scholarly journals Pseudomonas simiae WCS417: star track of a model beneficial rhizobacterium

2020 ◽  
Author(s):  
Corné M. J. Pieterse ◽  
Roeland L. Berendsen ◽  
Ronnie de Jonge ◽  
Ioannis A. Stringlis ◽  
Anja J. H. Van Dijken ◽  
...  
Keyword(s):  
Plant Growth ◽  
Molecular Mechanisms ◽  
Root Colonization ◽  
Dianthus Caryophyllus ◽  
Systemic Resistance ◽  
Systemic Immunity ◽  
Microbe Interactions ◽  
Promote Plant Growth ◽  
Root Microbiome ◽  
Take All

Abstract Background Since the 1980s, numerous mutualistic Pseudomonas spp. strains have been used in studies on the biology of plant growth-promoting rhizobacteria (PGPR) and their interactions with host plants. In 1988, a strain from the Pseudomonas fluorescens group, WCS417, was isolated from lesions of wheat roots growing in a take-all disease-suppressive soil. In subsequent trials, WCS417 limited the build-up of take-all disease in field-grown wheat and significantly increased wheat yield. In 1991, WCS417 was featured in one of the first landmark studies on rhizobacteria-induced systemic resistance (ISR), in which it was shown to confer systemic immunity in carnation (Dianthus caryophyllus) against Fusarium wilt. The discovery that WCS417 conferred systemic immunity in the model plant species Arabidopsis thaliana in 1996 incited intensive research on the molecular mechanisms by which PGPR promote plant growth and induce broad-spectrum disease resistance in plants. Since then, the strain name appeared in over 750 studies on beneficial plant-microbe interactions. Scope In this review, we will highlight key discoveries in plant-microbe interactions research that have emerged from over 30 years of research featuring WCS417 as a model rhizobacterial strain. WCS417 was instrumental in improving our understanding of the microbial determinants that are involved in root colonization and the establishment of mutually beneficial interactions with the host plant. The model strain also provided novel insight into the molecular mechanisms of plant growth promotion and the onset and expression of rhizobacteria-ISR. More recently, WCS417 has been featured in studies on host immune evasion during root colonization, and chemical communication in the rhizosphere during root microbiome assembly. Conclusions Numerous studies on the modes of action of WCS417 have provided major conceptual advances in our understanding of how free-living mutualists colonize the rhizosphere, modulate plant immunity, and promote plant growth. The concepts may prove useful in our understanding of the molecular mechanisms involved in other binary plant-beneficial microbe interactions, and in more complex microbial community contexts, such as the root microbiome.

scholarly journals Interrogating Plant-Microbe Interactions with Chemical Tools: Click Chemistry Reagents for Metabolic Labeling and Activity-Based Probes

Molecules ◽  
2021 ◽  
Vol 26 (1) ◽  
pp. 243
Author(s):  
Vivian S. Lin
Keyword(s):  
Plant Growth ◽  
Immune Responses ◽  
Click Chemistry ◽  
Chemical Biology ◽  
Molecular Mechanisms ◽  
Metabolic Labeling ◽  
Beneficial Microbes ◽  
Plant Hosts ◽  
Microbe Interactions ◽  
Growth Metabolism

Continued expansion of the chemical biology toolbox presents many new and diverse opportunities to interrogate the fundamental molecular mechanisms driving complex plant–microbe interactions. This review will examine metabolic labeling with click chemistry reagents and activity-based probes for investigating the impacts of plant-associated microbes on plant growth, metabolism, and immune responses. While the majority of the studies reviewed here used chemical biology approaches to examine the effects of pathogens on plants, chemical biology will also be invaluable in future efforts to investigate mutualistic associations between beneficial microbes and their plant hosts.

