Plant Interactions Research Articles

Agroforestry system construction in eastern coastal China: Insights from soil–plant interactions

AbstractAgroforestry, as a phytoremediation measure, shows great potential for mitigating land degradation by constructing multidimensional and efficient agroforestry composite systems through regulating the microenvironment of agroforestry sites and improving soil properties. However, the effects of different agroforestry composite management modes on saline soils and the interactions between soil–plant systems under salt stress conditions in coastal areas remain largely unexplored. In this study, two salt‐tolerant tree species (Sapium sebiferum (Linn.) Roxb and Zelkova serrata (Thunb.) Makino) and four crop species (Medicago sativa, Sesbania cannabina, Sorghum bicolour, and Avena sativa) were selected for intercropping in eight composite patterns via field experiments, with dynamics of soil physicochemical properties and crop photosynthesis observed. The results showed that treatments intercropped with M. sativa had the highest soil bulk density range (1.41–1.48 g cm−3). The dynamics of topsoil (0–10 cm) chemical properties showed similar change patterns among treatments, whereas those of the 10–40 cm soil chemical properties (especially soil pH, soil organic matter [SOM], and total nitrogen [TN]) showed heterogeneity. Moreover, planting S. sebiferum (L.) Roxb under the same crop conditions increased tree height growth rate and survival rate by 75%–114% and 14%–33%, respectively, relative to planting Z. serrata (T.) Makino. Furthermore, a significant negative correlation was observed between soil moisture with crop intercellular CO2 concentration (λ = −0.77), while significant positive correlations were found between crop net photosynthetic rate (Pn) with soil TN (λ = 0.71), as well as SOM with atmospheric CO2 content (λ = 0.72). Structural equation modeling showed significant direct effects between tree height growth rate with soil TN and SOM. Soil moisture (λ = 0.47) and tree height growth rate (λ = 0.53) were dominant drivers of crop Pn. Our findings provide useful information for the prevention of coastal saline soil degradation and sustainable development of agroforestry.

Secretory molecules from secretion systems fine-tune the host-beneficial bacteria (PGPRs) interaction.

Numerous bacterial species associate with plants through commensal, mutualistic, or parasitic association, affecting host physiology and health. The mechanism for such association is intricate and involves the secretion of multiple biochemical substances through dedicated protein systems called secretion systems SS. Eleven SS pathways deliver protein factors and enzymes in their immediate environment or host cells, as well as in competing microbial cells in a contact-dependent or independent fashion. These SS are instrumental in competition, initiation of infection, colonization, and establishment of association (positive or negative) with host organisms. The role of SS in infection and pathogenesis has been demonstrated for several phytopathogens, including Agrobacterium, Xanthomonas, Ralstonia, and Pseudomonas. Since there is overlap in mechanisms of establishing association with host plants, several studies have investigated the role of SSs in the interaction of plant and beneficial bacteria, including symbiotic rhizobia and plant growth bacteria (PGPB). Therefore, the present review updates the role of different SSs required for the colonization of beneficial bacteria such as rhizobia, Burkholderia, Pseudomonas, Herbaspirillum, etc., on or inside plants, which can lead to a long-term association. Most SS like T3SS, T4SS, T5SS, and T6SS are required for the antagonistic activity needed to prevent competing microbes, including phytopathogens, ameliorate biotic stress in plants, and produce substances for successful colonization. Others are required for chemotaxis, adherence, niche formation, and suppression of immune response to establish mutualistic association with host plants.

