APS Homepage

SPECIAL SESSION: Plant Pathologists of the Future: Showcasing Graduate Student Presentation Winners from APS Division Meetings

Evaluating Genetic Resistance To Downy Mildew In Chenopodium Species For Use In Breeding Programs
Haley Nolen - University of New Hampshire. Thomas Davis- University of New Hampshire, Anissa Poleatewich- University of New Hampshire

Quinoa is a potential new crop for New England; however, its susceptibility to downy mildew, caused by Peronospora variabilis is a key obstacle. The objective of this project was to evaluate differential resistance within the Chenopodium genus and identify novel genetic sources of resistance for use in future breeding programs. The long-term goal of this research is to develop a resistant variety of quinoa to be grown in North America. Field trials conducted at UNH evaluated downy mildew disease severity on ten Chenopodium accessions representing four species. Accessions were planted in a 2-factor randomized split plot design with three replicate plots per treatment. Disease severity for each treatment was compared and significant differences in disease severity was observed among treatments. C. berlandieri var. macrocalycium ecotypes collected from Rye Beach, NH and Appledore Island, ME exhibited the lowest mean disease severity of the season. P. variabilis was isolated from each of the 10 accessions and ITS and COX2 sequences were compared; phylogenetic analyses suggest no effect of host species; however, New Hampshire isolates formed a clear cluster when compared with Pennsylvania isolates. These results provide the first step in identifying potential New England native sources of resistance to downy mildew within the genus, and provide preliminary information needed to further investigate resistance at the genomic level in Chenopodium spp.