The entomopathogenic fungi Metarhizium brunneum and Beauveria bassiana promote systemic immunity and confer resistance to a broad range of pests and pathogens in tomato

2021 ◽  
Author(s):  
Rupali Gupta ◽  
Ravindran Keppanan ◽  
Meirav Leibman-Markus ◽  
Dalia Rav David ◽  
Yigal Elad ◽  
...  
Keyword(s):  
Disease Resistance ◽  
Plant Growth ◽  
Beauveria Bassiana ◽  
Entomopathogenic Fungi ◽  
Plant Pathogens ◽  
Plant Immunity ◽  
Systemic Immunity ◽  
Metarhizium Brunneum ◽  
Promote Plant Growth ◽  
Arthropod Pests

Biocontrol agents can control pathogens by re-enforcing systemic plant resistance through systemic acquired resistance (SAR) or induced systemic resistance (ISR). Trichoderma spp. can activate the plant immune system through ISR, priming molecular mechanisms of defense against pathogens. Entomopathogenic fungi (EPF) can infect a wide range of arthropod pests, and play an important role in reducing pests' population. Here, we investigated the mechanisms by which EPF control plant diseases. We tested two well studied EPF, Metarhizium brunneum isolate Mb7 and Beauveria bassiana as the commercial product Velifer, for their ability to induce systemic immunity and disease resistance against several fungal and bacterial phytopathogens, and their ability to promote plant growth. We compared the activity of these EPF to an established biocontrol agent, T. harzianum T39, a known inducer of systemic plant immunity and broad disease resistance. The three fungal agents were effective against several fungal and bacterial plant pathogens and arthropod pests. Our results indicate that EPF induce systemic plant immunity and disease resistance by activating the plant host defense machinery, as evidenced by increases in reactive oxygen species (ROS) production and defense gene expression, and that EPF promote plant growth. EPF should be considered as control means for Tuta absoluta. We demonstrate that, with some exceptions, biocontrol in tomato can be equally potent by the tested EPF and T. harzianum T39, against both insect pests and plant pathogens. Taken together, our findings suggest that EPF may find use in broad-spectrum pest and disease management and as plant growth promoting agents.

scholarly journals Involvement of the Reserve Material Poly-β-Hydroxybutyrate in Azospirillum brasilense Stress Endurance and Root Colonization

2003 ◽  
Vol 69 (6) ◽  
pp. 3244-3250 ◽  
Author(s):  
Daniel Kadouri ◽  
Edouard Jurkevitch ◽  
Yaacov Okon
Keyword(s):  
Plant Growth ◽  
Mutant Strain ◽  
Azospirillum Brasilense ◽  
Type Strain ◽  
Wild Type Strain ◽  
Root Colonization ◽  
Cell Aggregation ◽  
Wild Type ◽  
Phb Production ◽  
Promote Plant Growth

ABSTRACT When grown under suboptimal conditions, rhizobacteria of the genus Azospirillum produce high levels of poly-β-hydroxybutyrate (PHB). Azospirillum brasilense strain Sp7 and a phbC (PHB synthase) mutant strain in which PHB production is impaired were evaluated for metabolic versatility, for the ability to endure various stress conditions, for survival in soil inoculants, and for the potential to promote plant growth. The carbon source utilization data were similar for the wild-type and mutant strains, but the generation time of the wild-type strain was shorter than that of the mutant strain with all carbon sources tested. The ability of the wild type to endure UV irradiation, heat, osmotic pressure, osmotic shock, and desiccation and to grow in the presence of hydrogen peroxide was greater than that of the mutant strain. The motility and cell aggregation of the mutant strain were greater than the motility and cell aggregation of the wild type. However, the wild type exhibited greater chemotactic responses towards attractants than the mutant strain exhibited. The wild-type strain exhibited better survival than the mutant strain in carrier materials used for soil inoculants, but no difference in the ability to promote plant growth was detected between the strains. In soil, the two strains colonized roots to the same extent. It appears that synthesis and utilization of PHB as a carbon and energy source by A. brasilense under stress conditions favor establishment of this bacterium and its survival in competitive environments. However, in A. brasilense, PHB production does not seem to provide an advantage in root colonization under the conditions tested.

scholarly journals Bacterial Formulations in Induction of Resistance and Growth Promotion of Tomato Plants

