Mode of action of fungistatic fungicide ferimzone: search for target pathways that circumvent the emergence of tolerant strains

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K05658
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 39040:Plant protection science-related
• Research Institution: Ryukoku University
• Principal Investigator: Okuno Tetsuro 龍谷大学, 農学部, 教授 (00221151)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 殺菌剤 / フェリムゾンゾン / 作用機作 / 銅トランスポーター / いもち病菌 / ウリ類炭疽病菌 / 静菌作用 / 耐性菌問題

Outline of Final Research Achievements

Circumventing the emergence of fungicide-resistant strains is a crucial issue for robust disease management in agriculture. The fungicide ferimzone has been used for the control of rice diseases including rice blast. The emergence of ferimzone-resistant strains in rice fields has not been reported. In this research, we identified the copper transport ICT1 gene and the CCC2 gene as the ferimzone sensitivity genes in Colletotrichum orbiculare and the rice blast fungus Magnaporthe oryzae. Genetic and cytological analyses showed that functional defects in the copper transport pathways, consisting of Ict1 and Ccc2, led to the low sensitivity to ferimzone and the pathogenicity defect due to attenuated melanization in the appressorium. Importantly, the presence of CuSO4 induced high sensitivity to ferimzone even in the ict1 mutant. This study shows that there is a trade-off relation between the sensitivity to ferimzone and fungal pathogenicity.

Free Research Field

植物病理学

Academic Significance and Societal Importance of the Research Achievements

植物病害防除において殺菌剤の果たす役割は大きい。しかし、薬剤耐性菌株が多発して農業上大きな問題となっている。本研究では、イネ病害病防除剤として市販されてから約30年間、圃場で薬剤耐性菌株出現の報告のない静菌性殺菌剤フェリムゾンの作用機作研究を行い、薬剤感受性に関わる代謝系（銅輸送系）とその関連遺伝子を明らかにした。このことは、糸状菌病害防除において薬剤耐性菌の出現を回避できる薬剤ターゲット分子と代謝系を提示したことであり、その成果は新規薬剤開発にとって意義がある。また、フェリムゾン感受性と銅輸送系の関連性の発見は糸状菌におけるは銅輸送系ネットワーク解明の重要な情報源となると考えられる。