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Tomato (Solanum lycopersicum), an economically important vegetable crop cultivated worldwide, often suffers massive financial losses due to Phytophthora infestans (P. infestans) spread and breakouts. Arbuscular mycorrhiza (AM) fungi mediated biocontrol has demonstrated great potential in plant resistance. However, little information is available on the regulation of mycorrhizal tomato resistance against P. infestans. Therefore, microRNAs (miRNAs) sequencing technology was used to analyse miRNA and their targets in the mycorrhizal tomato after P. infestans infection. Our study showed a lower severity of necrotic lesions in mycorrhizal tomato than in nonmycorrhizal controls. We investigated 35 miRNAs that showed the opposite expression tendency in mycorrhizal and nonmycorrhizal tomato after P. infestans infection when compared with uninfected P. infestans. Among them, miR319c was upregulated in mycorrhizal tomato leaves after pathogen infection. Overexpression of miR319c or silencing of its target gene (TCP1) increased tomato resistance to P. infestans, implying that miR319c acts as a positive regulator in tomato after pathogen infection. Additionally, we examined the induced expression patterns of miR319c and TCP1 in tomato plants exposed to salicylic acid (SA) treatment, and SA content and the expression levels of SA-related genes were also measured in overexpressing transgenic plants. The result revealed that miR319c can not only participates in tomato resistance to P. infestans by regulating SA content, but also indirectly regulates the expression levels of key genes in the SA pathway by regulating TCP1. In this study, we propose a novel mechanism in which the miR319c in mycorrhizal tomato increases resistance to P. infestans. [ABSTRACT FROM AUTHOR]

Okra (Abelmochus esculentus L. Moench) has a fairly high nutritional content; every 10 gr of young okra fruit contains 33 calories, 7 gs of carbohydrates, 3.2 gs of fiber, and 81 mg calcium. Okra fruit contains a lot of mucilage due to its high fiber content. This study aimed to determine the effect of rock phosphate doses and types of mycorrhizae and the interaction between these two factors on the growth and yield of okra in saline soil. The research results showed that the dose of mycorrhiza had a very significant effect on the growth and yield of okra plants. The best dose of mycorrhiza was 10 g/plant, and the best type was Acauluspora. It showed that a dose of 10 g/plant with the Acauluspora type on okra yields on Ultiisol soil had given the best results in the vegetative phase, which could be seen in plant height parameters 15 and 30 ADP. The dose of rock phosphate is 150 g, which can be seen in the 300 g planting parameter and in almost all the observed variables. Hyphae in the soil can spread widely, which helps absorb more water. The best yields of okra plants were found by applying a mycorrhizal dose of 10 g on fruit weight variables of plants' mycorrhizal colonization on vase vegetative roots and mycorrhizal colonization on plant roots in the generative phase. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal fungi (AMF) play a crucial role in regulating the allocation of carbon between source and sink tissues in plants and in regulating their stress responses by changing the sucrose biosynthesis, transportation, and catabolism in plants. Invertase, a key enzyme for plant development, participates in the response of plants to drought stress by regulating sucrose metabolism. However, the detailed mechanisms by which INV genes respond to drought stress in mycorrhizal plants remain unclear. This study examined the sugar content, enzyme activity, and expression profiles of INV genes of Populus simonii × P. nigra (PsnINVs) under two inoculation treatments (inoculation or non‐inoculation) and two water conditions (well‐watered or drought stress). Results showed that under drought stress, AMF up‐regulated the expressions of PsnA/NINV1, PsnA/NINV2, PsnA/NINV3, and PsnA/NINV5 in leaves, which may be related to the enhancement of photosynthetic capacity. Additionally, AMF up‐regulated the expressions of PsnA/NINV6, PsnA/NINV10, and PsnA/NINV12 in leaves, which may be related to enhancing osmotic regulation ability and drought tolerance. [ABSTRACT FROM AUTHOR]

Using integrated pest management without relying on chemical pesticides is one of the most attractive approaches to controlling plant pathogens. Among them, using resistant cultivars or rootstocks against diseases in combination with beneficial microorganisms has attracted special attention. The citrus nematode is one of the major constraints of citrus cultivation worldwide. We showed that the mycorrhizal arbuscular fungus, Funneliformis mosseae , increased growth parameters including shoot and root length and biomass of two main rootstocks of citrus, sour orange and Volkamer lemon, in noninfected and infected plants with citrus nematode. It decreased the infection rate by citrus nematode in both rootstocks compared with nonmycorrhizal plants. The rate of decrease in nematode infection was highest when plants were pre-inoculated with F. mosseae and was lowest when nematode was inoculated before F. mosseae. However, when nematode was inoculated before the fungus, the fungus was still able to mitigate the negative effect of infection by nematode compared with plants inoculated with nematode only. This suggests that the timing of inoculation plays a crucial role in the effectiveness of F. mosseae in reducing nematode infection. Moreover, monitoring of the expression of two genes, phenylalanine ammonia-lyase and β -1,3-glucanase , which are involved in systemic-acquired resistance (SAR) showed that although they were significantly upregulated in mycorrhizal plants compared with nonmycorrhizal plants, they showed the highest expression when plants were pretreated with fungus before nematode inoculation, thus, indicating that plants were primed. In summary, F. mosseae primes the defense-related genes involved in SAR, increasing plant defensive capacity and boosting growth parameters in citrus rootstock. This has important implications for the agricultural industry. [ABSTRACT FROM AUTHOR]

The interaction between woody plants and mycorrhizal fungi is an important biological interaction; however, the driving factors behind the diversity of mycorrhizal trees formed through the symbiosis of mycorrhizal fungi and woody plants remain unclear. In this study, we collected and compiled the woody plant data of 34 forest dynamic plots containing 3350 species from habitats around the world and divided them into AM and EcM trees. We tested the contribution of AM and EcM trees to tree diversity and its components in forest communities worldwide. Our results showed that AM trees rather than EcM trees affect the tree diversity of forest communities, and that the diversity of AM trees has a significant latitudinal gradient pattern. Climate variables, especially temperature, are strongly correlated with the diversity patterns for AM trees rather than EcM trees. Topography is the most significant factor affecting the diversity of EcM trees. Our findings highlight the importance of AM trees for the tree diversity of forest communities worldwide. Our findings have important implications for understanding the response of complex woody plant communities with different types of mycorrhizal symbiosis to climate change. [ABSTRACT FROM AUTHOR]

Summary: It is well‐known that the mycorrhizal type of plants correlates with different modes of nutrient cycling and availability. However, the differences in drought tolerance between arbuscular mycorrhizal (AM) and ectomycorrhizal (EcM) plants remains poorly characterized.We synthesized a global dataset of four hydraulic traits associated with drought tolerance of 1457 woody species (1139 AM and 318 EcM species) at 308 field sites. We compared these traits between AM and EcM species, with evolutionary history (i.e. angiosperms vs gymnosperms), water availability (i.e. aridity index) and biomes considered as additional factors.Overall, we found that evolutionary history and biogeography influenced differences in hydraulic traits between mycorrhizal types. Specifically, we found that (1) AM angiosperms are less drought‐tolerant than EcM angiosperms in wet regions or biomes, but AM gymnosperms are more drought‐tolerant than EcM gymnosperms in dry regions or biomes, and (2) in both angiosperms and gymnosperms, variation in hydraulic traits as well as their sensitivity to water availability were higher in AM species than in EcM species.Our results suggest that global shifts in water availability (especially drought) may alter the biogeographic distribution and abundance of AM and EcM plants, with consequences for ecosystem element cycling and ultimately, the land carbon sink. [ABSTRACT FROM AUTHOR]

The cell and molecular bases of arbuscular mycorrhizal (AM) symbiosis, a crucial plant-fungal interaction for nutrient acquisition, have been extensively investigated by coupling traditional RNA sequencing techniques of roots sampled in bulk, with methods to capture subsets of cells such as laser microdissection. These approaches have revealed central regulators of this complex relationship, yet the requisite level of detail to effectively untangle the intricacies of temporal and spatial development remains elusive. The recent adoption of single-cell RNA sequencing (scRNA-seq) techniques in plant research is revolutionizing our ability to dissect the intricate transcriptional profiles of plant-microbe interactions, offering unparalleled insights into the diversity and dynamics of individual cells during symbiosis. The isolation of plant cells is particularly challenging due to the presence of cell walls, leading plant researchers to widely adopt nuclei isolation methods. Despite the increased resolution that single-cell analyses offer, it also comes at the cost of spatial perspective, hence, it is necessary the integration of these approaches with spatial transcriptomics to obtain a comprehensive overview. To date, few single-cell studies on plant-microbe interactions have been published, most of which provide high-resolution cell atlases that will become crucial for fully deciphering symbiotic interactions and addressing future questions. In AM symbiosis research, key processes such as the mutual recognition of partners during arbuscule development within cortical cells, or arbuscule senescence and degeneration, remain poorly understood, and these advancements are expected to shed light on these processes and contribute to a deeper understanding of this plant-fungal interaction. [ABSTRACT FROM AUTHOR]

In this study, we report the interaction between an arbuscular mycorrhizal fungus, Septoglomus constrictum, and tomato plants under heat stress. For the first time, this interaction was studied by Illumina RNA-seq, followed by a comprehensive bioinformatic analysis that investigated root and leaf tissue samples. The genome-wide transcriptional profiling displayed fewer transcriptomic changes in the root under heat-stress conditions caused by S. constrictum. The top 50 DEGs suggested significant changes in the expression of genes encoding heat-shock proteins, transporter proteins, and genes of phytohormone metabolism involving jasmonic acid signalling. S. constrictum induced the upregulation of genes associated with pathways such as 'drought-responsive' and the 'development of root hair' in the root, as well as 'glycolipid desaturation', 'intracellular auxin transport', and 'ethylene biosynthesis' in the leaf. The pathways 'biotin biosynthesis' and 'threonine degradation' were found in both investigated tissue types. Expression analysis of transcription factors showed 2 and 11 upregulated transcription factors in heat-stressed root and leaf tissues, respectively. However, we did not find shared transcription factors. Heat-stressed arbuscular mycorrhizal plants suffered less oxidative stress when exposed to high temperatures. Colorimetric tests demonstrated less accumulation of H2O2 and MDA in heat-stressed mycorrhizal plants. This phenomenon was accompanied by the higher expression of six stress genes that encode peroxidases, glutathione S-transferase and ubiquitin carboxyl-terminal hydrolase in roots and leaves. Our findings provide a new perspective on elucidating the functional metabolic processes of tomato plants under mycorrhizal-heat stressed conditions. [ABSTRACT FROM AUTHOR]

Differences between arbuscular (AM) and ectomycorrhizal (EcM) trees strongly influence forest ecosystem processes, in part through their impact on saprotrophic fungal communities. Ericoid mycorrhizal (ErM) shrubs likely also impact saprotrophic communities given that they can shape nutrient cycling by slowing decomposition rates and intensifying nitrogen limitation. We investigated the depth distributions of saprotrophic and EcM fungal communities in paired subplots with and without a common understory ErM shrub, mountain laurel (Kalmia latifolia L.), across an AM to EcM tree dominance gradient in a temperate forest by analyzing soils from the organic, upper mineral (0–10 cm), and lower mineral (cumulative depth of 30 cm) horizons. The presence of K. latifolia was strongly associated with the taxonomic and functional composition of saprotrophic and EcM communities. Saprotrophic richness was consistently lower in the Oa horizon when this ErM shrub species was present. However, in AM tree-dominated plots, the presence of the ErM shrub was associated with a higher relative abundance of saprotrophs. Given that EcM trees suppress both the diversity and relative abundance of saprotrophic communities, our results suggest that separate consideration of ErM shrubs and EcM trees may be necessary when assessing the impacts of plant mycorrhizal associations on belowground communities. [ABSTRACT FROM AUTHOR]

Purpose: Arbuscular mycorrhizal fungi (AMF) perform an ancestral and essential association with plant roots, where plants provide carbohydrates and lipids, and the fungi respond by translocating water and nutrients to the roots through the hyphae. There is a need to investigate the microbial community associated with the rhizosphere of mycorrhizal plants in response to the multiple benefits (e.g., improved nutrition and stress resistance) provided by the association. In this work, we analyzed the bacterial communities associated with the rhizosphere of plants and their response to mycorrhizae in low P conditions. Methods: For this purpose, inoculated and non-inoculated B73 corn plants were grown with a consortium of mycorrhizal fungi under low phosphorus conditions. Mycorrhiza response in B73 and the interaction with rhizosphere microbiome were characterized by sequencing the bacterial 16S rRNA gene. Results: Inoculated plants showed increased greater growth in leaf and root parameters in low P conditions. Bacterial microbiome showed changes in beta diversity and some OUTs significantly regulated by AMF presence. Conclusion: These data confirm the importance of mycorrhizae in phosphorus stress and rhizosphere community changes as a possible mechanism to improve plant growth. [ABSTRACT FROM AUTHOR]

Background and aims: Understanding biotic interactions within plant populations and with their symbiotic partners is crucial for elucidating plant responses to drought. While many studies have highlighted the importance of intraspecific plant or mutualistic fungal interactions in predicting drought responses, we know little about the combined effects of these two interactions on the recovery of plants after drought. Methods: We conducted an experiment to study the recovery after an extreme drought event of a native European plant species (Centaurea jacea) and its range-expanding congener (Centaurea stoebe), across a gradient of plant density and in association with an AM fungal species (Rhizophagus irregularis). Results: Our results showed strong intraspecific competition in C. jacea, which constrained their post-drought recovery. We further found that AM fungi constrained root biomass recovery of C. jacea after drought under high intraspecific competition. The post-drought recovery in C. stoebe was high potentially due to its greater plasticity in the root diameter under drought conditions. Conclusion: Strong intraspecific competition can constrain recovery in plants like C. jacea with lesser root trait plasticity after drought, independent of mycorrhizal symbiosis. [ABSTRACT FROM AUTHOR]

BACKGROUND: Mycorrhizal plants show enhanced resistance to biotic stresses, but few studies have addressed mycorrhiza‐induced resistance (MIR) against biotic challenges in woody plants, particularly citrus. Here we present a comparative study of two citrus species, Citrus aurantium, which is resistant to Tetranychus urticae, and Citrus reshni, which is highly susceptible to T. urticae. Although both mycorrhizal species are protected in locally infested leaves, they show very distinct responses to MIR. RESULTS: Previous studies have indicated that C. aurantium is insensitive to MIR in systemic tissues and MIR‐triggered antixenosis. Conversely, C. reshni is highly responsive to MIR which triggers local, systemic and indirect defense, and antixenosis against the pest. Transcriptional, hormonal and inhibition assays in C. reshni indicated the regulation of jasmonic acid (JA)‐ and abscisic acid‐dependent responses in MIR. The phytohormone jasmonic acid isoleucine (JA‐Ile) and the JA biosynthesis gene LOX2 are primed at early timepoints. Evidence indicates a metabolic flux from phenylpropanoids to specific flavones that are primed at 24 h post infestation (hpi). MIR also triggers the priming of naringenin in mycorrhizal C. reshni, which shows a strong correlation with several flavones and JA‐Ile that over‐accumulate in mycorrhizal plants. Treatment with an inhibitor of phenylpropanoid biosynthesis C4H enzyme impaired resistance and reduced the symbiosis, demonstrating that phenylpropanoids and derivatives mediate MIR in C. reshni. CONCLUSION: MIR's effectiveness is inversely correlated to basal immunity in different citrus species, and provides multifaceted protection against T. urticae in susceptible C. reshni, activating rapid local and systemic defenses that are mainly regulated by the accumulation of specific flavones and priming of JA‐dependent responses. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Biogeographical variation in community assembly processes forms the basis of the latitudinal gradient of biodiversity by driving β‐diversity. Classical studies on community assembly predict environmental filtering affecting β‐diversity more strongly at higher latitudes, where productivity is lower and abiotic stress is stronger. Contrary to this prediction, recent evidence indicates that plant community composition at higher latitudes exhibits more spatially clustered distributions independently of background environments, suggesting the importance of spatial processes, such as priority effects. In this study, we propose a hypothesis that resolves this paradox by considering plant–soil feedback and biogeographic variations in the dominant mycorrhizal type: we predict that the increasing prevalence of ectomycorrhizal (EcM) trees with latitude contributes to the spatially clustered distribution of plants, as EcM trees tend to exhibit positive plant–soil feedback. We analyzed a large‐scale standardized dataset of Japanese forests covering a latitudinal gradient of >10° and found that 1) the proportion of EcM trees was higher at higher latitudes, and 2) EcM tree‐rich communities exhibited more spatially clustered distributions likely due to positive plant–soil feedback. Consequently, 3) tree species composition at higher latitudes was better explained by spatial variables suggesting the importance of priority effects. Consistent with the predictions of the plant–soil feedback theory, these patterns were more pronounced in understory than in canopy communities. Taken together, our results lend support to our hypothesis that biogeographic variation in tree community assembly patterns is defined by mycorrhizal types and plant–soil feedback, thereby resolving a paradox in the latitudinal gradient of plant community assembly. Our work highlights that plant mycorrhizal type underlies the determinants of β‐diversity which is a critical component of the latitudinal gradient of diversity. [ABSTRACT FROM AUTHOR]