2018 ◽  
Vol 10 (10) ◽  
pp. 493
Author(s):  
José R. M. Campos Neto ◽  
Rafael Ribeiro Chaves ◽  
Diogo Herison Silva Sardinha ◽  
Luiz Gustavo de Lima Melo ◽  
Antônia Alice Costa Rodrigues
Keyword(s):  
Plant Growth ◽  
Fusarium Wilt ◽  
Seed Treatment ◽  
Dry Matter ◽  
Growth Promotion ◽  
Systemic Resistance ◽  
Tomato Plants ◽  
Vigor Index ◽  
Promote Plant Growth ◽  
Induction Of Resistance

The objective of this work was to evaluate the effectiveness of seed treatment with fresh suspensions and powder formulations with Bacillus methylotrophicus to promote plant growth and induction of resistance against fusarium wilt (Fusarium oxysporum f. sp. lycopersici) in tomato plants under greenhouse conditions, verifying the occurrence of morphological and biochemical changes in the evaluated plants. Powder formulations based on Cassava (Manihot esculenta), Arrowroot (Maranta arundinacea) and sodium alginate containing Bacillus, in addition to the commercial product Quartz®, were used to microbiolize the tomato seeds of the cultivar Santa Cruz. The formulations promoted plant growth, with a seedling vigor index greater than 50% for all treatments containing B. mthylotrophicus, in addition to a significant increase in total dry matter. The treatments induced systemic resistance, controlling the fusarium wilt with a 75% reduction of the disease and activation of enzymes such as peroxidase and polyphenoloxidase, only β-1,3-glucanase presented less activity than controls (treatments without B. mthylotrophicus). Thus, the use of formulations containing Bacillus are efficient in promoting plant growth of tomato plants and in inducing resistance to the control of fusarium wilt.

scholarly journals Unraveling the Interaction between Arbuscular Mycorrhizal Fungi and Camellia Plants

Horticulturae ◽  
2021 ◽  
Vol 7 (9) ◽  
pp. 322
Author(s):  
Rui-Cheng Liu ◽  
Zhi-Yan Xiao ◽  
Abeer Hashem ◽  
Elsayed Fathi Abd_Allah ◽  
Yong-Jie Xu ◽  
...  
Keyword(s):  
Plant Growth ◽  
Arbuscular Mycorrhizal Fungi ◽  
Mycorrhizal Fungi ◽  
Root Colonization ◽  
Heavy Metal Contamination ◽  
Arbuscular Mycorrhizal ◽  
Nutrient Acquisition ◽  
Comprehensive Overview ◽  
Promote Plant Growth ◽  
Amf Inoculation

Camellia is a genus of evergreen shrubs or trees, such as C. japonica, C. sinensis, C. oleifera, etc. A group of beneficial soil microorganisms, arbuscular mycorrhizal fungi (AMF), inhabit the rhizosphere of these Camellia spp. A total of eight genera of Acaulospora, Entrophospora, Funneliformis, Gigaspora, Glomus, Pacispora, Scutellospora, and Sclerocystis were found to be associated with Camellia plants with Glomus and/or Acaulospora being most abundant. These mycorrhizal fungi can colonize the roots of Camellia spp. and thus form arbuscular mycorrhizal symbionts. AMF is an important partner of Camellia spp. in the field of physiological activities. Studies indicated that AMF inoculation has been shown to promote plant growth, improve nutrient acquisition and nutritional quality, and increase resistance to drought, salinity and heavy metal contamination in potted Camellia. This review thus provides a comprehensive overview of AMF species occurring in the rhizosphere of Camellia spp. and summarizes the variation in root AMF colonization rate as well as the environmental factors and soil nutrients affecting root colonization. The paper also reviews the effects of AMF on plant growth response, nutrient acquisition, food quality, and stress tolerance of Camellia spp.

scholarly journals Examining the Effects of the Nitrogen Environment on Growth and N2-Fixation of Endophytic Herbaspirillum seropedicae in Maize Seedlings by Applying 11C Radiotracing

