Symbiosis最新文献

Abstract

Rhizospheric microbes help plants to acquire and assimilate nutrients, improve soil texture and modulate extracellular molecules. Rhizosphere bacteria regularly encounter a copious number of variables, such as temperature, pH, nutrients, pest resistance mechanisms, etc. The extracellular concentration of chemical messengers fabricated by plant growth promoting bacteria (PGPB) in a system is directly proportional to the bacterial population. To dwindle the use of chemically synthesised pesticides, plant growth-promoting rhizobacteria (PGPR) are new arsenals of imperishable agricultural practises for managing plant pathogens and resistance. This review aims to harness the rhizosphere milieu to raise climate smart crops. The PGPB mediated hormonal control of plant stress management pathway could be potentially modified for the benefit of plants. Nutrient solubilisation strengthens the rhizomicrobiome for phytoremediation and pathogen control. Quorum sensing as well as the role of enzymes and siderophores in rhizo-microbiome has been discussed. With advent of metagenomics, the understanding of soil microbiome ecology has acquired new dimensions and has enabled us to modify the microbiome for sustainable agriculture and enhanced productivity.

The safety and efficacy of probiotic Bacillus subtilis to raising animals in the livestock and poultry have been widely evaluated. Silkworm (Bombyx mori L.) is a well-known economic rearing insect, and its artificial diet rearing is gaining interest. However, the effects of probiotic B. subtilis as feed additive on silkworms fed with an artificial diet remain unknown. In this study, we adopted multiple biological approaches (enzyme activity assay, quantitative PCR, transcriptome sequencing, and LC-MS) to explore the beneficial effects of B. subtilis SWL−19 on silkworm physiology. Results showed that the body weights of the silkworms significantly increased (P < 0.05) after feeding with SWL−19 strain. B. subtilis SWL−19 evidently enhanced the antioxidant property in the silkworms, and the gene expression levels of antimicrobial peptides (attacin, lysozyme, and cecropins) were affected by the SWL−19 strain. Moreover, the levels of riboflavin, nicotinamide, pyridoxine, and pyridoxal in the hemolymph of the silkworms remarkably increased after SWL−19 strain feeding. The results of transcriptomic analysis indicated that the response of intestinal tissues to B. subtilis SWL−19 focused mainly on the categories of external biotic stimulus, interspecies interaction between organisms, immune system process, and stress response. In conclusion, probiotic B. subtilis SWL−19 substantially enhanced the body weight and antioxidant property of silkworm and simultaneously regulated the intestinal immunity and promoted the metabolism of B vitamins. The present study provides a theoretical reference for the application of probiotic B. subtilis SWL−19 to improve silkworm physiology under artificial diet rearing condition.

In this study, we have demonstrated the applicability of electroporation for the stable nuclear transformation of Coccomyxa solorinae-saccatae. An antibiogram revealed that Hygromycin B and G418 are the most effective selective agents among eight different antibiotics tested. We have shown that a plasmid vector containing the hptII gene, coding for hygromycin B phosphotransferase, with expression driven by the strong cauliflower mosaic virus CaMV35S promoter ensures sufficient protection of transformed algal cells against high concentrations of Hygromycin B. The ability to drive transgene expression in the alga C. solorinae-saccatae offers unique opportunities to study the physiology of lichenic algae, as it is one of the symbiotic strains of the Coccomyxa simplex group. Furthermore, our findings demonstrate that electroporation is a convenient and effective technique for the transformation of algae in the Coccomyxa genus.

Abstract

The crucial roles played by arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) in enhancing plant nutrient uptake and soil quality are widely recognized across various plant species. This study explored the effects and potential of Bacillus velezensis S141 as a plant growth-promoting rhizobacterium on promoting a symbiotic relationship of AMF, Rhizophagus irregularis with Lotus japonicus. B. velezensis S141 inoculation positively influenced fungal growth and development. B. velezensis S141 promoted fungal abundance, such as AM root colonization and spore number. It also boosted plant nutrient uptake, enhancing the nitrogen and phosphorus concentration by 1.65 and 1.51 times, respectively, under tripartite interaction conditions. However, the indole-3-acetic acid (IAA) producing capability of B. velezensis S141, based on the inoculation experiment test of S141 mutants defective in IAA synthesis, was not the key mechanism for promoting this symbiotic interaction. Interestingly, the S141 strain, originating from rhizospheric soil fields of soybeans, was found to penetrate plant root cells and establish itself as an endophyte. The presence of B. velezensis S141 not only triggered the expression of marker genes associated with early stages of AMF colonization and nutrient uptake in the host plant, but it also led to an upregulation of AMF genes responsible for cell cycle regulation. These results suggest that B. velezensis S141 holds promise as a helper bacterium in promoting plant-AMF symbiosis.

