Symbiosis最新文献

Understanding the ecological relationship between fungi and insects is essential for elucidating interactions in biodiverse regions such as South American biomes. This study aimed to evaluate the influence of biome, host species, and microhabitat on the community structure of yeasts (using culture-dependent methods) and fungi (culture-independent methods) in bees and to identify the functional characteristics of isolated strains. Samples were collected from the body, hive, honey, and beebread of bees from the genera Trigona, Scaptotrigona, Tetragona, Apis, Meliponas, and Tetragonisca in the Pantanal, Amazon, and Cerrado biomes. We isolated 176 strains representing 46 yeast species, predominantly from the genera Starmerella (44.32%), Hanseniaspora (5.16%), and Wickerhamiella (4.38%). Starmerella etchellsii (32%) was the most abundant species, while Aureobasidium leucospermi (< 0.01%) was the least abundant. Only S. etchellsii and S. apicola (11%) were present in all bee species. The composition and abundance of yeasts were significantly influenced by biome and host species (PERMANOVA, p < 0.05). Alpha diversity varied significantly among microhabitats (Dunn’s p < 0.05), bee species, and biomes (Duncan p < 0.05). Culture-independent methods identified 234 Ascomycota ASVs, 18 Basidiomycota ASVs, and 1 Mucoromycete ASV across 90 genera and 108 species. Saccharomycetales accounted for approximately 72% of the fungal abundance, with S. apicola (14.64%) and S. meliponinorum (11.21%) being the most abundant. Additionally, barcoding identified 100 ASVs of plants associated with bees, grouped into 22 families and 24 species, predominantly Asteraceae, Anacardiacea, Elaeocarpaceae, and Solanaceae. The functional characteristics of the yeasts showed potential for industrial applications, varying according to the strain.

Spirotropis longifolia (DC.) Baill. is organized in monodominant forest patches in French Guiana. S. longifolia root nodules and forest soil samples were collected in three monodominant populations of S. longifolia and in four zones, from the S. longifolia core dominance to the adjacent mixed forest where this species was absent. S. longifolia roots presented arbuscular mycorrhizal fungus (AMF) structures, but no ectomycorrhizae. The presence of myconodule-like structures was only noted once. Isolates of S. longifolia and of diverse French Guianese legume trees were 95% identified as Bradyrhizobium spp. and rarely as Rhizobium spp. On a partial 16S rDNA phylogenetic tree, S. longifolia-associated bradyrhizobia were positioned in a separate cluster including the Bradyrhizobium sp. Tv2a-2 strain isolated from Tachigali versicolor in Panama. Bradyrhizobia of other forest legume trees were positioned identically, or differently, in various clusters. A partial 16S-23S rDNA internal transcribed spacer (ITS) phylogenetic tree confirmed that the main cluster accounting for 82% of the direct or trapped bradyrhizobia associated with S. longifolia was situated outside the B. japonicum and B. elkanii superclades, in the Tv2a-2 superclade/Kakadu supergroup. In this cluster, other bradyrhizobia appeared that were associated with legumes from the tribes Ormosieae, Brongniartieae and Dalbergieae, suggesting the possibility of a shared pool of the most ancestral symbionts that are bradyrhizobia with the Caesalpinoid legumes and the early-branching Papilionoid legumes. Curiously, the seven monodominant Fabaceae of the Amazonian forests were exclusively part of these subfamilies. The link between ancestral symbiosis and monodominance still remains to be studied.

Aims

Plants alter the performance of other plants by changing soil conditions. These plant-soil feedback (PSF) can be shaped by plant interactions with other organisms and may be crucial for understanding plant coexistence. Here, we analyse how specialist and generalist symbionts change the legacy left in the soil by conspecific and heterospecific plants in the absence of pathogens and litter inputs.

Methods

We conducted a two-phase experiment to evaluate Trifolium repens establishment and its ability to form symbiotic associations with AMF and rhizobia in soils conditioned by Lolium multiflorum plants with contrasting levels of endophyte infection (heterospecific soils: Lm⁺ or Lm⁻) and inoculated or not with AMF (M⁺ or M⁻). We also conditioned the soils with T. repens plants inoculated with rhizobia on M⁺ and M⁻ soils (conspecific soils: Tr).

Results

In M- treatments, the number of established seedlings showed no difference between conspecific and heterospecific soils. In M + treatments, conditioned soils by Tr and Lm⁺ increased legume establishment by 64% compared to soils conditioned with Lm⁻. AMF colonization was higher in Tr and Lm + soils compared to Lm⁻. Regardless of AMF inoculation, legume biomass was higher in conspecific soils than in heterospecific ones, consistent with nodulation changes.

