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Drought stress poses increasingly serious threats to agricultural production in the era of global climate change. Arbuscular mycorrhizal (AM) fungi are well-recognized biostimulants promoting plant tolerance to drought stress. Lipids are indispensable for AM fungal colonization, however, the involvement of lipid metabolism in the drought tolerance conferred by AM fungi is largely unknown. In this study, we inoculated Poncirus trifoliata (L.) with Rhizophagus irregularis DAOM197198 under no drought stress, medium drought stress and severe drought stress, with non-inoculation under respective treatments as control. Results indicated that AM fungal inoculation significantly promoted the drought tolerance of P. trifoliata (L.), with the effect size decreasing along with drought severity. Moreover, the effect size was significantly related to arbuscule abundance. Fatty acid profiling showed that the arbuscule abundance was determined by the AM-specific phospholipids (PLs), whose biosynthesis and delivery were inhibited by drought stress as revealed by qRT-PCR of FatM, RAM1 and STR/STR2. More interestingly, AM fungal inoculation increased the lipid allocation to total PLs and the unsaturation rate of total neutral lipids (NLs), probably indicating the involvement of non-AM-specific lipids in the increased drought tolerance. Taken together, our results demonstrate that lipid metabolism in AM mediates the increased drought tolerance conferred by AM fungal inoculation, with AM-specific and non-AM-specific lipids functioning therein in different ways. [ABSTRACT FROM AUTHOR]

Global warming has been shifting climatic envelopes of many tree species to higher latitudes and elevations across the globe; however, unsuitable soil biota may inhibit tree migrations into these areas of suitable climate. Specifically, the role of mycorrhizal fungi in facilitating tree seedling establishment beyond natural species range limits has not been fully explored within forest ecosystems. We used three experiments to isolate and quantify the effects of mycorrhizal colonization and common mycorrhizal networks (CMN) on tree seedling survival and growth across (within and beyond) the elevational ranges of two dominant tree species in northeastern North America, which were associated with either arbuscular mycorrhiza (AMF, Acer saccharum) or ectomycorrhiza (EMF, Fagus grandifolia). In order to quantify the influence of mycorrhiza on seedling establishment independent of soil chemistry and climate, we grew seedlings in soils from within and beyond our study species ranges in a greenhouse experiment (GE) as well as in the field using a soil translocation experiment (STE) and another field experiment manipulating seedling connections to potential CMNs (CMNE). Root length colonized, seedling survival and growth, foliar nutrients, and the presence of potential root pathogens were examined as metrics influencing plant performance across species' ranges. Mycorrhizal inoculum from within species ranges, but not from outside, increased seedling survival and growth in a greenhouse setting; however, only seedling survival, and not growth, was significantly improved in field studies. Sustained potential connectivity to AMF networks increased seedling survival across the entire elevational range of A. saccharum. Although seedlings disconnected from a potential CMN did not suffer decreased foliar nutrient levels compared with connected seedlings, disconnected AM seedlings, but not EM seedlings, had significantly higher aluminum concentrations and more potential pathogens present. Our results indicate that mycorrhizal fungi may facilitate tree seedling establishment beyond species range boundaries in this forested ecosystem and that the magnitude of this effect is modulated by the dominant mycorrhizal type present (i.e., AM vs. EM). Thus, despite changing climate conditions beyond species ranges, a lack of suitable mutualists can still limit successful seedling establishment and stall adaptive climate‐induced shifts in tree species distributions. [ABSTRACT FROM AUTHOR]

Drought is increasingly becoming a production constraint in wheat world-wide. Arbuscular mycorrhizal fungi (AMF)-bread wheat symbiosis has been shown to improve the tolerance under drought stress. The objective of this study was to determine the effects of AMF inoculation on yield attributes (spike number per plant, spike weight per plant, number of grains per spike, grain weight per spike and 1000 grain weight) and protein quantity and quality in two bread wheat cultivars (PAN3497 and SST806) grown under drought stress. Plant growth was significantly reduced due to drought stress in both cultivars. Shoot dry weight was significantly increased (23%) due to AMF inoculation in SST806. AMF inoculation caused a further significant increase of protein content in both cultivars (10.70% and 13.42% in PAN3497 and SST806, respectively). Low molecular weight (LMW) glutenin was significantly decreased in PAN3497 under drought stress. However, the monomeric proteins were significantly increased by drought and/or a combination of drought and AMF inoculation in both cultivars. In cultivar SST806, significant reduction of polymeric protein was observed due to application of both AMF (6%) and a combination of AMF with drought stress (4%). Regarding the two-dimensional separation of the gluten proteins, drought had the largest effect on protein spots, with AMF causing up-regulation of only some spots. SST806 was generally more drought tolerant than PAN3497. [ABSTRACT FROM AUTHOR]

The systemic coordination of accumulation of plasma membrane aquaporins (PIP) was investigated in this study in relation to mycorrhized maize response to a rapid development of severe drought followed by rewatering. In non-mycorrhizal roots, drought led to a drop in PIP abundance, followed by a transient increase under rewatering, whereas leaves showed an opposite pattern. In contrast, mycorrhiza contributed to maintenance of high and stable levels of PIPs in both plant organs after an initial increase, prolonged over the irrigation period. Isoelectric focusing electrophoresis resolved up to 13 aquaporin complexes with highly reproducible pl positions across leaf and root samples, symbiotic and non-symbiotic, stressed or not. Mass spectrometry recognized in leaves and roots a different ratio of PIP1 and PIP2 subunits within 2D spots that accumulated the most. Regardless of symbiotic status, drought regulation of aquaporins in roots was manifested as the prevalence of complexes that comprise almost exclusively PIP2 monomers. In contrast, the leaf response involved enrichment in PIP1s. PIP1s are thought to enhance water transport, facilitate CO2 diffusion but also affect stomatal movements. These features, together with elevated aquaporin levels, might explain a stress tolerance mechanism observed in mycorrhizal plants, resulting in faster recovery of stomatal water conductance and CO2 assimilation rate after drought. [ABSTRACT FROM AUTHOR]

Summary: Mycorrhizal associations are key mutualisms that shape the structure of forest communities and multiple ecosystem functions. However, we lack a framework for predicting the varying dominance of distinct mycorrhizal associations in an integrated proxy of multifunctionality across ecosystems.Here, we used the datasets containing diversity of mycorrhizal associations and 18 ecosystem processes related to supporting, provisioning, and regulating services to examine how the dominance of ectomycorrhiza (EcM) associations affects ecosystem multifunctionality in subtropical mountain forests in Southwest China. Meanwhile, we synthesized the prevalence of EcM‐dominant effects on ecosystem functioning in forest biomes.Our results demonstrated that elevation significantly modified the distributions of EcM trees and fungal dominance, which in turn influenced multiple functions simultaneously. Multifunctionality increased with increasing proportion of EcM associations, supporting the ectomycorrhizal‐dominance hypothesis. Meanwhile, we observed that the impacts of EcM dominance on individual ecosystem functions exhibited different relationships among forest biomes.Our findings highlight the importance of ectomycorrhizal dominance in regulating multifunctionality in subtropical forests. However, this ectomycorrhizal feedback in shaping ecosystem functions cannot necessarily be generalized across forests. Therefore, we argue that the predictions for ecosystem multifunctionality in response to the shifts of mycorrhizal composition could vary across space and time. [ABSTRACT FROM AUTHOR]

