late successional plant species are less plastic in their reliance on AM fungi than early successional plants by growing 17 plant species of different successional status (9 early and 8 late successional) in full factorial combinations of inoculated or uninoculated with AM fungi, with ambient or high P levels, and with low or high levels of water.AM fungi positively affected the biomass of the 17 grassland plant species, but across all environments, late successional plant species generally responded more positively to AM fungi than early successional plants species.AM fungal growth promotion and change in below‐ground biomass allocation was generally diminished with P fertilizer across all plant species, and while there was significant variation among plant species in the sensitivity of AM fungal responsiveness to P fertilization, this differential sensitivity was not predicted by plant successional status.The role of AM fungi in plant growth promotion was not generally altered by variation in watering, however late successional plant species allocated a greater proportion of their biomass below‐ground in response to AM fungi in low versus high water conditions.Synthesis. Overall greater responsiveness to arbuscular mycorrhizal (AM) fungi by late successional species is consistent with an important role of AM fungi in plant succession, even while AM fungi are less impactful overall in high P soils. However, the increase in responsiveness of below‐ground allocation of late successional species to AM fungi in low water conditions suggests that successional dynamics may be more dependent on AM fungi in future climates that feature greater propensity for drought.more » « less
-
Abstract Plant‐microbial‐herbivore interactions play a crucial role in the structuring and maintenance of plant communities and biodiversity, yet these relationships are complex. In grassland ecosystems, herbivores have the potential to greatly influence the survival, growth and reproduction of plants. However, few studies examine interactions of above‐ and below‐ground grazing and arbuscular mycorrhizal (AM) mycorrhizal symbiosis on plant community structure.We established experimental mesocosms containing an assemblage of eight tallgrass prairie grass and forb species in native prairie soil, maintained under mycorrhizal and nonmycorrhizal conditions, with and without native herbivorous soil nematodes, and with and without grasshopper herbivory. Using factorial analysis of variance and principal component analysis, we examined: (a) the independent and interacting effects of above‐ and below‐ground herbivores on AM symbiosis in tallgrass prairie mesocosms, (b) independent and interacting effects of above‐ and below‐ground herbivores and mycorrhizal fungi on plant community structure and (c) potential influences of mycorrhizal responsiveness of host plants on herbivory tolerance and concomitant shifts in plant community composition.Treatment effects were characterized by interactions between AM fungi and both above‐ground and below‐ground herbivores, while herbivore effects were additive. The dominance of mycorrhizal‐dependent C4grasses in the presence of AM symbiosis was increased (p < 0.0001) by grasshopper herbivory but reduced (p < 0.0001) by nematode herbivory. Cool‐season C3grasses exhibited a competitive release in the absence of AM symbiosis but this effect was largely reversed in the presence of grasshopper herbivory. Forbs showed species‐specific responses to both AM fungal inoculation and the addition of herbivores. Biomass of the grazing‐avoidant, facultatively mycotrophic forbBrickellia eupatorioidesincreased (p < 0.0001) in the absence of AM symbiosis and with grasshopper herbivory, while AM‐related increases in the above‐ground biomass of mycorrhizal‐dependent forbsRudbeckia hirtaandSalvia azureawere eradicated (p < 0.0001) by grasshopper herbivory. In contrast, nematode herbivory enhanced (p = 0.001) the contribution ofSalvia azureato total biomass.Synthesis. Our research indicates that arbuscular mycorrhizal symbiosis is the key driver of dominance of C4grasses in the tallgrass prairie, with foliar and root herbivory being two mechanisms for maintenance of plant diversity.more » « less
-
Abstract BackgroundArbuscular mycorrhizal fungi (AMF) are beneficial root symbionts contributing to improved plant growth and development and resistance to abiotic and biotic stresses. Commercial bioinoculants containing AMF are widely considered as an alternative to agrochemicals in vineyards. However, their effects on grapevine plants grown in soil containing native communities of AMF are still poorly understood. In a greenhouse experiment, we evaluated the influence of five different bioinoculants on the composition of native AMF communities of young Cabernet Sauvignon vines grown in a non-sterile soil. Root colonization, leaf nitrogen concentration, plant biomass and root morphology were assessed, and AMF communities of inoculated and non-inoculated grapevine roots were profiled using high-throughput sequencing. ResultsContrary to our predictions, no differences in the microbiome of plants exposed to native AMF communities versus commercial AMF bioinoculants + native AMF communities were detected in roots. However, inoculation induced positive changes in root traits as well as increased AMF colonization, plant biomass, and leaf nitrogen. Most of these desirable functional traits were positively correlated with the relative abundance of operational taxonomic units identified asGlomus,RhizophagusandClaroideoglomusgenera. ConclusionThese results suggest synergistic interactions between commercial AMF bioinoculants and native AMF communities of roots to promote grapevine growth. Long-term studies with further genomics, metabolomics and physiological research are needed to provide a deeper understanding of the symbiotic interaction among grapevine roots, bioinoculants and natural AMF communities and their role to promote plant adaptation to current environmental concerns.more » « less
-
Summary Iron (Fe) is crucial for metabolic functions of living organisms. Plants access occluded Fe through interactions with rhizosphere microorganisms and symbionts. Yet, the interplay between Fe addition and plant–mycorrhizal interactions, especially the molecular mechanisms underlying mycorrhiza‐assisted Fe processing in plants, remains largely unexplored.We conducted mesocosms inPinusplants inoculated with different ectomycorrhizal fungi (EMF)Suillusspecies under conditions with and without Fe coatings. Meta‐transcriptomic, biogeochemical, and X‐ray fluorescence imaging analyses were applied to investigate early‐stage mycorrhizal roots.While Fe addition promotedPinusgrowth, it concurrently reduced mycorrhiza formation rate, symbiosis‐related metabolites in plant roots, and aboveground plant carbon and macronutrient content. This suggested potential trade‐offs between Fe‐enhanced plant growth and symbiotic performance. However, the extent of this trade‐off may depend on interactions between host plants and EMF species. Interestingly, dual EMF species were more effective at facilitating plant Fe uptake by inducing diverse Fe‐related functions than single‐EMF species. This subsequently triggered various Fe‐dependent physiological and biochemical processes inPinusroots, significantly contributing toPinusgrowth. However, this resulted in a greater carbon allocation to roots, relatively reducing the aboveground plant carbon content.Our study offers critical insights into how EMF communities rebalance benefits of Fe‐induced effects on symbiotic partners.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1111/nph.70358
