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ARS Home » Midwest Area » Madison, Wisconsin » Vegetable Crops Research » Research » Publications at this Location » Publication #354293
Research Project: Trait Discovery, Genetics, and Enhancement of Allium, Cucumis, and Daucus Germplasm

Location: Vegetable Crops Research

Title: Genetic analyses and mapping of pink-root resistance in onion

Author
item COLCOL MARZU, JEN - Monsanto Corporation
item STRALEY, ELIZABETH - University Of Wisconsin
item Havey, Michael

Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/23/2019
Publication Date: 12/19/2019
Citation: Colcol Marzu, J., Straley, E., Havey, M.J. 2019. Genetic analyses and mapping of pink-root resistance in onion. Journal of the American Society for Horticultural Science. 143(6):503-507. https://doi.org/10.21273/JASHS04509-18.
DOI: https://doi.org/10.21273/JASHS04509-18

Interpretive Summary: Pink root (PR) is a major disease of onion reducing both yield and quality of bulbs, and resistant cultivars offer the best control option for this disease. The objectives of this study were to identify sources of PR resistance in diverse onion germplasm and genetically map resistances from independent sources. Accessions from the USDA germplasm collection of onion previously reported to show PR resistance were evaluated using a seedling screen and sources of resistance validated. Segregating families were developed from two sources of PR resistance and survival measured using the seedling screen. PR severity in two segregating families mapped to one position on chromosome 4, explained 28% and 35% of the variation for severity, and was codominant. PR resistance from another source was assessed by seedling survival in the presence of the PR fungus, showed codominant inheritance, and mapped to the same region on chromosome 4. These results demonstrate that PR resistance from two separate sources map to the same chromosome region and show similar modes of inheritance. These results will be of interest to onion breeders and pathologists and useful for the development of PR resistant cultivars of onion.

Technical Abstract: Pink root (PR) is a major soil-borne disease of onion and reduces both yield and quality of bulbs. PR-resistant cultivars offer the best control option for this disease. The objectives of this study were to identify sources of PR resistance in diverse onion germplasm and genetically map resistances from independent sources. Accessions from the USDA germplasm collection of onion previously reported to show PR resistance were evaluated using a seedling screen and sources of resistance were validated. Segregating families were developed from two sources of PR resistance and survival measured using the seedling screen. PR severity in two segregating families mapped to one position on chromosome 4 with logarithm of odds (LOD) scores of 8.0 and 10.5, and explained 28% and 35% of the phenotypic variation. Estimates of additive and dominance effects revealed this source of PR resistance was codominantly inherited. PR resistance from a second source was assessed by seedling survival in the presence of the PR fungus, showed codominant inheritance, and mapped to the same region on chromosome 4. These results reveal that PR resistance from two separate sources map to the same chromosome region and show similar modes of inheritance.