Plant‐mycorrhizal type has been suggested as an integrator of plant functional traits, yet most of what is known about these relationships comes from studies of different plant taxa, where the effects of mycorrhizal type cannot be isolated. In addition to affecting carbon‐nutrient exchanges, plants that associate with distinct mycorrhizal types often differ in several traits, with consequences for myriad below‐ground processes.We used two common gardens planted with Populus fremontii, a tree species that can simultaneously associate with both arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) fungi, to examine the degree to which mycorrhizal‐type dominance influences root traits and trait relationships across the root economic space.While P. fremontii formed AM and ECM associations simultaneously, individuals displayed a dominant mycorrhizal type driven primarily by garden location. Trees in the low‐elevation garden, regardless of provenance, were colonized primarily by AM fungi, whereas trees in the high‐elevation garden were colonized primarily by ECM fungi. In root systems at the low‐elevation garden, AM colonization rates were negatively related to specific root length indicating trade‐off with investment in foraging roots. In contrast, root systems at the high‐elevation garden, ECM colonization was negatively related to root tissue density, demonstrating a potential trade‐off between resource acquisition and root growth/defence. All other root economic traits remained similar between mycorrhizal types.While root traits varied little between AM‐ and ECM‐dominated trees (and gardens), their relationships with one another differed in each garden, suggesting unique strategies and trait trade‐offs in a single species. As global change continues to alter environments, species like P. fremontii, which experience a range of abiotic conditions, could signal how other tree species might modify root traits and strategies in response. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

The REQUIRED FOR ARBUSCULAR MYCORRHIZATION1 (RAM1) transcription factor from the GRAS family is well known for its role as a master regulator of the arbuscular mycorrhizal (AM) symbiosis in dicotyledonous and monocotyledonous species, being essential in transcriptional reprogramming for the development and functionality of the arbuscules. In tomato, SlGRAS27 is the putative orthologue of RAM1 (here named SlRAM1), but has not yet been characterized. A reduced colonization of the root and impaired arbuscule formation were observed in SlRAM1 -silenced plants, confirming the functional conservation of the RAM1 orthologue in tomato. However, unexpectedly, SlRAM1 -overexpressing (UBIL:SlRAM1) plants also showed decreased mycorrhizal colonization. Analysis of non-mycorrhizal UBIL:SlRAM1 roots revealed an overall regulation of AM-related genes and a reduction of strigolactone biosynthesis. Moreover, external application of the strigolactone analogue GR244DO almost completely reversed the negative effects of SlRAM1 overexpression on the frequency of mycorrhization. However, it only partially recovered the pattern of arbuscule distribution observed in control plants. Our results strongly suggest that SlRAM1 has a dual regulatory role during mycorrhization and, in addition to its recognized action as a positive regulator of arbuscule development, it is also involved in different mechanisms for the negative regulation of mycorrhization, including the repression of strigolactone biosynthesis. [ABSTRACT FROM AUTHOR]

Rocky habitats, globally distributed ecosystems, harbour diverse biota, including numerous endemic and endangered species. Vascular plants thriving in these environments face challenging abiotic conditions, requiring diverse morphological and physiological adaptations. Their engagement with the surrounding microbiomes is, however, equally vital for their adaptation, fitness, and long‐term survival. Nevertheless, there remains a lack of understanding surrounding this complex interplay within this fascinating biotic ecosystem. Using microscopic observations and metabarcoding analyses, we examined the fungal abundance and diversity in the root system of the rock‐dwelling West Carpathian endemic shrub, Daphne arbuscula (Thymelaeaceae). We explored the diversification of root‐associated fungal communities in relation to microclimatic variations across the studied sites. We revealed extensive colonization of the Daphne roots by diverse taxonomic fungal groups attributed to different ecological guilds, predominantly plant pathogens, dark septate endophytes (DSE), and arbuscular mycorrhizal fungi (AMF). Notably, differences in taxonomic composition and ecological guilds emerged between colder and warmer microenvironments. Apart from omnipresent AMF, warmer sites exhibited a prevalence of plant pathogens, while colder sites were characterized by a dominance of DSE. This mycobiome diversification, most likely triggered by the environment, suggests that D. arbuscula populations in warmer areas may be more vulnerable to fungal diseases, particularly in the context of global climate change. [ABSTRACT FROM AUTHOR]

Exploring the responses of carbon component accumulation and allocation to arbuscular mycocorrhizal fungi ( AM) and earthworm inoculation can provide reference for improving carbon sequestration potential and bioremediation efficiency in rocky desertification soils. In this study, we chose Fraxinus malacophylla as the host plant to inoculate with Funneliformis mosseae (FM), earthworm (E), and E+FM, using no earthworm and mycor-rhizae addition as CK to examine the spatiotemporal variations in soil carbon components (i.e., total organic carbon, microbial biomass carbon, easily oxidized organic carbon, and recalcitrant organic carbon) and their allocation (i.e., microbial biomass carbon/total organic carbon, easily oxidized organic carbon/total organic carbon, and recalcitrant organic carbon/total organic carbon). The results showed that 1) The respective and interactive inoculation of E and AM significantly promoted the accumulation of each carbon component. In contrast with the control, the average carbon component levels under three inoculation treatments were ranked as E + FM>E>FM. The three inoculation treatments significantly promoted soil microbial carbon/total organic carbon ( 30.5%-68.5%) and easily oxidized carbon/total organic carbon (31.2%-39.2%), but decreased recalcitrant organic carbon/total organic carbon ( 2.9% -16.2%). 2) The spatiotemporal variation in accumulation and allocation of soil carbon components varied between the inoculation treatments. The maximum value of each carbon component occurred in June. The increase in each carbon component was significantly higher in E+FM ( 33.0%-122.1%) than that in E (31.2%-95.4%) and FM (9.2%-41.3%). The maximum value of microbial biomass carbon/total organic carbon and easily oxidized organic carbon/total organic carbon was observed in June, while that of recalcitrant organic carbon/total organic carbon was recorded in December. In contrast with CK, the amplitude of variation in the proportion of carbon components in total organic carbon under the three inoculation treatments was ranked as E + FM>E>FM. The accumulation and allocation of all carbon components decreased (9.7%-146.2%) along the soil profile. The level of carbon components in the E treatment decreased the smallest. The microbial biomass carbon/total organic carbon and easily oxidized carbon/total organic carbon decreased the least and the recalcitrant organic carbon/total organic carbon decreased the greatest under the E+FM treatment. 3) Changes in soil physicochemical properties under the three inoculation treatments significantly affected the accumulation and allocation of organic carbon components. Soil pH was negatively correlated with carbon component accumulation and allocation, whereas other soil variables were positively correlated with them. 4) The results of principal component analysis showed that soil water content, total nitrogen, and total phosphorus were the main factors driving carbon component accumulation, while soil water content, total phosphorus, and pH were the main factors controlling carbon component allocation. Therefore, we concluded that the earthworms, AM fungi and their interaction affected the accumulation and allocation of carbon components in Yunnan rocky desertification soils, which would primarily depend on the changes of soil water content, acid-base property, as well as nitrogen and phosphorus conditions. [ABSTRACT FROM AUTHOR]

