What makes <i>Pseudomonas</i> bacteria rhizosphere competent?

Lugtenberg, Ben; Dekkers, Linda C.

doi:10.1046/j.1462-2920.1999.00005.x

Cited by 308 publications

(188 citation statements)

References 39 publications

(52 reference statements)

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“…1). This finding is perhaps not surprising because monosaccharides, amino acids, and organic acids are thought to be the major constituents of plant root exudates (3,5,21). Lugtenberg and Dekkers (21) have shown that utilization of organic acids by P. fluorescens is the nutritional basis governing the ability of this organism to colonize tomato roots.…”

Section: Resultsmentioning

confidence: 96%

“…This finding is perhaps not surprising because monosaccharides, amino acids, and organic acids are thought to be the major constituents of plant root exudates (3,5,21). Lugtenberg and Dekkers (21) have shown that utilization of organic acids by P. fluorescens is the nutritional basis governing the ability of this organism to colonize tomato roots. Genes in pseudomonads encoding proteins with functions in nutrient acquisition and in energy generation are up-regulated in the rhizosphere or when bacteria were exposed to the soil environment as revealed by in vivo expression technology-based approaches (22,23).…”

Section: Resultsmentioning

confidence: 96%

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Transcriptome profiling of bacterial responses to root exudates identifies genes involved in microbe-plant interactions

Mark

Dow

Kiely

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

226

166

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Molecules exuded by plant roots are thought to act as signals to influence the ability of microbial strains to colonize the roots and to survive in the rhizosphere. Differential bacterial responses to signals from different plant species may mediate the selection of specific rhizosphere populations. Very little, however, is known about the effects of plant exudates on patterns of bacterial gene expression. Here, we have tested the concept that plant root exudates modulate expression of bacterial genes involved in establishing microbe-plant interactions. We have examined the influence on the Pseudomonas aeruginosa PA01 transcriptome of exudates from two varieties of sugarbeet that select for genetically distinct pseudomonad populations in the rhizosphere. The response to the two exudates showed only a partial overlap; the majority of those genes with altered expression was regulated in response to only one of the two exudates. Genes with altered expression included those with functions previously implicated in microbe-plant interactions, such as aspects of metabolism, chemotaxis and type III secretion, and a subset with putative or unknown function. Use of a panel of mutants with targeted disruptions allowed us to identify previously uncharacterized genes with roles in the competitive ability of P. aeruginosa in the rhizosphere within this subset. No genes with host-specific effects were identified. Homologues of the genes identified occur in the genomes of both beneficial and pathogenic root-associated bacteria, suggesting that this strategy may help to elucidate molecular interactions that are important for biocontrol, plant growth promotion, and plant pathogenesis.Pseudomonas ͉ Rhizosphere colonization

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Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 96%

Transcriptome profiling of bacterial responses to root exudates identifies genes involved in microbe-plant interactions

Mark

Dow

Kiely

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

226

166

View full text Add to dashboard Cite

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“…A number of studies on PGPR have shown the growth promotion of plant but only under controlled conditions (Glick et al 1995;Shaharoona et al 2006) where these bacteria do not compete with the normal array of microbes. For finding competent isolates in this study, we inoculated all 80 isolates as mixtures of isolates on rice seedling, because competition should possibly imitate the situation in raw soil, which contains approximately 10 8 bacteria g −1 (Lugtenberg and Dekkers 1999). Twelve out of 80 inoculated isolates colonized within the roots of rice seedlings under axenic conditions.…”

Section: Discussionmentioning

confidence: 99%

Bacterial biosynthesis of 1-aminocyclopropane-1-caboxylate (ACC) deaminase, a useful trait to elongation and endophytic colonization of the roots of rice under constant flooded conditions

