Plant-endophyte interplay protects tomato against a virulent Verticillium dahliae

dc.contributor.advisorRobb, Jane
dc.contributor.authorShittu, Hakeem Olalekan
dc.date.accessioned2010-10-05T12:47:58Z
dc.date.available2010-10-05T12:47:58Z
dc.date.copyright2010-04
dc.date.created2010-03-29
dc.date.issued2010-10-05T12:47:58Z
dc.degree.departmentDepartment of Molecular and Cellular Biologyen_US
dc.degree.grantorUniversity of Guelphen_US
dc.degree.nameDoctor of Philosophyen_US
dc.degree.programmeMolecular and Cellular Biologyen_US
dc.description.abstractWhen tomato Craigella is infected with Verticillium dahliae Dvd-E6 (Dvd-E6), a tolerant state is induced with substantial pathogen load, but few symptoms. Unexpectedly, these plants are more robust and taller with Dvd-E6 behaving as an endophyte. Some endophytes can protect plants from virulent pathogens. This research was undertaken to improve understanding of the cellular and molecular nature of Verticillium tolerance in tomato, especially whether infection by Dvd-E6 can protect Craigella from virulent V. dahliae, race 1 (Vd1). To permit mixed infection experiments a restriction fragment length polymorphism (RFLP)-based assay was developed and used for differentiating Dvd-E6 from Vd1, when present in mixed infections. The results suggested that protection involves molecular interplay between Dvd-E6 and Vd1 in susceptible Craigella (CS) tomatoes, resulting in restricted Vd1 colonization. Further studies showed a dramatic reduction of Vd1 spores and mycelia. To examine genetic changes that account for these biological changes, a customized DNA chip (TVR) was used to analyze defense gene mRNA levels. The defense gene response was categorized into four groups. Group 1 was characterized by strong induction of defense genes followed by suppression. However, Vd1-induced gene suppression was blocked by Dvd-E6 in mixed infections. These genes included some transcription factors and PR proteins such as class IV chitinases and beta glucanases which are known to target fungal spores and mycelia. Experiments also were repeated with a Craigella resistant (CR) isoline containing a fully active Ve locus (Ve1+ and Ve2+). The biological results showed that the presence of the Ve1+ allele resulted in restricted Vd1 colonization and, in a mixed infection with Dvd-E6, Vd1 was completely eliminated from the plant stem. Surprisingly, there was no significant increase in defense gene mRNAs. Rather, elevated basal levels of defense gene products appeared sufficient to combat pathogen attack. To investigate functional effects of the genetic changes observed, an inducible RNAi knockdown vector for a defense gene (TUS15G8) with unknown function (pMW4-TUS15G8) as well as the Ve2 resistance gene (pMW-Ve2) was prepared as a initial step for future transformation analyses. Taken together the results reveal intriguing but complex biological and molecular changes in mixed infections, which remain a basis for future experiments and potential agricultural benefits.en_US
dc.description.sponsorshipCanadian Commonwealth Scholarship and Fellowship Plan
dc.identifier.urihttp://hdl.handle.net/10214/2271
dc.language.isoenen_US
dc.publisherUniversity of Guelphen_US
dc.rights.licenseAll items in the Atrium are protected by copyright with all rights reserved unless otherwise indicated.
dc.subjectTomato-Verticillium responseen_US
dc.subjectPathogenesis related (PR) proteinen_US
dc.subjectResistant relationshipen_US
dc.subjectSusceptible relationshipen_US
dc.subjectEndophyte-induced protectionen_US
dc.subjectTolerant relationshipen_US
dc.subjectCompatible interactionen_US
dc.subjectIncompatible interactionen_US
dc.subjectDefence proteinen_US
dc.subjectMyceliaen_US
dc.subjectFungal sporesen_US
dc.subjectMixed infectionen_US
dc.subjectAgrobacteriumen_US
dc.subjectFunctional analysisen_US
dc.subjectRNAi constructen_US
dc.subjectpMW-Ve2en_US
dc.subjectpMW4-TUS15G8en_US
dc.subjectGene expressionen_US
dc.subjectSilencingen_US
dc.subjectVe geneen_US
dc.subjectSusceptibilityen_US
dc.subjectResistanceen_US
dc.subjectDefence genesen_US
dc.subjectplant-pathogen interactionen_US
dc.subjectRFLPen_US
dc.subjectVerticillium dahliae race 1en_US
dc.subjectDvd-E6en_US
dc.subjectCraigellaen_US
dc.subjectRT-PCRen_US
dc.subjectToleranceen_US
dc.subjectEndophyteen_US
dc.subjectPlant transformationen_US
dc.subjectRNAien_US
dc.subjectMicroarrayen_US
dc.subjectTomatoen_US
dc.subjectVerticilliumen_US
dc.titlePlant-endophyte interplay protects tomato against a virulent Verticillium dahliaeen_US
dc.typeThesisen_US

Files

Original bundle
Now showing 1 - 1 of 1
Loading...
Thumbnail Image
Name:
Shittu_HakeemO_201004_PhD.pdf
Size:
5.33 MB
Format:
Adobe Portable Document Format
Description:
License bundle
Now showing 1 - 1 of 1
No Thumbnail Available
Name:
license.txt
Size:
404 B
Format:
Item-specific license agreed upon to submission
Description: