Characterizing Peronospora belbahrii Effectors

Presenter

Isabelle A. Stephen

Campus

UMass Amherst

Sponsor

Li-Jun Ma, Department of Biochemistry and Molecular Biology, UMass Amherst

Schedule

Session 3, 1:30 PM - 2:15 PM [Schedule by Time][Poster Grid for Time/Location]

Location

Poster Board A47, Campus Center Auditorium, Row 3 (A41-A60) [Poster Location Map]

Abstract

The oomycete pathogen Peronospora belbahrii, infects basil plants causing Basil Downy Mildew. Since its detection in 2007 Basil Downy Mildew emerged as a devastating disease that is rapidly spreading across the US. This research project focuses on six candidate P. belbahrii effectors, proteins aiding infection, selected based on their high expression during infection in a susceptible plant. Specifically, RXLR effectors, found in oomycete pathogens like Phytophthora species, are explored for their crucial role in translocating into host plants, suppressing immunity, and supporting pathogen survival. We screened the candidate RLXR effectors to evaluate whether any of the individual effectors significantly contributed to the pathogen's infectivity. Because the pathogen is recalcitrant, effector sequences were cloned into Agrobacterium vectors, which we utilize to heterologously express our candidates and controls in Nicotiana benthamiana, a ubiquitous technique known as agroinfiltration. We first evaluated the responses of N. benthamiana leaves to agroinfiltration with each effector, using buffer as a negative control, and a cell-death-inducing Phytophthora infestans effector, INF1, as a positive visual indicator of expression.  By evaluating cell death, we can collect semi-quantitative data through a visual rating scale to characterize the effectors as inducers or suppressors of cell death. This assay doesn’t reveal a specific mechanism of action for the effectors but selecting individual(s) with strong phenotypes will allow a narrower list of candidates. In summary, our study has successfully established the assay and screened one effector, and while a robust phenotype wasn’t observed, we anticipate presenting the outcomes for the remaining five selected candidates.

Keywords

Fungi, Pathogenicity , Effector Proteins

Research Area

Biological Organisms

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