Apple (Malus ×domestica Borkh.) breeding at the University of Minnesota (UMN) has been ongoing continuously since 1908 when staff originally planted thousands of seedlings from open-pollinated (OP) seeds collected from regional orchards. The first cultivar from the program, ‘Minnehaha’, was introduced in 1920 and several others from these OP seeds followed over the next 3 decades. Controlled crosses were initiated in 1916, and until the time of this publication, 28 cultivars have been introduced. Historical records of parentage, as recorded by staff in notebooks and in 20th-century publications, have been used to inform breeding decisions but might be incorrect as indicated by earlier explorations of parentage using simple sequence repeat (SSR) markers. Our objective was to elucidate parentage and extended pedigrees of all available cultivars introduced from the UMN apple breeding program using evaluations of Mendelian errors and shared haplotype length information based on data from single nucleotide polymorphism (SNP) arrays. Sixteen of the 21 cultivars introduced before ‘Honeycrisp’ (1991) had incorrect or incomplete pedigrees that are now at least partially elucidated. These include the two most important regional cultivars in the 20th century: ‘Haralson’ (parents: ‘Malinda’ and ‘Wealthy’) and ‘Fireside’ (parents: ‘Wealthy’ and ‘Northwest Greening’). ‘Wealthy’, a widely grown cultivar in the United States in the late 19th and early 20th centuries, was a frequent parent of older UMN cultivars. ‘Malinda’ was a less frequent parent than indicated by breeding records. ‘Duchess of Oldenburg’ (synonym ‘Borowitsky’) was revealed as an ancestor of overwhelming importance in the UMN breeding program. It was an ancestor of 27 of the 28 UMN cultivars, including as a parent of two cultivars, and a grandparent of 15 cultivars, including ‘Honeycrisp’.
Bibliographical noteFunding Information:
Received for publication 3 Nov. 2021. Accepted for publication 31 Dec. 2021. Published online 11 February 2022. This research was funded in part by National Institute of Food and Agriculture (NIFA), U.S. Department of Agriculture (USDA) and State Agricultural Experiment Station—University of Minnesota Projects MIN-21-040 and MIN-21-097 and by the USDA-NIFA Specialty Crop Research Initiative Projects 2009-51181-05808 and 2014-51181-22378. SNP data were shared by collaborators at INRAe (Angers, France), the Fondazione Edmund Mach, and the Fruitbreedomics Project No. 265582, which was cofounded by the EU seventh Framework Programme. We thank Chares-Eric Durel, Hélène Mur-anty, and Caroline Denancé from INRAe for use of their MUNQ system. We gratefully acknowledge access to germplasm for genotyping provided by the USDA Plant Genetic Resources Unit (Geneva, NY), Dan Bussey and Seed Savers Exchange (Dec-orah, IA), Joanie Cooper and the Temperate Orchard Conservancy (Molalla, OR), and Addie Shuenemayer and the Montezuma Orchard Restoration Project (Cortez, CO). Technical assistance at the University of Minnesota was provided by Bay-lee Miller, Hannah Hauan, and Nicole Marshall. We thank Drs. Matthew Clark and Sarah Kostick for reviewing an earlier version of the manuscript. The University of Minnesota receives royalty payments related to the ‘Honeycrisp’, ‘Minnewashta’, ‘Wildung’, ‘Minneiska’, ‘MN55’, and ‘MN80’ apple cultivars. J.J.L., D.S.B., and the University of Minnesota have a royalty interest in these cultivars. These relationships have been reviewed and managed by the University of Minnesota in accordance with its Conflict of Interest policies. Current address for N.P.H.: Fresh Forward Breeding and Marketing, Eck en Wiel, the Netherlands J.J.L. is the corresponding author. E-mail: firstname.lastname@example.org. This is an open access article distributed under the CC BY-NC-ND license (https://creativecommons. org/licenses/by-nc-nd/4.0/).
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- Duchess of Oldenburg
- Malus ×domestica
- historical records
- pedigree reconstruction
- single nucleotide polymorphism (SNP) array