Molecular phylogeny and origins of Hordeum polyploid species

Abstract

The genus Hordeum in the tribe Triticeae comprises about thirty two species including diploids and polyploids. Although the phylogeny of diploid Hordeum species has been studied intensively, there have been incongruences between the datasets obtained from chloroplast and nuclear genes. Additionally, the origins of the polyploid species in the genus Hordeum have not been completely understood until now. In the present study, three chloroplast gene loci, trnT-trnF intergenic spacer, rps16 gene, and trnH-psbA intergenic spacer in addition to a single-copy nuclear gene, β-amylase gene, were used to explore the phylogeny and origins of Hordeum polyploid species. Eighty accessions from thirty two Hordeum species were used in this study. The present study supports previous suggestions on that H. brachyantherum ssp. californicum was one parent to the tetraploid species H. brachyantherum ssp. brachyantherum, H. jubatum, H. guatemalense, and H. depressum. Our nuclear DNA results suggest the diploid H. roshevitzii as one parent to tetraploid species H. brachyantherum ssp. brachyantherum, H. jubatum, and H. fuegianum. In addition, our results suggest H. cordobense, H. brahcyantherum ssp. californicum, and H. roshevitzii as the diploid genome donors to the hexaploid species H. procerum, the diploid species H. pusillum and H. brachyantherum ssp. californicum as genome donors to the hexaploid H. lechleri. Moreover, our study further confirms H. pusillum as a diploid parent to H. arizonicum and suggests H. brachyantherum ssp. californicum as another diploid genome donor to the hexaploid H. arizonicum.