title: Multiple origins of BBCC allopolyploid species in the rice genus (Oryza).
abstract: In the rice genus (Oryza), about one half of the species are allopolyploids. These species are not only important resources for rice breeding but also provide a unique opportunity for studying evolution of polyploid species. In the present study, we sequenced four biparentally inherited nuclear loci and three maternally inherited chloroplast fragments from all diploid and tetraploid species with the B- and C-genome types in this genus. We detected at least three independent origins of three BC-genome tetraploid species. Specifically, the diploid O. punctata (B-genome) and O. officinalis (C-genome) were the parental progenitors of O. minuta and O. malampuzhaensis with O. punctata being the maternal donors, whereas the diploid O. punctata and O. eichingeri (C-genome) were the progenitors of tetraploid O. punctata with O. punctata being the paternal donor. Our relaxed clock analyses suggest that all the BBCC species originated within the last one million years, which is coincident with the severe climate oscillations occurred during the last ice age, implying the potential impact of climate change on their formations and dispersals. In addition, our results support previous taxonomic arguments that the tetraploid O. punctata might be better treated as a separate species (O. schweinfurthiana).
authors.affiliation: State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.
authors.forename: Xin-Hui
authors.initials: XH
authors.lastname: Zou
authors.affiliation: State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.|University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Yu-Su
authors.initials: YS
authors.lastname: Du
authors.affiliation: State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Tang
authors.affiliation: State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.
authors.forename: Xin-Wei
authors.initials: XW
authors.lastname: Xu
authors.affiliation: School of Integrative Plant Biology, Plant Breeding &Genetics Section, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Jeff J
authors.initials: JJ
authors.lastname: Doyle
authors.affiliation: State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Sang
authors.affiliation: State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.|University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Song
authors.initials: S
authors.lastname: Ge
mesh_terms: D005075:Biological Evolution; D018744:DNA, Plant / Q000235:genetics*; D014644:Genetic Variation / Q000235:genetics*; D018745:Genome, Plant / Q000235:genetics*; D012275:Oryza / Q000145:classification / Q000235:genetics*; D011123:Polyploidy
chemical_list: D018744:DNA, Plant