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Spooren J, van Bentum S, Thomashow LS, Pieterse CMJ, Weller DM, Berendsen RL. Plant-Driven Assembly of Disease-Suppressive Soil Microbiomes. ANNUAL REVIEW OF PHYTOPATHOLOGY 2024; 62:1-30. [PMID: 38857541 DOI: 10.1146/annurev-phyto-021622-100127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2024]
Abstract
Plants have coevolved together with the microbes that surround them and this assemblage of host and microbes functions as a discrete ecological unit called a holobiont. This review outlines plant-driven assembly of disease-suppressive microbiomes. Plants are colonized by microbes from seed, soil, and air but selectively shape the microbiome with root exudates, creating microenvironment hot spots where microbes thrive. Using plant immunity for gatekeeping and surveillance, host-plant genetic properties govern microbiome assembly and can confer adaptive advantages to the holobiont. These advantages manifest in disease-suppressive soils, where buildup of specific microbes inhibits the causal agent of disease, that typically develop after an initial disease outbreak. Based on disease-suppressive soils such as take-all decline, we developed a conceptual model of how plants in response to pathogen attack cry for help and recruit plant-protective microbes that confer increased resistance. Thereby, plants create a soilborne legacy that protects subsequent generations and forms disease-suppressive soils.
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Affiliation(s)
- Jelle Spooren
- Plant-Microbe Interactions, Institute of Environmental Biology, Department of Biology, Science4Life, Utrecht University, Utrecht, The Netherlands
| | - Sietske van Bentum
- Plant-Microbe Interactions, Institute of Environmental Biology, Department of Biology, Science4Life, Utrecht University, Utrecht, The Netherlands
| | - Linda S Thomashow
- Wheat Health, Genetics and Quality Research Unit, US Department of Agriculture, Agricultural Research Service, Pullman, Washington, USA;
| | - Corné M J Pieterse
- Plant-Microbe Interactions, Institute of Environmental Biology, Department of Biology, Science4Life, Utrecht University, Utrecht, The Netherlands
| | - David M Weller
- Wheat Health, Genetics and Quality Research Unit, US Department of Agriculture, Agricultural Research Service, Pullman, Washington, USA;
| | - Roeland L Berendsen
- Plant-Microbe Interactions, Institute of Environmental Biology, Department of Biology, Science4Life, Utrecht University, Utrecht, The Netherlands
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2
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Balthazar C, St-Onge R, Léger G, Lamarre SG, Joly DL, Filion M. Pyoluteorin and 2,4-diacetylphloroglucinol are major contributors to Pseudomonas protegens Pf-5 biocontrol against Botrytis cinerea in cannabis. Front Microbiol 2022; 13:945498. [PMID: 36016777 PMCID: PMC9395707 DOI: 10.3389/fmicb.2022.945498] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 07/14/2022] [Indexed: 11/13/2022] Open
Abstract
Pseudomonas protegens Pf-5 is an effective biocontrol agent that protects many crops against pathogens, including the fungal pathogen Botrytis cinerea causing gray mold disease in Cannabis sativa crops. Previous studies have demonstrated the important role of antibiotics pyoluteorin (PLT) and 2,4-diacetylphloroglucinol (DAPG) in Pf-5-mediated biocontrol. To assess the potential involvement of PLT and DAPG in the biocontrol exerted by Pf-5 against B. cinerea in the phyllosphere of C. sativa, two knockout Pf-5 mutants were generated by in-frame deletion of genes pltD or phlA, required for the synthesis of PLT or DAPG respectively, using a two-step allelic exchange method. Additionally, two complemented mutants were constructed by introducing a multicopy plasmid carrying the deleted gene into each deletion mutant. In vitro confrontation assays revealed that deletion mutant ∆pltD inhibited B. cinerea growth significantly less than wild-type Pf-5, supporting antifungal activity of PLT. However, deletion mutant ∆phlA inhibited mycelial growth significantly more than the wild-type, hypothetically due to a co-regulation of PLT and DAPG biosynthesis pathways. Both complemented mutants recovered in vitro inhibition levels similar to that of the wild-type. In subsequent growth chamber inoculation trials, characterization of gray mold disease symptoms on infected cannabis plants revealed that both ∆pltD and ∆phlA significantly lost a part of their biocontrol capabilities, achieving only 10 and 19% disease reduction respectively, compared to 40% achieved by inoculation with the wild-type. Finally, both complemented mutants recovered biocontrol capabilities in planta similar to that of the wild-type. These results indicate that intact biosynthesis pathways for production of PLT and DAPG are required for the optimal antagonistic activity of P. protegens Pf-5 against B. cinerea in the cannabis phyllosphere.
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Affiliation(s)
- Carole Balthazar
- Department of Biology, Université de Moncton, Moncton, NB, Canada
| | - Renée St-Onge
- Department of Biology, Université de Moncton, Moncton, NB, Canada
| | - Geneviève Léger
- Department of Biology, Université de Moncton, Moncton, NB, Canada
| | - Simon G. Lamarre
- Department of Biology, Université de Moncton, Moncton, NB, Canada
| | - David L. Joly
- Department of Biology, Université de Moncton, Moncton, NB, Canada
| | - Martin Filion
- Department of Biology, Université de Moncton, Moncton, NB, Canada
- Agriculture and Agri-Food Canada, Saint-Jean-sur-Richelieu Research and Development Center, Saint-Jean-sur-Richelieu, QC, Canada
- *Correspondence: Martin Filion,
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Yang R, Li S, Li Y, Yan Y, Fang Y, Zou L, Chen G. Bactericidal Effect of Pseudomonas oryziphila sp. nov., a Novel Pseudomonas Species Against Xanthomonas oryzae Reduces Disease Severity of Bacterial Leaf Streak of Rice. Front Microbiol 2021; 12:759536. [PMID: 34803984 PMCID: PMC8600968 DOI: 10.3389/fmicb.2021.759536] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 10/04/2021] [Indexed: 11/13/2022] Open
Abstract
Pseudomonas is a diverse genus of Gammaproteobacteria with increasing novel species exhibiting versatile trains including antimicrobial and insecticidal activity, as well as plant growth-promoting, which make them well suited as biocontrol agents of some pathogens. Here we isolated strain 1257 that exhibited strong antagonistic activity against two pathovars of Xanthomonas oryzae, especially X. oryzae pv. oryzicola (Xoc) responsible for the bacterial leaf streak (BLS) in rice. The phylogenetic, genomic, physiological, and biochemical characteristics support that strain 1257 is a representative of a novel Pseudomonas species that is most closely related to the entomopathogenic bacterium Pseudomonas entomophila. We propose to name it Pseudomonas oryziphila sp. nov. Comparative genomics analyses showed that P. oryziphila 1257 possesses most of the central metabolic genes of two closely related strains P. entomophila L48 and Pseudomonas mosselii CFML 90-83, as well as a set of genes encoding the type IV pilus system, suggesting its versatile metabolism and motility properties. Some features, such as insecticidal toxins, phosphate solubilization, indole-3-acetic acid, and phenylacetic acid degradation, were disclosed. Genome-wide random mutagenesis revealed that the non-ribosomal peptide catalyzed by LgrD may be a major active compound of P. oryziphila 1257 against Xoc RS105, as well as the critical role of the carbamoyl phosphate and the pentose phosphate pathway that control the biosynthesis of this target compound. Our findings demonstrate that 1257 could effectively inhibit the growth and migration of Xoc in rice tissue to prevent the BLS disease. To our knowledge, this is the first report of a novel Pseudomonas species that displays a strong antibacterial activity against Xoc. The results suggest that the P. oryziphila strain could be a promising biological control agent for BLS.
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Affiliation(s)
- Ruihuan Yang
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Shengzhang Li
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Yilang Li
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Yichao Yan
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Yuan Fang
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Lifang Zou
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China.,State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China
| | - Gongyou Chen
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China.,State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China
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Durán P, Tortella G, Sadowsky MJ, Viscardi S, Barra PJ, Mora MDLL. Engineering Multigenerational Host-Modulated Microbiota against Soilborne Pathogens in Response to Global Climate Change. BIOLOGY 2021; 10:865. [PMID: 34571742 PMCID: PMC8472835 DOI: 10.3390/biology10090865] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 08/26/2021] [Accepted: 08/27/2021] [Indexed: 11/17/2022]
Abstract
Crop migration caused by climatic events has favored the emergence of new soilborne diseases, resulting in the colonization of new niches (emerging infectious diseases, EIDs). Soilborne pathogens are extremely persistent in the environment. This is in large part due to their ability to reside in the soil for a long time, even without a host plant, using survival several strategies. In this regard, disease-suppressive soils, characterized by a low disease incidence due to the presence of antagonist microorganisms, can be an excellent opportunity for the study mechanisms of soil-induced immunity, which can be applied in the development of a new generation of bioinoculants. Therefore, here we review the main effects of climate change on crops and pathogens, as well as the potential use of soil-suppressive microbiota as a natural source of biocontrol agents. Based on results of previous studies, we also propose a strategy for the optimization of microbiota assemblages, selected using a host-mediated approach. This process involves an increase in and prevalence of specific taxa during the transition from a conducive to a suppressive soil. This strategy could be used as a model to engineer microbiota assemblages for pathogen suppression, as well as for the reduction of abiotic stresses created due to global climate change.