Conclusions

We found that legume establishment depended significantly on the previous presence of heterospecific soils only when L. multiflorum was associated with Epichloë endophyte and AMF. The strength of PSF was determined by AMF inoculum, while the positive or negative nature of this effect was given by the level of endophyte infection. These findings unveil a new pathway by which these symbionts modulate the coexistence between legumes and grasses.

The coexistence of taxonomically related hosts often leads to their infestation by the same symbiont species. This study tested the hypothesis that, despite the taxonomic proximity of the hosts, morphological differences have a predominant effect on the composition of their symbiont faunas. For this purpose, we studied the species composition, species richness and abundance of symbiont communities, associated with two tropical venomous echinoids Toxopneustes pileolus and Tripneustes gratilla (Toxopneustidae) and analyzed their symbiont specificity. Our results showed that 65.5% of T. gratilla and 91.0% of T. pileolus individuals were inhabited by symbionts. Both hosts harbored eleven species of obligate symbionts (polychaetes, gastropods, copepods, decapods and ophiuroids) all of them first recorded off the coast of Vietnam. Mean species richness was similar in both species, mean intensity were higher in T. gratilla than in T. pileolus, while the level of dominance was higher in T. pileolus. We find out that toxicity per se did not affect the composition of symbiont faunas; the symbiont fauna of T. gratilla is similar to that of taxonomically unrelated regular echinoids; whereas the symbiont fauna of T. pileolus is less diverse and more specific. We concluded that the depleted composition and specificity of of T. pileolus symbiont fauna are associated with its unique morphological feature – a cavity between the surface of the test and the canopy of pedicellariae, preventing the penetration of invaders onto the surface of the test and protecting their symbionts from predators.

Host-associated microbes are increasingly recognized as important drivers of bee health. Surveys of bee microbiomes have primarily sampled social bees, yet non-social bees constitute the majority of species. We employed 16S and ITS amplicon sequencing to describe the diversity and composition of bacterial and fungal communities across multiple developmental stages of Osmia lignaria, an important native and managed solitary mason bee. Bacterial and fungal diversity were not significantly different across bee development. However, the composition of bacteria and fungi significantly changed between larval and fully pigmented adult stages, in agreement with dramatic changes in host morphology during metamorphosis. Many of the microbial taxa found in provisions were also present in larvae, indicating that immature bees likely acquire their microbiome from food. Notably, the most prevalent bacterial genus was Arsenophonus, a symbiont with many recorded phenotypes, ranging from reproductive parasitism to beneficial endosymbiont. Arsenophonus was found in samples from provisions and eggs, yet reached higher read counts in larvae and fully pigmented adults. The Arsenophonus amplicon sequencing variants (ASVs) detected in this study had high sequence similarity with a symbiont that displays the son-killing phenotype, suggesting that the ASVs in O. lignaria are also reproductive parasites. The causative agent of chalkbrood disease in bees, Ascosphaera, was also detected in provisions and larvae. Most other taxa present were plant pathogens or commonly found in soil. This study highlights that O. lignaria may harbor horizontally and vertically transmitted microbial taxa with diverse consequences for bee fitness.

Parasitoids, a distinct group of insects, rely on other insects for their offspring’s development, depositing their eggs within or atop a host insect, which is then consumed during the juvenile phase. These insects possess a wide array of microbial symbionts, including viruses, bacteria, and fungi. Unlike the symbionts in herbivorous and blood-feeding insects that supply nutrients, those associated with parasitoids are crucial for the reproduction of the parasitoid, the suppression of the host’s immune system, and the alteration of the host’s behaviour, including disrupting metamorphosis and affecting the metabolism of fats in herbivorous hosts. Additionally, recent research has shown that interactions between herbivores and parasitoids within plant-associated communities at different trophic levels can be influenced by parasitoid symbionts such polydnaviruses. This suggests that the role of these symbionts is significantly broader than previously understood. This review examines the influence of parasitoid symbionts on both direct and indirect interactions among species and its implications for the dynamics of ecological communities, particularly in terms of evolutionary processes and species interactions.

