Symbiosis最新文献

Information regarding the relationship between fertilization, mycorrhizas, and plant growth is scattered for non-conventional productive plant species. We evaluated the effect of different substrates and fertilization treatments on growth and colonization by arbuscular mycorrhizas of young Berberis microphylla plants, a native Patagonian shrub with edible fruits. We conducted a greenhouse experiment based on two factors: substrate (conventional or native soil) and fertilization (no fertilization, organic fertilization, or inorganic fertilization). When plants were grown in conventional substrate, both fertilizers promoted growth, having the inorganic fertilizer a greater effect. The effect of both fertilizers was similar when plants were cultivated in native soil, and lesser than in conventional substrate. Plants grown in native soil were larger than those in conventional substrate when organic fertilizer or no fertilizer was applied, but this was reversed when inorganic fertilizer was applied. There was no mycorrhization on plants grown in conventional substrate. In native soil, mycorrhization was highest for non-fertilized plants (60.1%), followed by those with organic fertilization (40.4%), and lowest when inorganic fertilizer was applied (29.9%). The relative abundances of both vesicles and arbuscules showed the opposite tendency, having both their highest values in treatments with inorganic fertilizer. Mycorrhization was positively correlated with plant size, but only when fertilizers were applied. Based on our results, we hypothesized that fertilization reduce mycorrhization but select more beneficial mycorrhizal fungi. We concluded that organic fertilizers have a comparable effect to inorganic fertilizers in terms of promoting plant growth, accompanied by a lesser reduction of mycorrhization.

Acacia longifolia is an aggressive invader in Mediterranean-type ecosystems severely impacting biodiversity and ecosystem functions. The species’ invasiveness has been linked to its ability to thrive in nutrient poor soils, high seed production, and quick establishment after fire. In this study, we identify and compare the bacterial endophytes of A. longifolia seeds collected from populations in the species’ native (Australia) and invasive (Portugal) ranges. For this, we characterised the morphology (length, width, and weight) of seeds from two sites in each range and isolated and cultivated bacteria from seeds. DNA fingerprinting and cluster analyses revealed slightly higher, and distinct, bacterial diversity associated with seeds collected from native range populations in comparison to those collected from invasive populations. Sequencing of the 16S rDNA gene identified 119 bacterial isolates from 15 genera, with Curtobacterium strains being common in both ranges. Several differences in bacterial genera were found among ranges and sites: Dermacoccus, Frigoribacterium, Kocuria, Pantoea and Phyllobacterium taxa were each unique to seeds from the native populations, while Brevundimonas, Microbacterium, Rhizobium and Sphingomonas taxa were only found in the invasive seeds. The genus Paraburkholderia occurred in all invasive-range seeds but was not isolated from the native-range. Bacillus and Paenibacillus co-occurred in seeds collected from all invaded sites, but the simultaneous presence of both taxa was not found in native-range seeds. We propose that the bacterial endophytes present in invasive-range seeds may be important players for the invasiveness of A. longifolia, due to their role as plant growth promoters, providing extra capabilities helping acacia expansion.

In this work, we analyzed the effect of water stress and acid pH on the growth of the endemic fodder legume Chamaecytisus albidus, inoculated with four strains of Bradyrhizobium, from three different symbiovars previously isolated from the plant grown in different eco-geographical areas of Morocco. We also assessed the competitiveness of the three symbiovars for plant nodulation under water stress and acidity. We analyzed the strain’s nodulation ability, rates of nodules occupancy, shoot, and root dry weights of plants grown at -100, -80, and − 60 MPa water potential, and 6.0 and 7.0 pH values. The strains CM64 and CJ2 belong to the symbiovar genistearum and strains CA20 and CB10 to the symbiovars retamae and lupini, respectively. The strains CB10 and CJ2 were the most infective regardless of the pH and water potential at which the plants were grown. The strain CB10 was also the most abundant in nodules from plants grown at any conditions examined. Reductions in the water potential altered the nodulation ability, the strains CB10 and CJ2 still being the more infective. These strains were also the most infective at pH 6.0 and 7.0. The highest values of shoot and root dry weights were recorded in plants inoculated with strain CA20 under all the irrigation regimes used. The reduction from 100% to 80 and 60% field capacity decreased the shoot dry weight of the plants by 31.23 and 67.06%, respectively. Moreover, there was a 37.95 and 61.74% decrease in plant root dry weight when grown at 80 and 60% of field capacity, respectively. Despite variations in the efficiency of each strain, overall, the pH did not affect either the SDW or the RDW of the plants. The inoculation of C. albidus with a mix of the four strains did not result in further improvement of nodulation or symbiotic efficiency. These results show that water deficiency drastically affects the growth of C. albidus and that the retamae symbiovar was the most effective under the conditions examined. This is the first report on the competitiveness of symbiovars for the nodulation of a legume under stress.

Symbiosis can benefit hosts in numerous ways, but less is known about whether interactions with hosts benefit symbionts—the smaller species in the relationship. To determine the fitness impact of host association on symbionts in likely mutualisms, we conducted a meta-analysis across 91 unique host-symbiont pairings under a range of spatial and temporal contexts. Specifically, we assess the consequences to symbiont fitness when in and out of symbiosis, as well as when the symbiosis is under suboptimal or varying environments and biological conditions (e.g., host age). We find that some intracellular symbionts associated with protists tend to have greater fitness when the symbiosis is under stressful conditions. Symbionts of plants and animals did not exhibit this trend, suggesting that symbionts of multicellular hosts are more robust to perturbations. Symbiont fitness also generally increased with host age. Lastly, we show that symbionts able to proliferate in- and outside host cells exhibit greater fitness than those found exclusively inside or outside cells. The ability to grow in multiple locations may thus help symbionts thrive. We discuss these fitness patterns in light of host-driven factors, whereby hosts exert influence over symbionts to suit their own needs.

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.