Mycorrhiza最新文献

Under drought conditions, arbuscular mycorrhizal (AM) fungi may improve plant performance by facilitating the movement of water through extensive hyphal networks. When these networks interconnect neighboring plants in common mycorrhizal networks (CMNs), CMNs are likely to partition water among many individuals. The consequences of CMN-mediated water movement for plant interactions, however, are largely unknown. We set out to examine CMN-mediated interactions among Andropogon gerardii seedlings in a target-plant pot experiment, with watering (watered or long-term drought) and CMN status (intact or severed) as treatments. Intact CMNs improved the survival of seedlings under drought stress and mediated positive, facilitative plant interactions in both watering treatments. Watering increased mycorrhizal colonization rates and improved P uptake, particularly for large individuals. Under drought conditions, improved access to water most likely benefited neighboring plants interacting across CMNs. CMNs appear to have provided the most limiting resource within each treatment, whether P, water, or both, thereby improving survival and growth. Neighbors near large, photosynthate-fixing target plants likely benefited from their establishment of extensive hyphal networks that could access water and dissolved P within soil micropores. In plant communities, CMNs may be vital during drought, which is expected to increase in frequency, intensity, and length with climate change.

Most cold-season grasses can be colonized by belowground arbuscular mycorrhizal (AM) fungi and foliar grass endophytes (Epichloë) simultaneously while also be attacked by insect herbivores. The colonization of AM fungi or the presence of grass endophytes is associated with increased resistance by the host plant. However, studies on how these two symbionts affect host plants and mitigate insect pest attack are currently lacking. In a glasshouse study we investigated the effects of an AM fungus (Acaulospora delicata), a foliar grass endophyte (Epichloë), and the insect pest Spodoptera frugiperda (fall armyworm, FAW) on plant growth, defense enzyme activity, and hormone concentrations of the important pasture grass Lolium perenne. Additionally, we assessed the selective behavior of FAW larvae in response to these interactions using olfactometer tests. Our results showed that the AM fungus and its co-colonization with Epichloë endophytes increased aboveground biomass, while Epichloë endophytes alone had no significant impact on ryegrass aboveground biomass. In contrast, FAW reduced aboveground biomass. The Epichloë endophytes and FAW significantly decreased the mycorrhizal colonization rate by 21.67% and 30.16%, respectively. Interestingly, compared to non-mycorrhizal plants, AM fungus colonized plants were more attractive to FAW larvae feeding, and the defense enzyme activity was not discernibly affected by any experimental treatments. The interactions of the AM fungus and Epichloë endophyte increased the jasmonic acid concentrations by 24.29% and decreased trasylol activity by 11.75% in the host plants under FAW attack. Neither the AM fungus nor Epichloë endophyte influenced the relative growth rate (RGR) of FAW. Overall, the AM fungus had a greater positive effect on plant growth than the Epichloë endophyte, regardless of FAW larvae infestation.

Lead (Pb) is a highly toxic metal and a contaminant of many soils across the world. Some fungi are known to be Pb tolerant, persisting in environments with high Pb levels. Here we investigate Pb tolerance in Suillus brevipes and S. tomentosus, two widespread ectomycorrhizal fungal species in the American West where soil contamination due to mining is common. We conducted in vitro growth assays, exposing previously studied isolates to a range of Pb concentrations. We found S. tomentosus to be more Pb tolerant compared to S. brevipes and that isolates from the two species showed both high and low Pb tolerance. There were no correlations between Pb tolerance and Pb soil concentration, isolate growth rate, or Zn tolerance. Lead tolerance was positively correlated with Cd tolerance in S. tomentosus. Our research contributes for understanding fungal metal tolerance variability and paves the way for future work addressing the mechanisms of Pb tolerance and the potential for using Suillus in the recovery of contaminated sites.

