Search Results (16)

Ectomycorrhizal (ECM) symbiosis is a fundamental mutualism crucial for forest eco-system health. Its establishment is governed by sophisticated molecular dialogue preceding physical colonization. This review synthesizes this pre-colonization crosstalk, beginning with reciprocal signal exchange where root exudates trigger fungal growth, and fungal lipochitooligosaccharides activate host symbiotic programming, often via the common symbiosis pathway. Successful colonization requires fungi to navigate plant immunity. They employ effectors, notably mycorrhiza-induced small secreted proteins (MiSSPs), to suppress defenses, e.g., by stabilizing jasmonate signaling repressors or inhibiting apoplastic proteases, establishing a localized “mycorrhiza-induced resistance.” Concurrent structural adaptations, including fungal hydrophobins, expansins, and cell wall-modifying enzymes like chitin deacetylase, facilitate adhesion and apoplastic penetration. While this sequential model integrates immune suppression with structural remodeling, current understanding is predominantly derived from a limited set of model systems. Significant knowledge gaps persist regarding species-specific determinants in non-model fungi and hosts, the influence of environmental variability and microbiome interactions, and methodological challenges in capturing early signaling in situ. This review’s main contributions are: providing a synthesized sequential model of molecular crosstalk; elucidating the dual fungal strategy of simultaneous immune suppression and structural remodeling; and identifying crucial knowledge gaps regarding non-model systems and species-specific determinants, establishing a research roadmap with implications for forest management and ecosystem sustainability. Full article

Volvariella volvacea were grown on an abandoned cotton-based substrate, which was divided into two conditions: a group with added nutrients (N3P3) and a control group (CK). Using metagenomic sequencing technology, the study investigated the effect of nutrient addition during the growth process of V. volvacea on the microbial community and metabolic pathways of the substrate. The study found that the main bacteria in the N3P3 group were Proteus and Microsporidium, while in the CK group, Bacillus marinosus and Microsporidium globosa were more common. At all stages of V. volvacea growth, Proteobacteria and Firmicutes dominated. Metabolic function analysis showed that the N3P3 group significantly increased amino acid metabolism, nitrogen metabolism, genetic information processing, and cellular processes, while reducing the contents of pathogenic and saprophytic symbiotic fungi. Nitrogen metabolism, phosphorus metabolism, and carbon metabolism were closely related to the growth of V. volvacea, and nutrient addition significantly improved microbial community diversity and metabolic levels, which can be used as a substrate optimization formula. This is of great significance for the development of sustainable agriculture. Full article

The fluctuating temperature poses challenges to the survival of amphibians. This study employed two cold-adapted brown frog species, Rana dybowskii and Rana amurensis, from high-latitude cold regions as research models. We explored the mechanism by which contrasting peak daily habitat temperatures affect their physiological function and symbiotic microbial community. The results indicate that these two cold-adapted brown frog species exhibit a common physiological response of enhanced immune capacity and suppressed antioxidant capacity when subjected to elevated temperatures. However, they demonstrate unique coping strategies and physiological regulatory effects on gut microbiota: R. dybowskii activates its immune system by reducing the abundance of Actinobacteria and inhibiting metabolic pathways, but the decrease in Bacteroidetes abundance impairs antioxidant efficacy. On the other hand, R. amurensis experiences impairment of antioxidant function due to the regulatory effects of a significant increase in Proteobacteria and Actinobacteria, a marked decrease in Bifidobacterium, and a decline in gut microbiota α-diversity. For the first time, this study reveals the adaptive mechanisms by which two cold-adapted amphibian species respond to the contrasting peak daily habitat temperatures, providing a scientific basis for understanding how ectotherms react to climate change and for predicting their population dynamics. Full article

Inflammatory facial dermatoses (atopic dermatitis [AD], acne vulgaris, contact dermatitis, seborrheic dermatitis, rosacea, perioral dermatitis, and demodicosis, etc.) often profoundly impact patients’ appearance and psychological well-being. In this narrative review, we wanted to present the current knowledge on the role of skin microbiota in common facial dermatoses. Skin keratinocytes are the primary producers of antimicrobial peptides (AMPs) and express Toll-like receptors (TLRs), which stimulate the T helper (Th1) immune response, with the production of interferon (IFN). They can also produce certain pro-inflammatory cytokines, namely IL-1β, IL-18, IL-6, IL-10, and the tumor necrosis factor (TNF). In healthy infants, the bacterial skin microbiota is predominantly composed of Firmicutes (genera Staphylococcus and Streptococcus), as well as Actinobacteria, Proteobactera, and Bacteroidota. The genera Cutibacterium and Staphylococcus, which have antimicrobial effects and compete with pathogens for nutrients/ecological niches, coexist symbiotically on the skin and can reduce the expression of TLR2 and TLR4. In patients with AD, lesional/non-lesional skin was found to have increased colonization by Staphylococcus aureus which reduces effector T lymphocytes’ ability to produce cytokines, such as IL-17A and IFN-γ, leading to decreased AMP production and impaired skin microbiota immune functionality. In patients with rosacea, the overexpression of TLR2 may stimulate elevated pro-inflammatory cytokine production (IL-8, IL-1β, and TNF-α, etc.), exacerbating the inflammatory response. Also, increased colonization by Malassezia yeasts triggers a Th2 immune response and cytokine secretion (IL-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, TNF-α, beta-defensin, IFN-γ, nitric oxide, and histamine), and participates in signaling pathways. Insight into these factors may further improve clinical approaches to patients with facial dermatoses. Full article

Sunflower (Helianthus annuus L.) is specifically infected by an obligatory root parasitic plant Orobanche cumana Wallr. (sunflower broomrape), which causes significant losses of sunflower yield. Breeding of sunflower varieties resistant to broomrape is an important challenge for agriculture. However, the selection of new resistant sunflower varieties was accompanied by the emergence of new virulent races of broomrape, which overcame the effect of resistance genes. Unraveling the molecular mechanisms underlying the resistance to broomrape in sunflowers should facilitate the development of new sunflower varieties with complex resistance to broomrape using genome editing technology. Here, we used CRISPR/Cas9-mediated genome editing in sunflower hairy roots for a specific knock-out of the gene encoding a GRAS transcription factor (HaNSP1a), acting as a possible regulator of strigolactone biosynthesis, a class of phytohormones known to induce the germination of broomrape seeds. According to HPLC-IT-TOF/MS analysis, the levels of orobanchol were decreased in the genetically modified roots with knock-out of the HaNSP1a gene, whereas, in contrast, 5-deoxystrigol levels were increased in the roots with HaNSP1a knock-out, suggesting the role of HaNSP1a in the regulation of the strigolactone biosynthetic pathway. The experimental approach described here could be used in further studies to test the effect of gene knock-out on the development of resistance to O. cumana in sunflowers. Full article

Rhizobia secrete effectors that are essential for the effective establishment of their symbiotic interactions with leguminous host plants. However, the signaling pathways governing rhizobial type III effectors have yet to be sufficiently characterized. In the present study, the type III effectors, NopAA and NopD, which perhaps have signaling pathway crosstalk in the regulation of plant defense responses, have been studied together for the first time during nodulation. Initial qRT-PCR experiments were used to explore the impact of NopAA and NopD on marker genes associated with symbiosis and defense responses. The effects of these effectors on nodulation were then assessed by generating bacteria in which both NopAA and NopD were mutated. RNA-sequencing analyses of soybean roots were further utilized to assess signaling crosstalk between NopAA and NopD. NopAA mutant and NopD mutant were both found to repress GmPR1, GmPR2, and GmPR5 expression in these roots. The two mutants also significantly reduced nodules dry weight and the number of nodules and infection threads, although these changes were not significantly different from those observed following inoculation with double-mutant (HH103ΩNopAA&NopD). NopAA and NopD co-mutant inoculation was primarily found to impact the plant–pathogen interaction pathway. Common differentially expressed genes (DEGs) associated with both NopAA and NopD were enriched in the plant–pathogen interaction, plant hormone signal transduction, and MAPK signaling pathways, and no further changes in these common DEGs were noted in response to inoculation with HH103ΩNopAA&NopD. Glyma.13G279900 (GmNAC27) was ultimately identified as being significantly upregulated in the context of HH103ΩNopAA&NopD inoculation, serving as a positive regulator of nodulation. These results provide new insight into the synergistic impact that specific effectors can have on the establishment of symbiosis and the responses of host plant proteins. Full article

The symbiotic fixation of atmospheric nitrogen (N) in root nodules of tropical legumes such as pigeonpea (Cajanus cajan) is a complex process, which is regulated by multiple genetic factors at the host plant genotype microsymbiont interface. The process involves multiple genes with various modes of action and is accomplished only when both organisms are compatible. Therefore, it is necessary to develop tools for the genetic manipulation of the host or bacterium towards improving N fixation. In this study, we sequenced the genome of a robust rhizobial strain, Rhizobium tropici ‘10ap3’ that was compatible with pigeonpea, and we determined its genome size. The genome consisted of a large circular chromosome (6,297,373 bp) and contained 6013 genes of which 99.13% were coding sequences. However only 5833 of the genes were associated with proteins that could be assigned to specific functions. The genes for nitrogen, phosphorus and iron metabolism, stress response and the adenosine monophosphate nucleoside for purine conversion were present in the genome. However, the genome contained no common nod genes, suggesting that an alternative pathway involving a purine derivative was involved in the symbiotic association with pigeonpea. Full article

Plants typically interact with a variety of microorganisms, including bacteria, mycorrhizal fungi, and other organisms, in their above- and below-ground parts. In the biosphere, the interactions of plants with diverse microbes enable them to acquire a wide range of symbiotic advantages, resulting in enhanced plant growth and development and stress tolerance to toxic metals (TMs). Recent studies have shown that certain microorganisms can reduce the accumulation of TMs in plants through various mechanisms and can reduce the bioavailability of TMs in soil. However, relevant progress is lacking in summarization. This review mechanistically summarizes the common mediating pathways, detoxification strategies, and homeostatic mechanisms based on the research progress of the joint prevention and control of TMs by arbuscular mycorrhizal fungi (AMF)-plant and Rhizobium-plant interactions. Given the importance of tripartite mutualism in the plant-microbe system, it is necessary to further explore key signaling molecules to understand the role of plant-microbe mutualism in improving plant tolerance under heavy metal stress in the contaminated soil environments. It is hoped that our findings will be useful in studying plant stress tolerance under a broad range of environmental conditions and will help in developing new technologies for ensuring crop health and performance in future. Full article

Terrestrial isopods are effective herbivorous scavengers with an important ecological role in organic matter cycling. Their guts are considered to be a natural enrichment environment for lignocellulosic biomass (LCB)-degrading bacteria. The main goal of this work was to assess the structural diversity of Porcellio dilatatus gut bacterial communities using NGS technologies, and to predict their functional potential using PICRUSt2 software. Pseudomonadota, Actinomycetota, Bacillota, Cyanobacteria, Mycoplasmatota, Bacteroidota, Candidatus Patescibacteria and Chloroflexota were the most abundant phyla found in P. dilatatus gut bacterial communities. At a family level, we identified the presence of eleven common bacterial families. Functionally, the P. dilatatus gut bacterial communities exhibited enrichment in KEGG pathways related to the functional module of metabolism. With the predicted functional profile of P. dilatatus metagenomes, it was possible to envision putative symbiotic relationships between P. dilatatus gut bacterial communities and their hosts. It was also possible to foresee the presence of a well-adapted bacterial community responsible for nutrient uptake for the host and for maintaining host homeostasis. Genes encoding LCB-degrading enzymes were also predicted in all samples. Therefore, the P. dilatatus digestive tract may be considered a potential source of LCB-degrading enzymes that is not to be neglected. Full article

Colletotrichum is a plant pathogenic fungus which is able to infect virtually every economically important plant species. Up to now no common infection mechanism has been identified comparing different plant and Colletotrichum species. Plant hormones play a crucial role in plant-pathogen interactions regardless whether they are symbiotic or pathogenic. In this review we analyze the role of ethylene, abscisic acid, jasmonic acid, auxin and salicylic acid during Colletotrichum infections. Different Colletotrichum strains are capable of auxin production and this might contribute to virulence. In this review the role of different plant hormones in plant—Colletotrichum interactions will be discussed and thereby auxin biosynthetic pathways in Colletotrichum spp. will be proposed. Full article

Common themes of EU social policy include: the promotion of employment; improved living and working conditions; the equal treatment of employees; adequate social protection; and capacity building of the European citizenship. However, it is often the case that rural dwellers and, more specifically, rural NEETs, experience higher levels of marginalisation than their urban counterparts. Such marginalisation is evidenced by their exclusion from decision-making, public life, community, and society. These issues are compounded by an underdeveloped rural infrastructure, problematic access to education, limited employment opportunities, and a lack of meaningful social interaction. This study, a cross-sectional analysis, assesses a number (n = 51) of social interventions under the Youth Guarantee Programme from a social innovation perspective and presents a characterisation of examples of best practice across different dimensions of social innovations. This paper presents an examination of the potential of sustainable rural–urban ecosystems that are focused on supporting the symbiotic social innovation diffusion methods which can help to establish and sustain rural–urban pathways to improved education, employment, and training. Full article

Since the last century, episodes of coral reef bleaching and mortality have occurred almost annually in tropical or subtropical seas. When the temperature exceeds the tolerant limit of a coral–zooxanthellae holobiont, it induces physiological stress and disrupts the vulnerable fine-tuned balance between the two partners, leading to bleaching. The gene expression profiles of a scleractinian coral and its symbiotic zooxanthellae can offer important information with which to decipher this balanced relationship at the functional level of genes. Here, we sequence a full-length transcriptome of a well-known, common and frequently dominant reef-building coral, Pocillopora damicornis, to acquire gene expression information for the coral–zooxanthellae holobiont. To this end, we identify 21,926 and 465 unique genes in the coral and algal symbiont, respectively, and examine the functional enrichment among these genes based on GO (gene ontology) terms and KEGG (the Kyoto Encyclopedia of Genes and Genomes) pathways. The results show that the zooxanthellae provide for their coral host through energy and nutrition metabolism by photosynthesis, and that both the coral host and zooxanthellae have an anti-stress molecular mechanism, though the two parties have independent abilities to survive in the short term. This work sheds light on the valuable gene expression profile of a coral–zooxanthellae holobiont and provides grounds for further molecular biological research to support ecological protection work. Full article

Nitrogen is a major determinant of plant growth and productivity and the ability of legumes to form a symbiotic relationship with nitrogen-fixing rhizobia bacteria allows legumes to exploit nitrogen-poor niches in the biosphere. But hosting nitrogen-fixing bacteria comes with a metabolic cost, and the process requires regulation. The symbiosis is regulated through three signal transduction pathways: in response to available nitrogen, at the initiation of contact between the organisms, and during the development of the nodules that will host the rhizobia. Here we provide an overview of our knowledge of how the three signaling pathways operate in space and time, and what we know about the cross-talk between symbiotic signaling for nodule initiation and organogenesis, nitrate dependent signaling, and autoregulation of nodulation. Identification of common components and points of intersection suggest directions for research on the fine-tuning of the plant’s response to rhizobia. Full article

Seeds of almost all orchids depend on mycorrhizal fungi to induce their germination in the wild. The regulation of this symbiotic germination of orchid seeds involves complex crosstalk interactions between mycorrhizal establishment and the germination process. The aim of this study was to investigate the effect of gibberellins (GAs) on the symbiotic germination of Dendrobium officinale seeds and its functioning in the mutualistic interaction between orchid species and their mycobionts. To do this, we used liquid chromatograph-mass spectrometer to quantify endogenous hormones across different development stages between symbiotic and asymbiotic germination of D. officinale, as well as real-time quantitative PCR to investigate gene expression levels during seed germination under the different treatment concentrations of exogenous gibberellic acids (GA₃). Our results showed that the level of endogenous GA₃ was not significantly different between the asymbiotic and symbiotic germination groups, but the ratio of GA₃ and abscisic acids (ABA) was significantly higher during symbiotic germination than asymbiotic germination. Exogenous GA₃ treatment showed that a high concentration of GA₃ could inhibit fungal colonization in the embryo cell and decrease the seed germination rate, but did not significantly affect asymbiotic germination or the growth of the free-living fungal mycelium. The expression of genes involved in the common symbiotic pathway (e.g., calcium-binding protein and calcium-dependent protein kinase) responded to the changed concentrations of exogenous GA₃. Taken together, our results demonstrate that GA₃ is probably a key signal molecule for crosstalk between the seed germination pathway and mycorrhiza symbiosis during the orchid seed symbiotic germination. Full article

Maintaining a symbiotic oral microbiota is essential for oral and dental health, and host genetic factors may affect the composition or function of the oral microbiota through a range of possible mechanisms, including immune pathways. The study included 836 Swedish twins divided into separate groups of adolescents (n = 418) and unrelated adults (n = 418). Oral microbiota composition and functions of non-enzymatically lysed oral bacteria samples were evaluated using 16S rRNA gene sequencing and functional bioinformatics tools in the adolescents. Adaptive immune responses were assessed by testing for serum IgG antibodies against a panel of common oral bacteria in adults. In the adolescents, host genetic factors were associated with both the detection and abundance of microbial species, but with considerable variation between species. Host genetic factors were associated with predicted microbiota functions, including several functions related to bacterial sucrose, fructose, and carbohydrate metabolism. In adults, genetic factors were associated with serum antibodies against oral bacteria. In conclusion, host genetic factors affect the composition of the oral microbiota at a species level, and host-governed adaptive immune responses, and also affect the concerted functions of the oral microbiota as a whole. This may help explain why some people are genetically predisposed to the major dental diseases of caries and periodontitis. Full article