Abstract The systemic coordination of accumulation of plasma membrane aquaporins (PIP) was investigated in this study in relation to mycorrhized maize response to a rapid development of severe drought followed by rewatering. In non-mycorrhizal roots, drought led to a drop in PIP abundance, followed by a transient increase under rewatering, whereas leaves showed an opposite pattern. In contrast, mycorrhiza contributed to maintenance of high and stable levels of PIPs in both plant organs after an initial increase, prolonged over the irrigation period. Isoelectric focusing electrophoresis resolved up to 13 aquaporin complexes with highly reproducible pl positions across leaf and root samples, symbiotic and non-symbiotic, stressed or not. Mass spectrometry recognized in leaves and roots a different ratio of PIP1 and PIP2 subunits within 2D spots that accumulated the most. Regardless of symbiotic status, drought regulation of aquaporins in roots was manifested as the prevalence of complexes that comprise almost exclusively PIP2 monomers. In contrast, the leaf response involved enrichment in PIP1s. PIP1s are thought to enhance water transport, facilitate CO2 diffusion but also affect stomatal movements. These features, together with elevated aquaporin levels, might explain a stress tolerance mechanism observed in mycorrhizal plants, resulting in faster recovery of stomatal water conductance and CO2 assimilation rate after drought.

Large quantities of cover crop residues in the soil, combined, or not, with the inoculation of seeds with diazotrophic bacteria, can increase organic matter (OM) and protect soil microorganisms, such as arbuscular mycorrhizal fungi (AMF) and dark septate endophytic (DSE) fungi. Thus, the use of these sustainable biotechnologies can benefit microbial interactions, soil fertility and rice production in the Brazilian Cerrado region. In this study, we evaluated the effects of maize and Urochloa ruziziensis, intercropped or individually, as cover crops and an inoculation of Azospirillum brasilense on the chemical (fertility) and biological (C–microbial biomass and C–CO2 released) attributes of soil and the effects of root colonization by AMF and DSE on the yield of rice grown in succession in highlands. The experiment was conducted under field conditions, in a typical dystrophic Red Oxisol. The experimental design consisted of randomized blocks arranged in strips, incorporating a combination of eight residual cover crops: ((1) maize, (2) maize–I (I = inoculation of seeds with A. brasilense), (3) Urochloa (U. ruziziensis), (4) Urochloa–I, (5) maize + Urochloa–I, (6) maize + Urochloa–I, (7) maize–I + Urochloa and (8) maize–I + Urochloa–I). This was accompanied by two treatments of rice as a successor crop (inoculated or not with A. brasilense), with four replicates, totaling 64 experimental units. A cover crop and rice seed inoculation prompted increases in OM and AMF relative to DSE, while the inoculation of rice, regardless of the cover crop treatment, increased the soil’s P content. The combination of maize + Urochloa–I and inoculated rice as the next crop generated increases in its sum of bases (SBs) and cation exchange capacity (CEC). There was a 19% increase in rice grain yields when the seed was inoculated.

Lettuce is one of our most important leaf vegetables that can be cultivated safely in organic farming, which is not only pesticide-free, but also aims to maintain and stimulate the presence of naturally occurring beneficial organisms, such as algae, mosses, bacteria, or arbuscular mycorrhiza (AM) fungi. These organisms are all beneficial for soil life and nutrient decomposition. The positive effects of beneficial microorganisms could be enhanced by mulching which is a widely used practice in organic farming. Mulching may also increase soil nutrient substance after decomposition and inhibit weed growth. In our experiment, we sought to determine the effect of different mulching techniques (alfalfa, rye, black foil) on AM root colonisation, leaf chlorophyll (Chl) content, and on peroxidase (POD) activity in Lactuca sativa plants and observe whether there are correlations between these parameters. Results show natural mulching has a positive effect on mycorrhiza fungi root colonisation and therefore lowers the stress in lettuce plant. On the other hand, there was no significant correlation between root colonisation and Chl content. As POD enzymes are directly linked to enzymatic browning, the high colonisation rate of AM may consequently lower post-harvest browning in lettuce.

Here we report the effect of Rhizophagus irregularis on maize leaf expression of six plasma membrane aquaporin isoforms from PIP1 and PIP2 subfamilies under severe drought development and recovery. The novelty of our study is the finding that leaf-specific mycorrhizal regulation of aquaporins is dependent on the position of the leaf on the shoot and changes in parallel with the rate of photosynthesis and the stomatal response to drought. The transcripts were isolated from the upper third (L3) or ear (L5) leaf, which differed greatly in physiological response to stress within each symbiotic variant. Aquaporins expression in upper L3 leaves appeared to be largely not sensitive to drought, regardless of symbiotic status. In contrast, L5 leaf of nonmycorrhizal plants, showed strong down-regulation of all PIPs. Mycorrhiza, however, protected L5 leaf from such limitation, which under maximal stress was manifested by 6-fold and circa 4-fold higher transcripts level for PIP1s and PIP2s, respectively. Distinct expression patterns of L3 and L5 leaves corresponded to differences in key parameters of leaf homeostasis - stomatal conductance, photosynthetic rates, and accumulation of ABA and SA as phytohormonal indicators of drought stress. In result symbiotic plants showed faster restoration of photosynthetic capability, regardless of leaf position, which we recognize as the hallmark of better stress tolerance. In summary, arbuscular mycorrhiza alleviates short-term drought effects on maize by preventing the down-regulation of plasma membrane aquaporins within middle leaves, thereby affecting stomatal conductance. [ABSTRACT FROM AUTHOR]

Societal Impact Statement Summary The discovery of a new genus within the family Thismiaceae, known as fairy lanterns, marks a significant scientific milestone in Japan, a country renowned for its botanical research. The unearthing of a new genus, especially in a well‐documented flora like Japan, is both rare and monumental. Unlike other fairy lanterns that bloom under leaf litter and can be easily overlooked, the new genus and species, Relictithismia kimotsukiensis, often does not even emerge above the surface of the soil when flowering. This captivating characteristic not only enriches our knowledge of botanical diversity but also emphasizes the importance of preserving natural habitats that harbor such rare species.The family Thismiaceae, known as “fairy lanterns”, is distinguished by its urn‐ or bell‐shaped, glasswork‐like flowers with basally fused tepals and its dependence on specific fungi for carbon. A new genus and species, Relictithismia kimotsukiensis, has been discovered in southern Japan. This species is notable for its unique anther‐stigma contact, hitherto unreported in the other Thismiaceae. Unlike typical fairy lanterns that bloom just above the leaf litter, Relictithismia often flowers beneath it. The underground habit is potentially associated with self‐pollination. The discovery of Relictithismia enhances our understanding of evolutionary pathways within the Thismiaceae, as it possesses characteristics previously thought to be unique to Thismia (the annulus with drooping stamens) as well as traits found in other genera (free stamens without expanded connectives). This paper reviews the morphology, ecology, and evolutionary history of Relictithismia, offering insights into the peculiarities of these enigmatic plants. [ABSTRACT FROM AUTHOR]