The agave weevil, Scyphophorus acupunctatus, is a pest of agave. Its larvae cause damage to agaves by boring holes in the plant. Boring requires that the insect consume the constituents of its host plant, which contains sugars and many recalcitrant polymers. It has been hypothesized for many years that the gut bacterial communities of S. acupunctatus play a role in its ability to metabolize agave components. However, studies exploring this insect's gut bacterial communities have yet to be performed. In this work, we used a 16S rRNA gene-based metabarcoding approach to characterize the gut bacterial communities of field-collected agave weevils from different localities in Mexico. We found that external factors, including host plants, have important effects on the structure of the gut bacterial communities of S. acupunctatus. Despite this variability, we found a discrete core bacterial community mainly composed of the genera Prevotella, Pectinatus, Liquorilactobacillus, Secundilactobacillus, Paucilactobacillus, and Pseudomonas. These genera may be necessary for S. acupunctatus as metabolic helpers and/or gatekeepers. Additional studies are needed to fully assess the functionality of the gut bacterial community of this species in terms of its metabolic contribution, which may help to decipher their potential ecological implications. The information we provided here is the first step for guiding further questions.

Cycads are the only gymnosperms forming a symbiosis with nitrogen-fixing cyanobacteria in a specialized organ: the coralloid root. This paper investigates the endophytic bacterial community inhabiting the coralloid roots of two cycads from Panama. We sampled coralloid roots from Zamia nana (terrestrial) and Zamia pseudoparasitica (epiphytic). Then, we used the 16S rRNA amplicon marker to describe the entire bacterial community. We also designed a new marker to amplify the rbcL-rbcX spacer and around 100 bp of the rbcX gene, targeting cyanobacteria. We found that using 16S, endophytic bacteria diversity is represented mainly by the phyla Actinobacteria, Cyanobacteria, and Proteobacteria. In addition, 16S analyses showed that Zamia species do not share a core cyanobacterial community (using stringent 75% and 90% thresholds), while the two species shared 4 ASVs at a 50% threshold. The newly developed rbcL-rbcX marker revealed that both species share a core cyanobacterial community represented by a single amplicon sequence variant (ASV1) (Nostoc sp.) at 90% threshold that is found in the same phylogenetic clade of that contain mostly Panamanian symbiotic cyanobacteria. Using a 75% threshold, only three ASVs (ASV1, ASV2, ASV3) were present across samples, and five ASVs at 50% threshold. This new marker can effectively identify cyanobacteria ASVs and provide a better resolution for microbial analyses in autotroph cyanobacterial symbioses.

Phoresy is likely a commensal interaction, in which a phoront attaches itself to the body of a host for dispersal. Host traits and environmental characteristics may determine phoresy patterns. We examined whether the density of microscopic phoronts on frogs living in the water between the leaves of bromeliads (phytotelma) was determined by the species, richness, size and abundance of anurans (frog hosts). We identified phoronts on the skin of three hylid species (Dendropsophus bromeliaceus, Phyllodytes luteolus, and Ololygon arduoa) associated to bromeliads at eight sites in the Atlantic Forest of Brazil. We report the first records of phoretic interaction between these bromeligenous frog hosts with the aquatic invertebrates of bromeliads e.g., Bdelloidea, Copepoda, Acari, and Ostracoda. The size of frog hosts had negative relationship with the abundance of phoronts. However, when the species were analyzed separately, the size of O. arduoa had positive relationship with the abundance of phoronts. The richness of anurans in bromeliads did not influence phoresy in any of the observed variables. Our results showed that host attributes, such as identity, size, and abundance, as well as the density of phoronts in their habitat, influenced the phoresy rates. This implies that not only host attributes, but also those of the phoront need to be considered in phoresy studies.

Soil microbes are influenced by their environment, and soil pH is well known as a driver of community structure, including within the plant root zone. However, the effect of pH induced changes on root-associated microbial communities for plant growth, resource allocation, and disease resistance is not well understood, especially for long-lived woody plants. In this study, we examined whether soil microbial communities altered by soil pH could affect tree growth, resource allocation, and resistance to a soil-borne pathogen. In a controlled greenhouse setting, we treated Fagus grandifolia saplings with small amounts of forest soil that had been manipulated to alter soil pH and microbial communities. In addition, 1-yr after inoculation with forest soil, half of the trees were also inoculated with the root rot pathogen Phytophthora cinnamomi to induce physiological stress. Tree growth showed no response to treatment with forest microbes; however, P. cinnamomi altered resource allocation, leading to increased ratios of aboveground to belowground biomass for trees treated with forest microbes. Interestingly, trees grown in pasteurized soil had a tendency toward the opposite pattern of reduced ratios of aboveground to belowground biomass. Soil treatment and pathogen inoculation interacted to alter water transport tissues; stems grown with microbes from acidic forest soil had higher vessel density when challenged with P. cinnamomi, while trees grown with microbes from neutral forest soil had higher vessel density in the absence of the pathogen. Our study suggests that the composition of root-associated microbes can affect resource allocation under stressful conditions for long-lived woody plants.