Etesami

Hosseini

Alikhani

2014

Physiol Mol Biol Plants

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This study was conducted to investigate the role of 1-aminocyclopropane-1-carboxylate (ACC) deaminase in Pseudomonas fluorescens strain REN 1 and its ability to reduce ethylene levels produced during stress, endophytically colonize and promote the elongation of the roots of rice seedlings under gnotobiotic conditions. We isolated 80 bacteria from inside roots of rice plants grown in the farmers' fields in Guilan, Iran. All of the isolates were characterized for plant growth promoting (PGP) traits. In addition, the colonization assay of these isolates on rice seedlings was carried out to screen for competent endophytes. The best bacterial isolate, based on ACC deaminase production, was identified and used for further study. 16S rDNA sequence analysis revealed that the endophyte was closely related to Pseudomonas fluorescens. The results of this study showed ACC deaminase containing P. fluorescens REN1 increased in vitro root elongation and endophytically colonized the root of rice seedlings significantly, as compared to control under constant flooded conditions. The trait of low amount of indole-3-acetic acid (IAA) production (<15 μg mL −1 ) and the high production of ACC deaminase by bacteria may be main factors in colonizing rice seedling roots compared to other PGP traits (siderophore production and phosphate solubilization) in this study. Endophytic IAA and ACC deaminase-producing bacteria may be preferential selections by rice seedlings. Therefore, it may be suggested that the utilization of ACC as a nutrient gives the isolates advantages in more endophytic colonization and increase of root length of rice seedlings.

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“…The Salmonellae efficiently attach to the roots, which is primarily dependent on the presence of using curli and lipopolysaccharides (Barak et al, 2005). In general the colonization of the plant roots by bacteria depends on the presence of flagella, the O-antigen of lipopolysaccharides, the growth rate and the ability to grow on root exudates (Lugtenberg and Dekkers, 1999). Upon root colonization the Salmonellae form a biofilm on the roots at natural openings or wounds, but also at the intercellular spaces between epidermal cells (Klerks et al, 2007).…”

Section: Tentative Route Of Infectionmentioning

confidence: 99%

Differential interaction of Salmonella enterica serovars with lettuce cultivars and plant-microbe factors influencing the colonization efficiency

et al. 2007

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The availability of knowledge of the route of infection and critical plant and microbe factors influencing the colonization efficiency of plants by human pathogenic bacteria is essential for the design of preventive strategies to maintain safe food. This research describes the differential interaction of human pathogenic Salmonella enterica with commercially available lettuce cultivars. The prevalence and degree of endophytic colonization of axenically grown lettuce by the S. enterica serovars revealed a significant serovar-cultivar interaction for the degree of colonization (S. enterica CFUs per g leaf), but not for the prevalence. The evaluated S. enterica serovars were each able to colonize soil-grown lettuce epiphytically, but only S. enterica serovar Dublin was able to colonize the plants also endophytically. The number of S. enterica CFU per g of lettuce was negatively correlated to the species richness of the surface sterilized lettuce cultivars. A negative trend was observed for cultivars Cancan and Nelly, but not for cultivar Tamburo. Chemotaxis experiments revealed that S. enterica serovars actively move toward root exudates of lettuce cultivar Tamburo. Subsequent micro-array analysis identified genes of S. enterica serovar Typhimurium that were activated by the root exudates of cultivar Tamburo. A sugar-like carbon source was correlated with chemotaxis, while also pathogenicity-related genes were induced in presence of the root exudates. The latter revealed that S. enterica is conditioned for host cell attachment during chemotaxis by these root exudates. Finally, a tentative route of infection is described that includes plant-microbe factors, herewith enabling further design of preventive strategies.

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What makes Pseudomonas bacteria rhizosphere competent?

Cited by 308 publications

References 39 publications

Transcriptome profiling of bacterial responses to root exudates identifies genes involved in microbe-plant interactions

Transcriptome profiling of bacterial responses to root exudates identifies genes involved in microbe-plant interactions

Bacterial biosynthesis of 1-aminocyclopropane-1-caboxylate (ACC) deaminase, a useful trait to elongation and endophytic colonization of the roots of rice under constant flooded conditions

Differential interaction of Salmonella enterica serovars with lettuce cultivars and plant-microbe factors influencing the colonization efficiency

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