Insights into plant interactions and the biogeochemical role of the globally widespread Acidobacteriota phylum

The prevalence and abundance of Acidobacteriota raise concerns about their ecological function and metabolic activity in the environment. Studies have reported the potential of some members of Acidobacteriota to interact with plants and play a significant role in biogeochemical cycles. However, their role in this context has not been extensively studied. Here, we performed a comprehensive genomic analysis of 758 metagenome-assembled genomes (MAGs). Our analysis revealed a high frequency of plant growth-promoting traits (PGPTs) genes in the Acidobacteriaceae, Bryobacteraceae, Koribacteraceae, and Pyrinomonadaceae families. The colonization and competitive exclusion classes of PGPTs were found to be present in numerous Acidobacteriota members. In addition, these PGPTs also include genes involved in nitrogen fixation, phosphorus solubilization, exopolysaccharide production, siderophore production, and plant growth hormone production. Expression of such genes was found to be transcriptionally active in different environments. In addition, we identified numerous carbohydrate-active enzymes and peptidases involved in plant polymer degradation. By applying an in-depth insight into the diversity of the phylum, we expand the understanding of the role played by Acidobacteriota in the cycling of carbon, nitrogen, sulfur, and trace metals. Together, this study underscores the distinct potential ecological roles of each of these taxonomic groups, providing valuable insights for future research.

Facilitation against herbivory more important than resource‐based niche differences for plant coexistence in a field experiment

Abstract Theory suggests that eutrophication impacts plant community biodiversity by constraining niche differences and increasing competitive inequalities among species, leading to the exclusion of weaker competitors. However, explicit tests of nutrient effects on the strength and direction of inter‐ and intraspecific plant–plant interactions that dictate coexistence are lacking, especially in complex field settings where multiple processes can simultaneously affect plant growth and reproduction. We conducted a field experiment in southeastern Vancouver Island, Canada, using four annual grassland plant species to test how species interactions responded to eutrophication and the covariation of herbivore pressure and neighbour species light‐ and moisture‐use. We found that focal species reproduction was limited by nutrient availability and herbivory, such that the nature of species interactions was context‐dependent. Competitive interactions failed to predict species persistence under these conditions. Instead, facilitation was critical—phytometers grown without neighbours consistently failed to produce seed under herbivore pressure meaning that fecundity significantly increased with neighbour density. Synthesis. Our work demonstrates the importance of species interactions in plant community responses to eutrophication but emphasizes that ‘indirect’ drivers of plant performance may influence or overwhelm nutrient effects on plant–plant competition. The widespread occurrence of mortality overcome primarily by facilitation highlights the importance of positive density dependence. Overall, our results suggest that knowledge of resource niche overlap may be insufficient to explain plant community responses to eutrophication. This highlights the necessity of considering the broader environmental context when leveraging ecological theory to understand global change effects in empirical settings.

Development and application of environmental passport of hardy-shrub species for Novosibirsk landscaping

The urbanization development has a negative impact on the quality of landscape. recreational and hardy-shrub species, one of the reasons for which is underestimation of environmental passports, in particular growth rates, allelopathy, requirements for multifunctionality of environmental objects.Purpose: Updating of environmental passport of hardy-shrub species for Novosibirsk landscaping.Methodology: Temporal analysis of hardy-shrub species, analysis of plant interaction with each other, composition and space analysis, evaluation and calculation methods.Research findings: The main parameters of updating environmental passports, principles of plant selection, and proposed unified type of the environmental passport.

Unveil the sugar diet and associated environmental compounds in the crop of the mosquito Culex pipiens

Culex pipiens (Linnaeus, 1758) mosquitoes search plant sources of sugars to cope with the energetic demand of various physiological processes. The crop as part of the digestive system is devoted to the storage of sugar-based meal obtained from various nectars sources. The profiling of sugars and metabolites in the Culex pipiens’ crop is scarce, and only few studies used Liquid Chromatography – Mass Spectrometry (LC-MS), which provides broad detection for biomonitoring environmental substances and even contaminants in the sugar diet of mosquitoes populations.Therefore, sugar and metabolite profiling were performed on crops obtained from mosquitoes exposed to plant nectar under laboratory or natural conditions by Ultra High-Performance LC-MS (UHPLC-MS). This method allowed us a precise quantitative and qualitative identification of sugar diet and associated environmental compounds in the crop of the mosquito C. pipiens. Under laboratory condition, mosquitoes were allowed to feed on either glucose solution, commercially-available flowers or field collected flowers. In addition, we collected mosquitoes from the field to compare those crop metabolomes with metabolome patterns occurring after nectar feeding in the lab.The sugar quantities and quality obtained from the crops of mosquitoes collected in the field were similar to those crops obtained from mosquitoes that fed on commercially-available flowers and from field collected flowers with a limit of detection of 10 μg/L for sucrose, glucose and sucrose. Next to sugar compounds, we identified 2 types of amino acids, 12 natural products, and 9 pesticides.Next to the diversity of sugar compounds, we could confirm that secondary metabolites and environmental pollutants are typically up taken from floral nectar sources by C. pipiens. The in-depth knowledge on mosquito–plant interactions may inspire the development and further optimization of mosquito trap systems and arboviral surveillance systems.

