Characterization of negative signaling between wheat rhizosphere bacteria and the biological control agent Pseudomonas aureofaciens strain 30-84

Persistent Link:
http://hdl.handle.net/10150/278800
Title:
Characterization of negative signaling between wheat rhizosphere bacteria and the biological control agent Pseudomonas aureofaciens strain 30-84
Author:
Morello, Joanne
Issue Date:
2002
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The biological control bacterium Pseudomonas aureofaciens strain 30-84 produces three phenazine antibiotics. Phenazines are responsible for pathogen inhibition by strain 30-84 as well as its ability to persist in the rhizosphere. Although this bacterium can suppress take-all of wheat disease when applied as a seed inoculum, performance of this agent, as with many biological control agents, can be variable in the field. A factor in establishment and pathogen inhibition may be the indigenous microbial community that competes with strain 30-84 and may interfere with phenazine production as a competitive mechanism. In this study, a wheat rhizosphere microbial community library was screened and ca. 4% of the isolates were found to inhibit phenazine production by strain 30-84. A sub-group of these isolates was characterized and found to produce extracellular signals that suppressed phenazine gene expression. The signal from isolate PU-15 was initially characterized and appeared to be chemically and mechanistically unlike other known negative-acting signals. A genetic region was cloned from this isolate that decreased phenazine gene expression and production in strain 30-84. Negative communication also affected the ability of strain 30-84 to inhibit the pathogenic fungus Gaeuman-nomyces graminis pv. tritici in vitro. Therefore, negative communication may contribute to the inconsistencies of biological control in the field.
Type:
text; Thesis-Reproduction (electronic)
Keywords:
Biology, Microbiology.; Agriculture, Plant Pathology.
Degree Name:
M.S.
Degree Level:
masters
Degree Program:
Graduate College; Plant Pathology
Degree Grantor:
University of Arizona
Advisor:
Pierson, Leland S., III

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleCharacterization of negative signaling between wheat rhizosphere bacteria and the biological control agent Pseudomonas aureofaciens strain 30-84en_US
dc.creatorMorello, Joanneen_US
dc.contributor.authorMorello, Joanneen_US
dc.date.issued2002en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe biological control bacterium Pseudomonas aureofaciens strain 30-84 produces three phenazine antibiotics. Phenazines are responsible for pathogen inhibition by strain 30-84 as well as its ability to persist in the rhizosphere. Although this bacterium can suppress take-all of wheat disease when applied as a seed inoculum, performance of this agent, as with many biological control agents, can be variable in the field. A factor in establishment and pathogen inhibition may be the indigenous microbial community that competes with strain 30-84 and may interfere with phenazine production as a competitive mechanism. In this study, a wheat rhizosphere microbial community library was screened and ca. 4% of the isolates were found to inhibit phenazine production by strain 30-84. A sub-group of these isolates was characterized and found to produce extracellular signals that suppressed phenazine gene expression. The signal from isolate PU-15 was initially characterized and appeared to be chemically and mechanistically unlike other known negative-acting signals. A genetic region was cloned from this isolate that decreased phenazine gene expression and production in strain 30-84. Negative communication also affected the ability of strain 30-84 to inhibit the pathogenic fungus Gaeuman-nomyces graminis pv. tritici in vitro. Therefore, negative communication may contribute to the inconsistencies of biological control in the field.en_US
dc.typetexten_US
dc.typeThesis-Reproduction (electronic)en_US
dc.subjectBiology, Microbiology.en_US
dc.subjectAgriculture, Plant Pathology.en_US
thesis.degree.nameM.S.en_US
thesis.degree.levelmastersen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplinePlant Pathologyen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorPierson, Leland S., IIIen_US
dc.identifier.proquest1411704en_US
dc.identifier.bibrecord.b43473118en_US
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