We assessed the impact of road disturbances on the dominant mycorrhizal types in ecosystems at the global level and how this mechanism can potentially lead to lasting plant community changes. We used a database of coordinated plant community surveys following mountain roads from 894 plots in 11 mountain regions across the globe in combination with an existing database of mycorrhizal–plant associations in order to approximate the relative abundance of mycorrhizal types in natural and disturbed environments. Our findings show that roadside disturbance promotes the cover of plants associated with arbuscular mycorrhizal (AM) fungi. This effect is especially strong in colder mountain environments and in mountain regions where plant communities are dominated by ectomycorrhizal (EcM) or ericoid‐mycorrhizal (ErM) associations. Furthermore, non‐native plant species, which we confirmed to be mostly AM plants, are more successful in environments dominated by AM associations. These biogeographical patterns suggest that changes in mycorrhizal types could be a crucial factor in the worldwide impact of anthropogenic disturbances on mountain ecosystems. Indeed, roadsides foster AM‐dominated systems, where AM‐fungi might aid AM‐associated plant species while potentially reducing the biotic resistance against invasive non‐native species, often also associated with AM networks. Restoration efforts in mountain ecosystems will have to contend with changes in the fundamental make‐up of EcM‐ and ErM plant communities induced by roadside disturbance. [ABSTRACT FROM AUTHOR]

Establishment of arbuscular mycorrhiza relies on a plant signaling pathway that can be activated by fungal chitinic signals such as short-chain chitooligosaccharides and lipo-chitooligosaccharides (LCOs). The tomato LysM receptor-like kinase SlLYK10 has high affinity for LCOs and is involved in root colonization by arbuscular mycorrhizal fungi (AMF); however, its role in LCO responses has not yet been studied. Here, we show that SlLYK10 proteins produced by the Sllyk10-1 and Sllyk10-2 mutant alleles, which both cause decreases in AMF colonization and carry mutations in LysM1 and 2, respectively, have similar LCO-binding affinities compared to the WT SlLYK10. However, the mutant forms were no longer able to induce cell death in Nicotiana benthamiana when co-expressed with MtLYK3, a Medicago truncatula LCO co-receptor, while they physically interacted with MtLYK3 in co-purification experiments. This suggests that the LysM mutations affect the ability of SlLYK10 to trigger signaling through a potential co-receptor rather than its ability to bind LCOs. Interestingly, tomato lines that contain a calcium (Ca2+) concentration reporter [genetically encoded Ca2+ indicators (GECO)], showed Ca2+ spiking in response to LCO applications, but this occurred only in inner cell layers of the roots, while short-chain chitooligosaccharides also induced Ca2+ spiking in the epidermis. Moreover, LCO-induced Ca2+ spiking was decreased in Sllyk10-1 * GECO plants, suggesting that the decrease in AMF colonization in Sllyk10-1 is due to abnormal LCO signaling. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal fungi can impact the host’s response to various environmental challenges, including lead (Pb) stress. Consequently, an investigation was set up to evaluate how the inoculation of Funneliformis mosseae (F.mosseae; FM) impacts the defense mechanisms in cotton plants subjected to Pb (1000 mg/kg) stress. The Pb treatment resulted in a substantial rise in Pb accumulation in both the roots and leaves. This led to elevated levels of methylglyoxal and hydrogen peroxide in the cotton leaves, accompanied by an increase in malondialdehyde content, ion leakage, and a reduction in photosynthetic pigments. The alterations were linked to a decline in photosynthetic performance and overall plant growth. Nevertheless, inoculation with the F. mosseae fungus resulted in the enhancement of photosynthetic pigment contents and the upregulation of Rubisco S and Rubisco L subunits, contributing to the protection of photosynthetic processes in stressed plants. Furthermore, this symbiotic fungus, through reducing Pb absorption and inducing increased activity of antioxidant and glyoxalase enzymes, led to the reduction of hydrogen peroxide and methylglyoxal levels while safeguarding membrane integrity under Pb stress. Plants inoculated with F. mosseae exhibited higher levels of metal-sequestering organic compounds, including glutathione and phytochelatins, in both roots and leaves, indicating their protective role in sequestering Pb from leaf tissues against Pb toxicity. This symbiosis also made photosynthetic organs more resistant to Pb toxicity by changing the metabolism of polyamines and making more spermidine and spermine levels in the leaves. Our research provides a theoretical foundation for the remediation of the symbiotic relationship between F. mosseae and cotton in environments contaminated with lead. [ABSTRACT FROM AUTHOR]

Summary: The cell wall is the major interface for arbuscular mycorrhizal (AM) symbiosis. However, the roles of cell wall proteins and cell wall synthesis in AM symbiosis remain unclear. We reported that a novel wall‐associated kinase 13 (GhWAK13) positively regulates AM symbiosis and negatively regulates Verticillium wilt resistance in cotton.GhWAK13 transcription was induced by AM symbiosis and Verticillium dahliae (VD) infection. GhWAK13 is located in the plasma membrane and expressed in the arbuscule‐containing cortical cells of mycorrhizal cotton roots.GhWAK13 silencing inhibited AM colonization and repressed gene expression of the mycorrhizal pathway. Moreover, GhWAK13 silencing improved Verticillium wilt resistance and triggered the expression of immunity genes. Therefore, GhWAK13 is considered an immune suppressor required for AM symbiosis and disease resistance. GhWAK7A, a positive regulator of Verticillium wilt resistance, was upregulated in GhWAK13‐silenced cotton plants. Silencing GhWAK7A improved AM symbiosis. Oligogalacturonides application also suppressed AM symbiosis. Finally, GhWAK13 negatively affected the cellulose content by regulating the transcription of cellulose synthase genes.The results of this study suggest that immunity suppresses AM symbiosis in cotton. GhWAK13 affects AM symbiosis by suppressing immune responses. See also the Commentary on this article by Giovanetti & Genre, 242: 1851–1853. [ABSTRACT FROM AUTHOR]