Singlet oxygen signalling and its potential roles in plant biotic interactions.

Singlet oxygen (SO) is among the most potent reactive oxygen species, and readily oxidizes proteins, lipidsand DNA. It can be generated at the plant surface by phototoxins in the epidermis, acting as a direct defense against pathogens and herbivores (including humans). SO can also accumulate within mitochondria, peroxisomes, cytosoland the nucleus through multiple enzymatic and nonenzymatic processes. However, the majority of research on intracellular SO generation in plants has focused on transfer of light energy to triplet oxygen by photopigments from the chloroplast. SO accumulates in response to diverse stresses that perturb chloroplast metabolism, and while its high reactivity limits diffusion distances, it participates in retrograde signalling through the EXECUTER1 sensor, generation of carotenoid metabolitesand possibly other unknown pathways. SO thereby reprogrammes nuclear gene expression and modulates hormone signalling and programmed cell death. While SO signalling has long been known to regulate plant responses to high-light stress, recent literature also suggests a role in plant interactions with insects, bacteriaand fungi. The goals of this review are to provide a brief overview of SO, summarize evidence for its involvement in biotic stress responsesand discuss future directions for the study of SO in defense signalling.

Modulation of the Host Defence System by Nematophagous Fungi and Chitosan

Nematophagous fungi (NFs), which are responsible for soil suppression of plant-parasitic nematodes, are multitrophic biocontrol agents. This raises the question of the transition between lifestyles (e.g., endophytism vs. egg parasitism). The NF Pochonia chlamydosporia colonises food crops and promotes their growth and yield. When colonising the plant, P. chlamydosporia induces the plant immunity (PI). However, it also evades the PI. To do this, both endophytic NF and pathogenic fungi (PF) secrete LysM effectors (LysM-effs). LysM effectors have been shown to have diverse functions in different organisms, including the protection of fungal chitin from plant chitinases. P. chlamydosporia is resistant to chitosan, which modulates gene expression in fungi and plants and has antimicrobial properties. P. chlamydosporia chitin deacetylases (CDA) and chitosanases (CSN) also help P. chlamydosporia evade plant immunity, resist exogenous chitosan, and are induced during fungal infection of nematode eggs. NF-chitosan formulations are new biomanagement tools against plant parasitic nematodes, fungal wilt pathogens and insect pests that currently threaten food security crops. Furthermore, omics techniques are useful tools to elucidate the role of CDAs, CSNs, LysM-effs, adhesion proteins and carbohydrate-active enzymes in pathogen–BCA–plant interactions, adhesion and infection to nematode eggs and their modulation by chitosan.

Host Response of Arabidopsis thaliana Interaction with Fungal Endophytes Involves microRNAs.

Plant and fungus interaction is a complex process involving many molecular factors determining the nature of relationship. The enigmatic methodology by which fungal endophytes are able to colonise a plant harmoniously is still inexplicable. Small RNAs have been identified as major regulatory elements under various biotic interactions. However, their role in endophytic plant-fungal interactions remain to be elucidated. Therefore, transcript expression data available on Gene Expression Omnibus for Arabidopsis thaliana was utilised for miRNAs identification under endophytism. The analysis predicted 15 miRNAs with differential expression of which the ath-miRNA398b modulation was significant. Application of psRNAtarget, C-mii, pmiREN, and TarDB provided a pool of 357 target genes for these miRNAs. Protein-protein interaction analysis identified major hub proteins, including BTB/POZ domain-containing protein, beta-Xylosidase-2 (AtBXL2), and Copper/Zinc Superoxide Dismutase-2 (AtSOD2). The quantitative real-time PCR validated the computational prediction and expression for selected target genes AtSOD2, AtBXL2, and AtRCA along with ath-miRNA398b under endophytism. Overall, results indicate that miRNAs have a significant role in regulating Arabidopsis thaliana-endophytic fungal interaction.

The RIN4-like/NOI proteins NOI10 and NOI11 modulate the response to biotic stresses mediated by RIN4 in Arabidopsis

Key messageNOI10 and NOI11 are two RIN4-like/NOI proteins that participate in the immune response of the Arabidopsis plant and affect the RIN4-regulated mechanisms involving the R-proteins RPM1 and RPS2.The immune response in plants depends on the regulation of signaling pathways triggered by pathogens and herbivores. RIN4, a protein of the RIN4-like/NOI family, is considered to be a central immune signal in the interactions of plants and pathogens. In Arabidopsis thaliana, four of the 15 members of the RIN4-like/NOI family (NOI3, NOI5, NOI10, and NOI11) were induced in response to the plant herbivore Tetranychus urticae. While overexpressing NOI10 and NOI11 plants did not affect mite performance, opposite callose accumulation patterns were observed when compared to RIN4 overexpressing plants. In vitro and in vivo analyses demonstrated the interaction of NOI10 and NOI11 with the RIN4 interactors RPM1, RPS2, and RIPK, suggesting a role in the context of the RIN4-regulated immune response. Transient expression experiments in Nicotiana benthamiana evidenced that NOI10 and NOI11 differed from RIN4 in their functionality. Furthermore, overexpressing NOI10 and NOI11 plants had significant differences in susceptibility with WT and overexpressing RIN4 plants when challenged with Pseudomonas syringae bacteria expressing the AvrRpt2 or the AvrRpm1 effectors. These results demonstrate the participation of NOI10 and NOI11 in the RIN4-mediated pathway. Whereas RIN4 is considered a guardee protein, NOI10 and NOI11 could act as decoys to modulate the concerted activity of effectors and R-proteins.

Bioinformatics investigation of the effect of volatile and non-volatile compounds of rhizobacteria in inhibiting late embryogenesis abundant protein that induces drought tolerance

Abstract Drought is a major problem worldwide for agriculture, horticulture, and forestry. In many cases, major physiological and biochemical changes occur due to drought stress. The plant’s response to drought stress includes a set of systems for intracellular regulation of gene expression and inter-tissue and inter-organ signaling, which ultimately leads to increased stress tolerance. Meanwhile, the role of plant growth-promoting bacteria in improving many harmful consequences of drought stress has been discussed. One of the new ways to increase tolerance to drought stress in plants is drug design using methods based on computer analysis, bioinformatics, pharmacokinetics, and molecular docking. The present study aimed to identify volatile and non-volatile compounds involved in drought tolerance using molecular docking methods. In this research, among the volatile and non-volatile compounds effective in increasing growth and inducing drought tolerance, compounds that have a high affinity for interacting with the active site of late embryogenesis abundant (LEA) protein were identified through molecular docking methods, and it was presented as a suitable inhibitor for this protein. Based on the docking results, the inhibition potentials of the studied compounds differed, and the most vital interaction in the case of LEA 3 protein was related to the gibberellic acid compound, whose energy is equivalent to −7.78 kcal/mol. Due to the basic understanding of many mechanisms operating in the interactions of plants and bacteria, it is expected that the practical use of these compounds will grow significantly in the coming years, relying on pharmacokinetic methods and molecular docking.

