Many animals are dependent on microbial partners that provide essential nutrients lacking from their diet. Ticks, whose diet consists exclusively on vertebrate blood, rely on maternally inherited bacterial symbionts to supply B vitamins. While previously studied tick species consistently harbor a single lineage of those nutritional symbionts, we evidence here that the invasive tick Hyalomma marginatum harbors a unique dual-partner nutritional system between an ancestral symbiont, Francisella, and a more recently acquired symbiont, Midichloria. Using metagenomics, we show that Francisella exhibits extensive genome erosion that endangers the nutritional symbiotic interactions. Its genome includes folate and riboflavin biosynthesis pathways but deprived functional biotin biosynthesis on account of massive pseudogenization. Co-symbiosis compensates this deficiency since the Midichloria genome encompasses an intact biotin operon, which was primarily acquired via lateral gene transfer from unrelated intracellular bacteria commonly infecting arthropods. Thus, in H. marginatum, a mosaic of co-evolved symbionts incorporating gene combinations of distant phylogenetic origins emerged to prevent the collapse of an ancestral nutritional symbiosis. Such dual endosymbiosis was never reported in other blood feeders but was recently documented in agricultural pests feeding on plant sap, suggesting that it may be a key mechanism for advanced adaptation of arthropods to specialized diets.

• MeSH
• Francisella genetika   metabolismus   MeSH
• Ixodidae mikrobiologie   fyziologie   MeSH
• přenos genů horizontální MeSH
• Rickettsiales genetika   metabolismus   MeSH
• symbióza fyziologie   MeSH
• vitamin B komplex biosyntéza   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The relationship between mycorrhiza functioning and composition of arbuscular mycorrhizal (AM) fungal communities is an important but experimentally still rather little explored topic. The main aim of this study was thus to link magnitude of plant benefits from AM symbiosis in different abiotic contexts with quantitative changes in AM fungal community composition. A synthetic AM fungal community inoculated to the model host plant Medicago truncatula was exposed to four different abiotic contexts, namely drought, elevated phosphorus availability, and shading, as compared to standard cultivation conditions, for two cultivation cycles. Growth and phosphorus uptake of the host plants was evaluated along with the quantitative composition of the synthetic AM fungal community. Abiotic context consistently influenced mycorrhiza functioning in terms of plant benefits, and the effects were clearly linked to the P requirement of non-inoculated control plants. In contrast, the abiotic context only had a small and transient effect on the quantitative AM fungal community composition. Our findings suggest no relationship between the degree of mutualism in AM symbiosis and the relative abundances of AM fungal species in communities in our simplified model system. The observed progressive dominance of one AM fungal species indicates an important role of different growth rates of AM fungal species for the establishment of AM fungal communities in simplified systems such as agroecosystems.

• MeSH
• fosfor analýza   MeSH
• Medicago truncatula mikrobiologie   MeSH
• mykobiom * MeSH
• mykorhiza fyziologie   MeSH
• období sucha MeSH
• sluneční záření MeSH
• symbióza * MeSH
• Publikační typ
• časopisecké články MeSH

Arbuscular mycorrhizal (AM) fungi establish symbiotic associations with many plant species, transferring significant amounts of soil nutrients such as phosphorus to plants and receiving photosynthetically fixed carbon in return. Functioning of AM symbiosis is thus based on interaction between two living partners. The importance of dead AM fungal biomass (necromass) in ecosystem processes remains unclear. Here, we applied either living biomass or necromass (0.0004 potting substrate weight percent) of monoxenically produced AM fungus (Rhizophagus irregularis) into previously sterilized potting substrate planted with Andropogon gerardii. Plant biomass production significantly improved in both treatments as compared to non-amended controls. Living AM fungus, in contrast to the necromass, specifically improved plant acquisition of nutrients normally supplied to the plants by AM fungal networks, such as phosphorus and zinc. There was, however, no difference between the two amendment treatments with respect to plant uptake of other nutrients such as nitrogen and/or magnesium, indicating that the effect on plants of the AM fungal necromass was not primarily nutritional. Plant growth stimulation by the necromass could thus be either due to AM fungal metabolites directly affecting the plants, indirectly due to changes in soil/root microbiomes or due to physicochemical modifications of the potting substrate. In the necromass, we identified several potentially bioactive molecules. We also provide experimental evidence for significant differences in underground microbiomes depending on the amendment with living or dead AM fungal biomass. This research thus provides the first glimpse into possible mechanisms responsible for observed plant growth stimulation by the AM fungal necromass.

