Format: ORAL

Sangtae Kim1, Se-Eun Jung1, Seungyeon Lee1, Bora Lee1, Yanghoon Cho2, Tamara Villaverde3, Pedro Jimnez-Mejas4, tienne Lveill-Bourret5, Carmen Bentez-Bentez6, Bruce A. Ford7, Julian R. Starr8, Bishnu Adhikari9, Sangchul Choi1, and Sungsik Kong10

1 Department of Biology, Sungshin Women’s University, Seoul 01133, South Korea 2 Uri Plant Research Institute, Kwangju 61431, South Korea 3 Department of Biology and Geology, Physics and Inorganic Chemistry, Universidad Rey Juan Carlos, Calle Tulipán s/n., Móstoles 28933, Madrid, Spain 4 Department of Molecular Biology and Biochemical Engineering, Universidad Pablo de Olavide, Seville 41013, Spain 5 Institut de recherche en biologie végétale (IRBV) and Département de sciences biologiques, Université de Montréal, Montréal H1X 2B2, Canada 6 Department of Plant Biology and Ecology, Universidad de Sevilla, Seville 41012, Spain 7 Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada 8 Department of Biology, University of Ottawa, Ontario K1N 6N5, Canada 9 Department of Biological Sciences, Univ. of Alabama, USA 10 The Wisconsin Institute for Discovery, University of Wisconsin-Madison, USA

With around 2,000 species, Carex (Cyperaceae) is the second-largest genus of monocots. Its great diversity means that extensive taxonomic sampling and genome-scale sequence data are necessary to unravel its detailed evolutionary history and evaluate its newly proposed infrageneric classification. In this study, we estimated both nuclear and plastid phylogenetic trees based on genome-scale data, incorporating 152 representative taxa. We recovered 490 single-copy nuclear gene loci using Carex-specific probes through the Hyb-Seq technique and sequenced 71 coding plastid genes through genome skimming. Results showed that four of the six subgenera proposed in the new classification system were highly supported (bootstrap support 95%) in nuclear and plastid trees. However, their positions in the plastid and nuclear trees differed for many taxa or clades, suggesting a putative hybrid origin, which was assessed by HyDe and GHDet analyses. We also obtained high-quality genome sequences from five Carex species (C. siderosticta, C. paxii, C. dickinsii, C. breviculmis, and C. capricornis) and analyzed them with two previously reported Carex genomes and representatives of other Poales lineages. The genome sequences from Amborella trichopoda, Oryza sativa, and Arabidopsis thaliana were employed as references to detect MADS-box genes in Carex. The maximum-likelihood tree, constructed using an amino-acid-aligned DNA matrix, showed unique duplication and deletion events in the evolutionary history of MADS-box genes in Carex. Furthermore, we generated transcriptomes for each floral organ from two Carex species and compared them with those from Arabidopsis and rice. Our findings 1) highlight conflicting phylogenetic relationships among some subgroups, possibly due to the different evolutionary histories of plastid and nuclear genomes, and 2) shed light on floral structure and genome evolution in Carex.