AUTHOR=Chen Shiyong , Yan Hao , Sha Lina , Chen Ning , Zhang Haiqin , Zhou Yonghong , Fan Xing 

TITLE=Chloroplast Phylogenomic Analyses Resolve Multiple Origins of the Kengyilia Species (Poaceae: Triticeae) via Independent Polyploidization Events

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.682040

DOI=10.3389/fpls.2021.682040

ISSN=1664-462X

ABSTRACT=<p><italic>Kengyilia</italic> is a group of allohexaploid species that arose from two hybridization events followed by genome doubling of three ancestral diploid species with different genomes St, Y, and P in the Triticeae. Estimating the phylogenetic relationship in resolution of the maternal lineages has been difficult, owing to the extremely low rate of sequence divergence. Here, phylogenetic reconstructions based on the plastome sequences were used to explore the role of maternal progenitors in the establishment of <italic>Kengyilia</italic> polyploid species. The plastome sequences of 11 <italic>Kengyilia</italic> species were analyzed together with 12 tetraploid species (PP, StP, and StY) and 33 diploid taxa representing 20 basic genomes in the Triticeae. Phylogenomic analysis and genetic divergence patterns suggested that (1) <italic>Kengyilia</italic> is closely related to <italic>Roegneria</italic>, <italic>Pseudoroegneria</italic>, <italic>Agropyron</italic>, <italic>Lophopyrum</italic>, <italic>Thinopyrum</italic>, and <italic>Dasypyrum</italic>; (2) both the StY genome <italic>Roegneria</italic> tetraploids and the PP genome <italic>Agropyron</italic> tetraploids served as the maternal donors during the speciation of <italic>Kengyilia</italic> species; (3) the different <italic>Kengyilia</italic> species derived their StY genome from different <italic>Roegneria</italic> species. Multiple origins of species <italic>via</italic> independent polyploidization events have occurred in the genus <italic>Kengyilia</italic>, resulting in a maternal haplotype polymorphism. This helps explain the rich diversity and wide adaptation of polyploid species in the genus <italic>Kengyilia</italic>.</p>