Excellence in Research: The evolutionary origins of sex chromosomes in docks and sorrels (Rumex)

许多植物同时具有雄性和雌性的功能，但某些群体提供了一个动态系统来研究雄性和雌性个体的分离进化及其在染色体水平上的控制。船坞和酢浆草为研究这些现象的进化发展提供了一个特别强大的系统，因为在这个植物群中存在两种不同的性染色体系统。此外，初步证据表明，这些植物中的一些可能有一个不寻常的进化逆转，从性染色体决定的单性到性染色体的丧失和性别分离。这个项目对这种模式的确认将改变研究人员对植物中这些染色体排列的进化和形成的思考方式。霍华德大学的本科生将与国家自然历史博物馆的一名科学家合作参与这项研究，研究人员将参加各种外展活动，向公众和霍华德大学的学生宣传植物性别决定的进化和多样性以及项目的发现。异型性染色体在植物中很少见。然而，尽管如此罕见，植物提供了一个令人信服的系统来研究性别决定的发展及其在染色体水平上的控制，因为在植物中，不像在脊椎动物中，这些进化过程通常是相对较新的。在植物类群中，由于在该属中存在两个独立的性染色体系统，因此特别为研究这些现象的进化发展提供了一个独特的系统。在本项目中，研究人员将使用下一代测序技术为具有异型染色体系统的Rumex acetosa一种物种构建高质量的从头核基因组，并为其他25种Rumex物种构建低覆盖率的基因组组装，代表生殖系统的多样性。有了这个项目产生的数据，研究人员将能够解开复杂生殖系统的进化起源，并重建属的性染色体结构。此外，他们将能够识别在染色体进化过程中发生的结构变异。该奖项由历史上的黑人学院和大学-卓越研究项目以及环境生物学部的系统学和生物多样性科学集群共同资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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 project’s 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.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.