Capacity Planning and Liquid Waste Management Strategy from Fishery Activities in the Samudera Belawan Fishery Port

Fishing ports are associated with environmental issues such as waste disposal into waters and land, air pollution, and noise. One effort to minimize polluted waste is the existence of a Waste Water Treatment Plant. Wastewater Treatment Plants are one of the functional facilities at fishing ports based on the Minister of Maritime Affairs and Fisheries Regulation No. 08/MEN/2012 Concerning Fisheries Ports. This research aims to identify liquid waste management at the Belawan Ocean Fishing Port, analyze the quality of liquid waste from fishing activities at the Belawan Ocean Fishing Port, analyze the capacity planning of the Waste Water Treatment Plant and stakeholder interaction patterns in waste handling, and develop a liquid waste management strategy at the Belawan OFP. The study conducted a direct survey in Belawan by interviewing the community, fishermen, and Belawan OFP staff and taking water samples for water quality data tested in the laboratory. The research results show that water pollution in the Belawan OFP comes from industry, residential areas, fisheries, and transportation. Laboratory analysis indicates that Total Suspended Solids and ammonia exceed quality standards caused by residential waste and the disposal of dead fish. The strategy for developing liquid waste management at Belawan OFP directs economic aspects as the main priority.

Effects of water extract from Cornus controversa on the expression levels of DiSOC1-b and DiCCoAOMT1 genes related with the growth of dove tree seedlings

Abstract Although characterization of plant interactions has become a research hotspot to assess the adaptability of endangered plants, the underlying molecular basis remains elusive. Dove tree (Davidia involucrata) seedlings were watered with distilled water (CK), leaf water extract (0.025 g mL−1) and branch water extract (0.1 g mL−1) from Cornus controversa, respectively. Subsequently, the morphology, biomass and gene expression levels of DiSOC1-b and DiCCoAOMT1 were analyzed. The results showed that morphological traits and biomass accumulation of D. involucrata seedlings were decreased by the addition of leaf water extracts, and increased by branch water extracts. Moreover, the gene expression level of DiSOC1-b was significantly down-regulated, while the gene expression level of DiCCoAOMT1 was significantly up-regulated in the stems and roots of D. involucrata upon treatment with leaf water extracts of C. controversa. In contrast, the gene expression level of DiSOC1-b was significantly up-regulated in the leaves and stems, while the gene expression level of DiCCoAOMT1 was significantly down-regulated in the roots of D. involucrata upon treatment with branch water extracts of C. controversa. In addition, the expression level of DiSOC1-b was positively correlated with most of morphological traits and total biomass (P < 0.05), while DiCCoAOMT1 was negatively correlated with the majority of morphological traits in D. involucrata seedlings (P < 0.05). Taken together, these results suggest that water extracts from the leaves and branches of the C. controversa exhibit opposite allelopathic effects and affect the expression levels of genes related to growth (DiSOC1-b) and environmental adaptability (DiCCoAOMT1) in D. involucrata seedlings.

Above and belowground phenotypic response to exogenous auxin across Arabidopsis thaliana mutants and natural accessions varies from seedling to reproductive maturity.

Plant hormones influence phenology, development, and function of above and belowground plant structures. In seedlings, auxin influences the initiation and development of lateral roots and root systems. How auxin-related genes influence root initiation at early life stages has been investigated from numerous perspectives. There is a gap in our understanding of how these genes influence root size through the life cycle and in mature plants. Across development, the influence of a particular gene on plant phenotypes is partly regulated by the addition of a poly-A tail to mRNA transcripts via alternative polyadenylation (APA). Auxin related genes have documented variation in APA, with auxin itself contributing to APA site switches. Studies of the influence of exogenous auxin on natural plant accessions and mutants of auxin pathway gene families exhibiting variation in APA are required for a more complete understanding of genotype by development by hormone interactions in whole plant and fitness traits. We studied Arabidopsis thaliana homozygous mutant lines with inserts in auxin-related genes previously identified to exhibit variation in number of APA sites. Our growth chamber experiment included wildtype Col-0 controls, mutant lines, and natural accession phytometers. We applied exogenous auxin through the life cycle. We quantified belowground and aboveground phenotypes in 14 day old, 21 day old seedlings and plants at reproductive maturity. We contrasted root, rosette and flowering phenotypes across wildtype, auxin mutant, and natural accession lines, APA groups, hormone treatments, and life stages using general linear models. The root systems and rosettes of mutant lines in auxin related genes varied in response to auxin applications across life stages and varied between genotypes within life stages. In seedlings, exposure to auxin decreased size, but increased lateral root density, whereas at reproductive maturity, plants displayed greater aboveground mass and total root length. These differences may in part be due to a shift which delayed the reproductive stage when plants were treated with auxin. Root traits of auxin related mutants depended on the number of APA sites of mutant genes and the plant's developmental stage. Mutants with inserts in genes with many APA sites exhibited lower early seedling belowground biomass than those with few APA sites but only when exposed to exogenous auxin. As we observed different responses to exogenous auxin across the life cycle, we advocate for further studies of belowground traits and hormones at reproductive maturity. Studying phenotypic variation of genotypes across life stages and hormone environments will uncover additional shared patterns across traits, assisting efforts to potentially reach breeding targets and enhance our understanding of variation of genotypes in natural systems.

