Moving Waves of Bacterial Populations and Total Organic Carbon along Roots of Wheat

Semenov, A. M.; Bruggen, A.H.C. van; Zelenev, V.V.

doi:10.1007/s002489900136

Cited by 155 publications

(75 citation statements)

References 28 publications

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“…The shifts in the fungal community patterns most likely occurred because of changing root morphology and root exudation patterns during plant development (5,28). The release of organic substances by plant roots has an interesting ecological aspect, since it influences the nutrient availability in the rhizosphere and indirectly acts on the soil microorganisms that in turn influence plant growth (9,10,15,34,38,45,46). Temporal changes in the bacterial communities in the rhizosphere were indicated by different cultivation-based studies (2,21,25).…”

Section: Discussionmentioning

confidence: 99%

Dynamics of Fungal Communities in Bulk and Maize Rhizosphere Soil in the Tropics

Gomes¹,

Fagbola²,

Costa

et al. 2003

Appl Environ Microbiol

246

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The fungal population dynamics in soil and in the rhizospheres of two maize cultivars grown in tropical soils were studied by a cultivation-independent analysis of directly extracted DNA to provide baseline data. Soil and rhizosphere samples were taken from six plots 20, 40, and 90 days after planting in two consecutive years. A 1.65-kb fragment of the 18S ribosomal DNA (rDNA) amplified from the total community DNA was analyzed by denaturing gradient gel electrophoresis (DGGE) and by cloning and sequencing. A rhizosphere effect was observed for fungal populations at all stages of plant development. In addition, pronounced changes in the composition of fungal communities during plant growth development were found by DGGE. Similar types of fingerprints were observed in two consecutive growth periods. No major differences were detected in the fungal patterns of the two cultivars. Direct cloning of 18S rDNA fragments amplified from soil or rhizosphere DNA resulted in 75 clones matching 12 dominant DGGE bands. The clones were characterized by their HinfI restriction patterns, and 39 different clones representing each group of restriction patterns were sequenced. The cloning and sequencing approach provided information on the phylogeny of dominant amplifiable fungal populations and allowed us to determine a number of fungal phylotypes that contribute to each of the dominant DGGE bands. Based on the sequence similarity of the 18S rDNA fragment with existing fungal isolates in the database, it was shown that the rhizospheres of young maize plants seemed to select the Ascomycetes order Pleosporales, while different members of the Ascomycetes and basidiomycetic yeast were detected in the rhizospheres of senescent maize plants.

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Section: Discussionmentioning

confidence: 99%

Dynamics of Fungal Communities in Bulk and Maize Rhizosphere Soil in the Tropics

Gomes¹,

Fagbola²,

Costa

et al. 2003

Appl Environ Microbiol

246

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“…However, both studies followed potential temporal shifts in the composition of bacterial rhizosphere communities for a much shorter period of time (up to 36 days after sowing and up to 10 weeks after planting, respectively) under growth chamber conditions, one factor which might have contributed to the contrasting results. Semenov et al (43) found a moderate rhizosphere effect in one experiment with soil rich in fresh plant debris and a very pronounced rhizosphere effect in a second experiment with soil low in organic matter content using cultivation techniques (by enumeration of copiotrophic and oligotrophic bacteria).…”

Section: Discussionmentioning

confidence: 99%

Bulk and Rhizosphere Soil Bacterial Communities Studied by Denaturing Gradient Gel Electrophoresis: Plant-Dependent Enrichment and Seasonal Shifts Revealed