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Affiliation(s)
- Paola Durán
- Scientific and Technological Bioresource Nucleus, Universidad de La Frontera, Temuco 4811230, Chile; (P.J.B.); (M.d.l.L.M.)
- Biocontrol Research Laboratory, Universidad de La Frontera, Temuco 4811230, Chile
| | - Gonzalo Tortella
- Centro de Excelencia en Investigación Biotecnológica Aplicada al Medio Ambiente (CIBAMA-BIOREN), Facultad de Ingeniería y Ciencias, Universidad de La Frontera, Temuco 4811230, Chile;
| | - Michael J. Sadowsky
- BioTechnology Institute, University of Minnesota, Minneapolis, MN 55108, USA;
| | - Sharon Viscardi
- Núcleo de Investigación en Producción Alimentaria, Facultad de Recursos Naturales, Universidad Católica de Temuco, P.O. Box 15-D, Temuco 4813302, Chile;
| | - Patricio Javier Barra
- Scientific and Technological Bioresource Nucleus, Universidad de La Frontera, Temuco 4811230, Chile; (P.J.B.); (M.d.l.L.M.)
- Biocontrol Research Laboratory, Universidad de La Frontera, Temuco 4811230, Chile
| | - Maria de la Luz Mora
- Scientific and Technological Bioresource Nucleus, Universidad de La Frontera, Temuco 4811230, Chile; (P.J.B.); (M.d.l.L.M.)
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Discovery and preliminary mechanism of 1-carbamoyl β-carbolines as new antifungal candidates. Eur J Med Chem 2021; 222:113563. [PMID: 34118721 DOI: 10.1016/j.ejmech.2021.113563] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 05/04/2021] [Accepted: 05/15/2021] [Indexed: 11/23/2022]
Abstract
Natural β-carboline alkaloids are ideal models for the discovery of pharmaceutically important entities. Various 1-substituted β-carbolines were synthesized from commercially inexpensive tryptophan and demonstrated significant in vitro antifungal activity against G. graminis. Significantly, compound 4m (EC50 = 0.45 μM) with carboxamide at 1-position displayed the best efficacy and nearly 20 folds enhancement in antifungal potential compared to Silthiopham (EC50 = 8.95 μM). Moreover, compounds 6, 7, and 4i exhibited excellent in vitro antifungal activities and in vivo protective and curative activities against B. cinerea and F. graminearum. Preliminary mechanism studies revealed that compound 4m caused reactive oxygen species accumulation, cell membrane destruction, and deregulation of histone acetylation. These findings indicated that 1-carbamoyl β-carboline can be selected as a promising model for the discovery of novel and broad-spectrum fungicide candidates.
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Biessy A, Filion M. Phloroglucinol Derivatives in Plant-Beneficial Pseudomonas spp.: Biosynthesis, Regulation, and Functions. Metabolites 2021; 11:metabo11030182. [PMID: 33804595 PMCID: PMC8003664 DOI: 10.3390/metabo11030182] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 03/12/2021] [Accepted: 03/17/2021] [Indexed: 11/16/2022] Open
Abstract
Plant-beneficial Pseudomonas spp. aggressively colonize the rhizosphere and produce numerous secondary metabolites, such as 2,4-diacetylphloroglucinol (DAPG). DAPG is a phloroglucinol derivative that contributes to disease suppression, thanks to its broad-spectrum antimicrobial activity. A famous example of this biocontrol activity has been previously described in the context of wheat monoculture where a decline in take-all disease (caused by the ascomycete Gaeumannomyces tritici) has been shown to be associated with rhizosphere colonization by DAPG-producing Pseudomonas spp. In this review, we discuss the biosynthesis and regulation of phloroglucinol derivatives in the genus Pseudomonas, as well as investigate the role played by DAPG-producing Pseudomonas spp. in natural soil suppressiveness. We also tackle the mode of action of phloroglucinol derivatives, which can act as antibiotics, signalling molecules and, in some cases, even as pathogenicity factors. Finally, we discuss the genetic and genomic diversity of DAPG-producing Pseudomonas spp. as well as its importance for improving the biocontrol of plant pathogens.
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Kusumaningsih T, Prasetyo WE, Firdaus M. A greatly improved procedure for the synthesis of an antibiotic-drug candidate 2,4-diacetylphloroglucinol over silica sulphuric acid catalyst: multivariate optimisation and environmental assessment protocol comparison by metrics. RSC Adv 2020; 10:31824-31837. [PMID: 35518163 PMCID: PMC9056496 DOI: 10.1039/d0ra05424k] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Accepted: 08/10/2020] [Indexed: 01/06/2023] Open
Abstract
Efforts toward the development of a straightforward greener Gram-scale synthesis of the antibiotic compound 2,4-diacetylphloroglucinol (DAPG) have been developed. This beneficial procedure was accomplished through the Friedel–Crafts acylation of phloroglucinol over inexpensive heterogeneous silica sulphuric acid (SSA) catalyst via ultrasound-assisted (US) synthesis under solvent-free condition. The influences of various parameters such as temperature, catalyst loading, and reaction time on the reaction performance were analysed using a multivariate statistical modelling response surface methodology (RSM). A high yield of DAPG (95%) was achieved at 60 °C after 15–20 min reaction with the presence of 10% (w/w) SSA as the catalyst. Column chromatography-free and a Gram scale-up reaction also exhibited the practical applicability of this newly developed protocol. The SSA catalyst was recovered and recycled up to 10 consecutive runs with no appreciable loss of activity. A plausible mechanism for the Friedel–Crafts acylation of phloroglucinol is proposed. Moreover, an environmental assessment has been carried out over this present method and compared with several established literature using the EATOS software and the Andraos algorithm to assess the consumption of the substrates, solvents, catalysts, and the production of coupled products or by-products. In addition, their energy consumptions were also determined. The data collected showed that the present method is the most promising one, characterised by the highest environmental impact profile against all the other reported methods. The physicochemical properties of the synthesised DAPG were assessed and exhibited reasonable oral bioavailability drug property as determined by Lipinski's rules. A greatly improved procedure for the synthesis of antibiotic 2,4-diacetylphloroglucinol has been developed via a newly advanced synthetic method.![]()
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Affiliation(s)
- Triana Kusumaningsih
- Department of Chemistry, Faculty of Mathematics and Natural Sciences, Sebelas Maret University Jl. Ir. Sutami No. 36A Surakarta 57126 Indonesia
| | - Wahyu Eko Prasetyo
- Department of Chemistry, Faculty of Mathematics and Natural Sciences, Sebelas Maret University Jl. Ir. Sutami No. 36A Surakarta 57126 Indonesia
| | - Maulidan Firdaus
- Department of Chemistry, Faculty of Mathematics and Natural Sciences, Sebelas Maret University Jl. Ir. Sutami No. 36A Surakarta 57126 Indonesia
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Gazengel K, Lebreton L, Lapalu N, Amselem J, Guillerm-Erckelboudt AY, Tagu D, Daval S. pH effect on strain-specific transcriptomes of the take-all fungus. PLoS One 2020; 15:e0236429. [PMID: 32730288 PMCID: PMC7392285 DOI: 10.1371/journal.pone.0236429] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 07/06/2020] [Indexed: 11/18/2022] Open
Abstract
The soilborne fungus Gaeumannomyces tritici (G. tritici) causes the take-all disease on wheat roots. Ambient pH has been shown to be critical in different steps of G. tritici life cycle such as survival in bulk soil, saprophytic growth, and pathogenicity on plants. There are however intra-specific variations and we previously found two types of G. tritici strains that grow preferentially either at acidic pH or at neutral/alkaline pH; gene expression involved in pH-signal transduction pathway and pathogenesis was differentially regulated in two strains representative of these types. To go deeper in the description of the genetic pathways and the understanding of this adaptative mechanism, transcriptome sequencing was achieved on two strains (PG6 and PG38) which displayed opposite growth profiles in two pH conditions (acidic and neutral). PG6, growing better at acidic pH, overexpressed in this condition genes related to cell proliferation. In contrast, PG38, which grew better at neutral pH, overexpressed in this condition genes involved in fatty acids and amino acid metabolisms, and genes potentially related to pathogenesis. This strain also expressed stress resistance mechanisms at both pH, to assert a convenient growth under various ambient pH conditions. These differences in metabolic pathway expression between strains at different pH might buffer the effect of field or soil variation in wheat fields, and explain the success of the pathogen.