Previous infestation by conspecifics leads to a transient increase of the performance of Sitobion avenae aphids on wheat leaves

Abstract The ecological niche of aphids is largely defined by the phloem sap of plants, which they consume. Previous studies revealed that aphids may change the phloem sap metabolome and that a previous aphid infestation may benefit them. As aphids reproduce parthenogenetically, the performance and preference of aphids of the same monoclonal aphid lineage can be compared between previously uninfested and previously aphid‐infested plants. Wheat (Triticum aestivum) leaves were infested by clonal lineages of Sitobion avenae aphids for 9–10 days. Leaf phloem exudates were analysed using amino acid profiling and metabolic fingerprinting, capturing mainly specialised metabolites. It was investigated whether aphid colony sizes differ between leaves that were previously uninfested or infested by aphids of a different clonal lineage or by aphids of the same clonal lineage and whether aphids show a preference for any of these leaves. The relative concentrations of metabolites in the phloem exudates were not affected by aphid infestation. Aphid colonies were partly larger on previously aphid‐infested leaves than on control leaves. However, this effect was transient and finally colonies had similar sizes. Given a choice between previously aphid‐infested and uninfested leaves, S. avenae nymphs showed no preferences. The findings that positive effects of previous aphid infestation on aphid performance are transient and that the performance but not the preference of the aphids was affected by previous aphid infestation highlight the temporal dynamics and complexity of aphid–plant interactions. Niche alteration processes may be partly involved in these interactions.

Trichothecenes and Fumonisins: Key Players in Fusarium-Cereal Ecosystem Interactions.

Fusarium fungi produce a diverse array of mycotoxic metabolites during the pathogenesis of cereals. Some, such as the trichothecenes and fumonisins, are phytotoxic, acting as non-proteinaceous effectors that facilitate disease development in cereals. Over the last few decades, we have gained some depth of understanding as to how trichothecenes and fumonisins interact with plant cells and how plants deploy mycotoxin detoxification and resistance strategies to defend themselves against the producer fungi. The cereal-mycotoxin interaction is part of a co-evolutionary dance between Fusarium and cereals, as evidenced by a trichothecene-responsive, taxonomically restricted, cereal gene competing with a fungal effector protein and enhancing tolerance to the trichothecene and resistance to DON-producing F. graminearum. But the binary fungal-plant interaction is part of a bigger ecosystem wherein other microbes and insects have been shown to interact with fungal mycotoxins, directly or indirectly through host plants. We are only beginning to unravel the extent to which trichothecenes, fumonisins and other mycotoxins play a role in fungal-ecosystem interactions. We now have tools to determine how, when and where mycotoxins impact and are impacted by the microbiome and microfauna. As more mycotoxins are described, research into their individual and synergistic toxicity and their interactions with the crop ecosystem will give insights into how we can holistically breed for and cultivate healthy crops.

Seed-Borne Bacterial Diversity of Fescue (Festuca ovina L.) and Properties Study.