• MeSH
• Andropogon * MeSH
• biomasa MeSH
• Glomeromycota * MeSH
• kořeny rostlin MeSH
• mykorhiza * MeSH
• symbióza MeSH
• Publikační typ
• časopisecké články MeSH

Arbuscular mycorrhizal (AM) symbiosis is among the factors contributing to plant survival in serpentine soils characterised by unfavourable physicochemical properties. However, AM fungi show a considerable functional diversity, which is further modified by host plant identity and edaphic conditions. To determine the variability among serpentine AM fungal isolates in their effects on plant growth and nutrition, a greenhouse experiment was conducted involving two serpentine and two non-serpentine populations of Knautia arvensis plants grown in their native substrates. The plants were inoculated with one of the four serpentine AM fungal isolates or with a complex AM fungal community native to the respective plant population. At harvest after 6-month cultivation, intraradical fungal development was assessed, AM fungal taxa established from native fungal communities were determined and plant growth and element uptake evaluated. AM symbiosis significantly improved the performance of all the K. arvensis populations. The extent of mycorrhizal growth promotion was mainly governed by nutritional status of the substrate, while the effect of AM fungal identity was negligible. Inoculation with the native AM fungal communities was not more efficient than inoculation with single AM fungal isolates in any plant population. Contrary to the growth effects, a certain variation among AM fungal isolates was revealed in terms of their effects on plant nutrient uptake, especially P, Mg and Ca, with none of the AM fungi being generally superior in this respect. Regardless of AM symbiosis, K. arvensis populations significantly differed in their relative nutrient accumulation ratios, clearly showing the plant's ability to adapt to nutrient deficiency/excess.

• MeSH
• biomasa MeSH
• Dipsacaceae růst a vývoj   mikrobiologie   fyziologie   MeSH
• fylogeneze MeSH
• houby klasifikace   izolace a purifikace   fyziologie   MeSH
• molekulární sekvence - údaje MeSH
• mykorhiza klasifikace   izolace a purifikace   fyziologie   MeSH
• očkovadla agrotechnická klasifikace   genetika   izolace a purifikace   fyziologie   MeSH
• půda chemie   MeSH
• symbióza MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Arbuscular mycorrhizal (AM) fungi play a positive role in plant water relations, and the AM symbiosis is often cited as beneficial for overcoming drought stress of host plants. Nevertheless, water uptake via mycorrhizal hyphal networks has been little addressed experimentally, especially so through isotope tracing. In a greenhouse study conducted in two-compartment rhizoboxes, Medicago truncatula was planted in the primary compartment (PC), either inoculated with Rhizophagus irregularis or left uninoculated. Plant roots were either allowed to enter the secondary compartment (SC) or were restricted to the PC by root-excluding mesh. Substrate moisture was manipulated in the PC such that the plants were grown either in high moisture (15% of gravimetric water content, GWC) or low moisture (8% GWC). Meanwhile, the SC was maintained at 15% GWC throughout and served as a water source accessible (or not) by roots and/or hyphae. Water in the SC was labeled with deuterium (D) to quantify water uptake by the plants from the SC. Significantly, increased D incorporation into plants indicated higher water uptake by mycorrhizal plants when roots had access to the D source, but this was mainly explained by generally larger mycorrhizal root systems in proximity to the D source. On the other hand, AM fungal hyphae with access to the D source increased D incorporation into plants more than twofold compared to non-mycorrhizal plants. Despite this strong effect, water transport via AM fungal hyphae was low compared to the transpiration demand of the plants.

• MeSH
• Glomeromycota * MeSH
• hyfy MeSH
• kořeny rostlin MeSH
• mykorhiza * MeSH
• symbióza MeSH
• voda MeSH
• Publikační typ
• časopisecké články MeSH

