Symbiosis最新文献

The effect of environmental factors on the proportion of the nitrogen (N) derived from the atmosphere (Ndfa) in soybean [Glycine max (L.) Merril] have been traditionally approached individually given their intrinsic complexity. Alternatively, a more in-depth investigation of such complex interactions can be pursued by delimiting environments where Ndfa is uniform. Thus, the aim of this study was to define environments on 24 sites by extensively characterizing weather, plant, and Ndfa-related traits to find discriminant variables defining three Ndfa classes (low, medium, and high). The Ndfa was determined at the beginning of the seed filling (R5 growth stage) using the ¹⁵N natural abundance method. Twenty environmental variables were utilized to categorize Ndfa in low (< 57%), medium (57–66%), and high (≥ 66%) classes via implementation of discriminant multivariate analysis. The Ndfa averaged 60%, lower to previous values reported for Brazil (ranging from 69 to 94%). Mean air temperature, associated to SOM and soil N, was the most important variable related to low Ndfa, while improving soil fertility (soil pH, base saturation, exchangeable Ca and Mg, and available P) was critical for high Ndfa and, consequently, seed yield. The high contribution of those factors highlight the importance of implementing strategies to improve soil fertility, to promote better plant growth, and thus enhancing Ndfa contribution to crop N uptake.

Dichrostachys cinerea (L.) Wight & Arn, which belongs to the Mimosoid clade of the legume subfamily Caesalpinioideae, was introduced into India and has since become invasive across wide areas of the country. It is nodulated, and like all other mimosoids it has indeterminate nodules with its microsymbionts housed in membrane-bound symbiosomes rather than within cell wall-enclosed fixation threads. Fifty-eight bacterial strains were isolated from root nodules on plants growing in soils from 13 sampling sites in India with various agroclimatic conditions. Genetic analysis of 36 strains resulted in diverse RAPD genotypes, with equal composition of Ensifer and Bradyrhizobium as its root nodule microsymbionts. Multi locus sequence analysis (MLSA) of 12 strains using the recA, glnII, atpD and 16S rRNA genes revealed significant genetic diversity forming novel clades and lineages and are potential new species. The D. cinerea strains were variants of local symbionts previously described as rhizobia associated with native and exotic mimosoid trees, as well as rhizobia associated with the non-mimosoid Caesalpinioid shrub Chamaecrista pumila and wild Papilionoid legumes from India. The symbiosis essential genes (nodA and nifH) of the D. cinerea strains were diverse and clustered according to geographical origin. Mosaic combinations of core and sym genes were harbored by both Ensifer and Bradyrhizobium suggesting gradual diversification and microevolution of rhizobia under pressure from the host in combination with edaphic and environmental factors. The dominant microsymbionts of native and invasive legumes, including D. cinerea, in alkaline soils of India are essentially of the ‘E. aridi’ and B. yuanmingense types. Dichrostachys cinerea rhizobia were symbiotically efficient on their homologous host, but also have ability to nodulate the crop Vigna radiata, and hence may be good candidates to be used for inoculants on legume crops as well as on Mimosoid trees (P. cineraria, V. nilotica, V. raddiana, S. senegal) used in sustainable agroforestry practices to enhance soil nitrogen content.

Toxic contaminants from intense industrial operations are entering wetlands, harming human health and biodiversity. Macrophytes serve as principal producers in aquatic environments including natural wetlands, providing shelter, food, and, most crucially, intricate relationships with the surrounding microbial assemblage for support and microorganisms attachment. Wetlands have been nature's kidneys, for filtering water. Recent research has examined macrophytes' phytoremediation abilities. With recent improvements focused on engineered wetland technology, microbiological characterization, and genetic engineering, phytoremediation strategies have also benefited. However, little research has examined the role surrounding microbial population play on macrophyte efficiency in pollutant degradation, the extent and even mechanisms of these interactions, and their potential utility in wastewater treatment of diverse industrial effluents. Our bid for greener solutions implies that macrophyte-microorganisms’ interspecific interactions for in situ treatment of effluents should be optimised to remove contaminants before discharge in natural waterbodies or for recycle water usage. This review provides for the varied types of plants and microbial interspecific interactions beneficial to effective phytoremediation processes in artificial wetland design as well as considerations and modifications in constructed wetland designs necessary to improve the bioremediation processes. Additionally, the review discusses the latest advancements in genetic engineering techniques that can enhance the effectiveness of phyto-assisted wastewater treatment. We will also explore the potential utilisation of invasive species for their demonstrated ability to remove pollutants in the controlled setting of constructed wetlands.

