Abstract

The genus Phytophthora includes some of the most notorious pathogens of plants. During infection, Phytophthora species secrete hundreds of effectors that are subsequently translocated into the host cell in order to promote infection and suppress host defenses. Understanding the specific targets and functions of these effectors is critical to unraveling the mechanism of pathogenicity for these damaging pathogens. The vast majority of Phythopthora effectors, however, remain uncharacterized. Budding yeast, Saccharomyces cerevisiae, has emerged as a powerful model system for studying these effectors on the premise that many target conserved eukaryotic pathways. The aim of this study was to generate hypotheses for the function of the Phytophthora sojae effector Avh110 (PsAvh110) by heterologously expressing it in yeast and determining the effect on genome-wide expression levels through RNA sequencing and differential gene expression analysis. Gene set enrichment analysis was used to identify functional themes within the list of the genes with effector-altered expression, and then the Saccharomyces Genome Database was used to identify conserved signaling pathways that regulate these functions. Most genes that were down-regulated more than two-fold were involved in the PHO regulon, which is responsible for phosphate homeostasis in yeast. The expression of most of these genes is controlled by the transcription factor PHO4, which is itself regulated by several well conserved signaling pathways. Highly conserved elements in these pathways represent putative targets of the effector in yeast, and orthologous genes in plants represent potential targets in the natural host.

Advisor

Morgan, William

Department

Biology

Disciplines

Bioinformatics | Molecular Genetics

Keywords

Phytophthora, effectors, RxLR, phosphate homeostasis, yeast, oomycetes, RNA-seq

Publication Date

2017

Degree Granted

Bachelor of Arts

Document Type

Senior Independent Study Thesis

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© Copyright 2017 Avery C. Wilson