Studies on genomic basis for parthenogenesis in nematodes

2020 Fiscal Year Final Research Report

• Project/Area Number: 17H03609
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Genome biology
• Research Institution: National Institute of Genetics
• Principal Investigator: KOHARA Yuji 国立遺伝学研究所, 先端ゲノミクス推進センター, 特任教授 (70135292)
• Project Period (FY): 2017-04-01 – 2021-03-31
• Keywords: ゲノム進化 / ロングリードシーケンス / PacBio / Irys / ハプロタイプ

Outline of Final Research Achievements

Although sexual reproduction is prevailing among eukaryotes, the nematode Diploscapter coronatus, a close relative of the model organism, C. elegans, reproduces parthenogenetically. Neither males nor sperm have been observed and some steps of meiosis are apparently skipped in this species. Our draft genome sequencing showed that there was about 6% heterozygosity between the diploid genome, which consists of two chromosomes (2n=2). Many genes involved in sex determination and meiosis are missing or very divergent.
In this study we carried out the phasing of the genome taking advantages of long read sequencing technology including PacBio and Irys to obtain clues to understand the evolution of the genome. The relationship of gene arrangements with the C. elegans genome suggests complex process of the genome evolution including chromosome fusion. Genome comparison with other close relatives will provide more clues to understand the basis for the occurrence of parthenogenesis.

Free Research Field

ゲノム生物学

Academic Significance and Societal Importance of the Research Achievements

線虫は多様な生殖様式を示す種があり、今後ゲノム解析が進展し、多くの近縁種との比較ができれば、単為生殖へのプロセスを明らかにし、有性生殖の意義にも迫れるかもしれない。生殖は社会的に興味が持たれる課題であり、生物学における長年の課題である有性生殖について手がかりを得られればインパクトは大きい。