Phylogenomics and Sex Chromosome Evolution in the plant genus Rumex (Polygonaceae)
Many plants have both male and female function, but certain groups provide a dynamic system in which to study the evolution of separate male and female individuals and its control at the chromosomal level. Docks and sorrels provide a particularly powerful system for studying the evolutionary development of these phenomena because two distinct sex chromosome systems are present in this plant group. Additionally, preliminary evidence suggests that some of these plants may have an unusual evolutionary reversal from sex chromosome-determined unisexuality to a loss of sex chromosomes and sex separation. Confirmation of this pattern by this project would change the way researchers think about the evolution and formation of these chromosomal arrangements in plants. Undergraduates from Howard University will participate in this research, collaborating with a scientist at the National Museum of Natural History, and researchers will participate in a variety of outreach activities to educate the general public and Howard University students about the evolution and diversity of plant sex determination and the projects findings. Heteromorphic sex chromosomes are rare in plants. Yet, despite this rarity, plants provide a compelling system in which to study the development of sex determination and its control at the chromosomal level because in plants, unlike in vertebrate animals, these evolutionary processes are often relatively recent. Among plant groups, Rumex in particular provides a unique system for investigating the evolutionary development of these phenomena because two separate sex chromosome systems are present in the genus. For this project, the researchers will use next-generation sequencing techniques to construct a high-quality de novo nuclear genome for one species with a heteromorphic chromosome system, Rumex acetosa, and lower coverage genome assemblies for 25 other Rumex species, representing diversity in reproductive system. With the data generated from this project, the researchers will be able to unravel the evolutionary origins of complex reproductive systems and reconstruct sex chromosome structure in the genus. In addition, they will be able to identify structural variants that have occurred within the evolution of the chromosomes over time. This award was co-funded by the Historically Black Colleges and Universities Excellence in Research Program and the Systematics and Biodiversity Science cluster in the Division of Environmental Biology.