host mechanism for preventing partner's cheating in legume-rhizobia symbiosis

• Project/Area Number: 18K06282
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 44030:Plant molecular biology and physiology-related
• Research Institution: National Institute for Basic Biology
• Principal Investigator: Nakagawa Tomomi 基礎生物学研究所, 共生システム研究部門, 特別協力研究員 (90396812)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Project Status: Completed (Fiscal Year 2020)
• Budget Amount: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000); Fiscal Year 2020: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000); Fiscal Year 2019: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000); Fiscal Year 2018: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
• Keywords: 根粒菌 / マメ科植物 / cheating / 相利共生 / 窒素固定 / 共生 / ミヤコグサ / cheater / 微生物叢

Outline of Final Research Achievements

Maintenance of good relationship is a key issue for our lives although the difficulty is always bothering us. On the other hand, legumes keep mutualistic relationships with soil bacteria, called rhizobia, more than 70 million years and provide carbon nutrients to rhizobia in exchange for the supply of nitrogen nutrient from rhizobia. In this relationships, rhizobial cheatings such as receiving carbon nutrients without nitrogen nutrients supply are rarely known in natural environment. We are focusing on this and studying the host mechanism for preventing partner's cheating in legume-rhizobia symbiosis.
We artificially create cheating rhizobia by disrupting genes for nitrogen fixation. The cheating rhizobia can infect and induce small nodules on host roots. Inside these nodules, cheating rhizobia are eliminated by host digestion. In contrast, honest rhizobia are markedly increased and released to surrounding soil. As a result, "honest rhizobia" are dominant around leguminous plants.

Academic Significance and Societal Importance of the Research Achievements

「異なる生物同士がどのように協調しあえるのか？」という問題は、自然界だけではなく我々人間社会においても常に重要な問題である。数理学的には少数で協調-非協調の二択などの限られた状況における解析などが行われているが、自然界や実社会のように無数の参加者があらゆる選択肢を持つ条件で理想的な答えを見つけるのは不可能である。マメ科植物は7千万年以上も根粒菌と相利共生を行っており、共生パートナーによる裏切り・不正などがほとんど問題にならない。我々が発見した「信賞必罰」を明確にして誠実なパートナーを維持する仕組みは、協調関係を築いて維持するための究極の答えであると期待される。

Research Products

• [Journal Article] Cytoplasmic interaction of LysM receptors contributes to the formation of symbiotic receptor complex (2020)
  • Author(s): Maruya Suzuki, Ryota Numazaki, Tomomi Nakagawa, Naoto Shibuya and Hanae Kaku
  • Journal Title: Plant Biotechnology Volume: 37 Issue: 3 Pages: 359362-359362
  • DOI: 10.5511/plantbiotechnology.20.0511a
  • NAID: 130007907445
  • Peer Reviewed
• [Journal Article] Assessment of Polygala paniculata (Polygalaceae) characteristics for evolutionary studies of legume-rhizobia symbiosis (2020)
  • Author(s): Tokumoto Y, Hashimoto K, Soyano T, Aoki S, Iwasaki W, Fukuhara M, Nakagawa T, Saeki K, Yokoyama J, Fujita H, Kawaguchi M
  • Journal Title: J Plant Res. Volume: 133 Issue: 1 Pages: 109-122
  • DOI: 10.1007/s10265-019-01159-x
  • NAID: 40022129850
  • Peer Reviewed
• [Journal Article] Isolation of Native Arbuscular Mycorrhizal Fungi within Young Thalli of the Liverwort Marchantia paleacea (2019)
  • Author(s): Kobae Y, Ohtomo R, Morimoto S, Sato D, Nakagawa T, Oka N, Sato S
  • Journal Title: Plants (Basel) Volume: 8 Issue: 6 Pages: 142-142
  • DOI: 10.3390/plants8060142
  • NAID: 120006901028
• [Presentation] Legumes strategically control their microbial enbironment (2018)
  • Author(s): Tomomi Nakagawa
  • Organizer: The Plant Microbiome 2018
  • Int'l Joint Research / Invited
• [Presentation] アーバスキュラー菌根菌の共生開始に防御応答を担うCERK1が関与する (2018)
  • Author(s): 中川知己
  • Organizer: JCOM2018