Microbiome of the Cool Season Forage Grass Timothy (\u3ci\u3ePhleum pratense\u3c/i\u3e L.) and Its Potential Role in Stress Tolerance

The functional attributes of the microbiome associated with timothy for growth promotion properties, antimicrobial and biosurfactant capacities were characterized. A total of 254 culturable bacteria were identified by 16S rRNA sequencing and grouped into 16 taxa that shared high homology of 98–99% with other known sequences. The majority of bacterial isolates exhibited multifunctional growth promotion attributes and plant stress improvement. The selection of competent and compatible strains for application in forage production is dependent on the recognition of root exudates and motility towards the roots, attachment to the root surface, formation of biofilm, penetration, and colonization of internal tissues. We selected competent rhizospheric bacteria to generate a multispecies consortium made of three strains that displayed growth-promoting abilities in timothy through the production of IAA, volatile organic compounds that increased root biomass, the production of siderophores and antibiotic resistance, as well as the ability to colonize plants. This study demonstrated that the multispecies consortium displayed biofilm formation and chemotactic behaviour towards several organic acids and towards root exudates released from the model grass Brachypodium distachyon. Organic acids were successful in stimulating the formation of biofilm of the multispecies consortium. In particular, fumaric and malic acids enhanced selective recruitment of the multispecies consortium in a dose-dependent manner thereby, promoting biofilm formation on root surface as demonstrated in SEM micrographs. The multispecies consortium exhibited biofilm-related traits including the production of exopolysaccharides (EPS) and alginate. EPS amounts were comparable in single strains and consortium forms and alginate production increased by 160% when the consortium was subjected to drought stress. These findings demonstrated that plant-microbe interaction is the hub of various factors directly affecting this balanced dual relation and that root exudates could be very selective in recruiting highly qualified multispecies consortium

Draft genome sequence of the plant-pathogenic soil fungus Rhizoctonia solani anastomosis group 3 strain Rhs1AP

The soil fungus Rhizoctonia solani is a pathogen of agricultural crops. Here, we report on the 51,705,945 bp draft consensus genome sequence of R. solani strain Rhs1AP. A comprehensive understanding of the heterokaryotic genome complexity and organization of R. solani may provide insight into the plant disease ecology and adaptive behavior of the fungus

Cannabis Microbiome and the Role of Endophytes in Modulating the Production of Secondary Metabolites: An Overview

Plants, including cannabis (Cannabis sativa subsp. sativa), host distinct beneficial microbial communities on and inside their tissues and organs, including seeds. They contribute to plant growth, facilitating mineral nutrient uptake, inducing defence resistance against pathogens, and modulating the production of plant secondary metabolites. Understanding the microbial partnerships with cannabis has the potential to affect the agricultural practices by improving plant fitness and the yield of cannabinoids. Little is known about this beneficial cannabis-microbe partnership, and the complex relationship between the endogenous microbes associated with various tissues of the plant, and the role that cannabis may play in supporting or enhancing them. This review will consider cannabis microbiota studies and the effects of endophytes on the elicitation of secondary metabolite production in cannabis plants. The review aims to shed light on the importance of the cannabis microbiome and how cannabinoid compound concentrations can be stimulated through symbiotic and/or mutualistic relationships with endophytes

The transcriptional landscape of Rhizoctonia solani AG1-IA during infection of soybean as defined by RNA-seq

Rhizoctonia solani Kühn infects most plant families and can cause significant agriculturalyield losses worldwide; however, plant resistance to this disease is rare and short-lived,and therefore poorly understood, resulting in the use of chemical pesticides for its control.Understanding the functional responses of this pathogen during host infection can help elucidatethe molecular mechanisms that are necessary for successful host invasion. Using thepathosystem model soybean-R. solani anastomosis group AG1-IA, we examined the globaltranscriptional responses of R. solani during early and late infection stages of soybean byapplying an RNA-seq approach. Approximately, 148 million clean paired-end reads, representing93% of R. solani AG1-IA genes, were obtained from the sequenced libraries. Analysisof R. solani AG1-IA transcripts during soybean invasion revealed that most genes weresimilarly expressed during early and late infection stages, and only 11% and 15% of theexpressed genes were differentially expressed during early and late infection stages,respectively. [...

FT-ICR/MS and GC-EI/MS Metabolomics Networking Unravels Global Potato Sprout's Responses to <em>Rhizoctonia solani</em> Infection

<div><p>The complexity of plant-pathogen interactions makes their dissection a challenging task for metabolomics studies. Here we are reporting on an integrated metabolomics networking approach combining gas chromatography/mass spectrometry (GC/MS) with Fourier transform ion cyclotron resonance/mass spectrometry (FT-ICR/MS) and bioinformatics analyses for the study of interactions in the potato sprout-<em>Rhizoctonia solani</em> pathosystem and the fluctuations in the global metabolome of sprouts. The developed bioanalytical and bioinformatics protocols provided a snapshot of the sprout's global metabolic network and its perturbations as a result of pathogen invasion. Mevalonic acid and deoxy-xylulose pathways were substantially up-regulated leading to the biosynthesis of sesquiterpene alkaloids such as the phytoalexins phytuberin, rishitin, and solavetivone, and steroidal alkaloids having solasodine and solanidine as their common aglycons. Additionally, the perturbation of the sprout's metabolism was depicted in fluctuations of the content of their amino acids pool and that of carboxylic and fatty acids. Components of the systemic acquired resistance (SAR) and hypersensitive reaction (HR) such as azelaic and oxalic acids were detected in increased levels in infected sprouts and strategies of the pathogen to overcome plant defense were proposed. Our metabolic approach has not only greatly expanded the multitude of metabolites previously reported in potato in response to pathogen invasion, but also enabled the identification of bioactive plant-derived metabolites providing valuable information that could be exploited in biotechnology, biomarker-assisted plant breeding, and crop protection for the development of new crop protection agents.</p> </div