Canavalia rosea is an extremophilic legume that grows in hypersaline and nutrient-deficient ecosystems. The extremophilic nature of C. rosea may be attributed to its ability to establish symbiotic associations with nutrient mineralizing and plant growth promoting (PGP) bacteria housed in the nodules. This study examined legume-microbe symbiosis and plant nutrition of C. rosea growing in subtropical coastal zone in KwaZulu-Natal province, South Africa. Canavalia rosea adult plants of the same age from Westbrook, Scottburgh and Durban were collected for plant biomass and plant nutrition and root nodules were used for bacterial extraction and identification. Rhizosphere soils sampled from the three localities were used for bacterial extraction and identification, extracellular enzyme assays and soil characteristics (pH, nutrient concentrations, total cation, and exchange acidity). Westbrook, Scottburgh and Durban soils were nutrient-deficient with varying total cations, acid saturation and a pH range of 7.3–7.6. Soil nutrient mineralizing extracellular enzyme activities varied across study sites. The culturable bacterial strains isolated from the sampled soils belonged to the Pseudomonas, Pantoea and Flavobacterium genera. Canavalia rosea root nodules were nodulated by Pseudomonas guariconensis, Pseudomonas fulva, Pseudomonas fluorescens, Pseudomonas chlororaphis and Pseudomonas chlororaphis subsp. aurantiaca. Plants growing in Westbrook soils had a significantly higher total plant biomass compared to Scottburgh and Durban plants. Plant P concentration did not vary significantly between sites while plant N and C concentrations varied significantly. Plant-associated and soil bacteria with phosphorus (P) solubilising, nitrogen (N) cycling, and N fixing functions and associated enzymes seem to facilitate the mobilization of nutrients enabling C. rosea to thrive in hypersaline and low-nutrient environments.

Lichen specific metabolites (LSMs) have interesting biological activities and quantitative variations may be present intraspecifically. For example, variations in medullary fumarprotocetraric acid (FA) and cortical usnic acid (UA) were observed in the lichen Cladonia foliacea, but the mechanism of variation is not well understood. The current study aimed to characterise the quantitative variation of FA and UA and to investigate the association between lichen metabolite content and ecological / biological variables. Fungal and algal trees were constructed using fungal (nrITS, RPB2) and algal (nrITS) loci, respectively. Using a chiral chromatographic method, the contents of (-)-UA were determined in 29 C. foliacea specimens and range from 6.88 to 34.27 mg/g dry wt. The FA contents were lower and varied from 1.44 to 9.87 mg/g dry wt. Although the fungal tree showed two well resolved clades, no significant differences of UA or FA contents were found between the two fungal clades. However, a significantly higher UA/FA ratio as well as a unique habitat were found to be associated with specimens which contained the alga Asterochloris lobophora than those specimens associated other Asterochloris algae. Taking all predictive variables into account (i.e. substrate type, elevation, collection season, photobiont identity), the multivariate data analysis indicated that photobiont identity explained most of the variance of LSM contents in C. foliacea. Thus future LSM biosynthetic studies should take the photobiont into consideration when dealing with intraspecific quantitative variation.

The plant compartment niche (i.e., the host plant provides various microhabitats for the microbial community, such as the rhizosphere, root endosphere, leaf endosphere, and phylloplane) and plant species play a significant role in shaping the plant-associated microbial community assembly. However, in the mycobiome associated with alpine herbs in the subnival belt research, little work has been done to assess the contribution of plant compartment niches and plant species to fungal community variation and to reveal the plant compartment niche differentiation of fungal communities. In this study, we quantified the fungal communities associated with the rhizosphere soil, root endospheres, and leaf endospheres of three alpine herbs (Rheum spiciforme, Eriophyton wallichii, and Rhodiola bupleuroides) in the subnival belt of the Qiangyong glacier using high-throughput DNA sequencing. Our results revealed that the variation in diversity and composition of the fungal community was predominantly shaped by plant compartment niche rather than plant species. Rhizosphere soil exhibited the highest level of fungal diversity and niche breadth, while the lowest level was observed in the leaf endosphere. The fungal community composition significantly differed across different plant compartment niches. Fungal co-occurrence networks of the root endosphere and leaf endosphere were more complex and showed higher centrality and connectedness than the rhizosphere soil. Moreover, we also found that the deterministic process governed the fungal community assembly, and the host plant exerts stronger selection pressure on the leaf endophytes in comparison with the root endophytes. The root endophytes are the primary potential contributors to the leaf endophytes, compared with the fungal community associated with rhizosphere soil. Further, the Pleosporaceae, Davidiellaceae, and Chaetomiaceae were significantly enriched and overlapped in two plant compartment niches (root endosphere and leaf endosphere). Collectively, this study reveals that the variation in the diversity and composition of fungal communities associated with three alpine herbs were primarily affected by plant compartment niches rather than plant species. Additionally, this study also reveals that the diversity, composition, co-occurrence pattern, and assembly process of fungal communities associated with three alpine herbs exhibited plant compartment niche differentiation. These results provide a novel insight into the community assembly and ecological interactions of fungal communities associated with plants in harsh environments.

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.