Cyanogenic Pseudomonads Influence Multitrophic Interactions in the Rhizosphere

Rudrappa, Thimmaraju; Splaine, Robert E.; Biedrzycki, Meredith L.; Bais, Harsh P.

doi:10.1371/journal.pone.0002073

Cited by 67 publications

(45 citation statements)

References 64 publications

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“…Contrary to the role of HCN as abiocontrol agent, several researchers concluded that HCN is hardly a universal biocontrol agent and even caused phytotoxic effects in most in vitro experiments (Alström and Burns, 1989;Pal et al, 2000;Kremer and Souissi, 2001;Rudrappa et al, 2008;Blom et al, 2011). In a recent study by Rijavec and Lapanje (2016) have shown that there is no correlation between the amount of HCN produced by a particular strain and its ability to inhibit the growth of phytopathogenic bacteria or fungi.…”

Section: Stress (Salt and Ph) Tolerant Pgprmentioning

confidence: 99%

See 1 more Smart Citation

Functional Diversity of Soil Bacteria from Organic Agro Ecosystem

Sagar¹,

Debbarma²,

Abraham³

et al. 2017

Int.J.Curr.Microbiol.App.Sci

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Section: Stress (Salt and Ph) Tolerant Pgprmentioning

confidence: 99%

“…ACCD activity was detected according to the method of Safronova et al, (2006). The bacteria were grown in test tube containing 100 ml of liquid medium: KH 2 PO 4 (2g), K 2 HPO 4 (0.5g), MgSO 4 (0.2g), Glucose (0.2g).…”

Section: Accd Activitymentioning

confidence: 99%

Functional Diversity of Soil Bacteria from Organic Agro Ecosystem

Sagar¹,

Debbarma²,

Abraham³

et al. 2017

Int.J.Curr.Microbiol.App.Sci

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“…Other physiological traits of PSM involve the release of cyanide, a secondary metabolite which is ecologically important (Wani et al 2007b) and gives a selective advantage to the producing strains (Rudrappa et al 2008;Badawi et al 2011). …”

Section: Physiological Functions Of Phosphate-solubilizing Microorganmentioning

confidence: 99%

Mechanism of Phosphate Solubilization and Physiological Functions of Phosphate-Solubilizing Microorganisms

Khan

Zaidi

Ahmad

2014

Phosphate Solubilizing Microorganisms

196

105

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Phosphorus (P) is the second important key plant nutrient after nitrogen. An adequate supply of P is therefore required for proper functioning and various metabolisms of plants. Majority of P in soils is fixed, and hence, plant available P is scarcely available despite the abundance of both inorganic and organic P forms in soils. A group of soil microorganisms capable of transforming insoluble P into soluble and plant accessible forms across different genera, collectively called phosphate-solubilizing microorganisms (PSM), have been found as best ecofriendly option for providing inexpensive P to plants. These organisms in addition to supplying soluble P to plants also facilitate the growth of plants by several other mechanisms, for instance, improving the uptake of nutrients and stimulating the production of some phytohormones. Even though several bacterial, fungal and actinomycetal strains have been identified as PSM, the mechanism by which they make P available to plants is poorly understood. This chapter focuses on the mechanism of P-solubilization and physiological functions of phosphate solubilizers in order to better understand the ecophysiology of PSM and consequently to gather knowledge for managing a sustainable environmental system. Conclusively, PSM are likely to serve as an efficient bio-fertilizer especially in areas deficient in P to increase the overall performance of crops.

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“…However, early reports proposed that the observed phytotoxicity of P. aeruginosa strains might be due to HCN production (1,3,4,9,23,37). More recently, Rudrappa et al (35) analyzed the effect of cyanogenic pseudomonads on A. thaliana seedlings. These authors observed reduced root growth in the presence of two Pseudomonas strains (P. aeruginosa PAO1 and P. fluorescens CHA0) but normal growth in the presence of the respective HCN-defective mutants.…”

mentioning

confidence: 99%

Volatile-Mediated Killing of Arabidopsis thaliana by Bacteria Is Mainly Due to Hydrogen Cyanide

Blom

Fabbri

Eberl

et al. 2011

Appl Environ Microbiol

143

108

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The volatile-mediated impact of bacteria on plant growth is well documented, and contrasting effects have been reported ranging from 6-fold plant promotion to plant killing. However, very little is known about the identity of the compounds responsible for these effects or the mechanisms involved in plant growth alteration. We hypothesized that hydrogen cyanide (HCN) is a major factor accounting for the observed volatile-mediated toxicity of some strains. Using a collection of environmental and clinical strains differing in cyanogenesis, as well as a defined HCN-negative mutant, we demonstrate that bacterial HCN accounts to a significant extent for the deleterious effects observed when growing Arabidopsis thaliana in the presence of certain bacterial volatiles. The environmental strain Pseudomonas aeruginosa PUPa3 was less cyanogenic and less plant growth inhibiting than the clinical strain P. aeruginosa PAO1. Quorumsensing deficient mutants of C. violaceum CV0, P. aeruginosa PAO1, and P. aeruginosa PUPa3 showed not only diminished HCN production but also strongly reduced volatile-mediated phytotoxicity. The double treatment of providing plants with reactive oxygen species scavenging compounds and overexpressing the alternative oxidase AOX1a led to a significant reduction of volatile-mediated toxicity. This indicates that oxidative stress is a key process in the physiological changes leading to plant death upon exposure to toxic bacterial volatiles.Bacteria interact with plants in many different ways. Over the past few years, the significance of volatile compounds as mediators of bacterium-plant interactions has become increasingly evident (14,18,33,46,50,54). Using compartmental petri dish assays with a bacterial culture on one side and Arabidopsis plants on the other, bacterial volatiles have been shown to either promote the growth of plants (14,36) or to reduce it (16,18,43,46). Despite the strong effects observed, very little is known at present about the identity of the compounds involved in this volatile-mediated impact of bacteria on plants. In addition to carbon dioxide (17), 2,3-butanediol and its precursor acetoin are, to our knowledge, the only organic volatiles which have been put forward as candidates to explain the beneficial effects of bacterial volatiles on plants (14,36). Likewise, the compounds responsible for the "killing" effect of some bacterial strains on Arabidopsis thaliana are yet to be discovered.In the course of a study to assess the volatile-mediated impact of a collection of rhizosphere bacterial isolates on the model plant A. thaliana, we observed contrasting effects, ranging from 6-fold growth promotion to plant killing. We noticed that the most virulent strains were known producers of hydrogen cyanide (e.g., Pseudomonas or Chromobacterium species). We therefore hypothesized that hydrogen cyanide (HCN), a potent inhibitor of cytochrome c oxidase and of other metalcontaining enzymes, might be responsible for the observed plant-killing effects.Few bacterial species are known to produc...

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Cyanogenic Pseudomonads Influence Multitrophic Interactions in the Rhizosphere

Cited by 67 publications

References 64 publications

Functional Diversity of Soil Bacteria from Organic Agro Ecosystem

Functional Diversity of Soil Bacteria from Organic Agro Ecosystem

Mechanism of Phosphate Solubilization and Physiological Functions of Phosphate-Solubilizing Microorganisms

Volatile-Mediated Killing of Arabidopsis thaliana by Bacteria Is Mainly Due to Hydrogen Cyanide

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