Large quantities of cover crop residues in the soil, combined, or not, with the inoculation of seeds with diazotrophic bacteria, can increase organic matter (OM) and protect soil microorganisms, such as arbuscular mycorrhizal fungi (AMF) and dark septate endophytic (DSE) fungi. Thus, the use of these sustainable biotechnologies can benefit microbial interactions, soil fertility and rice production in the Brazilian Cerrado region. In this study, we evaluated the effects of maize and Urochloa ruziziensis, intercropped or individually, as cover crops and an inoculation of Azospirillum brasilense on the chemical (fertility) and biological (C–microbial biomass and C–CO2 released) attributes of soil and the effects of root colonization by AMF and DSE on the yield of rice grown in succession in highlands. The experiment was conducted under field conditions, in a typical dystrophic Red Oxisol. The experimental design consisted of randomized blocks arranged in strips, incorporating a combination of eight residual cover crops: ((1) maize, (2) maize–I (I = inoculation of seeds with A. brasilense), (3) Urochloa (U. ruziziensis), (4) Urochloa–I, (5) maize + Urochloa–I, (6) maize + Urochloa–I, (7) maize–I + Urochloa and (8) maize–I + Urochloa–I). This was accompanied by two treatments of rice as a successor crop (inoculated or not with A. brasilense), with four replicates, totaling 64 experimental units. A cover crop and rice seed inoculation prompted increases in OM and AMF relative to DSE, while the inoculation of rice, regardless of the cover crop treatment, increased the soil's P content. The combination of maize + Urochloa–I and inoculated rice as the next crop generated increases in its sum of bases (SBs) and cation exchange capacity (CEC). There was a 19% increase in rice grain yields when the seed was inoculated. [ABSTRACT FROM AUTHOR]

The health of soil is paramount for sustaining life, as it hosts diverse communities of microorganisms that interact with plants, influencing their growth, health, and resilience. Beneficial microorganisms, including fungi and bacteria, form symbiotic relationships with plants, providing essential nutrients, promoting growth, and enhancing stress tolerance. These microorganisms, such as mycorrhizal fungi and plant growth-promoting bacteria, play crucial roles in nutrient cycling, soil health, and plant productivity. Additionally, they help lessen reliance on chemical fertilizers, thereby mitigating the environmental risks associated with their use. Advances in agricultural practices harness the potential of these beneficial microorganisms to improve crop yields while minimizing the environmental impact. However, challenges such as competition with indigenous microbial strains and environmental factors limit the universal utilization of microbial inoculants. Despite these challenges, understanding and leveraging the interactions between plants and beneficial microorganisms hold promise for sustainable agriculture and enhanced food security. [ABSTRACT FROM AUTHOR]

Taxus, a genus of conifers known for its medicinal significance, faces various conservation challenges with several species classified under different threat categories by the IUCN. The overharvesting of bark and leaves for the well-known chemotherapy drug paclitaxel has resulted in its population decline. Exploring the mycorrhizal relationship in Taxus is of utmost importance, as mycorrhizal fungi play pivotal roles in nutrition, growth, and ecological resilience. Taxus predominantly associates with arbuscular mycorrhizal fungi (AM), and reports suggest ectomycorrhizal (EM) or dual mycorrhizal associations as well. This review consolidates existing literature on mycorrhizal associations in Taxus species, focusing on structural, physiological, and molecular aspects. AM associations are well-documented in Taxus, influencing plant physiology and propagation. Conversely, EM associations remain relatively understudied, with limited evidence suggesting their occurrence. The review highlights the importance of further research to elucidate dual mycorrhizal associations in Taxus, emphasizing the need for detailed structural and physiological examinations to understand their impact on growth and survival. [ABSTRACT FROM AUTHOR]

Summary Phosphate starvation response (PHR) transcription factors play essential roles in regulating phosphate uptake in plants through binding to the P1BS cis‐element in the promoter of phosphate starvation response genes. Recently, PHRs were also shown to positively regulate arbuscular mycorrhizal colonization in rice and lotus by controlling the expression of many symbiotic genes. However, their role in arbuscule development has remained unclear. In Medicago, we previously showed that arbuscule degradation is controlled by two SPX proteins that are highly expressed in arbuscule‐containing cells. Since SPX proteins bind to PHRs and repress their activity in a phosphate‐dependent manner, we investigated whether arbuscule maintenance is also regulated by PHR. Here, we show that PHR2 is a major regulator of the phosphate starvation response in Medicago. Knockout of phr2 showed reduced phosphate starvation response, symbiotic gene expression, and fungal colonization levels. However, the arbuscules that formed showed less degradation, suggesting a negative role for PHR2 in arbuscule maintenance. This was supported by the observation that overexpression of PHR2 led to enhanced degradation of arbuscules. Although many arbuscule‐induced genes contain P1BS elements in their promoters, we found that the P1BS cis‐elements in the promoter of the symbiotic phosphate transporter PT4 are not required for arbuscule‐containing cell expression. Since both PHR2 and SPX1/3 negatively affect arbuscule maintenance, our results indicate that they control arbuscule maintenance partly via different mechanisms. While PHR2 potentiates symbiotic gene expression and colonization, its activity in arbuscule‐containing cells needs to be tightly controlled to maintain a successful symbiosis in Medicago. [ABSTRACT FROM AUTHOR]

This article is a Commentary on Giovannetti et al., 241: 1393–1400. [ABSTRACT FROM AUTHOR]

Summary: Phosphorus (P) for carbon (C) exchange is the pivotal function of arbuscular mycorrhiza (AM), but how this exchange varies with soil P availability and among co‐occurring plants in complex communities is still largely unknown.We collected intact plant communities in two regions differing c. 10‐fold in labile inorganic P. After a 2‐month glasshouse incubation, we measured 32P transfer from AM fungi (AMF) to shoots and 13C transfer from shoots to AMF using an AMF‐specific fatty acid. AMF communities were assessed using molecular methods.AMF delivered a larger proportion of total shoot P in communities from high‐P soils despite similar 13C allocation to AMF in roots and soil. Within communities, 13C concentration in AMF was consistently higher in grass than in blanketflower (Gaillardia aristata Pursh) roots, that is P appeared more costly for grasses. This coincided with differences in AMF taxa composition and a trend of more vesicles (storage structures) but fewer arbuscules (exchange structures) in grass roots. Additionally, 32P‐for‐13C exchange ratios increased with soil P for blanketflower but not grasses.Contrary to predictions, AMF transferred proportionally more P to plants in communities from high‐P soils. However, the 32P‐for‐13C exchange differed among co‐occurring plants, suggesting differential regulation of the AM symbiosis. [ABSTRACT FROM AUTHOR]

Summary: Variations in arbuscular mycorrhizae (AM) effects on plant growth (MGR) are commonly assumed to result from cost : benefit balances, with C as the cost and, most frequently, P as the benefit. The trade‐balance model (TBM) adopts these assumptions and hypothesizes that mycorrhizal benefit depends on C : N : P stoichiometry. Although widely accepted, the TBM has not been experimentally tested.We isolated the parameters included in the TBM and tested these assumptions using it as framework. Oryza sativa plants were supplied with different N : P ratios at low light level, establishing different C : P and C : N exchange rates, and C, N or P limitation. MGR and effects on nutrient uptake, %M, ERM, photosynthesis and shoot starch were measured.C distribution to AM fungi played no role in MGR, and N was essential for all AM effects, including on P nutrition. C distribution to AM and MGR varied with the limiting nutrient (N or P), and evidence of extensive interplay between N and P was observed.The TBM was not confirmed. The results agreed with the exchange of surplus resources and source–sink regulation of resource distribution among plants and AMF. Rather than depending on exchange rates, resource exchange may simply obey both symbiont needs, not requiring further regulation. [ABSTRACT FROM AUTHOR]