In recent years, the dispersal of potentially invasive plants, animals, and pathogens via international trading routes for fresh agricultural goods has been the subject of intensive research and risk assessment. Comparatively little is known about the potential impact of global food trade on the spreading of symbiotic soil microorganisms, such as arbuscular mycorrhizal (AM) fungi. The present study thus assessed whether internationally traded underground crop harvest products carry AM fungal propagules. Twenty batches of tubers, corms or bulbs originating from eight different countries were sampled and used to inoculate Sorghum bicolor (L.) Moench plants grown in a heat-sterilized, sandy dune soil from the United Arab Emirates (UAE). Results revealed that most of the underground crop harvest products contained AM fungal propagules able to establish AM symbioses in a pot experiment under greenhouse conditions. Though it is likely that most AM fungal propagules attached to harvest products will ultimately be eliminated in the waste or sewage stream, it is well possible that a certain portion would find its way into agricultural or natural ecosystems, e.g., via organic waste disposal or use of kitchen greywater for irrigation. Given the large volumes of underground crops traded worldwide, their impact on AM fungal dispersal and distribution deserves further investigation and assessment of associated risks of adulteration of soil microbial communities.

The application of arbuscular mycorrhizal (AM) fungi has been reported to confer multiple agronomic benefits to crop plants including cereals, vegetables, and fruit trees, as well as to improve soil structure and health. In this study, we conducted a meta-analysis to investigate whether AM fungal addition enhances potato yield. We further examined whether several experimental conditions (type of experiment, inoculation method, and source of AM fungi) and potato cultivar may explain the outcomes. We calculated the effect sizes of seven plant parameters by including a total of 106 independent pot and field experimental studies from 37 peer reviewed publications. Our results show that the addition of AM fungi has an overall positive effect on all potato plant parameters included in our analyses except for aboveground plant biomass. Potato cultivar was the main significant moderator explaining our findings, with some cultivars benefiting more from AM fungal presence than others. Our findings agree with several other global meta-analyses reporting positive effects of AM fungi on other important crops and highlights the potential application of these fungal symbionts in potato agro-ecosystems.

Truffles are possibly the only high-value cultivated organisms for which some aspects of the habit and life cycle have only recently been elucidated or remain unknown. Molecular techniques have helped explain the biological basis for some traditional empirical management techniques, such as inoculating soil with ascospores to improve yield, and have enhanced the detection of competitive or pathogenic soil microorganisms. Improved precision of assessment of the quality of inoculated seedlings is now possible. New knowledge of the genetic structure of populations has indicated that as trees age, the genotypes of mycorrhizae on inoculated trees change, and that there are large differences in the number of female and male genotypes participating in ascocarp formation. The plasticity of Tuber species has also been revealed, with maternal genotypes growing as an ectomycorrhiza in host tree roots and as surface mycelium or an endophyte in roots of adjacent non-mycorrhizal species. Refinement of management techniques has resulted from applying the new information, and the tools are now available to resolve the many outstanding gaps in our knowledge of Tuber biology.

Plant partnerships with arbuscular mycorrhizal fungi (AMF) improve plant resilience to stress by increasing the plant's access to and uptake of essential nutrients and water, as well as regulating the plant's stress response. The magnitude and direction of AMF effects during the relationship depend on multiple factors including plant identity and environmental context. To investigate how AMF influence plant responses to environmental stresses, we assessed the effects of drought and salinity on growth, final biomass, and reproduction of nine alfalfa (Medicago sativa) cultivars inoculated with Rhizophagus irregularis or grown alone. In absence of stress, the fungus increased nutrient content, but caused declines in biomass through a reduction in initial growth that was not overcome by a later growth spurt. Mycorrhizal fungus inoculation also magnified stress effects on growth in most scenarios, but this depended on the stress type and cultivar. For salinity, this stress increase in inoculated plants was mediated by increased salt accumulation. Flowering of each cultivar was affected by both inoculation and stress type, albeit erratically, whereas seed production was only affected by inoculation when drought stressed. We found no clear pattern distinguishing differences in mycorrhizal fungus effects on stress among cultivars; however, our results show that mycorrhizal fungus effects on plant stress responses are contingent on the plant performance metric and stress type, highlighting the complexity of responses to mycorrhizas.

