The goal of this project was to survey effector proteins produced by basil downy mildew (Peronospora belbahrii), during the colonization of host basil plants. These effectors are small, secreted proteins which inhibit the plants immune response, allowing for successful colonization of the pathogen. In recent years, basil growers have reported downy mildew infections on basil cultivars which were previously resistant to this pathogen. This newfound ability to bypass basil pathogen-resistance genes suggests emerging genetic diversity among the P. belbahrii population, specifically in their effector proteins.
Two effectors, REL1 and REL2, originally predicted through meta-transcriptomics, were detected in six P. belbahrii isolates using PCR, and then those PCR products were sequenced. From these preliminary sequencing results, several single nucleotide polymorphisms, often nonsynonymous mutations, were identified, suggesting that these effectors are changing across our collected isolates, and suggesting the need for further comparative genomic study.