Background and aims: In mature forests, tree and shrub mycorrhizal associations integrate plant and fungal functional traits, making these relationships important controls on soil nitrogen availability. Whether these plant-fungal effects are observed in forests during early succession following disturbances is largely unexplored. We quantify differences in soil nitrogen availability under an ectomycorrhizal tree (Betula lenta) and an ericoid mycorrhizal shrub (Kalmia latifolia) and explore the potential for known mechanisms, such as the availability of soil carbon, to explain the patterns observed. Methods: We analyze variables indicative of soil nitrogen and carbon availability for incubated soil samples collected from under ecto- or ericoid mycorrhizal plants within a recently harvested temperate forest. Specific measures include net nitrogen mineralization, nitrification, and carbon mineralization rates; active microbial biomass; particulate and mineral-associated soil organic carbon and nitrogen concentrations; and carbon and nitrogen concentrations in plant tissues. Results: Net nitrogen mineralization and nitrification rates were lower under ericoid shrubs than ectomycorrhizal trees. Soil carbon availabilities were similar, suggesting that mechanisms other than carbon accumulation likely create nitrogen limitation under the ericoid shrub in early successional forests. Ectomycorrhizal plant tissues also had higher nitrogen contents and lower carbon-to-nitrogen ratios than ericoid shrubs, providing further support for greater soil nitrogen limitation in the ericoid plots. Conclusion: Our findings suggest local heterogeneity of plant mycorrhizal associations, or at least plant functional types, will be important for understanding differences in soil nitrogen availability in early versus mid- to late-successional forests and hence forest ecosystem responses to intensifying disturbance regimes. [ABSTRACT FROM AUTHOR]

Summary: Root‐associated fungi (RAF) and root traits regulate plant acquisition of nitrogen (N), which is limiting to growth in Arctic ecosystems. With anthropogenic warming, a new N source from thawing permafrost has the potential to change vegetation composition and increase productivity, influencing climate feedbacks. Yet, the impact of warming on tundra plant root traits, RAF, and access to permafrost N is uncertain.We investigated the relationships between RAF, species‐specific root traits, and uptake of N from the permafrost boundary by tundra plants experimentally warmed for nearly three decades at Toolik Lake, Alaska.Warming increased acquisitive root traits of nonmycorrhizal and mycorrhizal plants. RAF community composition of ericoid (ERM) but not ectomycorrhizal (ECM) shrubs was impacted by warming and correlated with root traits. RAF taxa in the dark septate endophyte, ERM, and ECM guilds strongly correlated with permafrost N uptake for ECM and ERM shrubs. Overall, a greater proportion of variation in permafrost N uptake was related to root traits than RAF.Our findings suggest that warming Arctic ecosystems will result in interactions between roots, RAF, and newly thawed permafrost that may strongly impact feedbacks to the climate system through mechanisms of carbon and N cycling. [ABSTRACT FROM AUTHOR]

Summary: Nonmycorrhizal cluster root‐forming species enhance the phosphorus (P) acquisition of mycorrhizal neighbours in P‐impoverished megadiverse systems. However, whether mycorrhizal plants facilitate the defence of nonmycorrhizal plants against soil‐borne pathogens, in return and via their symbiosis, remains unknown.We characterised growth and defence‐related compounds in Banksia menziesii (nonmycorrhizal) and Eucalyptus todtiana (ectomycorrhizal, ECM) seedlings grown either in monoculture or mixture in a multifactorial glasshouse experiment involving ECM fungi and native oomycete pathogens.Roots of B. menziesii had higher levels of phytohormones (salicylic and jasmonic acids, jasmonoyl‐isoleucine and 12‐oxo‐phytodienoic acid) than E. todtiana which further activated a salicylic acid‐mediated defence response in roots of B. menziesii, but only in the presence of ECM fungi. We also found that B. menziesii induced a shift in the defence strategy of E. todtiana, from defence‐related secondary metabolites (phenolic and flavonoid) towards induced phytohormone response pathways.We conclude that ECM fungi play a vital role in the interactions between mycorrhizal and nonmycorrhizal plants in a severely P‐impoverished environment, by introducing a competitive component within the facilitation interaction between the two plant species with contrasting nutrient‐acquisition strategies. This study sheds light on the interplay between beneficial and detrimental soil microbes that shape plant–plant interaction in severely nutrient‐impoverished ecosystems. [ABSTRACT FROM AUTHOR]

We present a mechanistic model of coexistence among a mycorrhizal fungus and one or two plant species that compete for a single nutrient. Plant–fungal coexistence is more likely if the fungus is better at extracting the environmental nutrient than the plant and the fungus acquires carbon from the plant above a minimum rate. When they coexist, their interaction can shift from mutualistic to parasitic at high nutrient availability. The fungus is a second nutrient source for plants and can promote the coexistence of two plant competitors if one is better at environmental nutrient extraction and the other is better at acquiring the nutrient from the fungus. Because it extracts carbon from both plants, the fungus also serves as a conduit of apparent competition between the plants. Consequently, the plant with the lower environmental nutrient extraction rate can drive the plant with the higher environmental nutrient extraction rate extinct at high carbon supply rates. This model illustrates mechanisms to explain several observed patterns, including shifts in plant–mycorrhizal growth responses and coexistence along nutrient gradients, equivocal results among experiments testing the effect of mycorrhizal fungi on plant diversity, and differences in plant diversity among ecosystems dominated by different mycorrhizal groups. [ABSTRACT FROM AUTHOR]

Sustainable plant production requires less use of synthetic chemicals in plant nutrition and protection. Microbial products are among the most promising substitutes for chemicals. With the increasing popularity and availability of such products, it has become obligatory to use different microbes together. The effect of this has been tested in several studies, but their results have sometimes been contradictory depending on the microbial strains tested and the mode of application. We tested the effect of two commercially available antagonists and Funneliformis mosseae alone and in combination on tomato. Mycorrhizal treatment increased plant growth and yield, both alone and combined with the antagonists; however, mycorrhizal root colonization was not influenced by the antagonist. This treatment also led to a slight decrease in the occurrence of Trichoderma spp. on tomato roots but did not impede the colonization of roots by the applied Trichoderma strain. Our result confirmed that Trichoderma asperellum (T34) and Streptomyces griseoviridis (K61) can be safely combined with arbuscular mycorrhizal fungi (AMF), namely with F. mosseae. [ABSTRACT FROM AUTHOR]

Introduction: Arbuscular mycorrhizal fungi (AMF) have been demonstrated their ability to enhance the arsenic (As) tolerance of host plants, and making the utilization of mycorrhizal plants a promising and practical approach for remediating As-contaminated soils. However, comprehensive transcriptome analysis to reveal the molecular mechanism of As tolerance in the symbiotic process between AMF and host plants is still limited. Methods: In this study, transcriptomic analysis of Gossypium seedlings was conducted with four treatments: non-inoculated Gossypium under non-As stress (CK0), non-inoculated Gossypium under As stress (CK100), F. mosseaeinoculated Gossypium under non-As stress (FM0), and F. mosseae-inoculated Gossypium under As stress (FM100). Results: Our results showed that inoculation with F. mosseae led to a reduction in net fluxes of Ca2+, while increasing Ca2+ contents in the roots and leaves of Gossypium under the same As level in soil. Notably, 199 and 3129 differentially expressed genes (DEGs) were specially regulated by F. mosseae inoculation under As stress and non-As stress, respectively. Through Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) annotation and enrichment analyses, we found that under As stress, F. mosseae inoculation up-regulated a significant number of genes related to the Ca2+ signaling pathway genes, involved in cellular process, membrane part, and signal transduction. This suggests a potential role in mitigating As tolerance in Gossypium seedlings. Furthermore, our analysis identified specific DEGs in transcription factor families, including ERF, MYB, NAC, and WRKY, that were upregulated by F. mosseae inoculation. Conversely, MYB and HB-other were down-regulated. The ERF and MYB families exhibited the highest number of up- and down-regulated DEGs, respectively, which were speculated to play an important role in alleviating the As toxicity of Gossypium. Discussion: Our findings provided valuable insights into the molecular theoretical basis of the Ca2+ signaling pathway in improving As tolerance of mycorrhizal plants in the future. [ABSTRACT FROM AUTHOR]

Insect herbivory can affect interactions between plants and arbuscular mycorrhizal (AM) fungi through herbivore‐modified root carbon pools, while the specific metabolic changes underlying fungal responses to herbivory are poorly understood.Here we explored the impacts of foliar herbivory and mechanical wounding on AM colonisation and AM community composition of common ragweed (Ambrosia artemisiifolia) and the role of root metabolites in mediating these effects.Foliar insect herbivory enhanced AM colonisation, whereas mechanical wounding only enhanced AM colonisation in combination with application of caterpillar oral secretions. Meanwhile, the relative abundance of Glomus species was increased in root endosphere, rhizoplane and rhizosphere soils after foliar herbivory. Foliar herbivory also increased the concentrations of fatty acids in roots but decreased phenolics, and their concentrations were significantly correlated with AM colonisation. Addition of exudates from plants exposed to herbivory resulted in increases in AM colonisation of plants without herbivory. Moreover, widely targeted metabolomic analyses revealed that foliar herbivory enhanced the relative abundance of lipids and decreased phenols in root exudates.Synthesis. We show that plants can enhance their associations with arbuscular mycorrhizal (AM) fungi when subject to above‐ground herbivory, possibly mediated by herbivore‐induced increases in the levels of root lipids. Our findings highlight the role of root lipids in above‐below‐ground biological interactions, providing novel insights into plant‐AM fungi integrative responses to biotic stresses. [ABSTRACT FROM AUTHOR]

Salinity is an increasing problem in coastal areas affected by saltwater intrusion, with deleterious effects on tree health and forest growth. Ectomycorrhizal (ECM) fungi may improve the salinity tolerance of host trees, but the impact of external potassium (K+) availability on these effects is still unclear. Here, we performed several experiments with the ECM fungus Paxillus ammoniavirescens and loblolly pine (Pinus taeda L.) in axenic and symbiotic conditions at limited or sufficient K+ and increasing sodium (Na+) concentrations. Growth rate, biomass, nutrient content, and K+ transporter expression levels were recorded for the fungus, and the colonization rate, root development parameters, biomass, and shoot nutrient accumulation were determined for mycorrhizal and non‐mycorrhizal plants. P. ammoniavirescens was tolerant to high salinity, although growth and nutrient concentrations varied with K+ availability and increasing Na+ exposure. While loblolly pine root growth and development decreased with increasing salinity, ECM colonization was unaffected by pine response to salinity. The mycorrhizal influence on loblolly pine salinity response was strongly dependent on external K+ availability. This study reveals that P. ammoniavirescens can reduce Na+ accumulation of salt‐exposed loblolly pine, but this effect depends on external K+ availability. [ABSTRACT FROM AUTHOR]

Herbaceous layers in second-growth forests are shaped by past land use. Disturbances such as agriculture may impact populations of mycoheterotrophs, non-photosynthetic mycorrhizal plants that obtain carbon from fungal networks by altering mycorrhizal communities or removing trees they derive carbon from. I tested the hypotheses that two mycoheterotrophic forest herbs increase in abundance during succession and become most common in older forests as plant communities reassemble through time. Distributions of Hypopitys monotropa and Monotropa uniflora were sampled in Athens County, Ohio, USA. I surveyed populations in a 40-site post-agricultural forest chronosequence with five upland and five valley sites in each of four age classes: 40–60, 61–80, 81–100, and >130 years since canopy closure. Aspect and elevation were measured to assess environmental influence. Both H. monotropa and M. uniflora were most common in older stands with EM tree-rich canopy composition and west- or south-facing aspects, indicating influence of historical, biotic, and edaphic factors. Hypopitys was exclusive to forests >80 years old, while M. uniflora was present in younger stands. Abundance of both species was also significantly predicted by Fagaceae basal area. Because EM trees were also most abundant in south- and west-facing uplands, environmental influence appears to be mediated through canopy composition. [ABSTRACT FROM AUTHOR]

This study aims to evaluate whether a selected arbuscular mycorrhizal fungus, Diversispora spurca, improves growth in drought-stressed walnut (Juglans regia L. cv. Qingxiang) plants and whether this improvement is associated with changes in osmolyte (fructose, glucose, sucrose, soluble protein, proline, and betaine) levels. After 60 days of soil drought treatment (50% of maximum field water-holding capacity), root D. spurca colonization rate and soil mycelium length decreased by 13.57% and 64.03%, respectively. Soil drought also inhibited the growth performance of aboveground (stem diameter, leaf number, leaf biomass, and stem biomass) and underground (root projected area, surface area, and average diameter) parts, with uninoculated plants showing a stronger inhibition than D. spurca-inoculated plants. D. spurca significantly increased these growth variables, along with aboveground part variables and root areas being more prominent under drought stress versus non-stress conditions. Although drought treatment suppressed the chlorophyll index and nitrogen balance index in leaves, mycorrhizal inoculation significantly increased these indices. Walnut plants were able to actively increase leaf fructose, glucose, sucrose, betaine, and proline levels under such drought stress. Inoculation of D. spurca also significantly increased leaf fructose, glucose, sucrose, betaine, proline, and soluble protein levels under drought stress and non-stress, with the increasing trend in betaine and soluble protein being higher under drought stress versus non-stress. Drought stress dramatically raised leaf hydrogen peroxide (H2O2) levels in both inoculated and uninoculated plants, while mycorrhizal plants presented significantly lower H2O2 levels, with the decreasing trend higher under drought stress versus non-stress. In conclusion, D. spurca symbiosis can increase the growth of drought-stressed walnut plants, associated with increased osmolyte levels and decreased H2O2 levels. [ABSTRACT FROM AUTHOR]

Background: The establishment of mycorrhizal relationships between a fungus and a plant typically enhances nutrient and water uptake for the latter while securing a carbon source for the fungus. However, under a particular set of environmental conditions, such as low availability of light and abundant nutrients in the soil, the resources invested in the maintenance of the fungi surpass the benefits obtained by the host. In those cases, facultative mycorrhizal plants are capable of surviving without symbiosis. Facultative mycorrhization in ferns has been overlooked until now. The present study measured the response of Struthiopteris spicant L. Weiss, and its root-associated fungi to different levels of light and nutrient availability in terms of growth, mycorrhizal presence, and leaf nutrient content. This fern species exhibits a great tolerance to variable light, nutrient, and pH conditions, and it has been found with and without mycorrhizae. We conducted a greenhouse experiment with 80 specimens of S. spicant and three factors (Light, Phosphorus, and Nitrogen) resulting in eight treatments. Results: We found a significant influence of the factor light on fungal community composition, plant biomass, and nutrient accumulation. Departing from a lack of colonization at the initial stage, plants showed a remarkable increment of more than 80% in the arbuscular mycorrhizal fungi (AMF) richness and abundance in their roots when grown under high light conditions, compared with the ones in low light. We also observed an upward trend of C:P and C:N ratios and the above- and belowground biomass production when AMF abundance increased. Furthermore, the compositional analysis of the whole fungal communities associated with S. spicant roots revealed clear differences among low-light and high-light treatments. Conclusions: This study is the first to investigate the importance of light and nutrient availability in determining fern-AMF relationships. We confirmed that Struthiopteris spicant is a facultative mycorrhizal plant. The composition and diversity of AMF found in the roots of this fern are strongly influenced by light and less by nutrient conditions. Our study shows that ferns respond very sensitively to changes in environmental factors, leading to shifts in the associated mycorrhizal communities. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal fungi (AMF) can penetrate plant root cortical cells, establish a symbiosis with most land plant species, and form branched structures (known as arbuscules) for nutrient exchange. Plants have evolved a complete plant-AMF symbiosis system to sustain their growth and development under various types of abiotic stress. Here, we highlight recent studies of AM symbiosis and the regulation of symbiosis process. The roles of mycorrhizal symbiosis and host plant interactions in enhancing drought resistance, increasing mineral nutrient uptake, regulating hormone synthesis, improving salt resistance, and alleviating heavy metal stress were also discussed. Overall, studies of AM symbiosis and a variety of abiotic stresses will aid applications of AMF in sustainable agriculture and can improve plant production and environmental safety. [ABSTRACT FROM AUTHOR]

Nitrogen (N) resorption is an important pathway of N conservation, contributing to an important proportion of plant N requirement. However, whether the ratio of N resorption to N requirement may be affected by environmental factors, mycorrhizal types or atmospheric CO2 concentration remains unclear. Here, we conducted a meta‐analysis on the impacts of environmental factors and mycorrhizal types on this ratio. We found this ratio in ectomycorrhizal (EM) trees decreased with mean annual precipitation, mean annual temperature, soil total N content and atmospheric CO2 concentration and was significantly lower than that in arbuscular mycorrhizal (AM) trees. An in situ15N tracing experiment further confirmed that AM trees have a stronger reliance on N resorption than EM trees. Our study suggests that AM and EM trees potentially have different strategies for alleviation of progressive N limitation, highlighting the necessity of incorporating plant mycorrhizal types into Earth System Models. [ABSTRACT FROM AUTHOR]

The associations of arbuscular mycorrhizal (AM) or ectomycorrhiza (EcM) fungi with plants have sequentially evolved and significantly contributed to enhancing plant nutrition. Nonetheless, how evolutionary and ecological forces drive nutrient acquisition strategies of AM and EcM woody plants remains poorly understood. Our global analysis of woody species revealed that, over divergence time, AM woody plants evolved faster nitrogen mineralization rates without changes in nitrogen resorption. However, EcM woody plants exhibited an increase in nitrogen mineralization but a decrease in nitrogen resorption, indicating a shift towards a more inorganic nutrient economy. Despite this alteration, when evaluating present‐day woody species, AM woody plants still display faster nitrogen mineralization and lower nitrogen resorption than EcM woody plants. This inorganic nutrient economy allows AM woody plants to thrive in warm environments with a faster litter decomposition rate. Our findings indicate that the global pattern of nutrient acquisition strategies in mycorrhizal plants is shaped by the interplay between phylogeny and climate. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Viticulture & Enology / Ciência e Técnica Vitivinícola is the property of EDP Sciences 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.)

The efficacy of rhizospheric native arbuscular mycorrhizal fungi from naturally growing Cassia fistula L. trees was evaluated by utilizing seeds from the same trees to assess growth and biochemical properties. This study aimed to investigate whether biochemical content could be augmented in naturally growing trees, contrasting them with greenhouse-grown seedlings. The findings revealed that arbuscular mycorrhiza-inoculated seedlings exhibited significantly higher shoot and root length, leaf area, and shoot dry weight compared to non-mycorrhizal plants under greenhouse conditions. Furthermore, there was a noteworthy increase in biochemicals such as protein, carbohydrates, and phenols in mycorrhizal-inoculated plants and naturally growing trees when compared to non-mycorrhizal plants. Interestingly, carbohydrates and phenols were significantly more abundant in naturally growing trees than in greenhouse experiment plants. Additionally, the methanolic leaf extract of non-mycorrhizal plants exhibited the lowest inhibition percentage (%) on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals in comparison to mycorrhizal plants and naturally growing trees. Moreover, the effective concentration at 50% inhibition of DPPH radicals by mycorrhizal plants and naturally growing trees was lower than that observed in non-mycorrhizal plants. The biochemical estimates obtained from mycorrhizal plants substantiate the results observed in naturally growing trees, thereby supporting the assumption that native arbuscular mycorrhizal fungi may enhance the levels of biochemicals in naturally growing C. fistula trees. [ABSTRACT FROM AUTHOR]

Summary: Root hair is regarded as a pivotal complementary survival tactic for mycorrhizal plant like Abies beshanzuensis when symbiosis is disrupted. Relatively little is known about the mechanism underlying root hair morphogenesis in plant species that are strongly dependent on mycorrhizal symbiosis. Many of these species are endangered, and this knowledge is critical for ensuring their survival.Here, a MYB6/bHLH13‐sucrose synthase 2 (AbSUS2) module was newly identified and characterized in A. beshanzuensis using bioinformatics, histochemistry, molecular biology, and transgenesis.Functional, expression pattern, and localization analysis showed that AbSUS2 participated in sucrose synthesis and was involved in root hair initiation in A. beshanzuensis. Additionally, the major enzymatic product of AbSUS2 was found to suppress root hair initiation in vitro. Our data further showed that a complex involving the transcription factors AbMYB6 and AbbHLH13 directly interacted with the promoter of AbSUS2 and strengthened its expression, thereby inhibiting root hair initiation in response to exogenous sucrose.Our findings offer novel insights into how root hair morphogenesis is regulated in mycorrhizal plants and also provide a new strategy for the preservation of endangered mycorrhizal plant species. [ABSTRACT FROM AUTHOR]

Citrus, one of the most widely cultivated fruit crops in the world, relies on arbuscular mycorrhizal fungi (AMF) to absorb nutrients and water from soil. However, the molecular mechanism of AM symbiosis (AMS) in citrus in general have largely been understudied. Here, using a TMT labeling proteomic approach, we identified 365 differentially expressed proteins (DEPs) in roots of Poncirus trifoliata (a common citrus rootstock) upon Rhizophagus irregularis colonization as compared with uninoculated roots, of which 287 were up-regulated and 78 were down-regulated. GO analysis revealed that the DEPs were mainly involved in biological processes such as negative regulation of endopeptidase inhibitor activity, negative regulation of endopeptidase, one-carbon metabolic process and carbohydrate metabolic process. KEGG enrichment analysis indicated that the DEPs were mainly involved in regulating metabolic pathways such as fatty acid biosynthesis, phenylpropanoid biosynthesis and carbon metabolism. Furthermore, 194 of the 365 DEPs were found to be associated with AMSresponsive genes by association analysis with our previous transcriptomes data, which highlighted the important roles of these proteins in AMS. One of the 194 DEPs, neutral ceramidase (PtNCER), was further chosen for function analysis via RNAi interfering its homologous gene MtNCER in a mycorrhizal model plant Medicago truncatula, which confirmed a positive role of NCER in AM establishment. Our results provided basic data and key candidate genes for genetic improvement of efficient nutrient uptake through AM establishment in citrus and other crops. [ABSTRACT FROM AUTHOR]

Animals interact with and impact ecosystem biogeochemical cycling—processes known as zoogeochemistry. While the deposition of various animal materials (e.g. carcasses and faeces) has been shown to create nutrient hotspots and alter nutrient cycling and storage, the inputs from parturition (i.e. calving) have yet to be explored. We examine the effects of ungulate parturition, which often occurs synchronously during spring green‐up and therefore aligns with increased plant nitrogen demand in temperate biomes.Impacts of zoogeochemical inputs are likely context‐dependent, where differences in material quality, quantity and the system of deposition modulate their impacts. Plant mycorrhizal associations, especially, create different nutrient‐availability contexts, which can modify the effects of nutrient inputs. We, therefore, hypothesize that mycorrhizal associations modulate the consequences of parturition on soil nutrient dynamics and nitrogen pools.We established experimental plots that explore the potential of two kinds of zoogeochemical inputs deposited at ungulate parturition (placenta and natal fluid) in forest microsites dominated by either ericoid mycorrhizal (ErM) or ectomycorrhizal (EcM) plants. We assess how these inputs affect rates of nutrient cycling and nitrogen content in various ecosystem pools, using isotope tracers to track the fate of nitrogen inputs into plant and soil pools.Parturition treatments accelerate nutrient cycling processes and increase nitrogen contents in the plant leaf, stem and fine root pools. The ecosystem context strongly modulates these effects. Microsites dominated by ErM plants mute parturition treatment impacts on most nutrient cycling processes and plant pools. Both plant–fungal associations are, however, equally efficient at retaining nitrogen, although retention of nitrogen in the parturition treatment plots was more than two times lower than in control plots.Our results highlight the potential importance of previously unexamined nitrogen inputs from animal inputs, such as those from parturition, in contributing to fine‐scale heterogeneity in nutrient cycling and availability. Animal inputs should therefore be considered, along with their interactions with plant mycorrhizal associations, in terms of how zoogeochemical dynamics collectively affect nutrient heterogeneity in ecosystems. [ABSTRACT FROM AUTHOR]

Copyright of Lilloa is the property of Fundacion Miguel Lillo 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.)

In the initial stages of restoring rocky desertification, the proliferation of nutrients strongly influences plant survival. The carbon–nitrogen doctrine in plants argues that a lower leaf carbon–nitrogen (C:N) ratio enhances the growth of plant nutrients. However, the mechanisms by which inoculation with arbuscular mycorrhizal fungi (AMF) can influence plants during the restoration of rocky desertification are not thoroughly understood. This study used mulberry as a suitable example of a mycorrhizal plant in desertification areas to examine changes in growth, leaf carbon, nitrogen accumulation, and the carbon–nitrogen ratio post inoculation using AMF. The correlation between leaf carbon–nitrogen ratio and root morphology following AMF inoculation was also examined. The results demonstrated that inoculating mulberry with the dominant strains Funneliformis mosseae (Fm) and Rhizophagus intraradices (Ri) not only enhanced above-ground growth and improved carbon and nitrogen nutrient absorption but also had a more pronounced effect on leaf nitrogen accumulation than on carbon accumulation, resulting in a potential decrease in the leaf C:N ratio by 42.13%. It also significantly improved root morphology by exponentially increasing the number of connections and crossings by 120.5% and 109.8%, respectively. Further analysis revealed a negative correlation between leaf C:N ratio and root morphology, as well as between root length and the number of connections. Plants with more developed root systems exhibited greater competitiveness for nitrogen, resulting in a lower leaf C:N ratio. This study suggests that the inoculation of AMF could enhance leaf nitrogen accumulation and reduce the leaf C:N ratio by expanding the spatial absorption range of the root through positive changes in root morphology, thereby promoting plant nutrient growth. This study forms a fundamental scientific basis for the successful management of desertification. [ABSTRACT FROM AUTHOR]

Introduction: As a crucial factor in determining ecosystem functioning, interaction between plants and soil-borne fungal pathogens deserves considerable attention. However, little attention has been paid into the determinants of root-associated fungal pathogens in subtropical seedlings, especially the influence of different mycorrhizal plants. Methods: Using high-throughput sequencing techniques, we analyzed the rootassociated fungal pathogen community for 19 subtropical forest species, including 10 ectomycorrhizal plants and 9 arbuscular mycorrhizal plants. We identified the roles of different factors in determining the root-associated fungal pathogen community. Further, we identified the community assembly process at species and mycorrhizal level and managed to reveal the drivers underlying the community assembly. Results: We found that plant species identity, plant habitat, and plant mycorrhizal type accounted for the variations in fungal pathogen community composition, with species identity and mycorrhizal type showing dominant effects. The relative importance of different community assembly processes, mainly, homogeneous selection and drift, varied with plant species identity. Interestingly, functional traits associated with acquisitive resource-use strategy tended to promote the relative importance of homogeneous selection, while traits associated with conservative resource-use strategy showed converse effect. Drift showed the opposite relationships with functional traits compared with homogeneous selection. Notably, the relative importance of different community assembly processes was not structured by plant phylogeny. Drift was stronger in the pathogen community for ectomycorrhizal plants with more conservative traits, suggesting the predominant role of stochastic gain and loss in the community assembly. Discussion: Our work demonstrates the determinants of root-associated fungal pathogens, addressing the important roles of plant species identity and plant mycorrhizal type. Furthermore, we explored the community assembly mechanisms of root-associated pathogens and stressed the determinant roles of functional traits, especially leaf phosphorus content (LP), root nitrogen content (RN) and root tissue density (RTD), at species and mycorrhizal type levels, offering new perspectives on the microbial dynamics underlying ecosystem functioning. [ABSTRACT FROM AUTHOR]

Species interactions exhibit varying degrees of specialization, ranging from generalist to specialist interactions. For many interactions (e.g., plantmicrobiome) we lack standardized metrics of specialization, hindering our ability to apply comparative frameworks of specificity across niche axes and organismal groups. Here, we discuss the concept of plant host specificity of arbuscular mycorrhizal (AM) fungi and ectomycorrhizal (EM) fungi, including the predominant theories for their interactions: Passenger, Driver, and Habitat Hypotheses. We focus on five major areas of interest in advancing the field of plant-mycorrhizal fungal host specificity: phylogenetic specificity, host physiology specificity, functional specificity, habitat specificity, and mycorrhizal fungal-mediated plant rarity. Considering the need to elucidate foundational concepts of specificity in this globally important symbiosis, we propose standardized metrics and comparative studies to enhance our understanding. We also emphasize the importance of analyzing global mycorrhizal data holistically to draw meaningful conclusions and suggest a shift toward singlespecies analyses to unravel the complexities underlying these associations. [ABSTRACT FROM AUTHOR]

Mycorrhizal symbioses are known to strongly influence plant performance, structure plant communities and shape ecosystem dynamics. Plant mycorrhizal traits, such as those characterising mycorrhizal type (arbuscular (AM), ecto‐, ericoid or orchid mycorrhiza) and status (obligately (OM), facultatively (FM) or non‐mycorrhizal) offer valuable insight into plant belowground functionality. Here, we compile available plant mycorrhizal trait information and global occurrence data (∼100 million records) for 11,770 vascular plant species. Using a plant phylogenetic mega‐tree and high‐resolution climatic and edaphic data layers, we assess phylogenetic and environmental correlates of plant mycorrhizal traits. We find that plant mycorrhizal type is more phylogenetically conserved than plant mycorrhizal status, while environmental variables (both climatic and edaphic; notably soil texture) explain more variation in mycorrhizal status, especially FM. The previously underestimated role of environmental conditions has far‐reaching implications for our understanding of ecosystem functioning under changing climatic and soil conditions. [ABSTRACT FROM AUTHOR]

Both enemies and mutualists play crucial roles in shaping plant invasion processes. Recent studies have suggested that resource fluctuations could indirectly promote plant invasion through higher trophic levels, such as enemies. However, the influence of mutualists like arbuscular mycorrhizal fungi (AMF) on plant invasion under nitrogen fluctuations remains untested.We conducted a pot mesocosm experiment using a three‐factorial experimental design to assess the individual and interactive effects of nitrogen availability, nitrogen fluctuation and AMF on invasive success of alien plants. We grew nine invasive alien species alongside five different native communities in pot mesocosms. These were then subjected to varied nitrogen availabilities (low vs. high), nitrogen fluctuations (constant vs. pulsed) and AMF presence or absence within a sterile substrate.We found that pulsed nitrogen supply increased the dominance of invasive alien species in low nitrogen availability, regardless of the presence or absence of AMF inoculation. However, in high nitrogen availability, pulsed nitrogen supply only enhanced this dominance in pots without AMF inoculation. This was tentatively evidenced by the three‐way interaction among nitrogen‐availability, nitrogen‐fluctuation and AMF‐inoculation treatments. Furthermore, the dominance promotion by nitrogen addition was greater than that by AMF inoculation.Synthesis and applications. Our findings present, for the first time, evidence that AMF may play a crucial role in mediating the promotion effects of nitrogen fluctuations on alien plant invasion. To better understand the invasion process of alien plants and evaluate their impact on native communities, future research should integrate abiotic and biotic drivers into a single framework. Furthermore, our findings underscore the importance of prioritizing habitats with higher nutrient availability and variability for protection against alien plant invasions. [ABSTRACT FROM AUTHOR]

Background. Because of swift climate change, drought is a primary environmental factor that substantially diminishes plant productivity. Furthermore, the increased use of chemical fertilizers has given rise to numerous environmental problems and health risks. Presently, there is a transition towards biofertilizers to enhance crops' yield, encompassing medicinal and aromatic varieties. Methods. This study aimed to explore the impacts of plant growth-promoting rhizobacteria (PGPR), both independently and in conjunction with arbuscular my-corrhizal fungi (AMF), on various morphological, physiological, and phytochemical characteristics of Dracocephalum kotschyi Boiss. This experimentation took place under different irrigation conditions. The irrigation schemes encompassed well watering (WW), mild water stress (MWS), and severe water stress (SWS). The study evaluated the effects of various biofertilizers, including AMF, PGPR, and the combined application of both AMF and PGPR (AMF C PGPR), compared to a control group where no biofertilizers were applied. Results. The findings of the study revealed that under water-stress conditions, the dry yield and relative water content of D. kotschyi Boiss. experienced a decline. However, the application of AMF, PGPR, and AMF C PGPR led to an enhancement in dry yield and relative water content compared to the control group. Among the treatments, the co-application of AMF and PGPR in plants subjected to well watering (WW) exhibited the tallest growth (65 cm), the highest leaf count (187), and the most elevated chlorophyll a (0.59 mg g-1 fw) and b (0.24 mg g-1 fw) content. Regarding essential oil production, the maximum content (1.29%) and yield (0.13 g plant-1) were obtained from mild water stress (MWS) treatment. The co-application of AMF and PGPR resulted in the highest essential oil content and yield (1.31% and 0.15 g plant-1, respectively). The analysis of D. kotschyi Boiss. essential oil identified twenty-six compounds, with major constituents including geranyl acetate (11.4-18.88%), alpha-pinene (9.33-15.08%), Bis (2-Ethylhexyl) phthalate (8.43-12.8%), neral (6.80-9.32%), geranial (9.23-11.91%), and limonene (5.56-9.12%). Notably, the highest content of geranyl acetate, geranial, limonene, and alpha-pinene was observed in plants subjected to MWS treatment following AMF C PGPR application. Furthermore, the co-application of AMF, PGPR, and severe water stress (SWS) notably increased the total soluble sugar (TSS) and proline content. In conclusion, the results indicate that the combined application of AMF and PGPR can effectively enhance the quantity and quality of essential oil in D. kotschyi Boiss., particularly when the plants are exposed to water deficit stress conditions. [ABSTRACT FROM AUTHOR]

Plant mycorrhizal associations influence the accumulation and persistence of soil organic matter and could therefore shape ecosystem biogeochemical responses to global changes that are altering forest composition. For instance, arbuscular mycorrhizal (AM) tree dominance is increasing in temperate forests, and ericoid mycorrhizal (ErM) shrubs can respond positively to canopy disturbances. Yet how shifts in the co‐occurrence of trees and shrubs with different mycorrhizal associations will affect soil organic matter pools remains largely unknown. We examine the effects of ErM shrubs on soil carbon and nitrogen stocks and indicators of microbial activity at different depths across gradients of AM versus ectomycorrhizal (EcM) tree dominance in three temperate forest sites. We find that ErM shrubs strongly modulate tree mycorrhizal dominance effects. In surface soils, ErM shrubs increase particulate organic matter accumulation and weaken the positive relationship between soil organic matter stocks and indicators of microbial activity. These effects are strongest under AM trees that lack fungal symbionts that can degrade organic matter. In subsurface soil organic matter pools, by contrast, tree mycorrhizal dominance effects are stronger than those of ErM shrubs. Ectomycorrhizal tree dominance has a negative influence on particulate and mineral‐associated soil organic matter pools, and these effects are stronger for nitrogen than for carbon stocks. Our findings suggest that increasing co‐occurrence of ErM shrubs and AM trees will enhance particulate organic matter accumulation in surface soils by suppressing microbial activity while having little influence on mineral‐associated organic matter in subsurface soils. Our study highlights the importance of considering interactions between co‐occurring plant mycorrhizal types, as well as their depth‐dependent effects, for projecting changes in soil carbon and nitrogen stocks in response to compositional shifts in temperate forests driven by disturbances and global change. [ABSTRACT FROM AUTHOR]

Arsenic (As) pollution in wetlands, mainly as As(III) and As(V), has threatened wetland plant growth. It has been well documented that arbuscular mycorrhizal (AM) fungi can alleviate As stress in terrestrial plants. However, whether AM fungi can protect natural wetland plants from As stress remains largely unknown. Therefore, three hydroponic experiments were conducted in which Iris tectorum Maxim. (I. tectorum) plants were exposed to As(III) or As(V) stresses, to investigate the effects of mycorrhizal inoculation on As uptake, efflux, and accumulation. The results suggested that short-term kinetics of As influx in I. tectorum followed the Michaelis–Menten function. Mycorrhizal inoculation decreased the maximum uptake rate (Vmax) and Michaelis constant (Km) of plants for As(III) influx, while yielding no significant difference in As(V) influx. Generally, mycorrhizal plants released more As into environments after 72 h efflux, especially under As(V) exposure. Moreover, mycorrhizal plants exhibited potential higher As accumulation capacity, probably due to more active As reduction, which was one of the mechanisms through which AM fungi mitigate As phytotoxicity. Our study has revealed the role of aerobic microorganism AM fungi in regulating As translocation in wetland plants and supports the involvement of AM fungi in alleviating plant As stress in anaerobic wetlands. [ABSTRACT FROM AUTHOR]

Introduction: Ascochyta blight caused by the fungus Ascochyta rabiei plays an important role in reducing chickpea yield and seed quality in many parts of the world. The aim of this study was to investigate the potential of arbuscular mycorrhizal fungi (AMF) in improving plant growth parameters and the biocontrol of this pathogen on two chickpea varieties. Materials and Methods: Five AMF species including Funneliformis mosseae, Gigaspora margarita, Glomus fasciculatum, Glomus versiform, and Rhizophagus irregularis were investigated for their potential in suppressing the Ascochyta blight on two chickpea varieties, Saral and Bivanij in comparison with chlorothalonil fungicide. Their effects were also examined on some plant growth parameters in the presence of a pathogen. This research was performed in greenhouse in a factorial experiment based on a completely randomized design including 16 treatments with six replications. Results: Chlorothalonil had the highest suppression against A. rabiei in both chickpea varieties. All AMF (except G. fasciculatum in variety Saral) significantly decreased the disease index compared to the infected control. The highest disease suppression by AMF was obtained by R. irregularis (46.15%) and G. versiform (42.30%) on variety Saral and by G. fasciculatum (40%) on variety Bivanij. Most of AMF enhanced chickpea growth parameters in the presence of pathogen with R. irregularis and G. fasciculatum showing the best effects on Saral and Bivanij, respectively. G. fasciculatum had the highest root colonization on both chickpea varieties. Discussion and Conclusion: The results of this study showed that AMF can promote plant growth parameters and attenuate the A. rabiei-induced losses in two chickpeas varieties. The rates of disease suppression and growth promotion depended on plant genotype and AMF species. No relationship was observed between the rates of root colonization by AMF and the reduction of Ascochyta blight symptoms. [ABSTRACT FROM AUTHOR]

A greenhouse study was conducted to investigate the effect of arbuscular mycorrhiza fungus and plant growth-promoting rhizobacteria on maize (Zea mays L.) yield and boron (B) uptake under excessive B concentrations. Four levels of B (0, 10, 20 and 40 mg kg-1 soil) and four levels of microbial inoculation (noninoculation, Rhizophagus intraradices, Micrococcus yunnanensis and co-inoculation) were applied. In general, elevated B decreased the maize relative yield, plant dry weight, plant height, total leaf area and chlorophyll content. The highest B uptake was recorded in the 20 mg kg-1 B treatments, whereas the lowest uptake was in B treatments of 0 and 40 mg B kg-1. Excessive B supply increased the proline content and electrolyte leakage of maize leaves. Microbial inoculation did not change the yield of B-stressed plants. In addition, mycorrhiza inoculation and co-inoculation increased the shoot and root B uptake. Maize plants growing at high B concentrations with or without microbial inoculation showed leaf edge burning and necrosis when compared with control treatments. Microbial inoculation improved the maize yield under B stress up to 20 mg B kg-1. Thus, inoculation with arbuscular mycorrhiza and plant growth promoting rhizobacteria can increase the maize tolerance under B toxicity. Nonetheless, the inoculation of bacterium and arbuscular mycorrhiza had a more alleviative effect when the plants were exposed to excess B. [ABSTRACT FROM AUTHOR]

Watermelon (Citrullus lanatus) is susceptible to wilt disease caused by Fusarium oxysporum f. sp niveum (FON). AMF colonization alleviates watermelon wilt and regulates the composition of root exudates, but the effects of mycorrhizal watermelon root exudates on watermelon Fusarium wilt is not well understood. Root exudates of watermelon inoculated with AMF (Funeliformis mosseae or Glomus versiformme) were collected in this study. Then the root exudates of control plants and mycorrhizal plants were used to irrigate watermelon in continuous cropping soil, respectively. Meanwhile, the watermelon growth, antioxidant enzyme activity, rhizosphere soil enzyme activities and bacterial community composition, as well as the control effect on FON were analyzed. The results indicated that mycorrhizal watermelon root exudates promoted the growth of watermelon seedlings and increased soil enzyme activities, actinomyces, and the quantity of bacteria in rhizosphere soil. The proportion of Proteobacteria and Bacteroides was decreased, and the proportion of Actinobacteria, Firmicutes, and Chloroflexi in rhizosphere soil was increased when the seedlings were watered with high concentrations of mycorrhizal root exudates. The dominant bacterial genera in rhizosphere soil were Kaistobacter, Rhodanobacter, Thermomonas, Devosia, and Bacillus. The root exudates of mycorrhizal watermelon could reduce the disease index of Fusarium wilt by 6.7--30%, and five ml/L of watermelon root exudates inoculated with F. mosseae had the strongest inhibitory effect on watermelon Fusarium wilt. Our results suggest mycorrhizal watermelon root exudates changed the composition of bacteria and soil enzyme activities in rhizosphere soil, which increase the resistance of watermelon to Fusarium wilt and promoted the growth of plants in continuous cropping soil. [ABSTRACT FROM AUTHOR]

Background and Aims: Plant-arbuscular mycorrhizal fungi (AMF) symbiosis and nutrient resorption are key to resource use and conservation strategies for wild plants. However, it remains unclear how grazing and plant-AMF symbiosis affects nutrient resorption by perennial plants in grasslands. Methods: Using combined field grazing and AMF suppression with benomyl experiments, we examined the impact of grazing intensity and plant-AMF symbiosis on nitrogen (N) and phosphorus (P) resorption by dominant species, and quantified the relative contributions of leaves and culms to the total amount of nutrient resorption. Results: AMF suppression increased N rather than P concentrations in green and senesced leaves of dominant species, resulting in greater N:P ratios within these organs. AMF suppression increased P resorption efficiency under no-light and moderate grazing and negatively affected P resorption efficiency under heavy grazing. Additionally, the younger leaves had higher N and P concentrations and greater resorption efficiencies than the older leaves regardless of AMF suppression. Although less than leaves, culms (photosynthetic stems) contributed to a large proportion of the resorbed and remaining N and P in shoots. Conclusion: The effects of AMF on nutrient resorption by dominant perennial species are mediated by grazing intensity, which modifies the costs and benefits of plant-AMF symbiosis. Different aged leaves differ in their N and P resorption efficiencies, and nutrient resorption of culms also plays an important role in whole-plant nutrient budgets. This study provides new insight into the whole-plant economic spectrum and has important implications for optimizing grazing management and improving biogeochemical models. [ABSTRACT FROM AUTHOR]

Aims: Mycorrhiza and rhizodeposition are important for nutrient and water uptake but their role under variable water conditions remains unclear. We investigated how mycorrhiza and rhizodeposition contributed to plant uptake of water, nitrogen (N) and phosphorus (P) in response to water availability and variability. Methods: Two tomato genotypes (a mycorrhiza-defective tomato mutant, rmc, and its mycorrhizal wild-type progenitor, Solanum lycopersicum cv. Rio Grande 76R were grown in a greenhouse under different watering conditions (wet, medium, and dry conditions, and dry-rewet conditions). Results: We found that non-mycorrhizal plants were as successful as mycorrhizal plants in terms of N and water uptake under both reduced and variable water availability. However, we observed lower water use efficiency and shoot N recovery in mycorrhizal plants that could be driven by mycorrhizal requirements for water and N. Mycorrhizal plants were more extensively colonised and were more successful in taking up P under dry conditions compared to non-mycorrhizal plants. On the other hand, greater specific root exudation in non-mycorrhizal plants across all watering conditions resulted in relatively greater uptake of N than of P. Conclusions: A flexible carbon allocation towards mycorrhiza and root exudation may help plants in maintaining a balanced uptake of N and P under variable water conditions. [ABSTRACT FROM AUTHOR]

Plant colonization by arbuscular mycorrhizal fungi (AMF) is widespread and can offer considerable benefits in terms of growth, nutrient uptake and plant yield. However, it is still unresolved how different plant species and plant functional groups respond to AMF and to different AMF taxa.Here we established 336 grassland microcosms to determine the response of 14 plant species displaying contrasting functional groups (grasses, legumes and non‐leguminous forbs) for the presence of three different AMF taxa. For each plant species, we calculated the degree to which plant growth depended on AMF colonization (i.e. mycorrhizal dependency [MD]). We also determined the degree to which each plant species relied on specific AMF taxa for optimal growth (i.e. mycorrhizal species sensitivity [MSS]). Additionally, we determined whether MD and MSS correlated to specific plant traits (i.e. specific root length [SRL], specific leaf area [SLA]).The plant growth response to AMF ranged from −84.9% for a non‐mycorrhizal plant (Luzula campestris) to +94.0% for a legume (Trifolium arvensis). The MD was systematically higher in legumes (91.9% ± 2.4%), followed by non‐leguminous forbs (77.1% ± 11.06) and grasses (42.1% ± 15.73%). MSS was less variable (8.9%–37.7%); it was independent of plant functional group and did not correlate with MD. MD was linked to various mycorrhizal plant parameters, including AMF colonization (R2 = +0.80) and total dry biomass (R2 = +0.32). Moreover, among mycorrhizal plants (n = 12), MD negatively correlated with SRL (R2 = −0.24) and positively with SLA (R2 = +0.24).Synthesis. This study shows that plants relying on AMF for biomass production also show higher root colonization, lower SRL, higher SLA and that different plant traits are interlinked with the way how plants respond to AMF. Overall, this study further demonstrates that different plant functional groups vary in their response to AMF. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Strigolactones (SLs) are a class of plant hormones that regulate many aspects of plant growth and development. SLs also improve symbiosis with arbuscular mycorrhizal fungi (AMF) in the rhizosphere. Recent studies have shown that the DWARF14-LIKE (D14L)/KARRIKIN-INSENSITIVE2 (KAI2) family, paralogs of the SL receptor D14, are required for AMF colonization in several flowering plants, including rice. In this study, we found that (−)-GR5, a 2′ S -configured enantiomer of a synthetic SL analog (+)-GR5, significantly activated SL biosynthesis in rice roots via D14L. This result is consistent with a recent report, showing that the D14L pathway positively regulates SL biosynthesis in rice. In fact, the SL levels tended to be lower in the roots of the d14l mutant under both inorganic nutrient-deficient and -sufficient conditions. We also show that the increase in SL levels by (−)-GR5 was observed in other mycorrhizal plant species. In contrast, the KAI2 pathway did not upregulate the SL level and the expression of SL biosynthetic genes in Arabidopsis , a non-mycorrhizal plant. We also examined whether the KAI2 pathway enhances SL biosynthesis in the liverwort Marchantia paleacea , where SL functions as a rhizosphere signaling molecule for AMF. However, the SL level and SL biosynthetic genes were not positively regulated by the KAI2 pathway. These results imply that the activation of SL biosynthesis by the D14L/KAI2 pathway has been evolutionarily acquired after the divergence of bryophytes to efficiently promote symbiosis with AMF, although we cannot exclude the possibility that liverworts have specifically lost this regulatory system. [ABSTRACT FROM AUTHOR]

Societal Impact Statement: The world faces major changes in rainfall patterns and water availability, posing a significant threat to plant productions systems and food security. The arbuscular mycorrhizal (AM) fungi associate with most major crops and can support plant nutrient and water uptake. Here, AM fungi were shown to mitigate the negative effects of low water availability on sorghum growth and phosphorus uptake, an effect that was associated with shifts in the fungal community structure. To realise the potential of AM fungi in sustainable agriculture requires more examination of their interactions with edaphic stresses in crop systems. [ABSTRACT FROM AUTHOR]

Drought stress (DS) is one of the severe abiotic stresses that cause reductions in agricultural production. This study was conducted to examine the efficiency of arbuscular mycorrhizal fungi (M: consortium) and plant growth-promoting rhizobacteria (R: Z2 and Z4 strains, B: CHIN14, AAP22, AAP2, and CHIN15 strains), individually or in combination, as an appropriate strategy to improve durum wheat productivity under two water regimes: well-watered (75% FC) and DS (25% FC). DS exhibition reduced biomass, stomatal conductance, stem water potential, and increased malondialdehyde and hydrogen peroxide content. Under DS, AMF or B promoted plant growth, such as shoot height by 49 and 17%, respectively; by activating the photosynthetic mechanism and increasing the synthesis of proline content by 369% in plants treated with AMF, and antioxidant enzyme activities, such as polyphenoloxydase (PPO), in leaves by 36% in plant inoculated with B. After the experiment, total organic matter and carbon of the soil were improved by single application of B by 99 and 317%, respectively. This finding implies that the combination of mycorrhiza and PGPR regulates the physiological and biochemical processes utilized by wheat to cope with drought and improves the comprehension of the soil-plant relationship. [ABSTRACT FROM AUTHOR]