Pseudomonas for biocontrol of phytopathogens: from functional genomics to commercial exploitation

Walsh, U. F.; Morrissey, John P.; O’Gara, Fergal

doi:10.1016/s0958-1669(00)00212-3

Cited by 266 publications

(153 citation statements)

References 54 publications

Supporting

Mentioning

146

Contrasting

Unclassified

Order By: Relevance

“…1). Again, this finding could reflect differences in levels of key attractants in the two exudates that could conceivably play a role in host selection because chemotaxis plays an important role in successful colonization of the rhizosphere (21,(24)(25)(26)(27)(28). Some genes encoding proteins with functions previously implicated in microbial-plant interactions were down-regulated in response to both root exudates (Fig.…”

Section: Resultsmentioning

confidence: 93%

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.

Self Cite

224

166

View full text Add to dashboard Cite

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

show abstract

Section: Resultsmentioning

confidence: 93%

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.

Self Cite

224

166

View full text Add to dashboard Cite

show abstract

“…Pyrrolnitrin, which is produced by PfA, the nonfood source symbiont of D. discoideum, has potent antifungal activity against a variety of soil-borne fungi (20); it is also known to play a crucial role in other symbiotic associations between the producer P. fluorescens strain and plants. The decreased susceptibility of an infected host to soil-borne pathogens can be used as a form of biocontrol, and fluorescent pseudomonads play an important role as biocontrol agents (21)(22)(23)(24). It is possible that Dictyostelia carrying pyrrolnitrin-producing strains like PfA could be similarly protected.…”

Section: Differential Effect Of Pyrrolnitrin On Farmer and Nonfarmermentioning

confidence: 99%

A bacterial symbiont is converted from an inedible producer of beneficial molecules into food by a single mutation in the gacA gene

Stallforth

Brock

Cantley

et al. 2013

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

View full text Add to dashboard Cite

Stable multipartite mutualistic associations require that all partners benefit. We show that a single mutational step is sufficient to turn a symbiotic bacterium from an inedible but host-beneficial secondary metabolite producer into a host food source. The bacteria's host is a "farmer" clone of the social amoeba Dictyostelium discoideum that carries and disperses bacteria during its spore stage. Associated with the farmer are two strains of Pseudomonas fluorescens, only one of which serves as a food source. The other strain produces diffusible small molecules: pyrrolnitrin, a known antifungal agent, and a chromene that potently enhances the farmer's spore production and depresses a nonfarmer's spore production. Genome sequence and phylogenetic analyses identify a derived point mutation in the food strain that generates a premature stop codon in a global activator (gacA), encoding the response regulator of a twocomponent regulatory system. Generation of a knockout mutant of this regulatory gene in the nonfood bacterial strain altered its secondary metabolite profile to match that of the food strain, and also, independently, converted it into a food source. These results suggest that a single mutation in an inedible ancestral strain that served a protective role converted it to a "domesticated" food source.symbiosis | GacA-GacS two-component system | differential metabolomics S mall molecules regulate mutually beneficial associations between bacterial symbionts and their eukaryotic hosts. A fascinating set of structurally diverse molecules that defend the host, initiate host developmental changes, and carry out other important functions have been shaped by their evolutionary history (1-10). Recently, Brock et al. (11) described an association between the social amoeba Dictyostelium discoideum and a variety of Gram-negative bacteria, some of which it carries to initiate new food populations.D. discoideum is a popular model for studying multicellularity, chemical signaling, general eukaryotic cellular mechanisms, and social phenomena (12-15). The protist is typically found in soil, where it preys on bacteria; in nutrient-rich environments it lives as single-celled organisms that reproduce by binary fission. Upon starvation, cAMP-mediated aggregation occurs, leading to the formation of a multicellular pseudoplasmodium containing up to 10 5 individual cells. Eventually, the aggregate develops into a fruiting body in which some 20% of the cells differentiate into a dead stalk that supports a spherical structure known as the sorus; the latter contains 80% of the cells that turn into spores.Previous work by Brock et al. (11) showed that about one-third of wild-collected clones of D. discoideum engage in stable associations with bacteria throughout the sporulation and dispersal process. These clones are called "primitive farmers" because they carry, seed, and prudently harvest their bacterial food.Schultz and Brady (16) characterized agriculture as a specialized form of symbiosis known in only four animal groups: humans,...

show abstract

“…Within the rhizosphere microbial populations are a group of plant-beneficial bacteria referred to as plant growth promoting rhizobacteria (PGPR). PGPR are beneficial to plants via nutrient acquisition (Rodriguez and Fraga, 1999;Dobbelaere et al, 2003;Ladha and Reddy, 2003), biocontrol (Walsh et al, 2001;Chin-A-Woeng et al, 2003), plant hormone-like production, lowering of plant ethylene level (Glick, 1995;Steenhoudt and Vanderleyden, 2000) and induction of systemic resistance (van Loon et al, 1998). Other beneficial microbial partners of the plant are the ubiquitous symbiotic arbuscular mycorrhizal fungi (AMF).…”

Section: Introductionmentioning

confidence: 99%

Plant growth stage, fertiliser management and bio-inoculation of arbuscular mycorrhizal fungi and plant growth promoting rhizobacteria affect the rhizobacterial community structure in rain-fed wheat fields

Roesti

Gaur

Johri

et al. 2006

Soil Biology and Biochemistry

191

View full text Add to dashboard Cite

The goal of this study was first to assess the dynamics of the bacterial community during a growing season in three Indian rain-fed wheat fields which differ mainly through their fertilizer management and yield and then to study the effects of PGPR/AMF bio-inoculations on the bacterial community structure and wheat growth. The bacterial community structure of the rhizosphere soil (RS) and the rhizoplane/endorhizosphere (RE) was determined by PCR-denaturing gradient gel electrophoresis. Seed treatments consisted of consortia of two PGPR strains alone or combined with AMF or AMF alone. The PGPR strains were Pseudomonas spp. which included some or all of the following plant growth promoting properties: phosphate solubilisation and production of indole-3-acetic acid, siderophores, 1-aminocyclopropane-1-carboxylate deaminase and diacetyl-phloroglucinol. The mycorrhizal inoculum was an indigenous AMF consortium isolated from the field with the lowest level of fertilization and yield. Variation partitioning analysis of the DGGE data indicated a predominant effect of the wheat growth stage (30.4% of the variance, PZ0.001) over the type of field (9.0%, PZ0.027) on the bacterial community structure in the RE. The impact of plant age in the RS was less than in the RE and the bacterial community structure of the field with the highest input of fertilization was very different from the low input fields. The bio-inoculants induced a significant modification in the bacterial community structure. In the RS, the bacterial consortia explained 28.3% (PZ0.001) and the presence of AMF 10.6% (PZ0.02) of the variance and the same trend was observed in the RE. Plant yield or grain quality was either increased or remained unaffected. For example, protein content was significantly higher in the treated plants' grain compared to the control plants; maximum values were obtained when the PGPR were co-inoculated with the AMF. The percentage of root colonization by AMF was significantly higher in the treatments containing a mycorrhizal inoculum than in the untreated control and remained unaffected by the PGPR treatments. In conclusion, the wheat rhizobacterial community structure is highly dynamic and influenced by different factors such as the plant's age, the fertilizer input and the type of bio-inoculant. In addition, there is a distance-related effect of the root on the bacterial community. Finally, a combined bio-inoculation of diacetyl-phloroglucinol producing PGPR strains and AMF can synergistically improve the nutritional quality of the grain without negatively affecting mycorrhizal growth.

show abstract

Pseudomonas for biocontrol of phytopathogens: from functional genomics to commercial exploitation

Cited by 266 publications

References 54 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

A bacterial symbiont is converted from an inedible producer of beneficial molecules into food by a single mutation in the gacA gene

Plant growth stage, fertiliser management and bio-inoculation of arbuscular mycorrhizal fungi and plant growth promoting rhizobacteria affect the rhizobacterial community structure in rain-fed wheat fields

Contact Info

Product

Resources

About