The use of nitrogen-fixing bacteria in leguminous plants is a widespread approach, and the exploration of symbiotic bacteria that are efficient in biological nitrogen fixation (BNF) continues to be explored. The aim of the present study was to evaluate the effect of inoculation and coinoculation of mung bean plants with different combinations of Bradyrhizobium (B. elkanii BR 2003, B. pachyrhizi BR 3262, B. yuanmingense BR 3267, B. paxllaeri BR 10398 and B. icense BR 10399), Azospirillum baldaniorum (Sp245) and Bacillus pumilus (UFPEDA 472) on the contribution of biomass, the concentration of nitrogen (N) compounds and BNF. The experiment was carried out under greenhouse conditions with pots containing washed and autoclaved sand. Mung bean seeds were inoculated or coinoculated (double or triple) with Bradyrhizobium, A. baldaniorum and/or Bacillus pumilus, and one absolute control (not inoculated) was used. The experimental design was a completely randomized design with 21 treatments harvested in two different periods (flowering and pod maturation). Inoculation and coinoculation positively influenced the number of nodules, shoot dry weight, N accumulated, total N content and inorganic and organic compounds (free ammonia, nitrate, ureides and leghemoglobin), indicating that there was efficiency in BNF and synergistic interaction between the bacteria used and the mung bean plants. Inoculation with Bradyrhizobium species and the combination of these strains with A. baldaniorum and Bacillus pumilus positively influenced N fixation and metabolism in mung bean plants, especially when B. elkanii BR 2003 and B. pachyrhizi BR 3262 were used.

Chili pepper, widely recognized as a popular spice and an important cash crop worldwide, faces significant threats from climate change-related stress, particularly plant disease outbreaks. Emerging global diseases like Phytophthora blight, anthracnose fruit rot, and Ralstonia bacterial wilt threaten chili-producing countries, causing substantial annual yield losses. These major threatening diseases are difficult to control due to their widespread, extensive, and long-lived survival structures. Disease management practices rely on agrochemicals, leading to resistance to phytopathogens and environmental issues. Current research focuses on developing innovative, effective, chemical-free, and sustainable biosecurity strategies to address these challenges. Endophytes are plant endosymbionts that provide new insights for scientists due to their remarkable genome regulation to host plants. This review highlights the current state of emerging global diseases affecting chili pepper crops based on bibliometric analysis. We also focus on endophytes-mediated plant defense response as a sustainable solution for chemical pesticides. This review discusses the importance of omics-based technologies in deciphering the biochemical and molecular mechanisms of endophytes-mediated chili plant tolerance to various pathogens. A holistic approach of plant endophytes and multi-omics technologies can help develop effective mitigation strategies to prevent disease outbreaks for sustainable crop production and environmental restoration in the modern era of Agriculture 4.0 ‒ a green agricultural revolution.

Piper longum, the Indian long pepper, is widely used in Ayurvedic medicine system to cure respiratory and digestive disorders. In a previous study, we reported the isolation and characterization of plant growth promoting (PGP) endophytic bacteria from P. longum. Here, we have tested the effect of two native endophytic bacteria, Acinetobacter soli PlS14 and Enterobacter hormaechei PlR15, on growth attributes, adventitious root development and reactive oxygen species levels in P. longum PlR15. Our results indicate that stem cuttings treated with A. soli PlS14 and E. hormaechei PlR15 exhibited rooting in > 50% of stem cuttings, when none of the Control cuttings did. Further, the endophyte-inoculated plants showed better vegetative growth (in terms of shoot growth and leaf number); higher levels of chlorophyll, proline and phenylalanine ammonia lyase; and lesser accumulation of reactive oxygen species than Control plants. The improved growth performance of endophyte-inoculated plants could be corelated with results of localization studies that indicate higher bacterial population in roots of endophyte-inoculated plants. To our knowledge, this is the first report of use of native endophytic strains as bioinoculants for growth of P. longum. Altogether, our results highlight the (often neglected) role of PGP native endophytes for cultivation of plants including medicinal plant species.

Microbiome insect research has grown rapidly over the last years thanks to advances in next-generation sequencing. The bacterial microbiome inhabiting insects often involves mutualistic associations between the insect hosts and maternally transmitted symbiotic bacteria. Among insect groups, aphids are the most studied regarding insect symbiosis, but with a strong bias toward a few well studied species. Increased resistance to parasitic wasps, entomopathogenic fungi and tolerance to thermal stresses are the most common facultative endosymbiont-mediated effects in aphid biology. Here, we studied the microbiome of the woolly apple aphid Eriosoma lanigerum, a severe pest of apple orchards, which has been poorly studied concerning facultative symbionts. Our 16S rRNA gene Illumina sequencing-based taxonomic assignment, showed a high representation of reads assigned (99% similarity) to a recently recognized bacterial taxon, not previously described in aphids, identified as Symbiopectobacterium purcellii. This bacterial endosymbiont has been recognized as a new clade of Enterobacteriaceae, vertically transmitted and mutualistic in various invertebrate hosts, including one nematode species and four insect species from the order Hemiptera. This finding emphasizes the need to extend the study of symbionts from entire microbiomes of insect hosts, to understand the diversity of endosymbionts across host species and their role in insect ecology.