Summary: Arbuscular (AM) and orchid (OrM) mycorrhiza are the most widespread mycorrhizal symbioses among flowering plants, formed by distinct fungal and plant species. They are both endosymbioses because the fungal hyphae can enter inside the plant cell to develop intracellular fungal structures that are surrounded by the plant membrane. The symbiotic plant–fungus interface is considered to be the major site of nutrient transfer to the host plant. We summarize recent data on nutrient transfer in OrM and compare the development and function of the arbuscules formed in AM and the pelotons formed in OrM in order to outline differences and conserved traits. We further describe the unexpected similarities in the form and function of the intracellular mycorrhizal fungal structures observed in orchids and in the roots of mycoheterotrophic plants forming AM. We speculate that these similarities may be the result of convergent evolution of mycorrhizal types in mycoheterotrophic plants and highlight knowledge gaps and new research directions to explore this scenario. [ABSTRACT FROM AUTHOR]

Aims: Mycorrhizal fungi and microbial community play crucial roles in soil carbon (C) cycling within forest ecosystems. The various types of mycorrhizal fungi have distinct effects on the decomposition of soil organic C, primarily through their interactions with microbial members. However, there is currently a lack of understanding regarding the linkages between mycorrhizal types and microbial properties such as microbial keystone taxa and functions. Methods: In this study, we investigated the impact of converting ECM-dominated forests to AM-dominated forests on bacterial and fungal community composition, keystone taxa and potential functions by high -throughput sequencing. Results: The ECM fungal biomass in broadleaved forest soils showed a decrease of 45.07% compared to Masson pine forest soils. In contrast, the AM fungal biomass increased significantly by 25.57%. Our results demonstrated that the conversion from ECM- to AM-dominated forests enhanced soil organic carbon (SOC), total nitrogen (TN) and fungal diversity. There was no significant change in the microbial composition at the phylum level. Moreover, the conversion significantly altered the properties of microbial co-occurrence networks and the potential function of bacteria and fungi. Correlation analysis revealed close relationships between the relative abundance of microbial keystone taxa and microbial carbon degradation genes, as well as the biomass of mycorrhizal fungi. Conclusions: Our study suggested that the conversion of ECM- to AM-dominated forests altered microbial interaction, keystone taxa and function, which were significantly associated with changes in mycorrhizal fungal biomass and drove the increase in SOC content. [ABSTRACT FROM AUTHOR]

The study of tree species coexistence is crucial to understand the assembly of forest communities. In this context, trees adjust their traits in response to the interactions with other trees and, specifically, as a result of the competition for resources. Further, mycorrhizal fungal diversity and associations are important drivers of ecosystem functioning in forests, but their role as drivers of intraspecific trait variation has been disregarded. Here, we studied intraspecific trait variation of trees in response to tree and mycorrhizal fungal diversity.We sampled 3200 leaves from 640 trees belonging to 10 native, deciduous species in a tree diversity experiment in Central Germany. This experiment relies on the combination of gradients of tree richness and mycorrhizal associations. To handle large amounts of leaf samples, we acquired leaf‐level spectral data and used deep learning to predict values for five leaf traits from the leaf economics spectrum (LES): specific leaf area, leaf dry matter content, carbon to nitrogen ratio, carbon content and phosphorus content. For every tree, we calculated the mean value for every trait and two multi‐trait functional indices (functional richness and functional dispersion) based on values for individual leaves. Finally, we used sequencing‐based data to assess the richness of mycorrhizal fungi associated with the trees.We found that tree and mycorrhizal fungi richness had an effect on different leaf functional traits. Specifically, tree richness positively affected specific leaf area and, additionally, had a negative effect on the functional indicies, which revealed that the phenotypic diversity within the tree crown decreased with tree species richness. In addition, leaf carbon to nitrogen ratio decreased with increasing arbuscular mycorrhizal fungal richness in both arbuscular and ectomycorrhizal tree species. Finally, we did not find differences between arbuscular and ectomycorrhizal trees regarding their location within the LES.Our results suggest that trees modify their strategy in response to local tree diversity, not only by shifting trait values but also by shifting the variability intraindividually. In addition, higher mycorrhizal fungal diversity does not seem to lead to higher complementarity, but instead, tree and mycorrhizal fungi affect different aspects of leaf traits. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Both arbuscular mycorrhizal (AM) fungi and root hairs are crucial in facilitating plant uptake of phosphorus (P), while it is unclear whether and how they respond to varying P supplies. In order to explore how AM fungal colonization and root hair development are affected by substrate P supply, trifoliate orange (Poncirus trifoliata) seedlings were inoculated with AM fungus Rhizophagus intraradices and grown under low, moderate, and high P conditions; then, root hair morphological features and AM fungal colonization were measured. Following 120 days of AM fungal inoculation, root hair density, root hair length, AM fungal colonization rate, arbuscule colonization rate, and AM fungal colonization frequency all increased significantly under P-deficient conditions but decreased under high P conditions. Moreover, the colonization of AM fungi had a major impact on root hair formation by altering the expression of related genes and the growth of epidermal cells. The effect of AM fungi was dependent on P supply levels, as evidenced by the fact that root hair density and length increased at high P levels but decreased at low P levels. As a result, root hairs may serve as a preferential site for AM fungal colonization, and their morphology could influence the early stage of AM symbiosis establishment. [ABSTRACT FROM AUTHOR]

BackgroundArbuscular mycorrhiza (AM) refers to a symbiotic association between plant roots and fungi that enhances the uptake of mineral nutrients from the soil and enables the plant to tolerate abiotic and biotic stresses. Although previously reported RNA-seq analyses have identified large numbers of AM-responsive genes in model plants, such as Solanum lycopersicum L., further studies are underway to comprehensively understand the complex interactions between plant roots and AM, especially in terms of the short- and long-term responses after inoculation.ResultsHerein, we used RNA-seq technology to obtain the transcriptomes of tomato roots inoculated with the fungus Rhizophagus irregularis at 7 and 30 days post inoculation (dpi). Of the 1,019 differentially expressed genes (DEGs) in tomato roots, 635 genes showed differential expressions between mycorrhizal and non-mycorrhizal associations at the two time points. The number of upregulated DEGs far exceeded the number of downregulated ones at 7 dpi, and this difference decreased at 30 dpi. Several notable genes were particularly involved in the plant defense, plant growth and development, ion transport, and biological processes, namely, GABAT, AGP, POD, NQO1, MT4, MTA, and AROGP3. In addition, the Kyoto encyclopedia of genes and genomes pathway enrichment analysis revealed that some of the genes were involved in different pathways, including those of ascorbic acid (AFRR, GME1, and APX), metabolism (CYP, GAPC2, and CAM2), and sterols (CYC1 and HMGR), as well as genes related to cell division and cell cycle (CDKB2 and PCNA).ConclusionThese findings provide valuable new data on AM-responsive genes in tomato roots at both short- and long-term postinoculation stages, enabling the deciphering of biological interactions between tomato roots and symbiotic fungi.

