Characteristics of a plant deleterious rhizosphere pseudomonad and its inhibitory metabolite(s)

Åström, Boel; Gustafsson, Annika; Gerhardson, B.

doi:10.1111/j.1365-2672.1993.tb02991.x

Cited by 29 publications

(4 citation statements)

References 31 publications

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“…It has been reported widely (4,12,15,27,31,34) that the relative importance of biotic and abiotic determinants in microbial and plant-microbe interactions in the rhizosphere can be determined more precisely in gnotobiotic systems than in the field, where heterogeneous, mostly ill-defined factors come into play. The findings of the present work, which were obtained under gnotobiotic conditions, combined with previous reports (1,2,18,20,32,35), emphasize that proper assessment of the influence of bacterial properties on the outcome of root colonization requires careful consideration of the test plant and of the indicator effects that must be taken into account. This view is supported by several lines of evidence with respect to production of siderophores and HCN.…”

supporting

confidence: 55%

Growth Interactions during Bacterial Colonization of Seedling Rootlets

Bellis

Ercolani

2001

Appl Environ Microbiol

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Rootlet elongation and bacterial growth on rootlets were determined after inoculation of cucumber and spinach seedlings with Pseudomonas strains differing in production of siderophores and HCN. Siderophore producers grew more profusely than nonproducers on both species and promoted rootlet elongation on cucumber. Coinoculation of siderophore producers and nonproducers resulted in restricted growth of the latter. The total populations of nonproducers of HCN in the presence of HCN producers were not decreased, but the tenacity of their association with the rootlet surface was altered.Germinating seeds and growing plants influence the activities of soil microorganisms in the adjoining volumes of soil known as the spermosphere and the rhizosphere, respectively (24). Conversely, microorganisms in these settings condition the seeds and plants in a number of ways. Some of the microorganisms (e.g., the so-called plant-growth-promoting rhizobacteria) may enhance plant health and productivity by synthesizing phytohormones, increasing the local availability of nutrients, facilitating the uptake of nutrients by the plants, decreasing heavy metal toxicity in the plants, antagonizing plant pathogens, and inducing systemic resistance in the plants to pathogens (5, 8, 9). Detrimental effects are produced by other organisms, such as the so-called deleterious rhizosphere microorganisms, and these effects include release of toxic products of microbial metabolism, alteration of nutrient cycling, impairment of uptake of nutrients, competition for nutrients, and retardation of root growth (28). Among the factors involved in plant-microbe interactions, as well as in microbemicrobe interactions, in the rhizosphere, siderophores and hydrocyanic acid (HCN) have received special attention. Siderophores are high-affinity Fe 3ϩ chelators that are synthesized and released extracellularly under iron limitation conditions, where they make otherwise inaccessible supplies of insoluble iron available to organisms with specific membrane-bound siderophore receptors (14,17). Such receptors are present in the microorganisms that produce the corresponding siderophores but can also be found in plants. The iron nutrition of these plants is thus enhanced. In addition, since plant-growth-promoting rhizobacteria produce siderophores with higher Fe 3ϩ affinity than the siderophores produced by deleterious rhizosphere microorganisms, the latter microorganisms are outcompeted in their quest for iron. HCN is released as product of secondary metabolism by several microorganisms and affects sensitive organisms by inhibiting the synthesis of ATP mediated by cytochrome oxidase (22). Therefore, depending on the target organisms, HCN-producing microorganisms are regarded as harmful when they impair plant health and beneficial when they suppress unwanted components of the microbial community (23, 29). The significance of siderophore and HCN generation in rhizosphere management and engineering has been studied and reviewed extensively (11,13,16,21,26,36), but there is...