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Affiliation(s)
- Kévin Gazengel
- IGEPP, INRAE, Institut Agro, Univ Rennes, Le Rheu, France
- * E-mail:
| | | | - Nicolas Lapalu
- AgroParisTech, INRAE, Université Paris-Saclay, BIOGER, Thiverval-Grignon, France
| | - Joëlle Amselem
- INRAE, Université Paris-Saclay, URGI, Versailles, France
| | | | - Denis Tagu
- IGEPP, INRAE, Institut Agro, Univ Rennes, Le Rheu, France
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Castro Tapia MP, Madariaga Burrows RP, Ruiz Sepúlveda B, Vargas Concha M, Vera Palma C, Moya-Elizondo EA. Antagonistic Activity of Chilean Strains of Pseudomonas protegens Against Fungi Causing Crown and Root Rot of Wheat ( Triticum aestivum L.). FRONTIERS IN PLANT SCIENCE 2020; 11:951. [PMID: 32670339 PMCID: PMC7330486 DOI: 10.3389/fpls.2020.00951] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 06/10/2020] [Indexed: 06/11/2023]
Abstract
Seed treatments with antagonistic bacteria could reduce the severity of crown and root rot diseases in wheat crops. The objective of this study was to evaluate the potential antagonistic activity of a bacterial consortium of three Chilean strains of Pseudomonas protegens against the wheat crown and root rot pathogens Gaeumannomyces graminis var. tritici, Rhizoctonia cerealis, and Fusarium culmorum. Two field experiments were carried out on artificially infested soil during two consecutive seasons (2016-2017 and 2017-2018) in an Andisol soil of southern Chile. Control treatments (not inoculated with fungi) were also included. Each treatment included a seed treatment of spring wheat cv. Pantera-INIA with and without the bacterial consortium. Both phytosanitary damage (incidence and severity) and agronomic components were evaluated. Bacterial populations with the phlD+ gene in the wheat plant rhizosphere during anthesis state (Z6) were also quantified. In both seasons, infection severity decreased by an average of 16.8% in seeds treated with P. protegens consortium, while yield components such as spikes m-1 and number of grains per spike increased. The use of antagonistic bacteria resulted in a total yield increase only during the first experimental season (P < 0.05). In general, accumulated rainfall influenced the antagonistic effect of the consortium of P. protegens strains, accounting for the differences observed between the two seasons. The results suggest that this P. protegens consortium applied on seeds can promote plant growth and protect wheat crops against crown and root rot pathogens in Southern Chile under field conditions.
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Affiliation(s)
- María Paz Castro Tapia
- Departamento de Producción Vegetal, Facultad de Agronomía, Universidad de Concepción, Chillán, Chile
| | | | - Braulio Ruiz Sepúlveda
- Departamento de Producción Vegetal, Facultad de Agronomía, Universidad de Concepción, Chillán, Chile
| | - Marisol Vargas Concha
- Departamento de Producción Vegetal, Facultad de Agronomía, Universidad de Concepción, Chillán, Chile
| | - Carola Vera Palma
- National Agricultural Research Institute, INIA Quilamapu, Chillán, Chile
| | - Ernesto A. Moya-Elizondo
- Departamento de Producción Vegetal, Facultad de Agronomía, Universidad de Concepción, Chillán, Chile
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Yu XQ, Yan X, Zhang MY, Zhang LQ, He YX. Flavonoids repress the production of antifungal 2,4-DAPG but potentially facilitate root colonization of the rhizobacterium Pseudomonas fluorescens. Environ Microbiol 2020; 22:5073-5089. [PMID: 32363709 DOI: 10.1111/1462-2920.15052] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Accepted: 04/28/2020] [Indexed: 11/25/2022]
Abstract
In the well-known legume-rhizobia symbiosis, flavonoids released by legume roots induce expression of the Nod factors and trigger early plant responses involved in root nodulation. However, it remains largely unknown how the plant-derived flavonoids influence the physiology of non-symbiotic beneficial rhizobacteria. In this work, we demonstrated that the flavonoids apigenin and/or phloretin enhanced the swarming motility and production of cellulose and curli in Pseudomonas fluorescens 2P24, both traits of which are essential for root colonization. Using a label-free quantitative proteomics approach, we showed that apigenin and phloretin significantly reduced the biosynthesis of the antifungal metabolite 2,4-DAPG and further identified a novel flavonoid-sensing TetR regulator PhlH, which was shown to modulate 2,4-DAPG production by regulating the expression of 2,4-DAPG hydrolase PhlG. Although having similar structures, apigenin and phloretin could also influence different physiological characteristics of P. fluorescens 2P24, with apigenin decreasing the biofilm formation and phloretin inducing expression of proteins involved in the denitrification and arginine fermentation processes. Taken together, our results suggest that plant-derived flavonoids could be sensed by the TetR regulator PhlH in P. fluorescens 2P24 and acts as important signalling molecules that strengthen mutually beneficial interactions between plants and non-symbiotic beneficial rhizobacteria.
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Affiliation(s)
- Xiao-Quan Yu
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Xu Yan
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Meng-Yuan Zhang
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Li-Qun Zhang
- Department of Plant Pathology, China Agricultural University, Beijing, China
| | - Yong-Xing He
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
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Zhang J, Mavrodi DV, Yang M, Thomashow LS, Mavrodi OV, Kelton J, Weller DM. Pseudomonas synxantha 2-79 Transformed with Pyrrolnitrin Biosynthesis Genes Has Improved Biocontrol Activity Against Soilborne Pathogens of Wheat and Canola. PHYTOPATHOLOGY 2020; 110:1010-1017. [PMID: 32065038 PMCID: PMC7238759 DOI: 10.1094/phyto-09-19-0367-r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A four-gene operon (prnABCD) from Pseudomonas protegens Pf-5 encoding the biosynthesis of the antibiotic pyrronitrin was introduced into P. synxantha (formerly P. fluorescens) 2-79, an aggressive root colonizer of both dryland and irrigated wheat roots that naturally produces the antibiotic phenazine-1-carboxylic acid and suppresses both take-all and Rhizoctonia root rot of wheat. Recombinant strains ZHW15 and ZHW25 produced both antibiotics and maintained population sizes in the rhizosphere of wheat that were comparable to those of strain 2-79. The recombinant strains inhibited in vitro the wheat pathogens Rhizoctonia solani anastomosis group 8 (AG-8) and AG-2-1, Gaeumannomyces graminis var. tritici, Sclerotinia sclerotiorum, Fusarium culmorum, and F. pseudograminearum significantly more than did strain 2-79. Both the wild-type and recombinant strains were equally inhibitory of Pythium ultimum. When applied as a seed treatment, the recombinant strains suppressed take-all, Rhizoctonia root rot of wheat, and Rhizoctonia root and stem rot of canola significantly better than did wild-type strain 2-79.
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Affiliation(s)
- Jibin Zhang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, P. R. China
- Department of Plant Pathology, Washington State University, Pullman 99164-6430, U.S.A
| | - Dmitri V. Mavrodi
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS 39406, U.S.A
- Department of Plant Pathology, Washington State University, Pullman 99164-6430, U.S.A
| | - Mingming Yang
- Department of Plant Pathology, Washington State University, Pullman 99164-6430, U.S.A
- Department of Agronomy, Northwest A&F University, Yangling, P. R. China
| | - Linda S. Thomashow
- USDA-ARS Wheat Health, Genetics and Quality Research Unit, Pullman, WA 99164-6430, U.S.A
| | - Olga V. Mavrodi
- School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS 39406, U.S.A
- Department of Plant Pathology, Washington State University, Pullman 99164-6430, U.S.A
| | - Jason Kelton
- USDA-ARS Wheat Health, Genetics and Quality Research Unit, Pullman, WA 99164-6430, U.S.A
| | - David M. Weller
- USDA-ARS Wheat Health, Genetics and Quality Research Unit, Pullman, WA 99164-6430, U.S.A
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Yang M, Mavrodi DV, Thomashow LS, Weller DM. Differential Response of Wheat Cultivars to Pseudomonas brassicacearum and Take-All Decline Soil. PHYTOPATHOLOGY 2018; 108:1363-1372. [PMID: 29905506 PMCID: PMC6483097 DOI: 10.1094/phyto-01-18-0024-r] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
2,4-Diacetylphloroglucinol (DAPG)-producing Pseudomonas spp. in the P. fluorescens complex are primarily responsible for a natural suppression of take-all of wheat known as take-all decline (TAD) in many fields in the United States. P. brassicacearum, the most common DAPG producer found in TAD soils in the Pacific Northwest (PNW) of the United States, has biological control, growth promoting and phytotoxic activities. In this study, we explored how the wheat cultivar affects the level of take-all suppression when grown in a TAD soil, and how cultivars respond to colonization by P. brassicacearum. Three cultivars (Tara, Finley, and Buchanan) supported similar rhizosphere population sizes of P. brassicacearum when grown in a TAD soil, however they developed significantly different amounts of take-all. Cultivars Tara and Buchanan developed the least and most take-all, respectively, and Finley showed an intermediate amount of disease. However, when grown in TAD soil that was pasteurized to eliminate both DAPG producers and take-all suppression, all three cultivars were equally susceptible to take-all. The three cultivars also responded differently to the colonization and phytotoxicity of P. brassicacearum strains Q8r1-96 and L5.1-96, which are characteristic of DAPG producers in PNW TAD soils. Compared with cultivar Tara, cultivar Buchanan showed significantly reduced seedling emergence and root growth when colonized by P. brassicacearum, and the response of Finley was intermediate. However, all cultivars emerged equally when treated with a DAPG-deficient mutant of Q8r1-96. Our results indicate that wheat cultivars grown in a TAD soil modulate both the robustness of take-all suppression and the potential phytotoxicity of the antibiotic DAPG.
