Characterizing a New Race of the Basil Downy Mildew Pathogen Peronospora belbahrii

Presenter

Nicole I. deBlois

Campus

UMass Amherst

Sponsor

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

Schedule

Session 4, 2:30 PM - 3:15 PM [Schedule by Time][Poster Grid for Time/Location]

Location

Poster Board A44, Campus Center Auditorium, Row 3 (A41-A60) [Poster Location Map]

Abstract

Basil downy mildew is a significant disease caused by the oomycete pathogen Peronospora belbahrii. Several downy mildew-resistant (DMR) cultivated varieties (cultivars) of sweet basil were first released in 2018. The ‘Prospera’ DMR cultivars were selected through interspecific hybridization with resistant wild basil types, and carry qualitative resistance conferred by a single genetic source. Classical breeding methods were used to select Rutgers DMR cultivars with quantitative multigenic resistance. Unfortunately, the pathogen has rapidly adapted to overcome many resistant cultivars. We have observed that these two main sets of resistant cultivars perform differently in response to the adapted pathogen, suggesting that multigenic resistance may offer some advantages for breeding efforts. We are establishing and screening a panel of basil cultivars to differentiate and identify P. belbahrii isolates with virulence patterns that have emerged in multiple years and locations. We will use these virulence patterns to distinguish new races of the pathogen as they continue to emerge. Through a series of differential panel trials, we found that an isolate from Israel shared a virulence profile with our lab isolate HVO-21 collected in MA in 2021, indicating that these isolates belong to a shared race.. Here, we report the results of these evaluations on multiple tested isolates, and further examine the responses of resistant plants derived from different genetic sources.

Keywords

fungal pathogen, genetic resistance, characterization

Research Area

Biological Organisms

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