Fluctuations in <i>Solanum tuberosum</i> sprout metabolic pathways leading to the biosynthesis of sesquiterpene, steroidal, and nortropane alkaloids, saturated and unsaturated fatty acids and selected fatty acid oxidation products, 72 h after infection by <i>Rhizoctonia solani</i> AG3.

<p>Metabolite fluctuations are coded using a color code based on the means of scaled and centered PLS regression coefficients (CoeffCS) from eight replications. Dashed lines symbolize multistep or not fully elucidated reactions and solid lines one step reactions [3PGA; 3-phosphoglycerate, dxr; 1-deoxy-D-xylulose-5-phosphate reductoisomerase, FDFT1; farnesyl-diphosphate farnesyltransferase, ispA; farnesyl diphosphate synthase, HMG1; 3-hydroxy-3-methylglutaryl-CoA reductase, LOX; lipoxygenases, St-DES; 9-divinyl ether synthase, St-SGT1; galactose galactosyltransferase; St-SGT2; glucose glucotransferase, St-SGT3; rhamnosyltransferase, SQLE; squalene monooxygenase, TR-I; tropinone reductase I, VS1; vetispiradiene synthase].</p

Partial least squares (PLS) coefficient plots for the combined FT-ICR/MS (positive and negative electrospray modes) and GC/MS data matrix with values of scaled and centered PLS regression coefficients (CoeffCS) for selected identified metabolites.

<p>Influential metabolites for the observed separation between the metabolomes of control and infected <i>Solanum tuberosum</i> sprouts by <i>Rhizoctonia solani</i> AG3 72 h post-infection are displayed with Jack-knifed confidence intervals (<i>P</i><0.05) belonging to alkaloids (a), lipid acids and hydroperoxides (b), carboxylic acids and various metabolites (c), and amino acids (d). Metabolites marked with asterisk (*) denote metabolites detected exclusively in the infected spouts. Negative values of CoeffCS denote metabolites with higher concentration in infected sprouts whereas positive values those with higher concentration in non-infected sprouts.</p

Changes in the protein and non-protein amino acid pools of infected <i>Solanum tuberosum</i> sprouts 72 h after infection with <i>Rhizoctonia solani</i> AG3.

<p>Fluctuations in metabolite relative concentration are coded using a color code based on the means of scaled and centered PLS regression coefficients (CoeffCS) from eight replications. Dashed lines symbolize multistep or not fully elucidated reactions and solid lines one step reactions [3PGA; 3-phosphoglycerate, F6P; fructose-6-phosphate, G6P; glucose-6-phosphate, PEP; phosphoenolpyruvate].</p

Organic acids and root exudates of Brachypodium distachyon: effects on chemotaxis and biofilm formation of endophytic bacteria

Root colonization by plant-growth-promoting bacteria could not be useful without the beneficial properties of the bacterium itself. Thus, it is necessary to evaluate the bacterial capacity to form biofilms and establish a successful interaction with the plant roots. We assessed the ability of growth-promoting bacterial strains to form biofilm and display chemotactic behaviour in response to organic acids and (or) root exudates of the model plant Brachypodium distachyon. This assessment was based on the evaluation of single strains of bacteria and a multispecies consortium. The strains coexisted together and formed biofilm under biotic (living root) and abiotic (glass) surfaces. Citric acid stimulated biofilm formation in all individual strains, indicating a strong chemotactic behaviour towards organic acids. Recognizing that the transition from single strains of bacteria to a “multicellular” system would not happen without the presence of adhesion, the alginate and exopolysaccharide (EPS) contents were evaluated. The EPS amounts were comparable in single strains and consortium forms. Alginate production increased 160% in the consortium subjected to drought stress (10% PEG). These findings demonstrated that (i) bacteria–bacteria interaction is the hub of various factors that would not only affect their relation but also could indirectly affect the balanced plant–microbe relation and (ii) root exudates could be very selective in recruiting a highly qualified multispecies consortium.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

The <i>Solanum tuberosum</i> metabolome (A) visualized using the software Cytoscape (v.2.7.0.) and the reconstructed and curated PotatoCyc database.

<p>Changes in the sub-networks of sprouts' alkaloids (B), carboxylic (C), and amino acids (D) 72 h after infection by <i>Rhizoctonia solani</i> AG3 are displayed. All possible pathways between the detected metabolites are highlighted. Metabolite fluctuations are coded using a color code based on the means of scaled and centered PLS regression coefficients (CoeffCS) from eight replications. With asterisk (*) <i>de novo</i> produced metabolites are marked. Nodes represent metabolites, enzymes, nucleotides, CO₂, H₂O or reactions, while edges represent the connections between them.</p