Glucosinolates profile of Arabidopsis thaliana modified root colonization of Trichoderma species

Fungal volatile organic compounds (VOCs) emitted by Trichoderma species interact with a plant host and display multifaceted mechanisms. In this study, we investigated the antifungal activity of VOCs emitted by Trichoderma asperelloides PSU-P1 against fungal pathogens, as well as the ability of VOCs to activate defense responses and to promote plant growth in Arabidopsis thaliana. The strain’s VOCs had remarkable antifungal activity against fungal pathogens, with an inhibition range of 15.92–84.95% in a volatile antifungal bioassay. The VOCs of T. asperelloides PSU-P1 promoted the plant growth of A. thaliana, thereby increasing the fresh weight, root length, and chlorophyll content in the VOC-treated A. thaliana relative to those of the control. High expression levels of the chitinase (CHI) and β-1,3-glucanase (GLU) genes were found in the VOC-treated A. thaliana by quantitative reverse transcription polymerase chain reaction (RT-PCR). The VOC-treated A. thaliana had higher defense-related enzyme (peroxidase (POD)) and cell wall-degrading enzyme (chitinase and β-1,3-glucanase) activity than in the control. The headspace VOCs produced by PSU-P1, trapped with solid phase microextraction, and tentatively identified by gas chromatography–mass spectrometry, included 2-methyl-1-butanol, 2-pentylfuran, acetic acid, and 6-pentyl-2H-pyran-2-one (6-PP). The results suggest that T. asperelloides PSU-P1 emits VOCs responsible for antifungal activity, for promoting plant growth, and for inducing defense responses in A. thaliana.

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Experimental evolution of Bacillus subtilis on Arabidopsis thaliana roots reveals fast adaptation and improved root colonization in the presence of soil microbes

10.1101/2021.07.09.451762 ◽

2021 ◽

Author(s):

Mathilde Nordgaard ◽

Christopher Blake ◽

Gergely Maroti ◽

Mikael L. Strube ◽

Akos T. Kovacs

Keyword(s):

Arabidopsis Thaliana ◽

Bacillus Subtilis ◽

Experimental Evolution ◽

Soil Microbes ◽

Root Colonization ◽

Plant Root ◽

Phenotypic Characterization ◽

Plant Interactions ◽

Plant Polysaccharide ◽

Selective Environment

The soil ubiquitous Bacillus subtilis is known to promote plant growth and protect plants against disease. These characteristics make B. subtilis highly relevant in an agricultural perspective, fueling the interest in studying B. subtilis-plant interactions. Here, we employ an experimental evolution approach to explore adaptation of B. subtilis to Arabidopsis thaliana roots. B. subtilis rapidly adapts to the plant root environment, as evidenced by improved root colonizers observed already after 12 consecutive transfers between seedlings in a hydroponic setup. Further phenotypic characterization of evolved isolates from transfer 30 revealed that increased root colonization was associated with robust biofilm formation in response to the plant polysaccharide xylan. Additionally, several evolved isolates across independent populations were impaired in motility, a redundant trait in the selective environment. Interestingly, two evolved isolates outcompeted the ancestor during competition on the root but suffered a fitness disadvantage in non-selective environment, demonstrating an evolutionary cost of adaptation to the plant root. Finally, increased root colonization by a selected evolved isolate was also demonstrated in the presence of resident soil microbes. Our findings provide novel insights into how a well-known PGPR rapidly adapts to an ecologically relevant environment and reveal evolutionary consequences that are fundamental to consider when evolving strains for biocontrol purposes.

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Serendipita indica changes host sugar and defense status in Arabidopsis thaliana: cooperation or exploitation?

