Genetics Comprehensive Exam Seminar of Jeff Schachterle

9:00 AM; 1455 BPS
"The role of E. amylovora small RNA ArcZ during fire blight disease development"


Erwinia amylovora causes the devastating fire blight disease of apple and pear trees.  Fire blight infects flowers leading to yield losses and also infects shoots and spreads systemically through the host tree.  Conditions that favor disease can lead to death of the tree in a single season.  Current control of the disease relies heavily on antibiotics, and in some regions resistance has emerged.  E. amylovora coordinates regulation of flagellar motility to migrate to susceptible host tissues, produces exopolysaccharides and forms biofilms to build large populations, and expresses type III secretion to manipulate host cells.  Through these virulence factors, E. amylovora overcomes host defenses, induces necrosis, and acquires the nutrients it needs to proliferate.  The Hfq dependent small RNA ArcZ is involved in regulating each of these critical virulence factors and an arcZ mutant loses virulence.  Although ArcZ is well conserved in enteric pathogens, it is not known how levels of the small RNA are regulated.  Nor is it known with which specific mRNAs ArcZ interacts to affect virulence factors.  To address these unknowns, I propose to characterize the role of ArcZ by determining how it is being regulated and how it regulates virulence.  To determine how ArcZ is regulated, I will test for control at the transcriptional and post-transcriptional levels.  To identify virulence factor associated mRNA targets, a combination of genetic screens and candidate gene approaches will be used.  To place ArcZ regulation in context of disease development, I propose in planta transcriptomic analyses with spatio-temporal resolution by sampling different host tissues across time during disease development.  It is anticipated that the findings of this work will contribute to understanding of virulence gene regulation to facilitate current and future efforts to control fire blight.