Dr. Lina Quesada-Ocampo
Professor and University Faculty Scholar at North Carolina State University
Morrill Science Center 2 South, Room 222
Dr. Quesada integrates genomics and molecular plant pathology into a research and extension program focused on diseases of vegetable crops.
Pseudoperonospora cubensis, an obligate oomycete pathogen, causes cucurbit downy mildew (CDM) on a broad range of host plants including cucumber, cantaloupe, watermelon, pumpkin, and squash. In 2004, CDM re-emerged in the United States (US) by overcoming host resistance in cucumber and fungicides used for disease control in other cucurbits. Population genetics analysis revealed two host-adapted clades in P. cubensis with clade 1 preferentially infecting squash, pumpkin, and watermelon, and clade 2 infecting cucumber and cantaloupe. Using Next Generation Sequencing (NGS), species-specific and host-preference diagnostic markers were identified in the nuclear genome and developed into qPCR assays. Clade-specific assays were able to detect low amounts of P. cubensis sporangia sampled using spore traps as a first step to develop a biosurveillance system for CDM. Assays to detect resistance to Carboxylic Acid Amide (CAA) and Quinone Outside Inhibitor (QoI) fungicides were also developed and indicated widespread fungicide resistance in both clades for QoIs but showed that clade 2 isolates are less sensitive to CAAs than clade 1. Similarly, effector repertoire analyses in clade 1 and clade 2 isolates revealed effectors with clade specific occurrence or expression during host colonization. Overall, findings indicate that understanding population clade composition is critical for effective management of P. cubensis using crop-specific cultural practices, chemical control, and host resistance.
For more information about the research being conducted in Dr. Quesada-Ocampo's lab, please visit her website: https://veggiepathology.wordpress.ncsu.edu/
Sponsored by Stockbridge School of Agriculture and Plant Biology