title: Genetic structure of Miscanthus sinensis and Miscanthus sacchariflorus in Japan indicates a gradient of bidirectional but asymmetric introgression.
abstract: Unilateral introgression from diploids to tetraploids has been hypothesized to be an important evolutionary mechanism in plants. However, few examples have been definitively identified, perhaps because data of sufficient depth and breadth were difficult to obtain before the advent of affordable high-density genotyping. Throughout Japan, tetraploid Miscanthus sacchariflorus and diploid Miscanthus sinensis are common, and occasionally hybridize. In this study, 667 M. sinensis and 78 M. sacchariflorus genotypes from Japan were characterized using 20 704 SNPs and ten plastid microsatellites. Similarity of SNP genotypes between diploid and tetraploid M. sacchariflorus indicated that the tetraploids originated through autopolyploidy. Structure analysis indicated a gradient of introgression from diploid M. sinensis into tetraploid M. sacchariflorus throughout Japan; most tetraploids had some M. sinensis DNA. Among phenotypically M. sacchariflorus tetraploids, M. sinensis ancestry averaged 7% and ranged from 1-39%, with introgression greatest in southern Japan. Unexpectedly, rare (~1%) diploid M. sinensis individuals from northern Japan were found with 6-27% M. sacchariflorus ancestry. Population structure of M. sinensis in Japan included three groups, and was driven primarily by distance, and secondarily by geographic barriers such as mountains and straits. Miscanthus speciation is a complex and dynamic process. In contrast to limited introgression between diploid M. sacchariflorus and M. sinensis in northern China, selection for adaptation to a moderate maritime climate probably favoured cross-ploidy introgressants in southern Japan. These results will help guide the selection of Miscanthus accessions for the breeding of biomass cultivars.
authors.affiliation: Department of Crop Sciences, University of Illinois, Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Lindsay V
authors.initials: LV
authors.lastname: Clark
authors.affiliation: Department of Plant and Wildlife Sciences, Brigham Young University, Provo, UT 84602, USA.
authors.forename: J Ryan
authors.initials: JR
authors.lastname: Stewart
authors.affiliation: Field Science Center, Faculty of Agriculture, University of Miyazaki, Miyazaki, Miyazaki 889-2192, Japan.
authors.forename: Aya
authors.initials: A
authors.lastname: Nishiwaki
authors.affiliation: Faculty of Agriculture, Ehime University, Matsuyama, Ehime 790-8566, Japan.
authors.forename: Yo
authors.initials: Y
authors.lastname: Toma
authors.affiliation: Department of Agroecology, Aarhus University, Tjele DK-8830, Denmark.
authors.forename: Jens Bonderup
authors.initials: JB
authors.lastname: Kjeldsen
authors.affiliation: Department of Agroecology, Aarhus University, Tjele DK-8830, Denmark.
authors.forename: Uffe
authors.initials: U
authors.lastname: Jørgensen
authors.affiliation: College of Horticulture and Forestry Science, Huazhong Agricultural University, Wuhan, Hubei 430070, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Zhao
authors.affiliation: Science and Technology Center, China Seed Group Co. Ltd, Wuhan, Hubei 430040, China.
authors.forename: Junhua
authors.initials: J
authors.lastname: Peng
authors.affiliation: Kangwon National University, Chuncheon, Gangwon 200-701, South Korea.
authors.forename: Ji Hye
authors.initials: JH
authors.lastname: Yoo
authors.affiliation: Kangwon National University, Chuncheon, Gangwon 200-701, South Korea.
authors.forename: Kweon
authors.initials: K
authors.lastname: Heo
authors.affiliation: Kangwon National University, Chuncheon, Gangwon 200-701, South Korea.
authors.forename: Chang Yeon
authors.initials: CY
authors.lastname: Yu
authors.affiliation: Field Science Center for Northern Biosphere, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Yamada
authors.affiliation: Department of Crop Sciences, University of Illinois, Urbana-Champaign, Urbana, IL 61801, USA esacks@illinois.edu.
authors.forename: Erik J
authors.initials: EJ
authors.lastname: Sacks
mesh_terms: D006824:Hybridization, Genetic; D007564:Japan; D018895:Microsatellite Repeats / Q000235:genetics; D018087:Plastids / Q000235:genetics; D006109:Poaceae / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide
keywords: Biomass crop; Poaceae; RAD-seq.; cross-ploidy introgression; hybridization; polyploidy; population genetics