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Affiliation(s)
| | - Dmitri V. Mavrodi
- Department of Cell and Molecular Biology, The University of Southern Mississippi, Hattiesburg 39406
| | - Linda S. Thomashow
- U.S. Department of Agriculture, Agricultural Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA 99164-6430
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Kwon YS, Jeon CW, Bae DW, Seo JS, Thomashow LS, Weller DM, Kwak YS. Construction of a proteome reference map and response of Gaeumannomyces graminis var. tritici to 2,4-diacetylphloroglucinol. Fungal Biol 2018; 122:1098-1108. [PMID: 30342625 DOI: 10.1016/j.funbio.2018.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 08/31/2018] [Accepted: 09/07/2018] [Indexed: 10/28/2022]
Abstract
Take-all disease, caused by Gaeumannomyces graminis var. tritici (Ggt), is one of the most serious root diseases in wheat production. In this study, a proteomic platform based on 2-dimensional gel electrophoresis (2-DE) and Matrix-Assisted Laser Desorption/Ionization Time of Flight Tandem Mass Spectrometry (MALDI-TOF/TOF MS) was used to construct the first proteome database reference map of G. graminis var. tritici and to identify the response of the pathogen to 2,4-diacetylphloroglucinol (DAPG), which is a natural antibiotic produced by antagonistic Pseudomonas spp. in take-all suppressive soils. For mapping, a total of 240 spots was identified that represented 209 different proteins. The most abundant biological function categories in the Ggt proteome were related to carbohydrate metabolism (21%), amino acid metabolism (15%), protein folding and degradation (12%), translation (11%), and stress response (10%). In total, 51 Ggt proteins were affected by DAPG treatment. Based on gene ontology, carbohydrate metabolism, amino acid metabolism, stress response, and protein folding and degradation proteins were the ones most modulated by DAPG treatment. This study provides the first extensive proteomic reference map constructed for Ggt and represents the first time that the response of Ggt to DAPG has been characterized at the proteomic level.
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Affiliation(s)
- Young Sang Kwon
- Environmental Toxicology Research Center, Korea Institute of Toxicology (KIT), Jinju 52834, Republic of Korea
| | - Chang-Wook Jeon
- Division of Applied Life Science (BK21Plus) and Institute of Agriculture & Life Sciences, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Dong-Won Bae
- Center for Research Facilities, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Jong-Su Seo
- Environmental Toxicology Research Center, Korea Institute of Toxicology (KIT), Jinju 52834, Republic of Korea
| | - Linda S Thomashow
- United States Department of Agriculture-Agriculture Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA 99164, USA
| | - David M Weller
- United States Department of Agriculture-Agriculture Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA 99164, USA
| | - Youn-Sig Kwak
- Division of Applied Life Science (BK21Plus) and Institute of Agriculture & Life Sciences, Gyeongsang National University, Jinju 52828, Republic of Korea.
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Wang L, Zhang Y, Wang D, Wang M, Wang Y, Feng J. Mitochondrial Signs and Subcellular Imaging Provide Insight into the Antifungal Mechanism of Carabrone against Gaeumannomyces graminis var. tritici. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018; 66:81-90. [PMID: 29232953 DOI: 10.1021/acs.jafc.7b03913] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Carabrone, a botanical bicyclic sesquiterpenic lactone, has broad-spectrum antifungal activity and is particularly efficient against the devastating phytopathogen Gaeumannomyces graminis var. tritici (Ggt). The antifungal mechanism of carabrone against Ggt, however, remains unclear. The main objective of this study was to investigate the subcellular localization of carabrone in Ggt to gain a better understanding of its mechanism of action. When Ggt was exposed to carabrone (EC50 value of 28.45 μg/mL) for 7 days, a decline in mitochondrial concentration together with some obvious alternations in mitochondrial structure, including hazy outlines, medullary transitions, excess accumulation of unclear settlings, and vacuolar degeneration, were observed, indicating that carbrone may act on the mitochondria directly. A fluorescent conjugate (TTY) was thus designed and synthesized as a surrogate of carabrone that possessed comparable antifungal activity against Ggt (EC50 of 33.68 μg/mL). Additionally, a polyclonal antibody specific to carabrone and with a high titer (256 000) was also prepared by immunizing mice. Subsequently, two imaging techniques, the use of the fluorescent conjugate (FC) and immunofluorescence (IF), were applied to determine the subcellular localization of carabrone. Both FC and IF fluorescent signals demonstrated its mitochondrial localization with a Pearson's coefficient of 0.83 for FC and 0.86 for IF. These results imply that carabrone exerts its antifungal activity against Ggt by interfering with mitochondrial function.
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Affiliation(s)
- Lanying Wang
- Research and Development Center of Biorational Pesticide, Northwest A&F University , Yangling 712100, Shaanxi, China
- Institute of Tropical Agriculture and Forestry, Hainan University , Haikou 570228, Hainan, China
| | - Yunfei Zhang
- Research and Development Center of Biorational Pesticide, Northwest A&F University , Yangling 712100, Shaanxi, China
| | - Delong Wang
- Research and Development Center of Biorational Pesticide, Northwest A&F University , Yangling 712100, Shaanxi, China
| | - Mei Wang
- Research and Development Center of Biorational Pesticide, Northwest A&F University , Yangling 712100, Shaanxi, China
| | - Yong Wang
- Research and Development Center of Biorational Pesticide, Northwest A&F University , Yangling 712100, Shaanxi, China
| | - Juntao Feng
- Research and Development Center of Biorational Pesticide, Northwest A&F University , Yangling 712100, Shaanxi, China
- Engineering and Research Center of Biological Pesticide of Shaanxi Province , Yangling 712100, Shaanxi, China
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Schlatter D, Kinkel L, Thomashow L, Weller D, Paulitz T. Disease Suppressive Soils: New Insights from the Soil Microbiome. PHYTOPATHOLOGY 2017; 107:1284-1297. [PMID: 28650266 DOI: 10.1094/phyto-03-17-0111-rvw] [Citation(s) in RCA: 178] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Soils suppressive to soilborne pathogens have been identified worldwide for almost 60 years and attributed mainly to suppressive or antagonistic microorganisms. Rather than identifying, testing and applying potential biocontrol agents in an inundative fashion, research into suppressive soils has attempted to understand how indigenous microbiomes can reduce disease, even in the presence of the pathogen, susceptible host, and favorable environment. Recent advances in next-generation sequencing of microbiomes have provided new tools to reexamine and further characterize the nature of these soils. Two general types of suppression have been described: specific and general suppression, and theories have been developed around these two models. In this review, we will present three examples of currently-studied model systems with features representative of specific and general suppressiveness: suppression to take-all (Gaeumannomyces graminis var. tritici), Rhizoctonia bare patch of wheat (Rhizoctonia solani AG-8), and Streptomyces. To compare and contrast the two models of general versus specific suppression, we propose a number of hypotheses about the nature and ecology of microbial populations and communities of suppressive soils. We outline the potential and limitations of new molecular techniques that can provide novel ways of testing these hypotheses. Finally, we consider how this greater understanding of the phytobiome can facilitate sustainable disease management in agriculture by harnessing the potential of indigenous soil microbes.
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Affiliation(s)
- Daniel Schlatter
- First, third, and fourth authors: U.S. Department of Agriculture-Agricultural Research Service, Wheat Health, Genetics, and Quality Research Unit, Washington State University, Pullman 99164-6430; and second author: Department of Plant Pathology, University of Minnesota, St. Paul 55108
| | - Linda Kinkel
- First, third, and fourth authors: U.S. Department of Agriculture-Agricultural Research Service, Wheat Health, Genetics, and Quality Research Unit, Washington State University, Pullman 99164-6430; and second author: Department of Plant Pathology, University of Minnesota, St. Paul 55108
| | - Linda Thomashow
- First, third, and fourth authors: U.S. Department of Agriculture-Agricultural Research Service, Wheat Health, Genetics, and Quality Research Unit, Washington State University, Pullman 99164-6430; and second author: Department of Plant Pathology, University of Minnesota, St. Paul 55108
| | - David Weller
- First, third, and fourth authors: U.S. Department of Agriculture-Agricultural Research Service, Wheat Health, Genetics, and Quality Research Unit, Washington State University, Pullman 99164-6430; and second author: Department of Plant Pathology, University of Minnesota, St. Paul 55108
| | - Timothy Paulitz
- First, third, and fourth authors: U.S. Department of Agriculture-Agricultural Research Service, Wheat Health, Genetics, and Quality Research Unit, Washington State University, Pullman 99164-6430; and second author: Department of Plant Pathology, University of Minnesota, St. Paul 55108
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16
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Liu H, Huo L, Yang B, Yuan Y, Zhang W, Xu Z, Qiu S, Tan H. Biomimetic-Inspired Syntheses of Myrtucommuacetalone and Myrtucommulone J. Org Lett 2017; 19:4786-4789. [DOI: 10.1021/acs.orglett.7b02159] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Hongxin Liu
- State
Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial
Key Laboratory of Microbial Culture Collection and Application, Guangdong
Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou 510070, P.R. China
- Key
Laboratory of Plant Resources Conservation and Sustainable Utilization,
Guangdong Provincial Key Laboratory of Applied Botany, South China
Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, P.R. China
| | - Luqiong Huo
- Key
Laboratory of Plant Resources Conservation and Sustainable Utilization,
Guangdong Provincial Key Laboratory of Applied Botany, South China
Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, P.R. China
| | - Bao Yang
- Key
Laboratory of Plant Resources Conservation and Sustainable Utilization,
Guangdong Provincial Key Laboratory of Applied Botany, South China
Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, P.R. China
| | - Yunfei Yuan
- Key
Laboratory of Plant Resources Conservation and Sustainable Utilization,
Guangdong Provincial Key Laboratory of Applied Botany, South China
Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, P.R. China
| | - Weimin Zhang
- State
Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial
Key Laboratory of Microbial Culture Collection and Application, Guangdong
Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou 510070, P.R. China
| | - Zhifang Xu
- Key
Laboratory of Plant Resources Conservation and Sustainable Utilization,
Guangdong Provincial Key Laboratory of Applied Botany, South China
Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, P.R. China
| | - Shengxiang Qiu
- Key
Laboratory of Plant Resources Conservation and Sustainable Utilization,
Guangdong Provincial Key Laboratory of Applied Botany, South China
Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, P.R. China
| | - Haibo Tan
- Key
Laboratory of Plant Resources Conservation and Sustainable Utilization,
Guangdong Provincial Key Laboratory of Applied Botany, South China
Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, P.R. China
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17
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Jaaffar AKM, Parejko JA, Paulitz TC, Weller DM, Thomashow LS. Sensitivity of Rhizoctonia Isolates to Phenazine-1-Carboxylic Acid and Biological Control by Phenazine-Producing Pseudomonas spp. PHYTOPATHOLOGY 2017; 107:692-703. [PMID: 28383281 DOI: 10.1094/phyto-07-16-0257-r] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Rhizoctonia solani anastomosis groups (AG)-8 and AG-2-1 and R. oryzae are ubiquitous in cereal-based cropping systems of the Columbia Plateau of the Inland Pacific Northwest and commonly infect wheat. AG-8 and R. oryzae, causal agents of Rhizoctonia root rot and bare patch, are most commonly found in fields in the low-precipitation zone, whereas R. solani AG-2-1 is much less virulent on wheat and is distributed in fields throughout the low-, intermediate-, and high-precipitation zones. Fluorescent Pseudomonas spp. that produce the antibiotic phenazine-1-carboxylic acid (PCA) also are abundant in the rhizosphere of crops grown in the low-precipitation zone but their broader geographic distribution and effect on populations of Rhizoctonia is unknown. To address these questions, we surveyed the distribution of PCA producers (Phz+) in 59 fields in cereal-based cropping systems throughout the Columbia Plateau. Phz+ Pseudomonas spp. were detected in 37 of 59 samples and comprised from 0 to 12.5% of the total culturable heterotrophic aerobic rhizosphere bacteria. The frequency with which individual plants were colonized by Phz+ pseudomonads ranged from 0 to 100%. High and moderate colonization frequencies of Phz+ pseudomonads were associated with roots from fields located in the driest areas whereas only moderate and low colonization frequencies were associated with crops where higher annual precipitation occurs. Thus, the geographic distribution of Phz+ pseudomonads overlaps closely with the distribution of R. solani AG-8 but not with that of R. oryzae or R. solani AG-2-1. Moreover, linear regression analysis demonstrated a highly significant inverse relationship between annual precipitation and the frequency of rhizospheres colonized by Phz+ pseudomonads. Phz+ pseudomonads representative of the four major indigenous species (P. aridus, P. cerealis, P. orientalis, and P. synxantha) suppressed Rhizoctonia root rot of wheat when applied as seed treatments. In vitro, mean 50% effective dose values for isolates of AG-8 and AG-2-1 from fields with high and low frequencies of phenazine producers did not differ significantly, nor was there a correlation between virulence of an isolate and sensitivity to PCA, resulting in rejection of the hypothesis that tolerance in Rhizoctonia spp. to PCA develops in nature upon exposure to Phz+ pseudomonads.
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Affiliation(s)
- Ahmad Kamil Mohd Jaaffar
- First and second authors: Department of Plant Pathology, Washington State University, Pullman 99164-6430; and third, fourth, and fifth authors: United States Department of Agriculture-Agricultural Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA 99164-6430
| | - James A Parejko
- First and second authors: Department of Plant Pathology, Washington State University, Pullman 99164-6430; and third, fourth, and fifth authors: United States Department of Agriculture-Agricultural Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA 99164-6430
| | - Timothy C Paulitz
- First and second authors: Department of Plant Pathology, Washington State University, Pullman 99164-6430; and third, fourth, and fifth authors: United States Department of Agriculture-Agricultural Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA 99164-6430
| | - David M Weller
- First and second authors: Department of Plant Pathology, Washington State University, Pullman 99164-6430; and third, fourth, and fifth authors: United States Department of Agriculture-Agricultural Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA 99164-6430
| | - Linda S Thomashow
- First and second authors: Department of Plant Pathology, Washington State University, Pullman 99164-6430; and third, fourth, and fifth authors: United States Department of Agriculture-Agricultural Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA 99164-6430
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18
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Kandel SL, Firrincieli A, Joubert PM, Okubara PA, Leston ND, McGeorge KM, Mugnozza GS, Harfouche A, Kim SH, Doty SL. An In vitro Study of Bio-Control and Plant Growth Promotion Potential of Salicaceae Endophytes. Front Microbiol 2017; 8:386. [PMID: 28348550 PMCID: PMC5347143 DOI: 10.3389/fmicb.2017.00386] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 02/23/2017] [Indexed: 11/13/2022] Open
Abstract
Microbial communities in the endosphere of Salicaceae plants, poplar (Populus trichocarpa) and willow (Salix sitchensis), have been demonstrated to be important for plant growth promotion, protection from biotic and abiotic stresses, and degradation of toxic compounds. Our study aimed to investigate bio-control activities of Salicaceae endophytes against various soil borne plant pathogens including Rhizoctonia solani AG-8, Fusarium culmorum, Gaeumannomyces graminis var. tritici, and Pythium ultimum. Additionally, different plant growth promoting traits such as biological nitrogen fixation (BNF), indole-3-acetic acid (IAA) biosynthesis, phosphate solubilization, and siderophore production were assessed in all bio-control positive strains. Burkholderia, Rahnella, Pseudomonas, and Curtobacterium were major endophyte genera that showed bio-control activities in the in-vitro assays. The bio-control activities of Burkholderia strains were stronger across all tested plant pathogens as compared to other stains. Genomes of sequenced Burkholderia strains WP40 and WP42 were surveyed to identify the putative genes involved in the bio-control activities. The ocf and hcnABC gene clusters responsible for biosynthesis of the anti-fungal metabolites, occidiofungin and hydrogen cyanide, are present in the genomes of WP40 and WP42. Nearly all endophyte strains showing the bio-control activities produced IAA, solubilized tricalcium phosphate, and synthesized siderophores in the culture medium. Moreover, some strains reduced acetylene into ethylene in the acetylene reduction assay, a common assay used for BNF. Salicaceae endophytes could be useful for bio-control of various plant pathogens, and plant growth promotion possibly through the mechanisms of BNF, IAA production, and nutrient acquisition.
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Affiliation(s)
- Shyam L Kandel
- School of Environmental and Forest Sciences, College of the Environment, University of Washington Seattle, WA, USA
| | - Andrea Firrincieli
- Department for Innovation in Biological, Agro-Food and Forest Systems, University of Tuscia Viterbo, Italy
| | - Pierre M Joubert
- Department of Biology, University of Washington Seattle, WA, USA
| | - Patricia A Okubara
- Wheat Health, Genetics and Quality Research Unit, USDA-ARS Pullman, WA, USA
| | - Natalie D Leston
- Department of Plant Pathology, Washington State University Pullman, WA, USA
| | - Kendra M McGeorge
- Department of Plant Pathology, Washington State University Pullman, WA, USA
| | - Giuseppe S Mugnozza
- Department for Innovation in Biological, Agro-Food and Forest Systems, University of Tuscia Viterbo, Italy
| | - Antoine Harfouche
- Department for Innovation in Biological, Agro-Food and Forest Systems, University of Tuscia Viterbo, Italy
| | - Soo-Hyung Kim
- School of Environmental and Forest Sciences, College of the Environment, University of Washington Seattle, WA, USA
| | - Sharon L Doty
- School of Environmental and Forest Sciences, College of the Environment, University of Washington Seattle, WA, USA
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Novel synthesized 2, 4-DAPG analogues: antifungal activity, mechanism and toxicology. Sci Rep 2016; 6:32266. [PMID: 27562341 PMCID: PMC4999805 DOI: 10.1038/srep32266] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 08/04/2016] [Indexed: 11/08/2022] Open
Abstract
2, 4-Diacetylphloroglucinol (2,4-DAPG), a natural phenolic compound, has been investigated in light of its biological activities against plant pathogens. To improve its potential application, fourteen 2,4-DAPG analogous were synthesized through the Friedel-Crafts reaction using acyl chlorides and phloroglucinol. Of the 2,4-DAPG derivatives, MP4 exhibited much higher antifungal activity against Penicillium digitatum and P. italicum, the major pathogenic fungi in citrus fruit, than 2, 4-DAPG in vitro, and significantly inhibited the development of decay in harvested mandarin (Citrus reticulata Blanco cv. Shatang.) fruit in vivo. It was found that MP4 resulted in the wrinkle of the hyphae in both fungi with serious folds and breakage. In addition, the expression of several cytochrome P450 (CYP) genes were also modified in both fungi by MP4, which might be associated with the disorder of cell membrane formation. Furthermore, the toxicology of MP4 by evaluating the cell proliferation effect on human normal lung epithelial (16HBE) and kidney 293 (HEK293) cells, was significantly lower than that of albesilate, a widely used fungicide in harvested citrus fruit. In summary, the synthesized MP4 has shown a great potential as a novel fungicide that might be useful for control of postharvest decay in citrus fruit.
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Jaaffar AKM, Paulitz TC, Schroeder KL, Thomashow LS, Weller DM. Molecular Characterization, Morphological Characteristics, Virulence, and Geographic Distribution of Rhizoctonia spp. in Washington State. PHYTOPATHOLOGY 2016; 106:459-473. [PMID: 26780436 DOI: 10.1094/phyto-09-15-0208-r] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Rhizoctonia root rot and bare patch, caused by Rhizoctonia solani anastomosis group (AG)-8 and R. oryzae, are chronic and important yield-limiting diseases of wheat and barley in the Inland Pacific Northwest (PNW) of the United States. Major gaps remain in our understanding of the epidemiology of these diseases, in part because multiple Rhizoctonia AGs and species can be isolated from the same cereal roots from the field, contributing to the challenge of identifying the causal agents correctly. In this study, a collection totaling 498 isolates of Rhizoctonia was assembled from surveys conducted from 2000 to 2009, 2010, and 2011 over a wide range of cereal production fields throughout Washington State in the PNW. To determine the identity of the isolates, PCR with AG- or species-specific primers and/or DNA sequence analysis of the internal transcribed spacers was performed. R. solani AG-2-1, AG-8, AG-10, AG-3, AG-4, and AG-11 comprised 157 (32%), 70 (14%), 21 (4%), 20 (4%), 1 (0.2%), and 1 (0.2%), respectively, of the total isolates. AG-I-like binucleate Rhizoctonia sp. comprised 44 (9%) of the total; and 53 (11%), 80 (16%), and 51 (10%) were identified as R. oryzae genotypes I, II, and III, respectively. Isolates of AG-2-1, the dominant Rhizoctonia, occurred in all six agronomic zones defined by annual precipitation and temperature within the region sampled. Isolates of AG-8 also were cosmopolitan in their distribution but the frequency of isolation varied among years, and they were most abundant in zones of low and moderate precipitation. R. oryzae was cosmopolitan, and collectively the three genotypes comprised 37% of the isolates. Only isolates of R. solani AG-8 and R. oryzae genotypes II and III (but not genotype I) caused symptoms typically associated with Rhizoctonia root rot and bare patch of wheat. Isolates of AG-2-1 caused only mild root rot and AG-I-like binucleate isolates and members of groups AG-3, AG-4, and AG-11 showed only slight or no discoloration of the roots. However, all isolates of AG-2-1 caused severe damping-off of canola, resulting in 100% mortality. Isolates of Rhizoctonia AG-8, AG-2-1, AG-10, AG-I-like binucleate Rhizoctonia, and R. oryzae genotypes I, II, and III could be distinguished by colony morphology on potato dextrose agar, by PCR with specific primers, or by the type and severity of disease on wheat and canola seedlings, and results of these approaches correlated completely. Based on cultured isolates, we also identified the geographic distribution of all of these Rhizoctonia isolates in cereal-based production systems throughout Washington State.
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Affiliation(s)
- Ahmad Kamil Mohd Jaaffar
- First and third authors: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; and second, fourth, and fifth authors: U.S. Department of Agriculture-Agricultural Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA 99164-6430
| | - Timothy C Paulitz
- First and third authors: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; and second, fourth, and fifth authors: U.S. Department of Agriculture-Agricultural Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA 99164-6430
| | - Kurtis L Schroeder
- First and third authors: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; and second, fourth, and fifth authors: U.S. Department of Agriculture-Agricultural Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA 99164-6430
| | - Linda S Thomashow
- First and third authors: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; and second, fourth, and fifth authors: U.S. Department of Agriculture-Agricultural Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA 99164-6430
| | - David M Weller
- First and third authors: Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430; and second, fourth, and fifth authors: U.S. Department of Agriculture-Agricultural Research Service, Wheat Health, Genetics and Quality Research Unit, Pullman, WA 99164-6430
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L. F. MEYER SUSAN, L. EVERTS KATHRYNE, MCSPADDEN GARDENER BRIAN, P. MASLER EDWARD, M. E. ABDELNABBY HAZEM, M. SKANTAR ANDREA. Assessment of DAPG-producing Pseudomonas fluorescens for Management of Meloidogyne incognita and Fusarium oxysporum on Watermelon. J Nematol 2016. [DOI: 10.21307/jofnem-2017-008] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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22
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Analysis of simple sequence repeats in the Gaeumannomyces graminis var. tritici genome and the development of microsatellite markers. Curr Genet 2014; 60:237-45. [PMID: 24789608 DOI: 10.1007/s00294-014-0428-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 04/02/2014] [Accepted: 04/11/2014] [Indexed: 10/25/2022]
Abstract
Understanding the genetic structure of Gaeumannomyces graminis var. tritici is essential for the establishment of efficient disease control strategies. It is becoming clear that microsatellites, or simple sequence repeats (SSRs), play an important role in genome organization and phenotypic diversity, and are a large source of genetic markers for population genetics and meiotic maps. In this study, we examined the G. graminis var. tritici genome (1) to analyze its pattern of SSRs, (2) to compare it with other plant pathogenic filamentous fungi, such as Magnaporthe oryzae and M. poae, and (3) to identify new polymorphic SSR markers for genetic diversity. The G. graminis var. tritici genome was rich in SSRs; a total 13,650 SSRs have been identified with mononucleotides being the most common motifs. In coding regions, the densities of tri- and hexanucleotides were significantly higher than in noncoding regions. The di-, tri-, tetra, penta, and hexanucleotide repeats in the G. graminis var. tritici genome were more abundant than the same repeats in M. oryzae and M. poae. From 115 devised primers, 39 SSRs are polymorphic with G. graminis var. tritici isolates, and 8 primers were randomly selected to analyze 116 isolates from China. The number of alleles varied from 2 to 7 and the expected heterozygosity (He) from 0.499 to 0.837. In conclusion, SSRs developed in this study were highly polymorphic, and our analysis indicated that G. graminis var. tritici is a species with high genetic diversity. The results provide a pioneering report for several applications, such as the assessment of population structure and genetic diversity of G. graminis var. tritici.
