Sarah Lim
Sarah Lim
Year: 2011
Faculty Advisor: Greg Martin

Investigating the molecular basis of AvrPto C-terminal domain (CTD) activity within members of theSolanaceae family

Pseudomonas syringae is a y-proteobacterium that causes disease in over 50 plant species including economically important species such as tomato, tobacco, rice, apple, and many members of the Brassicaceae. These bacteria use a syringe-like secretion device to inject virulence proteins, termed effectors, into the plant cell, which collectively are essential for colonization of the host and subsequent disease. AvrPto is one important effector to study because some plants appear to have evolved machinery to recognize its virulence domains, stimulating an immune response. This summer I investigated a region of AvrPto called the C-terminal domain (CTD), which contributes to virulence in tomato but triggers a defense mechanism in tobacco. I used a combination of modern molecular and classical plant pathology techniques to test for virulence activity of the CTD in Nicotiana glutinosa, a tobacco species which we believe lacks the appropriate machinery to recognize the CTD. I also investigated the critical determiants of CTD recognition using Pseudomonas mutants, which I tested in N. sylvestris, a common tobacco species that mounts an immune response against the CTD. In addition to these projects, I also harvested RNA from susceptible tomato plants infected with Pseudomonas mutants to test whether the various AvrPto virulence domains affect host defense gene regulation differentially, and the data generated from this investigation may also serve to locate host proteins involved in CTD recognition.

My Experience

I highly recommend this summer experience to any intern looking for a fun, fast-paced summer. This program is well equipped with facilities and mentors that will challenge you, but there were extracurricular events planned throughout the summer as well. The lectures were great and a nice way to see your fellow interns during the week, and the program coordinator was accessible and open to any concerns. You will learn how to work closely with others inside the lab and how to be an independent individual outside of it. You will work very hard, and learn how to talk about your research. You will make friends and get a taste of what life is like as a graduate student. Like all experiences involving growth, this summer was exhausting, exciting, challenging, inspiring, and at the end of the day, satisfying. It cultivated my love for plant pathology and gave me a great research experience that I can confidently discuss in future stages of my academic career.