Arbuscular mycorrhizal fungi (AMF) are the most widespread plant symbionts associated with plant roots, and theyperform numerous functions that contribute to plants' health and physiology. However, there are many knowledge gaps in how the interactions between AMF and root mycobiomes influence the performance of the host plants. To this end, we inoculated a local chickpea cultivar grown in agricultural soil under semi-controlled conditions with Rhizophagus irregularis. In addition to examining mycorrhizal colonization, plant biomass, and mineral nutrition, we sequenced the ITS region of the rDNA to assess the chickpea mycobiome and identify key fungal taxa potentially responding to R. irregularis inoculation. Our results showed that inoculation had a positive effect on chickpea biomass and mineral nutrition, especially the total aboveground phosphorus, potassium and sodium contents. Fusarium, Sporomia, Alternaria, and unknown Pleosporales were the most abundant taxa in the roots, while Stachybotris, Penicillum, Fusarium, Ascobolus, an unknown Pleosporales and Acrophialophora were the most abundant in the rhizosphere. Among the ASVs that either were enriched or depleted in the rhizosphere and roots are potential plant pathogens from the genera Didymella, Fusarium, Neocosmospora, and Stagonosporopsis. This study highlights the relevance of AMF inoculation not only for enhancing chickpea growth and mineral nutrition in semi-arid conditions but also for influencing the composition of the plants' fungal community which contributes to improved plant performance and resilience against biotic and abiotic stress.

Soil metal contamination can affect growth, metabolism, and reproduction of organisms, and can lead to death. However, some fungi have evolved metal tolerance and are able to live in contaminated soils. Species in the ectomycorrhizal genus Suillus from Europe and Asia display variation in metal tolerance, yet it is unknown whether this is a widespread trait in the genus and whether it occurs in North America. Here we investigate cadmium (Cd) and zinc (Zn) tolerance in S. brevipes and S. tomentosus isolates collected from sites in the Rocky Mountains of Colorado displaying different metal content. In line with previous findings for other Suillus species, we hypothesized (1) S. brevipes and S. tomentosus to display intra-specific metal tolerance variation, (2) Zn and Cd tolerance to be correlated to soil metal content, and (3) tolerant isolates to show lower metal tissue content compared to sensitive isolates (due to increased metal exclusion). We found ample intra- and inter-specific Zn and Cd tolerance variation in both S. brevipes and S. tomentosus, but no correlation between soil metal content and tolerance. There was a negative correlation between tolerance level and Zn uptake, indicating an exclusion-based Zn tolerance strategy. Sensitive and tolerant isolates showed no difference in Cd accumulation, indicating that Cd tolerance in these species is likely not dependent on exclusion. Our study sets the groundwork for further investigation into the genetic basis of Suillus metal tolerance and whether and how it impacts pine mycorrhizal partners.

Coccoloba uvifera L. (Polygonacaeae), named also seagrape, is an ectomycorrhizal (ECM) Caribbean beach tree, introduced pantropically for stabilizing coastal soils and producing edible fruits. This review covers the pantropical distribution and micropropagation of seagrape as well as genetic diversity, functional traits and use of ECM symbioses in response to salinity, both in its native regions and areas where it has been introduced. The ECM fungal diversity associated with seagrape was found to be relatively low in its region of origin, with Scleroderma bermudense Coker being the predominant fungal species. In regions of introduction, seagrape predominantly associated with Scleroderma species, whereas S. bermudense was exclusively identified in Réunion and Senegal. The introduction of S. bermudense is likely through spores adhering to the seed coats of seagrape, suggesting a vertical transmission of ECM colonization in seagrape by S. bermudense. This ECM fungus demonstrated its capacity to enhance salt tolerance in seagrape seedlings by reducing Na concentration and increasing K and Ca levels, consequently promoting higher K/Na and Ca/Na ratios in the tissues of ECM seedlings vs. non-ECM plants in nursery conditions. Moreover, the ECM symbiosis positively influenced growth, photosynthetic and transpiration rates, chlorophyll fluorescence and content, stomatal conductance, intercellular CO₂, and water status, which improved the performance of ECM seagrape exposed to salt stress in planting conditions. The standardization of seagrape micropropagation emerges as a crucial tool for propagating homogeneous plant material in nursery and planting conditions. This review also explores the use of the ECM symbiosis between seagrape and S. bermudense as a strategy for restoring degraded coastal ecosystems in the Caribbean, Indian Ocean, and West African regions.