Research efforts directed to elucidation of mechanisms behind trading of resources between the partners in the arbuscular mycorrhizal (AM) symbiosis have seen a considerable progress in the recent years. Yet, despite of the recent developments, some key questions still remain unanswered. For example, it is well established that the strictly biotrophic AM fungus releases phosphorus to- and receives carbon molecules from the plant symbiont, but the particular genes, and their products, responsible for facilitating this exchange, are still not fully described, nor are the principles and pathways of their regulation. Here, we made a de novo quest for genes involved in carbon transfer from the plant to the fungus using genome-wide gene expression array targeting whole root and whole shoot gene expression profiles of mycorrhizal and non-mycorrhizal Medicago truncatula plants grown in a glasshouse. Using physiological intervention of heavy shading (90% incoming light removed) and the correlation of expression levels of MtPT4, the mycorrhiza-inducible phosphate transporter operating at the symbiotic interface between the root cortical cells and the AM fungus, and our candidate genes, we demonstrate that several novel genes may be involved in resource tradings in the AM symbiosis established by M. truncatula. These include glucose-6-phosphate/phosphate translocator, polyol/monosaccharide transporter, DUR3-like, nucleotide-diphospho-sugar transferase or a putative membrane transporter. Besides, we also examined the expression of other M. truncatula phosphate transporters (MtPT1-3, MtPT5-6) to gain further insights in the balance between the "direct" and the "mycorrhizal" phosphate uptake pathways upon colonization of roots by the AM fungus, as affected by short-term carbon/energy deprivation. In addition, the role of the novel candidate genes in plant cell metabolism is discussed based on available literature.

• MeSH
• fosfor metabolismus   MeSH
• Medicago truncatula genetika   metabolismus   mikrobiologie   MeSH
• metabolické sítě a dráhy MeSH
• mykorhiza genetika   fyziologie   MeSH
• regulace genové exprese u rostlin MeSH
• rostlinné proteiny genetika   MeSH
• sekvenování exomu MeSH
• stanovení celkové genové exprese MeSH
• symbióza MeSH
• uhlík metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Arbuscular mycorrhizal (AM) fungi can enhance plant Cr tolerance through immobilizing Cr in mycorrhizal roots. However, the detailed processes and mechanisms are unclear. The present study focused on cellular distribution and speciation of Cr in both extraradical mycelium (ERM) and mycorrhizal roots exposed to Cr(VI) by using field emission scanning electron microscopy equipped with energy dispersive X-ray spectrometer (FE-SEM-EDS), scanning transmission soft X-ray microscopy (STXM) and X-ray absorption fine structure (XAFS) spectroscopy techniques. We found that amounts of particles (possibly extracellular polymeric substances, EPS) were produced on the AM fungal surface upon Cr(VI) stress, which contributed greatly to Cr(VI) reduction and immobilization. With EDS of the surface of AM fungi exposed to various Cr(VI) levels, a positive correlation between Cr and P was revealed, suggesting that phosphate groups might act as counter ions of Cr(III), which was also confirmed by the XAFS analysis. Besides, STXM and XAFS analyses showed that Cr(VI) was reduced to Cr(III) in AM fungal structures (arbuscules, intraradical mycelium, etc.) and cell walls in mycorrhizal roots, and complexed possibly with carboxyl groups or histidine analogues. The present work provided evidence of Cr immobilization on fungal surface and in fungal structures in mycorrhizal roots at a cellular level, and thus unraveled the underlying mechanisms by which AM symbiosis immobilize Cr.

• MeSH
• chrom analýza   chemie   MeSH
• fosfáty metabolismus   MeSH
• kořeny rostlin metabolismus   mikrobiologie   MeSH
• mikroskopie elektronová rastrovací MeSH
• mycelium metabolismus   MeSH
• mykorhiza metabolismus   MeSH
• povrchové vlastnosti MeSH
• rostliny metabolismus   MeSH
• spektrometrie rentgenová emisní MeSH
• struktury hub * MeSH
• symbióza MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Environmental stressors can be key drivers of phenotypes, including reproductive strategies and morphological traits. The response to stress may be altered by the presence of microbial associates. For example, in aphids, facultative (secondary) bacterial symbionts can provide protection against natural enemies and stress induced by elevated temperatures. Furthermore, aphids exhibit phenotypic plasticity, producing winged (rather than wingless) progeny that may be better able to escape danger, and the combination of these factors improves the response to stress. How symbionts and phenotypic plasticity, both of which shape aphids' stress response, influence one another, and together influence host fitness, remains unclear. In this study, we investigate how environmental stressors drive shifts in fecundity and winged/wingless offspring production, and how secondary symbionts influence the process. We induced production of winged offspring through distinct environmental stressors, including exposure to aphid alarm pheromone and crowding, and, in one experiment, we assessed whether the aphid response is influenced by host plant. In the winged morph, energy needed for wing maintenance may lead to trade-offs with other traits, such as reproduction or symbiont maintenance. Potential trade-offs between symbiont maintenance and fitness have been proposed but have not been tested. Thus, beyond studying the production of offspring of alternative morphs, we also explore the influence of symbionts across wing/wingless polyphenism as well as symbiont interaction with cross-generational impacts of environmental stress on reproductive output. All environmental stressors resulted in increased production of winged offspring and shifts in fecundity rates. Additionally, in some cases, aphid host-by-symbiont interactions influenced fecundity. Stress on first-generation aphids had cross-generational impacts on second-generation adults, and the impact on fecundity was further influenced by the presence of secondary symbionts and presence/absence of wings. Our study suggests a complex interaction between beneficial symbionts and environmental stressors. Winged aphids have the advantage of being able to migrate out of danger with more ease, but energy needed for wing production and maintenance may come with reproductive costs for their mothers and for themselves, where in certain cases, these costs are altered by secondary symbionts.