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Yang MM, Wen SS, Mavrodi DV, Mavrodi OV, von Wettstein D, Thomashow LS, Guo JH, Weller DM. Biological control of wheat root diseases by the CLP-producing strain Pseudomonas fluorescens HC1-07. PHYTOPATHOLOGY 2014; 104:248-56. [PMID: 24512115 PMCID: PMC5523110 DOI: 10.1094/phyto-05-13-0142-r] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Pseudomonas fluorescens HC1-07, previously isolated from the phyllosphere of wheat grown in Hebei province, China, suppresses the soilborne disease of wheat take-all, caused by Gaeumannomyces graminis var. tritici. We report here that strain HC1-07 also suppresses Rhizoctonia root rot of wheat caused by Rhizoctonia solani AG-8. Strain HC1-07 produced a cyclic lipopeptide (CLP) with a molecular weight of 1,126.42 based on analysis by electrospray ionization mass spectrometry. Extracted CLP inhibited the growth of G. graminis var. tritici and R. solani in vitro. To determine the role of this CLP in biological control, plasposon mutagenesis was used to generate two nonproducing mutants, HC1-07viscB and HC1-07prtR2. Analysis of regions flanking plasposon insertions in HC1-07prtR2 and HC1-07viscB revealed that the inactivated genes were similar to prtR and viscB, respectively, of the well-described biocontrol strain P. fluorescens SBW25 that produces the CLP viscosin. Both genes in HC1-07 were required for the production of the viscosin-like CLP. The two mutants were less inhibitory to G. graminis var. tritici and R. solani in vitro and reduced in ability to suppress take-all. HC1-07viscB but not HC-07prtR2 was reduced in ability to suppress Rhizoctonia root rot. In addition to CLP production, prtR also played a role in protease production.
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Troppens DM, Chu M, Holcombe LJ, Gleeson O, O'Gara F, Read ND, Morrissey JP. The bacterial secondary metabolite 2,4-diacetylphloroglucinol impairs mitochondrial function and affects calcium homeostasis in Neurospora crassa. Fungal Genet Biol 2013; 56:135-46. [PMID: 23624246 DOI: 10.1016/j.fgb.2013.04.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Revised: 03/25/2013] [Accepted: 04/12/2013] [Indexed: 10/26/2022]
Abstract
The bacterial secondary metabolite 2,4-diacetylphloroglucinol (DAPG) is of interest as an active ingredient of biological control strains of Pseudomonas fluorescens and as a potential lead pharmaceutical molecule because of its capacity to inhibit growth of diverse microbial and non-microbial cells. The mechanism by which this occurs is unknown and in this study the filamentous fungus Neurospora crassa was used as a model to investigate the effects of DAPG on a eukaryotic cell. Colony growth, conidial germination and cell fusion assays confirmed the inhibitory nature of DAPG towards N. crassa. A number of different fluorescent dyes and fluorescent protein reporters were used to assess the effects of DAPG treatment on mitochondrial and other cellular functions. DAPG treatment led to changes in mitochondrial morphology, and rapid loss of mitochondrial membrane potential. These effects are likely to be responsible for the toxicity of DAPG. It was also found that DAPG treatment caused extracellular calcium to be taken up by conidial germlings leading to a transient increase in cytosolic free Ca(2+) with a distinct concentration dependent Ca(2+) signature.
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Troppens DM, Dmitriev RI, Papkovsky DB, O'Gara F, Morrissey JP. Genome-wide investigation of cellular targets and mode of action of the antifungal bacterial metabolite 2,4-diacetylphloroglucinol in Saccharomyces cerevisiae. FEMS Yeast Res 2013; 13:322-34. [PMID: 23445507 DOI: 10.1111/1567-1364.12037] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Revised: 02/01/2013] [Accepted: 02/02/2013] [Indexed: 01/18/2023] Open
Abstract
Saccharomyces cerevisiae is a proven model to investigate the effects of small molecules and drugs on fungal and eukaryotic cells. In this study, the mode of action of an antifungal metabolite, 2,4-diacetylphloroglucinol (DAPG), was determined. Applying a combination of genetic and physiological approaches, it was established that this bacterial metabolite acts as a proton ionophore and dissipates the proton gradient across the mitochondrial membrane. The uncoupling of respiration and ATP synthesis ultimately leads to growth inhibition and is the primary toxic effect of DAPG. A genome-wide screen identified 154 DAPG-tolerant mutants and showed that there are many alterations in cellular metabolism that can confer at least some degree of tolerance to this uncoupler. One mutant, ydc1, was studied in some more detail as it displayed increased tolerance to both DAPG and the uncoupler carbonylcyanide m-chlorophenylhydrazone (CCCP) and appears to be unconnected to other tolerant mutant strains. Deleting YDC1 alters sphingolipid homoeostasis in the cell, and we suggest here that this may be linked to reduced drug sensitivity. Sphingolipids and their derivatives are important eukaryotic signal molecules, and the observation that altering homoeostasis may affect yeast response to metabolic uncoupling agents raises some intriguing questions for future studies.
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Yun Y, Yu F, Wang N, Chen H, Yin Y, Ma Z. Sensitivity to silthiofam, tebuconazole and difenoconazole of Gaeumannomyces graminis var. tritici isolates from China. PEST MANAGEMENT SCIENCE 2012; 68:1156-1163. [PMID: 22411909 DOI: 10.1002/ps.3277] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Revised: 09/25/2011] [Accepted: 01/13/2012] [Indexed: 05/31/2023]
Abstract
BACKGROUND Wheat take-all caused by Gaeumannomyces graminis var. tritici (Ggt) has become an emerging threat to wheat production in the last few years. Silthiofam is very effective against Ggt, and recently it has been widely used for the control of take-all in China. However, farmers have noted a decline in control efficacy with this compound in some wheat fields, suggesting that the pathogen may have developed resistance to silthiofam. RESULTS Of the 66 Ggt isolates collected from different locations in China, 27 were resistant to silthiofam. There was no cross-resistance between silthiofam and tecuconazole or difenoconazole. The effectiveness of silthiofam in controlling take-all was compromised on wheat inoculated with silthiofam-resistant isolates. Based on the DNA fingerprinting generated by microsatellite PCR, two predominant genetic clusters were found among these isolates and were clearly associated with the sensitivity to silthiofam. CONCLUSION Silthiofam has a high risk in the development of resistance in Ggt. Tebuconazole and difenoconazole show great potential for control of take-all on wheat. Results from this study provide useful information for take-all control and the management of fungicide resistance.
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Affiliation(s)
- Yingzi Yun
- Institute of Biotechnology, Zhejiang University, Hangzhou, China
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Weller DM, Mavrodi DV, van Pelt JA, Pieterse CMJ, van Loon LC, Bakker PAHM. Induced systemic resistance in Arabidopsis thaliana against Pseudomonas syringae pv. tomato by 2,4-diacetylphloroglucinol-producing Pseudomonas fluorescens. PHYTOPATHOLOGY 2012; 102:403-12. [PMID: 22409433 DOI: 10.1094/phyto-08-11-0222] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Pseudomonas fluorescens strains that produce the polyketide antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG) are among the most effective rhizobacteria that suppress root and crown rots, wilts, and damping-off diseases of a variety of crops, and they play a key role in the natural suppressiveness of some soils to certain soilborne pathogens. Root colonization by 2,4-DAPG-producing P. fluorescens strains Pf-5 (genotype A), Q2-87 (genotype B), Q8r1-96 (genotype D), and HT5-1 (genotype N) produced induced systemic resistance (ISR) in Arabidopsis thaliana accession Col-0 against bacterial speck caused by P. syringae pv. tomato. The ISR-eliciting activity of the four bacterial genotypes was similar, and all genotypes were equivalent in activity to the well-characterized strain P. fluorescens WCS417r. The 2,4-DAPG biosynthetic locus consists of the genes phlHGF and phlACBDE. phlD or phlBC mutants of Q2-87 (2,4-DAPG minus) were significantly reduced in ISR activity, and genetic complementation of the mutants restored ISR activity back to wild-type levels. A phlF regulatory mutant (overproducer of 2,4-DAPG) had ISR activity equivalent to the wild-type Q2-87. Introduction of DAPG into soil at concentrations of 10 to 250 μM 4 days before challenge inoculation induced resistance equivalent to or better than the bacteria. Strain Q2-87 induced resistance on transgenic NahG plants but not on npr1-1, jar1, and etr1 Arabidopsis mutants. These results indicate that the antibiotic 2,4-DAPG is a major determinant of ISR in 2,4-DAPG-producing P. fluorescens, that the genotype of the strain does not affect its ISR activity, and that the activity induced by these bacteria operates through the ethylene- and jasmonic acid-dependent signal transduction pathway.