Adaptation to drought of woody and shrubby plants is associated with species features/characteristics and the presence of symbiotic relationships with arbuscular mycorrhiza. There is a wide variety of arbuscular mycorrhiza in nature, the most widespread genera are: Glomus, Diversispora, Paraglomus, Acaulospora, Entrophospora, Gigaspora, Scutellospora. The signaling proteins Hog1, 14-3-3, Ste11 in arbuscular mycorrhiza fungi play an important role in triggering mechanisms of adaptation to stress in the symbiotic relationship "fungus-plant". In this regard, the goal of the work was to evaluate the homology of amino acid sequences of the signaling proteins Hog1, 14-3-3 and Ste11 in different symbiotic mycorrhizal fungi. For the study, their amino acid sequences were taken from the Protein database (NCBI) using the BLAST program, a search for protein homologues was performed, subsequently multiple alignment was performed by the MEGA11 program using the MUSCLE algorithm. Phylogenetic analysis was carried out in the MEGA11 program using the maximum likelihood method. As a result, high conservativity for the Hog1, 14-3-3 proteins and high variability for Ste11 were revealed. The divergence of a pair of homologues of the protein 14-3-3 in Glomeromycotina before the separation of the subphylum and Ste11 in Glomeraceae after the formation of the family was also shown. As a result, we determined that Ste11 is a promising protein of interest for searching for intraspecific variations associated with resistance to drought and other abiotic stress factors in the mushroom-plant system.

This two-year field study aims to investigate the impact of organic pesticides used in organic Damask rose (Rosa damascena Mill.) fields on Arbuscular Mycorrhizal Fungal (AMF) colonization. Conducted in the renowned Rose Valley of Bulgaria, specifically in the village of Kliment, the experiment employed a randomized complete block design with two rows of 21 plants each in organic certified plots. The results revealed low AMF colonization in the first year, ranging between 14.78% and 20.89%, with no significant differences between treatments. In the second year, while no significant differences were observed between treatments (ranging from 48.00% to 76.49%), there was a notable increase in AMF colonization compared to the initial sampling. The study concluded that specific organic pesticides, including Neemazal, Limocide, Phytosev, and Nano sulfur, had minimal negative effects on AMF colonization. These findings contribute to understanding the implications of organic farming practices on AMF and soil health in the context of Damask rose cultivation.

This two-year field study aims to investigate the impact of organic pesticides used in organic Damask rose (Rosa damascena Mill.) fields on Arbuscular Mycorrhizal Fungal (AMF) colonization. Conducted in the renowned Rose Valley of Bulgaria, specifically in the village of Kliment, the experiment employed a randomized complete block design with two rows of 21 plants each in organic certified plots. The results revealed low AMF colonization in the first year, ranging between 14.78% and 20.89%, with no significant differences between treatments. In the second year, while no significant differences were observed between treatments (ranging from 48.00% to 76.49%), there was a notable increase in AMF colonization compared to the initial sampling. The study concluded that specific organic pesticides, including Neemazal, Limocide, Phytosev, and Nano sulfur, had minimal negative effects on AMF colonization. These findings contribute to understanding the implications of organic farming practices on AMF and soil health in the context of Damask rose cultivation. [ABSTRACT FROM AUTHOR]

Accumulation and concentration of contaminants in the soil have long been a byproduct of industrialisation and urbanisation, and which has become a primary environmental concern. Mitigation of soil pollutants using chemical procedures and their long-term application have originated a detrimental impact on all ecosystems. The application of green technologies such as bioremediation to solve environmental risk factors contributes to a long-term preservation of the fauna and flora, ensuring at the same time human health and well-being. Bioremediation refers to naturally occurring or any introduced microorganisms that break down or sequestrate environmental contaminants to clean the soil from pollutants. This review discusses different mechanisms of mycorrhizae related to the soil habitats and the factors affecting their functions in removing contaminants from the soil itself. The mycorrhizae remediate the soil contaminants either by phytoremediation (arbuscular mycorrhizal fungi [AMF]) or degradation (ectomycorrhizae and ericoid mycorrhizae). AMF are involved in remediating the non-degradable pollutants (heavy metals and metalloids), while ectomycorrhizae and ericoid mycorrhizae are preferred to remediate polar and non-polar organic pollutants in soil using mycorrhizal enzymes. The efficiency of the bioremediation depends mainly on factors such as the species of AMF involved, host plant species, type and dose of the contaminants, the methods used in bioremediation, the soil, and environmental conditions. Combining bioremediation with advanced technologies like metagenomics, metatranscriptomics, and metabolomics accelerates the remediation processes that neutralise the environmental toxicity generated through present and future anthropogenic activities. [ABSTRACT FROM AUTHOR]

• Melatonin, a natural signaling compound (hormone) is present in animals, plants, bacteria even in Fungi. • In fungi, it regulates circadian rhythms, growth, development and morphogenesis by maintaining cellular homeostasis. • Melatonin has potential in crop production, mushroom biotechnology and pharmaceutical industry as antioxidant, antimicrobial and anticancer metabolite. • Fungal melatonin has advantageous over animal and plant sources. Melatonin performs a critical part in the reduction of biotic and abiotic stressors of plants, triggering defence systems and pathogen diminutions. As there are lot of reports available on the effects on melatonin on plants and animals, our decision is to focus primarily on fungi. A diverse group of melatonin producer fungi from unicellular Saccharomyces to filamentous Trichoderma , even the advanced basidiomycetous edible mushroom Agaricus, Pleurotus etc. provide an enriched panorama for exploration. This review article is composed of the report about the properties of melatonin, their role on the plant-fungal interactions, covering its effects on fungi from various ecological niche viz. soil/leaf-borne pathogenic fungi, endophytes as well as the fungi occurring in arbuscular mycorrhiza (AM). There were both positive as well as negative impacts of melatonin on the fungal mycelia, primordia, fruiting bodies and spores. The biotechnological applications of melatonin in enhancing abiotic stress responses, signalling pathways, antioxidant and probable secondary metabolite productions and developing biocontrol agents have also been discussed. Melatonin plays an essential role in cultivation of edible mushroom. Melatonin and its homologues also possess anti-cancerous activity and can be used in different therapeutic applications as an anti-fungal, antibacterial, anti-viral, anti-inflammatory and anti-ageing agents. [ABSTRACT FROM AUTHOR]