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supporting

confidence: 55%

Growth Interactions during Bacterial Colonization of Seedling Rootlets

Bellis

Ercolani

2001

Appl Environ Microbiol

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“…[34]. Bacterial production of sufficiently high concentrations of phytohormones may explain the observed root hair deformations in our study as well as the plant growthpromoting effects observed in studies with P. putida and Azospirillum [7,29,35,36].…”

Section: Root Colonizationsupporting

confidence: 64%

Rhizoplane colonisation of peas by Rhizobium leguminosarum bv. viceae and a deleterious Pseudomonas putida

Berggren

Alström

Vuurde³

et al. 2005

FEMS Microbiology Ecology

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Pseudomonas putida strain A313, a deleterious rhizosphere bacterium, reduced pea nitrogen content when inoculated alone or in combination with Rhizobium leguminosarum bv. viceae on plants in the presence of soil under greenhouse conditions. When plants were grown gnotobiotically in liquid media, mixed inocula of A313 and rhizobia gave a higher proportion of small evenly distributed nodules when compared with a single rhizobial inoculation. In addition, the rhizobial root establishment was reduced by A313 irrespective of inoculum density, indicating that A313 has the capacity to interact with the early rhizobial infection process. When pea seedlings were simultaneously inoculated with A313 and rhizobia, A313 colonised the root hairs to the same extent as the rhizobia, according to analysis by immunofluorescence microscopy. This suggests that the root hair colonisation trait of P. putida interferes with the onset of the symbiotic process.

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“…Soil bacteria produce a wealth of metabolites, a few of which have been identiWed and characterized. An example of a plant growth inhibitory compound produced by some pseudomonads is hydrogen cyanide (Schippers et al 1990), but pseudomonads have also been found to produce other unidentiWed phytotoxins reducing root growth (Frederickson and Elliott 1985;Åström et al 1993), and production of thaxtomin A that also reduces seedling root growth (KrasnoV et al 2005) is well-known among streptomycetes. Our results suggest that the ratio between bacteria producing such inhibitory substances and bacteria producing plant root growth stimulating compounds increased with plant age.…”

Section: Discussionmentioning

confidence: 97%

Decreasing prevalence of rhizosphere IAA producing and seedling root growth promoting bacteria with barley development irrespective of protozoan grazing regime

Vestergård¹,

Bjørnlund²,

Henry³

et al. 2007

Plant Soil

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Barley was grown in soil with either bacteria and a mixed protozoan community (Mixed protozoa) or bacteria and a single vahlkampWid amoebal species (Single amoeba). We assessed the inXuence of plant age (day 29, 43 and 57 after sowing) on two aspects of rhizosphere bacterial functioning: (1) the proportion of indole-3-acetic acid (IAA) producing bacteria and (2) the eVect of mixed rhizosphere bacterial assemblages on barley seedling root growth in an agar based assay. The proportion of IAA producers was signiWcantly lower at day 57 than at day 29 and 43, and mixed bacterial assemblages extracted from rhizospheres of 29 days old plants were signiWcantly less harmful to seedling growth than bacterial assemblages from older plants. Hence both assays indicated that bacterial communities from rhizospheres of older plants were less beneWcial for root growth than bacterial communities from younger plants. Genetic Wngerprinting of rhizosphere bacterial communities was compared by use of length heterogeneity polymerase chain reaction (LH-PCR). This analysis showed a clear succession from the inoculum bacterial community with a rather low diversity to a community with much higher diversity at day 29. However, diversity did not change after day 29, and no relationship between protozoan treatment nor plant age and genetic Wngerprinting was found.

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Characteristics of a plant deleterious rhizosphere pseudomonad and its inhibitory metabolite(s)

Cited by 29 publications

References 31 publications

Growth Interactions during Bacterial Colonization of Seedling Rootlets

Growth Interactions during Bacterial Colonization of Seedling Rootlets

Rhizoplane colonisation of peas by Rhizobium leguminosarum bv. viceae and a deleterious Pseudomonas putida

Decreasing prevalence of rhizosphere IAA producing and seedling root growth promoting bacteria with barley development irrespective of protozoan grazing regime

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