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Affiliation(s)
- David M Weller
- United States Department of Agriculture–Agricultural Research Service, Root Disease and Biological Control Research Unit, Pullman, WA 99164-6430, USA.
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Yang MM, Mavrodi DV, Mavrodi OV, Bonsall RF, Parejko JA, Paulitz TC, Thomashow LS, Yang HT, Weller DM, Guo JH. Biological control of take-all by fluorescent Pseudomonas spp. from Chinese wheat fields. PHYTOPATHOLOGY 2011; 101:1481-1491. [PMID: 22070279 DOI: 10.1094/phyto-04-11-0096] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Take-all disease of wheat caused by the soilborne fungus Gaeumannomyces graminis var. tritici is one of the most important root diseases of wheat worldwide. Bacteria were isolated from winter wheat from irrigated and rainfed fields in Hebei and Jiangsu provinces in China, respectively. Samples from rhizosphere soil, roots, stems, and leaves were plated onto King's medium B agar and 553 isolates were selected. On the basis of in vitro tests, 105 isolates (19% of the total) inhibited G. graminis var. tritici and all were identified as Pseudomonas spp. by amplified ribosomal DNA restriction analysis. Based on biocontrol assays, 13 strains were selected for further analysis. All of them aggressively colonized the rhizosphere of wheat and suppressed take-all. Of the 13 strains, 3 (HC9-07, HC13-07, and JC14-07, all stem endophytes) had genes for the biosynthesis of phenazine-1-carboxylic acid (PCA) but none had genes for the production of 2,4-diacetylphloroglucinol, pyoluteorin, or pyrrolnitrin. High-pressure liquid chromatography (HPLC) analysis of 2-day-old cultures confirmed that HC9-07, HC13-07, and JC14-07 produced PCA but no other phenazines were detected. HPLC quantitative time-of-flight 2 mass-spectrometry analysis of extracts from roots of spring wheat colonized by HC9-07, HC13-07, or Pseudomonas fluorescens 2-79 demonstrated that all three strains produced PCA in the rhizosphere. Loss of PCA production by strain HC9-07 resulted in a loss of biocontrol activity. Analysis of DNA sequences within the key phenazine biosynthesis gene phzF and of 16S rDNA indicated that strains HC9-07, HC13-07, and JC14-07 were similar to the well-described PCA producer P. fluorescens 2-79. This is the first report of 2-79-like bacteria being isolated from Asia.
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Affiliation(s)
- Ming-Ming Yang
- Department of Plant Pathology, Nanjing Agricultural University, Jiangsu Province, China
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Kwak YS, Han S, Thomashow LS, Rice JT, Paulitz TC, Kim D, Weller DM. Saccharomyces cerevisiae genome-wide mutant screen for sensitivity to 2,4-diacetylphloroglucinol, an antibiotic produced by Pseudomonas fluorescens. Appl Environ Microbiol 2011; 77:1770-6. [PMID: 21193664 PMCID: PMC3067262 DOI: 10.1128/aem.02151-10] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Accepted: 12/21/2010] [Indexed: 11/20/2022] Open
Abstract
2,4-Diacetylphloroglucinol (2,4-DAPG), an antibiotic produced by Pseudomonas fluorescens, has broad-spectrum antibiotic activity, inhibiting organisms ranging from viruses, bacteria, and fungi to higher plants and mammalian cells. The biosynthesis and regulation of 2,4-DAPG in P. fluorescens are well described, but the mode of action against target organisms is poorly understood. As a first step to elucidate the mechanism, we screened a deletion library of Saccharomyces cerevisiae in broth and agar medium supplemented with 2,4-DAPG. We identified 231 mutants that showed increased sensitivity to 2,4-DAPG under both conditions, including 22 multidrug resistance-related mutants. Three major physiological functions correlated with an increase in sensitivity to 2,4-DAPG: membrane function, reactive oxygen regulation, and cell homeostasis. Physiological studies with wild-type yeast validated the results of the mutant screens. The chemical-genetic fitness profile of 2,4-DAPG resembled those of menthol, sodium azide, and hydrogen peroxide determined in previous high-throughput screening studies. Collectively, these findings indicate that 2,4-DAPG acts on multiple basic cellular processes.
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Affiliation(s)
- Youn-Sig Kwak
- Department of Plant Pathology, Washington State University, Pullman, Washington 99164-6430, Department of Bio and Brain Engineering, KAIST, Daejeon 305-701, South Korea, USDA-ARS, Root Disease and Biological Control Research Unit, 367 Johnson Hall, Washington State University, Pullman, Washington 99164-6430, Institute for the Biocentury, KAIST, Daejeon 305-701, South Korea
| | - Sangjo Han
- Department of Plant Pathology, Washington State University, Pullman, Washington 99164-6430, Department of Bio and Brain Engineering, KAIST, Daejeon 305-701, South Korea, USDA-ARS, Root Disease and Biological Control Research Unit, 367 Johnson Hall, Washington State University, Pullman, Washington 99164-6430, Institute for the Biocentury, KAIST, Daejeon 305-701, South Korea
| | - Linda S. Thomashow
- Department of Plant Pathology, Washington State University, Pullman, Washington 99164-6430, Department of Bio and Brain Engineering, KAIST, Daejeon 305-701, South Korea, USDA-ARS, Root Disease and Biological Control Research Unit, 367 Johnson Hall, Washington State University, Pullman, Washington 99164-6430, Institute for the Biocentury, KAIST, Daejeon 305-701, South Korea
| | - Jennifer T. Rice
- Department of Plant Pathology, Washington State University, Pullman, Washington 99164-6430, Department of Bio and Brain Engineering, KAIST, Daejeon 305-701, South Korea, USDA-ARS, Root Disease and Biological Control Research Unit, 367 Johnson Hall, Washington State University, Pullman, Washington 99164-6430, Institute for the Biocentury, KAIST, Daejeon 305-701, South Korea
| | - Timothy C. Paulitz
- Department of Plant Pathology, Washington State University, Pullman, Washington 99164-6430, Department of Bio and Brain Engineering, KAIST, Daejeon 305-701, South Korea, USDA-ARS, Root Disease and Biological Control Research Unit, 367 Johnson Hall, Washington State University, Pullman, Washington 99164-6430, Institute for the Biocentury, KAIST, Daejeon 305-701, South Korea
| | - Dongsup Kim
- Department of Plant Pathology, Washington State University, Pullman, Washington 99164-6430, Department of Bio and Brain Engineering, KAIST, Daejeon 305-701, South Korea, USDA-ARS, Root Disease and Biological Control Research Unit, 367 Johnson Hall, Washington State University, Pullman, Washington 99164-6430, Institute for the Biocentury, KAIST, Daejeon 305-701, South Korea
| | - David M. Weller
- Department of Plant Pathology, Washington State University, Pullman, Washington 99164-6430, Department of Bio and Brain Engineering, KAIST, Daejeon 305-701, South Korea, USDA-ARS, Root Disease and Biological Control Research Unit, 367 Johnson Hall, Washington State University, Pullman, Washington 99164-6430, Institute for the Biocentury, KAIST, Daejeon 305-701, South Korea
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Kwak YS, Bakker PAHM, Glandorf DCM, Rice JT, Paulitz TC, Weller DM. Isolation, characterization, and sensitivity to 2,4-diacetylphloroglucinol of isolates of Phialophora spp. from Washington wheat fields. PHYTOPATHOLOGY 2010; 100:404-414. [PMID: 20373960 DOI: 10.1094/phyto-100-5-0404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Dark pigmented fungi of the Gaeumannomyces-Phialophora complex were isolated from the roots of wheat grown in fields in eastern Washington State. These fungi were identified as Phialophora spp. on the basis of morphological and genetic characteristics. The isolates produced lobed hyphopodia on wheat coleoptiles, phialides, and hyaline phialospores. Sequence comparison of internal transcribed spacer regions indicated that the Phialophora isolates were clearly separated from other Gaeumannomyces spp. Primers AV1 and AV3 amplified 1.3-kb portions of an avenacinase-like gene in the Phialophora isolates. Phylogenetic trees of the avenacinase-like gene in the Phialophora spp. also clearly separated them from other Gaeumannomyces spp. The Phialophora isolates were moderately virulent on wheat and barley and produced confined black lesions on the roots of wild oat and two oat cultivars. Among isolates tested for their sensitivity to 2,4-diacetylphloroglucinol (2,4-DAPG), the 90% effective dose values were 11.9 to 48.2 microg ml(-1). A representative Phialophora isolate reduced the severity of take-all on wheat caused by two different isolates of Gaeumannomyces graminis var. tritici. To our knowledge, this study provides the first report of an avenacinase-like gene in Phialophora spp. and demonstrated that the fungus is significantly less sensitive to 2,4-DAPG than G. graminis var. tritici.
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Affiliation(s)
- Youn-Sig Kwak
- Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430, USA
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