• MeSH
• Bacteria MeSH
• hrách setý MeSH
• křídla zvířecí MeSH
• mšice * MeSH
• symbióza MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Research Support, N.I.H., Extramural MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH

Dispersal of mycorrhizal fungi via animals and the importance for the interacting partners' life history as well as for ecosystems is an understudied topic. In this review, we describe the available evidence and the most important knowledge gaps and finally suggest ways to gain the missing information. So far, 33 articles have been published proving a successful transfer of mycorrhizal propagules by animals. The vast majority of research on invertebrates was focused on arbuscular mycorrhizal (AM) fungi, whereas papers on vertebrates (mainly rodents and artiodactyls) equally addressed ectomycorrhizal (ECM) and AM fungi. Effective dispersal has been mostly shown by the successful inoculation of bait plants and less commonly by spore staining or germination tests. Based on the available data and general knowledge on animal lifestyles, collembolans and oribatid mites may be important in transporting ECM fungal propagules by ectozoochory, whereas earthworms, isopods, and millipedes could mainly transfer AM fungal spores in their gut systems. ECM fungal distribution may be affected by mycophagous dipterans and their hymenopteran parasitoids, while slugs, snails, and beetles could transport both mycorrhizal groups. Vertebrates feeding on fruit bodies were shown to disperse mainly ECM fungi, while AM fungi are transported mostly accidentally by herbivores. The important knowledge gaps include insufficient information on dispersal of fungal propagules other than spores, the role of invertebrates in the dispersal of mycorrhizal fungi, the way in which propagules pass through food webs, and the spatial distances reached by different dispersal mechanisms both horizontally and vertically.

• MeSH
• bezobratlí fyziologie   MeSH
• houby fyziologie   MeSH
• mykorhiza fyziologie   MeSH
• potravní řetězec * MeSH
• půdní mikrobiologie MeSH
• symbióza MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Root hairs and arbuscular mycorrhiza (AM) coexist in root systems for nutrient and water absorption, but the relation between AM and root hairs is poorly known. A pot study was performed to evaluate the effects of four different AM fungi (AMF), namely, Claroideoglomus etunicatum, Diversispora versiformis, Funneliformis mosseae, and Rhizophagus intraradices on root hair development in trifoliate orange (Poncirus trifoliata) seedlings grown in sand. Mycorrhizal seedlings showed significantly higher root hair density than non-mycorrhizal seedlings, irrespective of AMF species. AMF inoculation generally significantly decreased root hair length in the first- and second-order lateral roots but increased it in the third- and fourth-order lateral roots. AMF colonization induced diverse responses in root hair diameter of different order lateral roots. Considerably greater concentrations of phosphorus (P), nitric oxide (NO), glucose, sucrose, indole-3-acetic acid (IAA), and methyl jasmonate (MeJA) were found in roots of AM seedlings than in non-AM seedlings. Levels of P, NO, carbohydrates, IAA, and MeJA in roots were correlated with AM formation and root hair development. These results suggest that AMF could alter the profile of root hairs in trifoliate orange through modulation of physiological activities. F. mosseae, which had the greatest positive effects, could represent an efficient AM fungus for increasing fruit yields or decreasing fertilizer inputs in citrus production.

• MeSH
• biomasa MeSH
• Citrus růst a vývoj   mikrobiologie   MeSH
• Glomeromycota fyziologie   MeSH
• kořeny rostlin růst a vývoj   metabolismus   mikrobiologie   MeSH
• mykorhiza růst a vývoj   fyziologie   MeSH
• Poncirus růst a vývoj   mikrobiologie   MeSH
• půda MeSH
• půdní mikrobiologie MeSH
• semenáček růst a vývoj   metabolismus   mikrobiologie   MeSH
• symbióza fyziologie   MeSH
• výhonky rostlin růst a vývoj   metabolismus   mikrobiologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH