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Epichloë is a genus of filamentous fungal endophytes that have co-evolved with cool-season grasses with which they form long-term, symbiotic associations. In natural ecosystems Epichloë have implications for species diversity, food web structures and fundamental ecological processes. Epichloë produce a range of secondary metabolites that can have negative effects on herbivores, be they invertebrates or vertebrates. In many managed pastoral systems, selected asexual Epichloë strains are purposefully associated with grass cultivars (termed novel endophyte-grass associations) as they confer beneficial traits that protect the host from abiotic stresses (e.g. drought) and biotic stresses (e.g. herbivory from invertebrates) while having minimal impact on the health and welfare of ruminant livestock. As well as conferring beneficial traits, agriculturally selected strains of Epichloë can also increase plant biomass and seed yield. Epichloë endophyte-technology has and continues to be a scientific, agricultural, and marketing success with selected asexual strains of Epichloë now essential components of many pasture ecosystems, within New Zealand and abroad. An estimated 90% of proprietary ryegrass now sold in New Zealand contains a selected endophyte strain while the economic impact in New Zealand of AR37 alone has been estimated at NZ$3.6 billion over 20 years. With a changing climate, agriculture will continue to experience increasing temperatures, elevated atmospheric CO2 levels and changing precipitation patterns that will likely increase the geographic range and overwintering survival rates of pests. Furthermore, plant disease outbreaks are expected to intensify due to increases in the severity of existing phytopathogens and/or invasions by new phytopathogens. Functional symbioses, such as those between temperate grasses and Epichloë, are among the most successful mechanisms by which plants can improve their ability to tolerate stress. Future research is likely to utilise targeted genetic manipulation techniques to broaden the biocontrol ability of Epichloë strains, particularly to mitigate climate related stresses. [ABSTRACT FROM AUTHOR]

Gastrodia elata Blume, a fully mycoheterotrophic perennial plant of the family Orchidaceae, is a traditional Chinese herb with medicinal and edible value. Interestingly, G. elata requires symbiotic relationships with Mycena and Armillaria strains for seed germination and plant growth, respectively. However, there is no comprehensive summary of the symbiotic mechanism between fungi and G. elata. Here, the colonization and digestion of hyphae, the bidirectional exchange of nutrients, the adaptation of fungi and G. elata to symbiosis, and the role of microorganisms and secondary metabolites in the symbiotic relationship between fungi and G. elata are summarized. We comprehensively and deeply analyzed the mechanism of symbiosis between G. elata and fungi from three perspectives: morphology, nutrition, and molecules. The aim of this review was to enrich the understanding of the mutualistic symbiosis mechanisms between plants and fungi and lay a theoretical foundation for the ecological cultivation of G. elata. [ABSTRACT FROM AUTHOR]

Summary: Ectomycorrhizal (EcM) symbiosis, a ubiquitous plant–fungus interaction in forests, evolved in parallel in fungi. Why the evolution of EcM fungi did not necessarily increase ecological opportunities for explosive diversification remains unclear. This study aimed to reveal the driving mechanism of the evolutionary diversification in the fungal class Agaricomycetes, specifically by testing whether the evolution of EcM symbiosis in the Late Cretaceous increased ecological opportunities.The historical character transitions of trophic state and fruitbody form were estimated based on phylogenies inferred from fragments of 89 single‐copy genes. Moreover, five analyses were used to estimate the net diversification rates (speciation rate minus extinction rate).The results indicate that the unidirectional evolution of EcM symbiosis occurred 27 times, ranging in date from the Early Triassic to the Early Paleogene. The increased diversification rates appeared to occur intensively at the stem of EcM fungal clades diverging in the Late Cretaceous, coinciding with the rapid diversification of EcM angiosperms. By contrast, the evolution of fruitbody form was not strongly linked with the increased diversification rates.These findings suggest that the evolution of EcM symbiosis in the Late Cretaceous, supposedly with coevolving EcM angiosperms, was the key drive of the explosive diversification in Agaricomycetes. [ABSTRACT FROM AUTHOR]

Mutualistic symbioses are common, especially in nutrient-poor environments where an association between hosts and symbionts can allow the symbiotic partners to persist and collectively out-compete non-symbiotic species. Usually these mutualisms are built on an intimate transfer of energy and nutrients (e.g. carbon and nitrogen) between host and symbiont. However, resource availability is not consistent, and the benefit of the symbiotic association can depend on the availability of resources to mutualists. We manipulated the diets of two temperate sea anemone species in the genus Anthopleura in the field and recorded the responses of sea anemones and algal symbionts in the family Symbiodiniaceae to our treatments. Algal symbiont density, symbiont volume and photosynthetic efficiency of symbionts responded to changes in sea anemone diet, but the responses depended on the species of sea anemone. We suggest that temperate sea anemones and their symbionts can respond to changes in anemone diet, modifying the balance between heterotrophy and autotrophy in the symbiosis. Our data support the hypothesis that symbionts are upregulated or downregulated based on food availability, allowing for a flexible nutritional strategy based on external resources.

Abstract Background The termite-fungus symbiosis is an ancient stable mutualism of two partners that reproduce and disperse independently. With the founding of each termite colony the symbiotic association must be re-established with a new fungus partner. Complementarity in the ability to break down plant substrate may help to stabilize this symbiosis despite horizontal symbiont transmission. An alternative, non-exclusive, hypothesis is that a reduced rate of evolution may contribute to stabilize the symbiosis, the so-called Red King Effect. Methods To explore this concept, we produced the first linkage map of a species of Termitomyces, using genotyping by sequencing (GBS) of 88 homokaryotic offspring. We constructed a highly contiguous genome assembly using PacBio data and a de-novo evidence-based annotation. This improved genome assembly and linkage map allowed for examination of the recombination landscape and its potential effect on the mutualistic lifestyle. Results Our linkage map resulted in a genome-wide recombination rate of 22 cM/Mb, lower than that of other related fungi. However, the total map length of 1370 cM was similar to that of other related fungi. Conclusions The apparently decreased rate of recombination is primarily due to genome expansion of islands of gene-poor repetitive sequences. This study highlights the importance of inclusion of genomic context in cross-species comparisons of recombination rate.

Symbiotic mutualisms are essential to ecosystems and numerous species across the tree of life. For reef-building corals, the benefits of their association with endosymbiotic dinoflagellates differ within and across taxa, and nutrient exchange between these partners is influenced by environmental conditions. Furthermore, it is widely assumed that corals associated with symbionts in the genus Durusdinium tolerate high thermal stress at the expense of lower nutrient exchange to support coral growth. We traced both inorganic carbon (H13CO3–) and nitrate (15NO3–) uptake by divergent symbiont species and quantified nutrient transfer to the host coral under normal temperatures as well as in colonies exposed to high thermal stress. Colonies representative of diverse coral taxa associated with Durusdinium trenchii or Cladocopium spp. exhibited similar nutrient exchange under ambient conditions. By contrast, heat-exposed colonies with D. trenchii experienced less physiological stress than conspecifics with Cladocopium spp. while high carbon assimilation and nutrient transfer to the host was maintained. This discovery differs from the prevailing notion that these mutualisms inevitably suffer trade-offs in physiological performance. These findings emphasize that many host–symbiont combinations adapted to high-temperature equatorial environments are high-functioning mutualisms; and why their increased prevalence is likely to be important to the future productivity and stability of coral reef ecosystems. [ABSTRACT FROM AUTHOR]

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Ecto- and endo-mycorrhizal colonization of Populus roots have a positive impact on the overall tree health and growth. A complete molecular understanding of these interactions will have important implications for increasing agricultural or forestry sustainability using plant:microbe-based strategies. These beneficial associations entail extensive morphological changes orchestrated by the genetic reprogramming in both organisms. In this study, we performed a comparative analysis of two Populus species (Populus deltoides and P. trichocarpa) that were colonized by either an arbuscular mycorrhizal fungus (AmF), Rhizophagus irregularis or an ectomycorrhizal fungus (EmF), Laccaria bicolor, to describe the small RNA (sRNA) landscape including small open reading frames (sORFs) and micro RNAs (miRNAs) involved in these mutualistic interactions. We identified differential expression of sRNAs that were, to a large extent, (1) within the genomic regions lacking annotated genes in the Populus genome and (2) distinct for each fungal interaction. These sRNAs may be a source of novel sORFs within a genome, and in this regard, we identified potential sORFs encoded by the sRNAs. We predicted a higher number of differentially-expressed miRNAs in P. trichocarpa (4 times more) than in P. deltoides (conserved and novel). In addition, 44 miRNAs were common in P. trichocarpa between the EmF and AmF treatments, and only 4 miRNAs were common in P. deltoides between the treatments. Root colonization by either fungus was more effective in P. trichocarpa than in P. deltoides, thus the relatively few differentially-expressed miRNAs predicted in P. deltoides might reflect the extent of the symbiosis. Finally, we predicted several genes targets for the plant miRNAs identified here, including potential fungal gene targets. Our findings shed light on additional molecular tiers with a role in Populus-fungal mutualistic associations and provides a set of potential molecular targets for future enhancement.

Background: The termite-fungus symbiosis is an ancient stable mutualism of two partners that reproduce and disperse independently. With the founding of each termite colony the symbiotic association must be re-established with a new fungus partner. Complementarity in the ability to break down plant substrate may help to stabilize this symbiosis despite horizontal symbiont transmission. An alternative, non-exclusive, hypothesis is that a reduced rate of evolution may contribute to stabilize the symbiosis, the so-called Red King Effect. Methods: To explore this concept, we produced the first linkage map of a species of Termitomyces, using genotyping by sequencing (GBS) of 88 homokaryotic offspring. We constructed a highly contiguous genome assembly using PacBio data and a de-novo evidence-based annotation. This improved genome assembly and linkage map allowed for examination of the recombination landscape and its potential effect on the mutualistic lifestyle. Results: Our linkage map resulted in a genome-wide recombination rate of 22 cM/Mb, lower than that of other related fungi. However, the total map length of 1370 cM was similar to that of other related fungi. Conclusions: The apparently decreased rate of recombination is primarily due to genome expansion of islands of gene-poor repetitive sequences. This study highlights the importance of inclusion of genomic context in cross-species comparisons of recombination rate. [ABSTRACT FROM AUTHOR]

Insect biological invasion causes great ecological and economic damage to invaded areas. The insect invasion process can be influenced by many biotic and abiotic factors. In recent years, an increasing number of studies have indicated that microbes play important roles during the insect invasion process. The presence of microbes may directly influence the successful invasion of insects. However, the complex relationship between invasive insects and microbes has not received adequate attention. In this review, the influence of specific microbes on the biological invasion of insects will be discussed. The review will highlight the important roles of insect-microbe interactions in biological invasions. The potential applications of symbiotic microbes in predicting the history and invasive routes of insects and the symbiotic microbes originated strategies for invasive insect management will be discussed. [ABSTRACT FROM AUTHOR]

The Lanping salt-horse ancient road realistically met the practical needs of survival within short-distance areas in historical society, and has a value that cannot be ignored during a certain period of the local social development in Yunnan. While scholars have focused on the discussion of single or multiple impacts brought about by the interaction between the routes and the local society, there were relatively few studies on the reasons that drove the development of the routes and the ancient Yunnan salt road. This paper traces the factors that prompted the extension of the salt-horse ancient road in Lanping. The opening of the Lajing and the social situation of salt shortage in the "four border counties" along the Nujiang river provided space for the extension and development of the salt road. The development of the salt road increased the number of the merchants trading with one another, thus promoting Lajing town, where salt was produced, and Yingpan town, where salt materials were distributed, to become the salt capital and distribution capital of western Yunnan, respectively. The flourishing of the streets and towns also enlivened the Lanping salt-horse ancient road, and the salt road achieved symbiosis in interaction with the streets and towns. [ABSTRACT FROM AUTHOR]

Chinese mitten crab (Eriocheir sinensis) culture in rice paddy fields is a representative model of integrated agriculture‐aquaculture systems developed in China over the last 30 years. The economic and ecological benefits of rice‐crab coculture are significantly improved compared to those of rice monoculture. Under coculture conditions, rice provides shelter for crabs and improves the aquatic environment, while crabs eliminate pests and weeds, reduce the need for chemical fertilizers and pesticides, and stabilize rice production. At the same time, rice‐crab coculture helps protect biodiversity and reduce greenhouse gas emissions. An in‐depth study has led to the significant development of rice‐crab coculture technology in China and has established ecological breeding models with regional characteristics. These studies have established breeding industry standards for paddy field engineering, stocking mode, water quality control, rice management, feeding, pest control and breeding management. However, more research is needed to standardize rice field engineering specifications, optimize coculture modes, clarify crab nutritional needs, develop disease prevention and control methods, elucidate the operational mechanism of rice‐crab coculture and ascertain energy‐material exchange with the external environment. Eventually, rice‐crab coculture can be highly integrated to utilize the fewest resources while providing the greatest economic and environmental benefits. This review provides a theoretical reference for further research in the field of rice‐crab coculture, examining aspects such as development history, economic benefits, organisms in the system (rice, crabs, plankton, zoobenthos, weeds and microorganisms), internal and external environmental benefits, and the direction of future development. [ABSTRACT FROM AUTHOR]

The mutualistic interaction specificity between attine ants and antibiotic-producing Actinobacteria has been controversial because Pseudonocardia strains cannot always be isolated from worker cuticles across attine ant species, while other actinobacteria can apparently replace Pseudonocardia and also inhibit growth of Escovopsis mycopathogens. Here we report that across field samples of Panamanian species: (i) Cuticular Pseudonocardia were largely restricted to species in the crown of the attine phylogeny and their appearance likely coincided with the first attines colonizing Central/North America. (ii) The phylogenetically basal attines almost always had cuticular associations with other Actinobacteria than Pseudonocardia . (iii) The sub-cuticular glands nourishing cuticular bacteria appear to be homologous throughout the phylogeny, consistent with an ancient general attine-Actinobacteria association. (iv) The basal attine species investigated always had Pseudonocardia as gut symbionts while Pseudonocardia presence appeared mutually exclusive between cuticular and gut microbiomes. (v) Gut-associated Pseudonocardia were phylogenetically ancestral while cuticular symbionts formed a derived crown group within the Pseudonocardia phylogeny. We further show that laboratory colonies often secondarily acquire cuticular Actinobacteria that they do not associate with in the field, suggesting that many previous studies were uninformative for questions of co-adaptation in the wild. An exhaustive literature survey showed that published studies concur with our present results, provided that they analyzed field colonies and that Actinobacteria were specifically isolated from worker cuticles shortly after field collection. Our results offer several testable hypotheses for a better overall understanding of attine- Pseudonocardia interaction dynamics and putative coevolution throughout the Americas., (© The Author(s) 2024. Published by Oxford University Press on behalf of National Academy of Sciences.)

Summary: Pathogenic microbes are known to manipulate the defences of their hosts through the production of secreted effector proteins. More recently, mutualistic mycorrhizal fungi have also been described as using these secreted effectors to promote host colonization. Here we characterize a mycorrhiza‐induced small secreted effector protein of 10 kDa produced by the ectomycorrhizal fungus Pisolithus albus, PaMiSSP10b.We demonstrate that PaMiSSP10b is secreted from fungal hyphae, enters the cells of its host, Eucalyptus grandis, and interacts with an S‐adenosyl methionine decarboxylase (AdoMetDC) in the polyamine pathway. Plant polyamines are regulatory molecules integral to the plant immune system during microbial challenge.Using biochemical and transgenic approaches we show that expression of PaMiSSP10b influences levels of polyamines in the plant roots as it enhances the enzymatic activity of AdoMetDC and increases the biosynthesis of higher polyamines. This ultimately favours the colonization success of P. albus.These results identify a new mechanism by which mutualistic microbes are able to manipulate the host´s enzymatic pathways to favour colonization. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal (AM) fungi often colonize the roots of mangrove plants, forming symbiotic associations with them, but colonization rates differ greatly among mangrove species. To examine differences in the colonization patterns of AM fungi, we focused on two species of mangroves (Rhizophora stylosa and Bruguiera gymnorhiza ; Rhizophoraceae) and conducted a pot experiment using seedlings grown in mangrove soil watered with fresh water or brackish water (200 mM NaCl). We observed AM fungal structures such as hyphae, arbuscles, and vesicles in the roots of all B. gymnorhiza seedlings in the freshwater treatment, but rarely in the brackish water treatment. By contrast, we found no AM fungal structures in roots of any R. stylosa seedlings in either the freshwater or brackish water treatment. These results imply that B. gymnorhiza are facultatively mycorrhizal plants that have maintained the ability to form associations with AM fungi, whereas R. stylosa , which dominate habitats more seaward than those of B. gymnorhiza , may have lost the ability to form mycorrhizal associations through adaptation to extreme seaside conditions. • Arbuscular mycorrhizal (AM) fungi colonized Bruguiera gymnorhiza roots. • Salinity may determine mycorrhizal colonization of mangrove plants. • Regardless of salinity, no AM fungal structures were found in Rhizophora stylosa. • Rhizophora stylosa may have lost the ability to associate with AM fungi. [ABSTRACT FROM AUTHOR]

Résumé: Les Polydnavirus illustrent un exemple unique d'interactions symbiotiques entre un virus et un organisme eucaryote. Ces sont des mutualistes obligatoires, associés à de nombreuses espèces d'hyménoptères parasitoïdes. Ils sont caractérisés par un génome encapsidé constitué de plusieurs molécules d'ADN et sont nécessaires à la réussite parasitaire. Les particules virales sont produites dans les ovaires à partir d'un corpus de séquences « virales » intégrées au génome de la guêpe. Les associations polydnavirus/guêpe telles qu'observées aujourd'hui résultent d'événements d'intégration de génomes viraux dans le génome des guêpes survenus au cours de l'évolution. Ces dernières années ont été marquées par la découverte des ancêtres viraux des deux types de Polydnavirus connus, les Bracovirus et les Ichnovirus, ce qui a permis d'éclairer en partie l'évolution de la symbiose. Une partie des gènes viraux a été conservée dans le génome du parasitoïde, permettant à ce dernier de produire des particules virales non réplicatives, car contenant un génome constitué essentiellement de gènes dits de « virulence », probablement d'origine insecte. Les Polydnavirus peuvent être considérés comme des éléments endogènes viraux (EVE) qui ont été domestiqués par la guêpe pour devenir au fil du temps une « arme » garantissant sa survie. Polydnaviruses are unique mutualistic viruses associated with thousands of parasitoid wasps. They are characterized by a segmented packaged DNA genome and are necessary for parasitic success. Virus particles are produced in the wasp ovaries from a set of "viral" sequences integrated into the wasp genome. The polydnavirus/wasp associations as observed today result from the integration of a viral genomes into the wasp genome during evolution. Recent years have been marked by the discovery of the viral ancestors of the two known types of polydnavirus, bracovirus and ichnovirus, which has helped to shed some light on the evolution of the symbiosis. Some of the viral genes have been conserved in the genome of the parasitoid, allowing the latter to produce non-replicative viral particles, that contain DNA molecules encoding essentially "virulence" genes, probably of insect origin. Thus polydnaviruses can be considered as endogenous viral elements (EVE) that have been domesticated by the wasp to become a "weapon" allowing its survival. [ABSTRACT FROM AUTHOR]

Highlights • The evolution of mutualism in multi-species communities is analyzed. • The conditions for the evolutionarily stable equilibria are derived. • The evolutionary rates and fate do not always show monotonic relationships. • The evolutionary fate of fast species can be predictable from the payoff matrix. Abstract Mutualistic interspecific interactions, including Müllerian mimicry and division of labor, are common in nature. In contrast to antagonistic interactions, where faster evolution is favored, mutualism can favor slower evolution under certain conditions. This is called the Red King effect. Since Bergstrom and Lachmann (2003) proposed the Red King effect, it has been investigated only in two-species models. However, biological examples suggest that mutualism can include three or more species. Here, I modeled the evolutionary dynamics of mutualism in communities where involving two or more species, and in which all species mutually interact. Regardless of the number of species in the community, it is possible to derive conditions for stable equilibria. Although nonlinear relationships exist between the evolutionary rates and the evolutionary fate of each species in the multi-species communities, the model suggests that it is possible to predict whether faster evolution is favored or disfavored for the relatively rapidly evolving species; however, it is difficult to predict the evolutionary fate of species that evolve relatively slowly because their evolutionary dynamics are affected by the evolutionary fate of species evolving rapidly. [ABSTRACT FROM AUTHOR]

Summary: Acquisition of mutualistic symbiosis could provide hosts and/or symbionts with novel ecological opportunities for evolutionary diversification. Such a mechanism is one of the major components of coevolutionary diversification. However, whether the origin of mycorrhizal symbiosis promotes diversification in fungi still requires clarification. Here, we aimed to reveal evolutionary diversification in a clade comprising ectomycorrhizal (ECM) fungi.Based on a phylogenic tree inferred from the sequences of 87 single‐copy genes, we reconstructed the origins of ECM symbiosis in a species‐rich basidiomycetous order, Boletales.High‐resolution phylogeny of Boletales revealed that ECM symbiosis independently evolved from non‐ECM states at least four times in the group. Among them, only the second most recent event, occurring in the clade of Boletaceae, was inferred to involve an almost synchronous rapid diversification and rapid transition from non‐ECM to ECM symbiosis.Our results contradict the hypothesis of evolutionary priority effect, which postulates the greatest ecological opportunities in the oldest lineages. Therefore, the novel resources that had not been pre‐empted by the old ECM fungal lineages – supposedly the coevolving angiosperm hosts – could be available for the young ECM fungal lineages, which resulted in evolutionary diversification occurring only in the young ECM fungal lineages. See also the Commentary on this article by Matheny & Fordyce, 222: 1670–1672. [ABSTRACT FROM AUTHOR]

Understanding the behavior of mycorrhiza-originated glomalin, either of plant or soil origin, is anticipated to facilitate better opportunities of modulating antioxidants and carbon distribution in plants. In this study, trifoliate orange seedlings with half of roots were colonized by Acaulospora scrobiculata and Funneliformis mosseae in a split-root rootbox. Mycorrhizal inoculation showed a significantly higher plant biomass of trifoliate orange, regardless of mycorrhizal species. Glomalin-related root protein showed a systematic increase in non-mycorrhiza-inoculated chamber under inoculation with A. scrobiculata and F. mosseae than under non-mycorrhizal inoculation. Similar increase was also observed in easily extractable glomalin-related soil protein and total glomalin-related soil protein as a result of F. mosseae colonization only. Mean weight diameter and soil organic carbon were significantly higher under mycorrhization than non-mycorrhization, irrespective of mycorrhized or non-mycorrhized chamber. Mycorrhizal inoculation stimulated an increase in soil protease activity in the mycorrhized chamber, without any distinctive change in the non-mycorrhized chamber. These results, hence, suggested that mycorrhization conferred a systematic increase in glomalin synthesis in roots and soils, collectively, aiding in better aggregate stability and soil carbon sequestration.

Ecto- and endo-mycorrhizal colonization of Populus roots have a positive impact on the overall tree health and growth. A complete molecular understanding of these interactions will have important implications for increasing agricultural or forestry sustainability using plant:microbe-based strategies. These beneficial associations entail extensive morphological changes orchestrated by the genetic reprogramming in both organisms. In this study, we performed a comparative analysis of two Populus species (Populus deltoides and P. trichocarpa) that were colonized by either an arbuscular mycorrhizal fungus (AmF), Rhizophagus irregularis or an ectomycorrhizal fungus (EmF), Laccaria bicolor, to describe the small RNA (sRNA) landscape including small open reading frames (sORFs) and micro RNAs (miRNAs) involved in these mutualistic interactions. We identified differential expression of sRNAs that were, to a large extent, (1) within the genomic regions lacking annotated genes in the Populus genome and (2) distinct for each fungal interaction. These sRNAs may be a source of novel sORFs within a genome, and in this regard, we identified potential sORFs encoded by the sRNAs. We predicted a higher number of differentially-expressed miRNAs in P. trichocarpa (4 times more) than in P. deltoides (conserved and novel). In addition, 44 miRNAs were common in P. trichocarpa between the EmF and AmF treatments, and only 4 miRNAs were common in P. deltoides between the treatments. Root colonization by either fungus was more effective in P. trichocarpa than in P. deltoides, thus the relatively few differentially-expressed miRNAs predicted in P. deltoides might reflect the extent of the symbiosis. Finally, we predicted several genes targets for the plant miRNAs identified here, including potential fungal gene targets. Our findings shed light on additional molecular tiers with a role in Populus-fungal mutualistic associations and provides a set of potential molecular targets for future enhancement.

A new species and a new monotypic genus of legless mealybug,Orbuspedum machinatorgen. et sp. nov., are described and illustrated, based on material collected from bamboo twigs in southern Thailand. Larvae and females of the new species each live inside an individual conical domicile constructed from densely packed fungal hyphae of the sooty mouldCapnodiumsp., mixed with small quantities of wax, secreted by the mealybug. The domicile is enlarged as the insect grows; the insect irrigates the hyphae with honeydew through a small orifice at the apex of the domicile. While the insect produces honeydew and feeds the fungus, the fungus grows around the insect, protects it from predators, and buttresses the soft apodal body of the mealybug. Such a remarkable example of mutualistic symbiosis between an animal and a fungus is reported for the first time. www.zoobank.org/urn:lsid:zoobank.org:pub:C0A84631-C6A0-4177-BC50-A71D6281107F [ABSTRACT FROM PUBLISHER]

Asphondylia spp. (Diptera: Cecidomyiidae) are known for inducing gall formation on many diverse plants in both wild and agricultural contexts. The species Asphondylia serpylli is herewith reported for the first time on thyme ( Thymus vulgaris) cropped in Poland. The associated fungus has been identified as Botryosphaeria dothidea, representing its first record from cecidomyiid galls on a species of Lamiaceae. Moreover, a short account is given on the parasitoid species active in this particular ecological context. These findings point out the basic role of B. dothidea in the organization of these three-component biotic systems regardless of the varied assortments between the midge species and their host plant. [ABSTRACT FROM AUTHOR]

Evolutionary trade-offs are key to beneficial manipulation of crops by microbes Keywords: agriculture; auxin; crop plants; hormones; mutualistic symbiosis; PGPR; plant-growth-promoting rhizobacteria; rhizosphere; root-nodule rhizobia; water-use efficiency However, a microbe-manipulated plant phenotype could perhaps be superior if the microbes have information that the plant lacks. Relative to microbes in the rhizosphere, rhizobia in root nodules might be particularly useful manipulators of their legume hosts. [Extracted from the article]

The majority of terrestrial vascular plants are capable of forming mutualistic associations with obligate biotrophic arbuscular mycorrhizal (AM) fungi from the phylum Glomeromycota. This mutualistic symbiosis provides carbohydrates to the fungus, and reciprocally improves plant phosphate uptake. AM fungal transporters can acquire phosphate from the soil through the hyphal networks. Nevertheless, the precise functions of AM fungal phosphate transporters, and whether they act as sensors or as nutrient transporters, in fungal signal transduction remain unclear. Here, we report a high-affinity phosphate transporter GigmPT from Gigaspora margarita that is required for AM symbiosis. Host-induced gene silencing of GigmPT hampers the development of G. margarita during AM symbiosis. Most importantly, GigmPT functions as a phosphate transceptor in G. margarita regarding the activation of the phosphate signaling pathway as well as the protein kinase A signaling cascade. Using the substituted-cysteine accessibility method, we identified residues A 146 (in transmembrane domain [TMD] IV) and Val 357 (in TMD VIII) of GigmPT, both of which are critical for phosphate signaling and transport in yeast during growth induction. Collectively, our results provide significant insights into the molecular functions of a phosphate transceptor from the AM fungus G. margarita . [ABSTRACT FROM AUTHOR]

In many animals, sex differences in hormones, behavior, and immunity lead to differences in their gut microbial communities. One of the best-known examples of mutualistic symbiosis is that between lower termites and their intestinal protozoa. Although differences in the protozoan communities of different castes have been studied in lower termites, nothing is known about the sex differences in protozoan communities in neuter castes. Here, we show that termite workers have different protozoan communities according to sex depending on the colony. We investigated the communities of symbiotic protozoa living in lower termites, Reticulitermes speratus, and how they are affected by sex and caste. Workers had the largest numbers of protozoa, followed by soldiers, whereas reproductives (primary kings and secondary queens) had no protozoa. Workers showed colony-dependent sex differences in the total abundance of protozoa, whereas soldiers showed no such sex differences. There were significant sex effect and/or interaction effect between colony and sex in abundances of five species of protozoa in workers. Workers also showed significant sex differences and/or colony-dependent sex differences in proportion of six species of protozoa. These may result in sex differences in the host-symbiont interaction due to physiological or behavioral sex differences in workers that have not been recognized previously. This study has an important implication: although workers are not engaged in reproduction, their potential sex difference may affect various aspects of social interactions. [ABSTRACT FROM AUTHOR]

Any attempt to outline a logical framework in which to interpret the honey bee health decline and its contribution to elevated colony losses should recognize the importance of the multifactorial nature of the responsible syndrome and provide a functional model as a basis for defining and testing working hypotheses. We propose that covert infections by deformed wing virus (DWV) represent a sword of Damocles permanently threatening the survival of honey bee colonies and suggest that any factor affecting the honey bee’s antiviral defenses can turn this pathogen into a killer. Here we discuss the available experimental evidence in the framework of a model based on honey bee immune competence as affected by multiple stress factors that is proposed as a conceptual tool for analyzing bee mortality and its underlying mechanisms.

The biology of Korarchaeia remains elusive due to the lack of genome representatives. Here, we reconstruct 10 closely related metagenome-assembled genomes from hot spring habitats and place them into a single species, proposed herein as Panguiarchaeum symbiosum. Functional investigation suggests that Panguiarchaeum symbiosum is strictly anaerobic and grows exclusively in thermal habitats by fermenting peptides coupled with sulfide and hydrogen production to dispose of electrons. Due to its inability to biosynthesize archaeal membranes, amino acids, and purines, this species likely exists in a symbiotic lifestyle similar to DPANN archaea. Population metagenomics and metatranscriptomic analyses demonstrated that genes associated with amino acid/peptide uptake and cell attachment exhibited positive selection and were highly expressed, supporting the proposed proteolytic catabolism and symbiotic lifestyle. Our study sheds light on the metabolism, evolution, and potential symbiotic lifestyle of Panguiarchaeum symbiosum , which may be a unique host-dependent archaeon within the TACK superphylum. [Display omitted] • Panguiarchaeum symbiosum belongs to a previously unknown order within the Korarchaeia • P. symbiosum has a symbiotic lifestyle by fermenting peptides and reducing sulfur • Genes related to proteolytic catabolism and cell attachment exhibit positive selection • Genes related to proteolytic catabolism and cell attachment are highly expressed Qu et al. report 10 closely related genomes from hot springs with the name Panguiarchaeum symbiosum proposed. By focusing on ecological niches and evolution, they reveal a symbiotic lifestyle of these microbes, where genes associated with nutrient acquisition and cell attachment are prone to be positively selected and highly transcribed. [ABSTRACT FROM AUTHOR]

Honey bee colony losses are triggered by interacting stress factors consistently associated with high loads of parasites and/or pathogens. A wealth of biotic and abiotic stressors are involved in the induction of this complex multifactorial syndrome, with the parasitic mite Varroa destructor and the associated deformed wing virus (DWV) apparently playing key roles. The mechanistic basis underpinning this association and the evolutionary implications remain largely obscure. Here we narrow this research gap by demonstrating that DWV, vectored by the Varroa mite, adversely affects humoral and cellular immune responses by interfering with NF-κB signaling. This immunosuppressive effect of the viral pathogen enhances reproduction of the parasitic mite. Our experimental data uncover an unrecognized mutualistic symbiosis between Varroa and DWV, which perpetuates a loop of reciprocal stimulation with escalating negative effects on honey bee immunity and health. These results largely account for the remarkable importance of this mite-virus interaction in the induction of honey bee colony losses. The discovery of this mutualistic association and the elucidation of the underlying regulatory mechanisms sets the stage for a more insightful analysis of how synergistic stress factors contribute to colony collapse, and for the development of new strategies to alleviate this problem. [ABSTRACT FROM AUTHOR]

The root endophytic fungus Piriformospora indica (Sebacinacea) forms mutualistic symbioses with a broad range of host plants, increasing their biomass production and resistance to fungal pathogens. This study evaluated the effect of P. indica on fusarium crown rot disease of wheat, under in vitro and glasshouse conditions. Interaction of P. indica and Fusarium isolates under axenic culture conditions indicated no direct antagonistic activity of P. indica against Fusarium isolates. Seedlings of wheat were inoculated with P. indica and pathogenic Fusarium culmorum or F. graminearum and grown in sterilized soil-free medium or in a non-sterilized mix of soil and sand. Fusarium alone reduced emergence and led to visible browning and reduced root growth. Roots of seedlings in pots inoculated with both Fusarium isolates and P. indica were free of visible symptoms; seed emergence and root biomass were equivalent to the uninoculated. DNA was quantified by real-time polymerase chain reaction ( qPCR). The ratio of Fusarium DNA to wheat DNA rose rapidly in the plants inoculated with Fusarium alone; isolates and species were not significantly different. Piriformospora indica inoculation reduced the ratio of Fusarium to host DNA in the root systems. The reduction increased with time. The ratio of P. indica to wheat DNA initially rose but then declined in root systems without Fusarium. With Fusarium, the ratio rose throughout the experiment. The absolute amount of Fusarium DNA in root systems increased in the absence of P. indica but was static in plants co-inoculated with P. indica. [ABSTRACT FROM AUTHOR]