G3: Genes|Genomes|Genetics Early Online, published on July 16, 2020 as doi:10.1534/g3.120.401327 1 Title 2 Reconstruction of the largest pedigree network for pear cultivars and evaluation of the 3 genetic diversity of the USDA-ARS National Pyrus collection 4 5 Authors 6 Sara Montanari*1, Joseph Postman†, Nahla V. Bassil† and David B. Neale* 7 8 * Department of Plant Sciences, University of California, Davis, CA, USA 9 † USDA Agricultural Research Service, National Clonal Germplasm Repository, Corvallis, 10 OR, USA. 11 1 © The Author(s) 2020. Published by the Genetics Society of America. 12 Short running title: Pyrus germplasm genetic characterization 13 14 Key words 15 population structure; germplasm characterization; single nucleotide polymorphism markers; 16 biodiversity conservation; pear breeding 17 18 1 Corresponding author: Department of Plant Sciences, University of California, One Shields 19 Avenue, 95616 Davis, CA, USA. Email:
[email protected]; current email address: 20
[email protected] 21 22 Abstract 23 The USDA-ARS National Clonal Germplasm Repository (NCGR) in Corvallis, Oregon, 24 maintains one of the world’s largest and most diverse living Pyrus collection. A thorough 25 genetic characterization of this germplasm will provide relevant information to optimize the 26 conservation strategy of pear biodiversity, support the use of this germplasm in breeding, and 27 increase our knowledge of Pyrus taxonomy, evolution, and domestication. In the last two 28 decades simple sequence repeat (SSR) markers have been used at the NCGR for cultivar 29 identification and small population structure analysis. However, the recent development of 30 the Applied Biosystems™ Axiom™ Pear 70K Genotyping Array has allowed high-density 31 single nucleotide polymorphism (SNP)-based genotyping of almost the entire collection.