Smalla

Wieland

Buchner

et al. 2001

Appl Environ Microbiol

1,035

608

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The bacterial rhizosphere communities of three host plants of the pathogenic fungus Verticillium dahliae, field-grown strawberry (Fragaria ananassa Duch.), oilseed rape (Brassica napus L.), and potato (Solanum tuberosum L.), were analyzed. We aimed to determine the degree to which the rhizosphere effect is plant dependent and whether this effect would be increased by growing the same crops in two consecutive years. Rhizosphere or soil samples were taken five times over the vegetation periods. To allow a cultivationindependent analysis, total community DNA was extracted from the microbial pellet recovered from root or soil samples. 16S rDNA fragments amplified by PCR from soil or rhizosphere bacterium DNA were analyzed by denaturing gradient gel electrophoresis (DGGE). The DGGE fingerprints showed plant-dependent shifts in the relative abundance of bacterial populations in the rhizosphere which became more pronounced in the second year. DGGE patterns of oilseed rape and potato rhizosphere communities were more similar to each other than to the strawberry patterns. In both years seasonal shifts in the abundance and composition of the bacterial rhizosphere populations were observed. Independent of the plant species, the patterns of the first sampling times for both years were characterized by the absence of some of the bands which became dominant at the following sampling times. Bacillus megaterium and Arthrobacter sp. were found as predominant populations in bulk soils. Sequencing of dominant bands excised from the rhizosphere patterns revealed that 6 out of 10 bands resembled gram-positive bacteria. Nocardia populations were identified as strawberry-specific bands.

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“…This ecological behavior is more consistent with organisms that are influenced by bulk soil (for example soil organic matter). Soil organic matter can be a significant source of carbon for rhizosphere organisms (Toal et al, 2000), and high levels of organic matter and nutrients, such as those that are supplied via compost amendment, can influence the strength of the observed rhizosphere effect (Semenov et al, 1999). Although Chryseobacterium spp are found frequently in organic-rich environments such as composted materials (Ryckeboer et al, 2003), these organisms are not particularly well known as rhizosphere organisms, even though they have been previously detected in or isolated from rhizosphere environments (McSpadden Gardener and Weller, 2001;Young et al, 2005;Park et al, 2006).…”

Section: Seed and Root-colonizing Bacteria Sj Green Et Almentioning

confidence: 99%

Contrasting patterns of seed and root colonization by bacteria from the genus Chryseobacterium and from the family Oxalobacteraceae

Green

Michel²,

Hadar

et al. 2007

The ISME Journal

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Microbial colonization of plant seeds and roots is a highly complex process in which soil and plant type can influence the composition of the root-associated and rhizosphere microbial communities. Amendment of compost, a common agricultural technique, introduces exogenous nutrients and microorganisms to the soil-plant environment, and can further influence microbial community composition in the plant environment. Although compost amendments can strongly influence soil and rhizosphere microbial communities, there is evidence that with increasing proximity to the root, plant influences predominate over soil effects. We hypothesized that the 'rhizosphere effect' observed with proximity to plant surfaces does not act equally on all microorganisms. To explore this issue, we examined two bacterial taxa that reproducibly colonized seed and root surfaces in an experiment examining the influence of compost amendment on plant-associated bacterial communities. Population-specific analyses revealed striking differences in the ecology of bacteria from the genus Chryseobacterium and the family Oxalobacteraceae in potting mix and plantassociated environments. Seed-and root-colonizing Oxalobacteraceae populations were highly sensitive to plant effects, and phylogenetic analyses of root-colonizing Oxalobacteraceae revealed the presence of root-associated populations that were highly similar, regardless of treatment, and differed from the potting mix populations detected at the same sampling points. Conversely, Chryseobacterium community composition was found to be essentially invariant within treatments, but was strongly influenced by compost amendment. This persistence and stable nature of the Chryseobacterium community composition demonstrates that rhizosphere selection is not the exclusive factor involved in determining the composition of the cucumber spermosphere and rhizosphere communities.

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Moving Waves of Bacterial Populations and Total Organic Carbon along Roots of Wheat

Cited by 155 publications

References 28 publications

Dynamics of Fungal Communities in Bulk and Maize Rhizosphere Soil in the Tropics

Dynamics of Fungal Communities in Bulk and Maize Rhizosphere Soil in the Tropics

Bulk and Rhizosphere Soil Bacterial Communities Studied by Denaturing Gradient Gel Electrophoresis: Plant-Dependent Enrichment and Seasonal Shifts Revealed

Contrasting patterns of seed and root colonization by bacteria from the genus Chryseobacterium and from the family Oxalobacteraceae

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