Rich endophytic bacterial communities exist in fescue (Festuca ovina L.) and play an important role in fescue growth, cold tolerance, drought tolerance and antibiotic tolerance. To screen for probiotics carried by fescue seeds, seven varieties were collected from three different regions of China for isolation by the milled seed method and analyzed for diversity and motility, biofilm and antibiotic resistance. A total of 91 bacterial isolates were obtained, and based on morphological characteristics, 36 representative dominant strains were selected for 16S rDNA sequencing analysis. The results showed that the 36 bacterial strains belonged to four phyla and nine genera. The Firmicutes was the dominant phylum, and Bacillus, Paenibacillus and Pseudomonas were the dominant genera. Most of the strains had motility (80%) and were biofilm-forming (91.7%). In this study, 15 strains were capable of Indole-3-acetic acid (IAA) production, 24 strains were capable of nitrogen fixation, and some strains possessed amylase and protease activities, suggesting their potential for growth promotion. Determination of the minimum inhibitory concentration (MIC) against the bacteria showed that the strains were not resistant to tetracycline and oxytetracycline. Pantoea (QY6, LH4, MS2) and Curtobacterium (YY4) showed resistance to five antibiotics (ampicillin, kanamycin, erythromycin, sulfadiazine and rifampicin). Using Pearson correlation analysis, a significant correlation was found between motility and biofilm, and between biofilm and sulfadiazine. In this study, we screened two strains of Pantoea (QY6, LH4) with excellent growth-promoting ability as well as broad-spectrum antibiotic resistance. which provided new perspectives for subsequent studies on the strong ecological adaptations of fescue, and mycorrhizal resources for endophytic bacteria and plant interactions.

The beneficial endophytic microbes enhanced tobacco defense system to resist bacterial wilt disease

BackgroundThe vital role of rhizosphere microbiome in protecting plants against pathogen infection has been well characterized. By contrast, beneficial effects of the plant endophytic microbiome and interactions with plants remain poorly understood. Here, we integrated microbial community analysis, culture-based methods and plant defense gene quantification to systematically investigate the responses of endophytic root and stem microbiomes and the defense system of the tobacco plant to Ralstonia solanacearum, a bacterial pathogen causing bacterial wilt disease worldwide.ResultsAn obvious reduction of community diversity and changes of microbial composition were observed in tobacco root and stem compartments upon R. solanacearum infection. Beneficial endophytic microbes were enriched in both diseased root and stem compartments, and beneficial microbes enriched in roots were more diverse than those in stems. Several beneficial bacteria enriched in diseased roots showed positive correlations with the pathogen abundance and exhibited great antagonistic activities against R. solanacearum. At the same time, the expression of key genes participating in plant defense signaling pathways and activities of plant defense enzymes were activated with R. solanacearum infection. Inoculation of beneficial endophyte Burkholderia ASV_550 in soils could greatly enhance the tobacco defense system in the presence of pathogen and decrease the disease incidence.ConclusionsThe recruited beneficial microbes exhibited an enhancement of the defense system of host plants. This work provides endophyte evidence for the “cry for help” strategy in plants and advances the current understanding of plant–microbe interactions in resisting plant disease.Graphical

Plant interaction networks reveal the limits of our understanding of diversity maintenance.

Species interactions are key drivers of biodiversity and ecosystem stability. Current theoretical frameworks for understanding the role of interactions make many assumptions which unfortunately, do not always hold in natural, diverse communities. This mismatch extends to annual plants, a common model system for studying coexistence, where interactions are typically averaged across environmental conditions and transitive competitive hierarchies are assumed to dominate. We quantify interaction networks for a community of annual wildflowers in Western Australia across a natural shade gradient at local scales. Whilst competition dominated, intraspecific and interspecific facilitation were widespread in all shade categories. Interaction strengths and directions varied substantially despite close spatial proximity and similar levels of local species richness, with most species interacting in different ways under different environmental conditions. Contrary to expectations, all networks were predominantly intransitive. These findings encourage us to rethink how we conceive of and categorize the mechanisms driving biodiversity in plant systems.

Effects of Plant and Avian Frugivore Interaction Networks on Landscape Patterns and Seed Dispersal Functions in the Southern Western Ghats, India

Effects of Plant and Avian Frugivore Interaction Networks on Landscape Patterns and Seed Dispersal Functions in the Southern Western Ghats, India