Here, we studied the effects of the PGPR bacterial model Burkholderia phytofirmans PsJN on the whole life cycle of Arabidopsis thaliana plants. Burkholderia phytofirmans sp. nov., a novel plant-associated bacterium with plant -beneficial properties. A. Sessitsch,1 T. Coenye,2 A. V. Sturz,3 P. Vandamme,2. ABSTRACT. Burkholderia phytofirmans PsJNT is able to efficiently colonize the rhizosphere, root, and above-ground plant tissues of a wide variety of genetically .

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From laboratory to applications: This transition is often accompanied by intensified gene expression and activity of invertases Roitsch et al. Moreover, the callose deposition was primed in PsJN-bacterized plants suggesting the involvement of callose deposition in grapevine disease resistance toward B. Molecular design of the photosystem II light-harvesting antenna: Micrographs were taken by fluorescence microscopy using a nm diode laser for aniline blue excitation.

Alamo by bacterial endophyte Burkholderia phytofirmans strain PsJN. This protocol was used for measures of necrosis diameter. A similar pattern was reported in grapevine leaves infected by Plasmopara viticola Gamm et al. To further elucidate possible mechanisms contributing to B. This study provided new insights in deciphering the mechanisms of B.

Herein, a callose deposition was observed in stomatal guard cells of bacterized plantlets confirming earlier reports indicating that callose deposition is triggered by classical bacterial MAMPs, flg22 Luna et al. Other strains belonging to this species have been isolated from soils and rhizospheres. A Gram-negative, non-sporulating, rod-shaped, motile bacterium, with a single polar flagellum, designated strain PsJN Burkholdeeiawas isolated from surface-sterilized onion roots. In control and bacterized plants without the pathogen, no H 2 O 2 generation was visualized except in veins Phytoirmans 4B,Cwhich may probably correspond to the lignification process.


Plantlets of Vitis vinifera cv. Microscopic observations of infected grapevine leaves root-inoculated or not with B. Arabidopsis is susceptible to infection by a downy mildew fungus.

Home – Burkholderia phytofirmans PsJN

The strain does not produce nitrate or nitrite. As far we know, this is the first time that such behavior was reported in vivo for a PGPR. Further, fungal growth was monitored in planta at 2, 8, 24, 48, and 72 hpi by analyzing the transcript levels of the B. Direct effect of B. Introduction Plants have to face a broad range of invading pathogens.

Interestingly, while PsJN was not observed at the leaves surface in the absence of the pathogen, the bacteria were detected at the surface, surrounding the fungal mycelium in botrytized leaves Figure 2. Fresh leaves were collected at 24 h post infection with B. Assays performed on detached leaves from bacterized plantlets inoculated with drops of B.

The spectrophotometer was zeroed with the control blankand absorbance was read at nm. Magistra der Naturwissenschaften Mag. Relative gene expression was determined with the formula fold induction: In response, they can deploy a large set of defense responses including constitutive pre-existing physical and chemical barriers as well as an innate immunity activated after pathogen perception Zipfel, ; Boller and Felix, This endophyte also confers mild pathogen resistance.

The induced source-to-sink transition is not without consequences for photosynthesis and primary metabolism. Benefits of in vitro “biotization” of plant tissue cultures with microbial inoculants. When lonely inoculated, B. The photosynthesis decreases through the infection process as a result of leaf metabolism perturbation attributed to sugar-mediated repression of photosynthetic gene expression Bonfig et al.

PsJN produces ACC deaminase activity probably contributing to the plant growth promoting abilities of the strain. In addition, the bacterium improves tolerance against biotic stress as Verticillium sp.


Analysis of whole-cell protein profiles and DNA-DNA hybridization experiments confirmed that all eight strains belonged to a single species. Inhibitory effect of endophyte bacteria on Botrytis cinerea and its influence to promote grapevine growth. It has also been shown that this strain reduces damages caused by chilling in grapevine through a priming of plant defense responses and changes in primary metabolism, particularly an increase of soluble sugars concentration and an accumulation of proline Ait Barka et al.

Additionally, starch reserves may also be converted burkhoderia soluble sugars Chou et al. Chardonnay 24, 48, 72, and 96 hpi with B.

Therefore, the impact of B. However, fungal hyphae growth was clearly inhibited in bacterized plantlets 72 hpi with B. Sugar related-gene expression in grapevine leaves inoculated or not with B.

No significant H 2 O 2 production was observed in response to bacterium or fungus inoculation Figure 4A. The observed callose accumulation has been strengthened after infection by Botrytis. These data indicated that the presence of B.

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Cells are gram-negative, non-sporulating rods that grows in the presence phytofirnans various sugars. As indicated above, the decrease in photosynthetic metabolism, in parallel with an enhanced cellular demands during the resistance response, initiate the transition from source status to sink status in infected tissues. The second stage of perception corresponds to the direct or indirect recognition of pathogen effectors by intracellular immune receptors leading to effector-triggered immunity ETI; Jones phytofiemans Dangl, However, no study has deciphered triggered-mechanisms during the tripartite interaction between grapevine, B.