2021 ◽  
Vol 9 (8) ◽  
pp. 1582
Author(s):  
Spenser Waller ◽  
Stacy L. Wilder ◽  
Michael J. Schueller ◽  
Alexandra B. Housh ◽  
Stephanie Scott ◽  
...  
Keyword(s):  
Plant Growth ◽  
Root Colonization ◽  
Growth Promotion ◽  
Nitrogenase Activity ◽  
Growth Conditions ◽  
Significant Inhibition ◽  
Cereal Crops ◽  
Herbaspirillum Seropedicae ◽  
Promote Plant Growth ◽  
Biological Nitrogen

Herbaspirillum seropedicae, as an endophyte and prolific root colonizer of numerous cereal crops, occupies an important ecological niche in agriculture because of its ability to promote plant growth and potentially improve crop yield. More importantly, there exists the untapped potential to harness its ability, as a diazotroph, to fix atmospheric N2 as an alternative nitrogen resource to synthetic fertilizers. While mechanisms for plant growth promotion remain controversial, especially in cereal crops, one irrefutable fact is these microorganisms rely heavily on plant-borne carbon as their main energy source in support of their own growth and biological functions. Biological nitrogen fixation (BNF), a microbial function that is reliant on nitrogenase enzyme activity, is extremely sensitive to the localized nitrogen environment of the microorganism. However, whether internal root colonization can serve to shield the microorganisms and de-sensitize nitrogenase activity to changes in the soil nitrogen status remains unanswered. We used RAM10, a GFP-reporting strain of H. seropedicae, and administered radioactive 11CO2 tracer to intact 3-week-old maize leaves and followed 11C-photosynthates to sites within intact roots where actively fluorescing microbial colonies assimilated the tracer. We examined the influence of administering either 1 mM or 10 mM nitrate during plant growth on microbial demands for plant-borne 11C. Nitrogenase activity was also examined under the same growth conditions using the acetylene reduction assay. We found that plant growth under low nitrate resulted in higher nitrogenase activity as well as higher microbial demands for plant-borne carbon than plant growth under high nitrate. However, carbon availability was significantly diminished under low nitrate growth due to reduced host CO2 fixation and reduced allocation of carbon resources to the roots. This response of the host caused significant inhibition of microbial growth. In summary, internal root colonization did little to shield these endophytic microorganisms from the nitrogen environment.

scholarly journals Induced systemic resistance impacts the phyllosphere microbiome through plant-microbe-microbe interactions

2021 ◽  
Author(s):  
Anna Sommer ◽  
Marion Wenig ◽  
Claudia Knappe ◽  
Susanne Kublik ◽  
Baerbel Foesel ◽  
...  
Keyword(s):  
Plant Growth ◽  
Induced Systemic Resistance ◽  
Bacterial Species ◽  
Plant Growth Promoting Rhizobacteria ◽  
Systemic Resistance ◽  
Bacillus Thuringiensis Israelensis ◽  
Plant Growth Promoting ◽  
Microbe Interactions ◽  
Growth Promoting ◽  
Dramatic Shift

Both above- and below-ground parts of plants are constantly confronted with microbes, which are main drivers for the development of plant-microbe interactions. Plant growth-promoting rhizobacteria enhance the immunity of above-ground tissues, which is known as induced systemic resistance (ISR). We show here that ISR also influences the leaf microbiome. We compared ISR triggered by the model strain Pseudomonas simiae WCS417r (WCS417) to that triggered by Bacillus thuringiensis israelensis (Bti) in Arabidopsis thaliana. In contrast to earlier findings, immunity elicited by both strains depended on salicylic acid. Both strains further relied on MYC2 for signal transduction in the plant, while WCS417-elicited ISR additionally depended on SAR-associated metabolites, including pipecolic acid. A metabarcoding approach applied to the leaf microbiome revealed a significant ISR-associated enrichment of amplicon sequence variants with predicted plant growth-promoting properties. WCS417 caused a particularly dramatic shift in the leaf microbiota with more than 50% of amplicon reads representing two bacterial species: WCS417 and Flavobacterium sp.. Co-inoculation experiments using WCS417 and At-LSPHERE Flavobacterium sp. Leaf82, suggest that the proliferation of these bacteria is influenced by both microbial and plant-derived factors. Together, our data connect systemic immunity with leaf microbiome dynamics and highlight the importance of plant-microbe-microbe interactions for plant health.

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