Planta ◽

10.1007/s00425-021-03587-3 ◽

2021 ◽

Vol 253 (3) ◽

Author(s):

Michael W. Opitz ◽

Roshanak Daneshkhah ◽

Cindy Lorenz ◽

Roland Ludwig ◽

Siegrid Steinkellner ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Endophytic Fungus ◽

Abiotic Stresses ◽

Root Colonization ◽

Growth Promotion ◽

Sugar Metabolism ◽

Defense Responses ◽

Marker Genes ◽

Wild Type ◽

Biotic And Abiotic Stresses

Abstract Main conclusion Manipulation of sugar metabolism upon S. indica root colonization triggers changes in sugar pools and defense responses in A. thaliana. Abstract Serendipita indica is an endophytic fungus that establishes mutualistic relationships with many different plants including important crops as well as the model plant A. thaliana. Successful root colonization typically results in growth promotion and enhanced tolerance against various biotic and abiotic stresses. The fungus delivers phosphorus to the host and receives in exchange carbohydrates. There are hints that S. indica prefers hexoses, glucose, and fructose, products of saccharose cleavage driven by invertases (INVs) and sucrose synthases (SUSs). Carbohydrate metabolism in this interaction, however, remains still widely unexplored. Therefore, in this work, the sugar pools as well as the expression of SUSs and cytosolic INVs in plants colonized by S. indica were analyzed. Using sus1/2/3/4 and cinv1/2 mutants the importance of these genes for the induction of growth promotion and proper root colonization was demonstrated. Furthermore, the expression of several defense-related marker genes in both multiple mutants in comparison to the wild-type plants was determined. Our results show that in colonized A. thaliana plants S. indica manipulates the sugar metabolism by altering the expression of host’s INV and SUS and modulates both the sugar pools and plant defense in its favor. We conclude that the interaction A. thaliana–S. indica is a balancing act between cooperation and exploitation, in which sugar metabolism plays a crucial role. Small changes in this mechanism can lead to severe disruption resulting in the lack of growth promotion or altered colonization rate.

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Arabidopsis thaliana root colonization by the nematophagous fungus Pochonia chlamydosporia is modulated by jasmonate signaling and leads to accelerated flowering and improved yield

New Phytologist ◽

10.1111/nph.14106 ◽

2016 ◽

Vol 213 (1) ◽

pp. 351-364 ◽

Cited By ~ 25

Author(s):

Ernesto A. Zavala-Gonzalez ◽

Encarnación Rodríguez-Cazorla ◽

Nuria Escudero ◽

Almudena Aranda-Martinez ◽

Antonio Martínez-Laborda ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Root Colonization ◽

Nematophagous Fungus ◽

Pochonia Chlamydosporia ◽

Jasmonate Signaling

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Specific Flavonoids Promote Intercellular Root Colonization of Arabidopsis thaliana by Azorhizobium caulinodans ORS571

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.1997.10.5.560 ◽

1997 ◽

Vol 10 (5) ◽

pp. 560-570 ◽

Cited By ~ 58

Author(s):

Clare Gough ◽

Christine Galera ◽

Jacques Vasse ◽

Gordon Webster ◽

Edward C. Cocking ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Root Colonization ◽

Lateral Roots ◽

Nod Factors ◽

Azorhizobium Caulinodans ◽

Nutritional Factors ◽

High Frequencies ◽

Cell Layers ◽

Azorhizobium Caulinodans Ors571 ◽

Stimulation Of

The ability of Azorhizobium caulinodans ORS571 and other diazotrophic bacteria to internally colonize roots of Arabidopsis thaliana has been studied. Strains tagged with lacZ or gusA reporter genes were used, and the principal colonization sites were found to be the points of emergence of lateral roots, lateral root cracks (LRCs). High frequencies of colonization were found; 63 to 100% of plants were colonized by ORS571, and 100% of plants were colonized by Herbaspirillum seropedicae. After LRCs were colonized, bacteria moved into intercellular spaces between the cortical and endodermal cell layers. Specific flavonoids, naringenin and daidzein, at 5 × 10-5 M, significantly promoted colonization by ORS571. By using a nodC and a nodD mutant of ORS571, it was shown that neither Nod factors nor NodD are involved in colonization or flavonoid stimulation of colonization. Flavonoids did not appear to be stimulating LRC colonization by their activity as nutritional factors. LRC and intercellular colonization by H. seropedicae was stimulated by naringenin and daidzein at the same concentration that stimulated colonization by ORS571.

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Diversification of B. subtilis during experimental evolution on A. thaliana leads to synergism in root colonization of evolved subpopulations

10.1101/2021.03.06.434191 ◽

2021 ◽

Author(s):

Christopher Blake ◽

Mathilde Nordgaard Christensen ◽

Gergely Maróti ◽

Ákos T. Kovács

Keyword(s):

Arabidopsis Thaliana ◽

Bacillus Subtilis ◽

Plant Growth ◽

Plant Species ◽

Experimental Evolution ◽

Root Colonization ◽

Plant Root ◽

Plant Roots ◽

Stable Strategy ◽

Pellicle Formation

SummaryThe soil bacterium Bacillus subtilis is known to suppress pathogens as well as promote plant growth. However, in order to fully exploit the potential as natural fertilizer, we need a better understanding of the interactions between B. subtilis and plants. Here, B. subtilis was examined for root colonization through experimental evolution on Arabidopsis thaliana. The populations evolved rapidly, improved in root colonization and diversified into three distinct morphotypes. In order to better understand the adaptation that had taken place, single evolved isolates from the final transfer were randomly selected for further characterization, revealing changes in growth and pellicle formation in medium supplemented with plant polysaccharides. Intriguingly, certain evolved isolates showed improved root colonization only on the plant species they evolved on, but not on another plant species, namely tomato, suggesting A. thaliana specific adaption paths. Finally, synergism in plant root colonization was observed for a mix of all three morphotypes, as the mix performed better than the sum of its constituents in monoculture. Our results suggest, that genetic diversification occurs in an ecological relevant setting on plant roots and proves to be a stable strategy for root colonization.Significance StatementUnderstanding how plant-growth-promoting rhizobacteria colonize plant roots is crucial to fully utilize their potential for agricultural applications. Here, we utilized experimental evolution of the PGPR Bacillus subtilis on Arabidopsis thaliana to study root colonization. We revealed that evolving populations rapidly improve in root colonization and diversify into distinct morphotypes. Notably, improved root colonization by evolved isolates was observed on A. thaliana, not on tomato. Moreover, isolates of distinct morphotypes interacted during root colonization and the mixture of morphotypes showed higher productivity then predicted. These findings suggest that genetic diversification might be a stable strategy to maximize root colonization.

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Arabidopsis thaliana and Pisum sativum models demonstrate that root colonization is an intrinsic trait of Burkholderia cepacia complex bacteria

Microbiology ◽

10.1099/mic.0.074351-0 ◽

2014 ◽

Vol 160 (2) ◽

pp. 373-384 ◽

Cited By ~ 4

Author(s):

J. Cristian Vidal-Quist ◽

Louise A. O’Sullivan ◽

Annaëlle Desert ◽

Amanda S. Fivian-Hughes ◽

Coralie Millet ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Pisum Sativum ◽

Burkholderia Cepacia ◽

Statistical Difference ◽

Root Colonization ◽

Bioluminescence Imaging ◽

Burkholderia Cepacia Complex ◽

Plant Model ◽

Burkholderia Vietnamiensis ◽

Transposon Mutants

Burkholderia cepacia complex (Bcc) bacteria possess biotechnologically useful properties that contrast with their opportunistic pathogenicity. The rhizosphere fitness of Bcc bacteria is central to their biocontrol and bioremediation activities. However, it is not known whether this differs between species or between environmental and clinical strains. We investigated the ability of 26 Bcc strains representing nine different species to colonize the roots of Arabidopsis thaliana and Pisum sativum (pea). Viable counts, scanning electron microscopy and bioluminescence imaging were used to assess root colonization, with Bcc bacteria achieving mean (±sem) levels of 2.49±0.23×106 and 5.16±1.87×106 c.f.u. per centimetre of root on the A. thaliana and P. sativum models, respectively. The A. thaliana rhizocompetence model was able to reveal loss of colonization phenotypes in Burkholderia vietnamiensis G4 transposon mutants that had only previously been observed in competition experiments on the P. sativum model. Different Bcc species colonized each plant model at different rates, and no statistical difference in root colonization was observed between isolates of clinical or environmental origin. Loss of the virulence-associated third chromosomal replicon (>1 Mb DNA) did not alter Bcc root colonization on A. thaliana. In summary, Bcc bacteria possess intrinsic root colonization abilities irrespective of their species or source. As Bcc rhizocompetence does not require their third chromosomal replicon, the possibility of using synthetic biology approaches to engineer virulence-attenuated biotechnological strains is tractable.

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