Degree Type

Thesis

Date of Award

2008

Degree Name

Master of Science

Department

Plant Pathology and Microbiology

First Advisor

Roger Wise

Second Advisor

Dan Nettleton

Third Advisor

Steve Whitham

Abstract

Programmed Cell Death (PCD) plays a pivotal role in plant development and defense. Pathogen dependent cell-death mutants were used to investigate the complex regulatory pathways between PCD and R-gene mediated resistance. Time-course expression profiles of Blumeria graminis f. sp. hordei (Bgh) challenged C.I. 16151 (harboring the Mla6 powdery mildew resistance allele) and its fast-neutron-derived "Bgh-induced tip cell death1" mutant, bcd1, were compared using the 22K Barley1 GeneChip. Contrasts were made to identify genes associated with the cell death phenotype as opposed to R-gene mediated resistance. One hundred eighty-two genes were found in the intersection of these contrasts at a threshold p value < 0.001 (equivalent false discovery rate < 5%). One hundred forty-seven of these 182 genes were found to be constitutively overexpressed in the bcd1 mutant. GO annotation indicates that these genes are mainly involved in metabolism, showing common physiological process with other stressed-induced genes. Six deleted genes that co-segregated with the cell death phenotype mapped to the same region on chromosome 7 (5H), and are highly syntenous with rice. F2 segregation analysis of crosses between genotypes harboring bcd1 and Mla6 x Bcd1 and mla6 demonstrated that the tip cell death was independent of R-gene mediated resistance. Virus induced gene silencing (VIGS) of one of the six deleted genes, CA031190, phenocopied bcd1-mediated tip cell death. These findings suggest that Bcd1 mediates metabolism involved in cell death progression as a result of signaling during the barley-powdery mildew interaction, but is independent of gene-for-gene resistance.

DOI

https://doi.org/10.31274/rtd-180813-16575

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Liu Xi

Language

en

Proquest ID

AAI1453166

OCLC Number

694902000

ISBN

9780549543411

File Format

application/pdf

File Size

78 pages

Share

COinS