"Physiological and Molecular Analysis of Dnd ""Defense, No Death"" Mutants of Arabidopsis"
Smith, Roger Kenneth, Jr
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/87031
Description
Title
"Physiological and Molecular Analysis of Dnd ""Defense, No Death"" Mutants of Arabidopsis"
Author(s)
Smith, Roger Kenneth, Jr
Issue Date
2002
Doctoral Committee Chair(s)
Andrew F. Bent
Department of Study
Plant Biology
Discipline
Plant Biology
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Genetics
Language
eng
Abstract
"Plant diseases cause billions of dollars in damage to crops annually, making dissection of the molecular mechanisms of plant disease resistance an economically important task. Gene-for-gene resistance mediated by plant R genes and pathogen avr genes has long been associated with the hypersensitive response (HR). Previously, Arabidopsis thaliana ""defense, no death"" (dnd) mutants were identified based on their failure to produce the HR when inoculated with P. syringae carrying the avirulence gene avrRpt2. The first objective of this study was to characterize the dnd2 mutants in relation to defense. Like the previously characterized dnd1 mutant plants, dnd2 mutants responded to avirulent pathogens by activating avr-dependent defenses despite the absence of the HR. In addition, dnd2 plants exhibited a constitutive systemic resistance associated with elevated levels of salicylic acid (SA). SA was found to be required for the systemic resistance of dnd2 plants, but was not necessary for the HR- phenotype displayed by the mutant plants. SA-independent pathways not normally activated by P. syringae infection were activated in dnd plants, as indicated by the marker for SA-independent signaling, PDF 1.2. A map-based cloning project was initiated which identified a precise genetic interval spanning DND2. Focused shotgun complementation experiments were initiated using subclones from within this region. The roles of reactive oxygen species (ROS) and the enzymes that scavenge these signaling molecules were examined in relation to the HR- phenotype of dnd plants. Northern analysis of ROS scavenger mRNA revealed no significant differences in gene expression between wild type and dnd plants, suggesting that ROS scavengers are not blocking ROS signaling for the HR. Finally, the dwarfed stature of dnd plants was could be partially corrected by altered growth conditions, specifically the soil mix. Chemical analysis of soil mixes after 6 weeks of use suggested that cations and pH might be involved in the growth phenotype. The effect of K+ , Ca2+, Na+, and pH on dnd plant growth was then tested in agar-based media. The dnd plants did not respond to increasing concentrations of Ca2+ in parallel with wild-type plants. K+, Na+ and pH impacted dnd1, dnd2, and wild-type plants similarly."
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