Mycorrhizal fungi form symbiotic relationships with most terrestrial plants. Soil nutrients affect the mycorrhizal symbiotic formation, further determine plant growth. However, little is known on the role of mycorrhiza in response of host plant growth to nutritional additions in natural ecosystem. A new database was established including the index of plant growth and their mycorrhizal status based on a global database of interactive effects of nitrogen (N) and phosphorus (P) additions on plant growth. We examined effects of mycorrhizal strategy on the responses of plant growth to N or P addition. We found that plant growth was closely related to mycorrhizal strategies. N addition increased 35% aboveground biomass (AGB) of host plants associated with arbuscular mycorrhiza (AM), whereas decreased it by 9% in plants non-associated with AM (nonAM). P addition or NP addition all increased AGB regardless of mycorrhizal type, but the effect of nonAM plants was stronger than that of AM plants. Structural equation modelling (SEM) analysis showed that N addition had an positive effect on leaf N:P ratios through affecting leaf N of AM plants (r = 0.25) and nonAM plants (r = 0.33) whereas P addition had an negative effect on leaf N:P ratios through affecting leaf P of AM plants (r = 0.29) and nonAM plants (r = 0.45). Our results highlighted the biomass production of plants was controlled mainly by P addition and AM increased the accumulation of AGB by promoting plant P uptake. Moreover, AMF have different functions depending on the nutritional conditions, further regulated plant growth. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Henan University of Science & Technology, Natural Science is the property of Editorial Office of Journal of Henan University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Summary: Chitin oligomers (COs) are among the most common and active fungal elicitors of plant responses. Short‐chain COs from symbiotic arbuscular mycorrhizal fungi activate accommodation responses in the host root, while long‐chain COs from pathogenic fungi are acknowledged to trigger defence responses. The modulation of intracellular calcium concentration – a common second messenger in a wide variety of plant signal transduction processes – plays a central role in both signalling pathways with distinct signature features. Nevertheless, mounting evidence suggests that plant immunity and symbiosis signalling partially overlap at multiple levels. Here, we elaborate on recent findings on this topic, highlighting the nonbinary nature of chitin‐based fungal signals, their perception and their interpretation through Ca2+‐mediated intracellular signals. Based on this, we propose that plant perception of symbiotic and pathogenic fungi is less clear‐cut than previously described and involves a more complex scenario in which partially overlapping and blurred signalling mechanisms act upstream of the unambiguous regulation of gene expression driving accommodation or defence responses. [ABSTRACT FROM AUTHOR]

Copyright of Forest Research is the property of Forest Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Cr (VI) hampers plant growth and yield by reducing essential nutrient uptake as it competes for phosphate and sulfate transporters. Nitric oxide (NO) and mycorrhization play important roles in mitigating Cr (VI) toxicity. Present study aimed to compare the potential of AMF (Arbuscular mycorrhizal fungi)-Rhizoglomusintraradices and NO (0.25 mM) in alleviating Cr (VI) stress (0, 10 and 20 mg/kg) in two differentially tolerant pigeonpea genotypes (Pusa 2001 and AL 201). Cr (VI) toxicity reduced growth, mycorrhizal colonization, nutrient uptake, and overall productivity by inducing reactive oxygen species (ROS) generation, with AL 201 more sensitive than Pusa 2001. NO and AM enhanced activities of soil enzymes, thereby increasing nutrients availability as well as their uptake, with AM more effective than NO. Both amendments reduced oxidative stress and restricted Cr (VI) uptake by increasing the activities of antioxidant and S- assimilatory enzymes, with Pusa 2001 more responsive than AL 201. NO was relatively more efficient in regulating cysteine-H2S system by increasing the activities of biosynthetic enzymes (ATP-sulfurylase (ATPS), O-acetylserine thiol lyase (OASTL), D-cysteine desulfhydrase (DCD) and L-cysteine desulfhydrase (LCD), while AM significantly increased glutathione reductase (GR), γ-glutamylcysteine synthetase (γ-ECS) enzymes activities and resultant glutathione (GSH), phytochelatins (PCs), and non-protein thiols (NP-SH) synthesis. Moreover, co-application of NO and AM proved to be highly beneficial in negating the toxic effects of Cr (VI) due to functional complementarity between them. Study suggested the combined use of NO and AM as a useful strategy in re-establishing pigeonpea plants growing in Cr (VI)-stressed environments. [ABSTRACT FROM AUTHOR]

This article is a Commentary on Zhang et al. (2024), 242: 2180–2194. [ABSTRACT FROM AUTHOR]

Mycorrhizal symbiosis, the mutually beneficial association between plants and fungi, has gained significant attention in recent years due to its widespread significance in agricultural productivity. Specifically, arbuscular mycorrhizal fungi (AMF) provide a range of benefits to grain and oil crops, including improved nutrient uptake, growth, and resistance to (a)biotic stressors. Harnessing this symbiotic interaction using molecular and systems biology approaches presents promising opportunities for sustainable and economically-viable agricultural practices. Research in this area aims to identify and manipulate specific genes and pathways involved in the symbiotic interaction, leading to improved cereal and oilseed crop yields and nutrient acquisition. This review provides an overview of the research frontier on utilizing molecular and systems biology approaches for harnessing the symbiotic interaction in mycorrhizal symbiosis for grain and oil crop cultivation. Moreover, we address the mechanistic insights and molecular determinants underpinning this exchange. We conclude with an overview of current efforts to harness mycorrhizal diversity to improve cereal and oilseed health through systems biology. [ABSTRACT FROM AUTHOR]

Insect herbivory may influence arbuscular mycorrhizal (AM) fungal colonisation by changing plant chemistry, and these effects can vary from negative to positive. Yet the underlying mechanisms are unclear.We investigated AM fungal colonization of Chinese tallow tree (Triadica sebifera) after exposing its seedlings to four different foliar‐feeding insects at two levels of herbivory. We then examined the potential role of induced carbon allocation and secondary metabolites, particularly flavonoids, in AM fungal colonization.Light herbivory (ca. 10% leaf area removed) promoted early colonization by AM fungi whereas heavy herbivory (ca. 60% leaf area removed) decreased it. Root flavonoids were increased (in the short‐term) under light herbivory but decreased under heavy herbivory. Further, herbivore‐induced changes to root flavonoids were positively correlated with those of AM fungal colonisation. Moreover, quercitrin, one of the root‐secreted flavonoids, could mediate these AM fungal responses. Surprisingly, however, AM fungal colonization was not correlated with herbivore‐induced carbon allocation in roots or root exudates.We show that AM fungal responses to insect herbivory are at least partially flavonoid‐based and depend on herbivory intensity. Our work highlights the importance of secondary metabolites rather than carbon allocation in interactions between above‐ground herbivory and below‐ground mycorrhiza. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Nitrogen (N) deposition increases soil carbon (C) storage by reducing microbial activity. These effects vary in soil beneath trees that associate with arbuscular (AM) and ectomycorrhizal (ECM) fungi. Variation in carbon C and N uptake traits among microbes may explain differences in soil nutrient cycling between mycorrhizal associations in response to high N loads, a mechanism not previously examined due to methodological limitations. Here, we used quantitative Stable Isotope Probing (qSIP) to measure bacterial C and N assimilation rates from an added organic compound, which we conceptualize as functional traits. As such, we applied a trait‐based approach to explore whether variation in assimilation rates of bacterial taxa can inform shifts in soil function under chronic N deposition. We show taxon‐specific and community‐wide declines of bacterial C and N uptake under chronic N deposition in both AM and ECM soils. N deposition‐induced reductions in microbial activity were mirrored by declines in soil organic matter mineralization rates in AM but not ECM soils. Our findings suggest C and N uptake traits of bacterial communities can predict C cycling feedbacks to N deposition in AM soils, but additional data, for instance on the traits of fungi, may be needed to connect microbial traits with soil C and N cycling in ECM systems. Our study also highlights the potential of employing qSIP in conjunction with trait‐based analytical approaches to inform how ecological processes of microbial communities influence soil functioning. [ABSTRACT FROM AUTHOR]