Investigation of phyllody symptoms caused by downy mildew in foxtail millet

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K06062
• 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: National Agriculture and Food Research Organization (2020-2021); Iwate Biotechnology Research Center (2019)
• Principal Investigator: Kobayashi Michie 国立研究開発法人農業・食品産業技術総合研究機構, 生物機能利用研究部門, 研究員 (10751539)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: アワしらが病 / べと病 / 植物病原菌エフェクター / 葉化病徴

Outline of Final Research Achievements

When Sclerospora graminicola (Sg) colonized the panicles, the organs are transformed into leafy structures (phyllody). In phyllody-induced panicles, SVP-MADS expression was induced. We have analyzed the regulatory mechanism of SVP-MADS expression, but without clear results.
Jacalin-related lectin (JRL) gene family has significantly expanded in Sg genome. We identified eight JRLs via protein mass spectrometry analysis of extracellular fluid from Sg-inoculated foxtail millet leaves. JRL expression was induced by Sg infection. Heterologous expression of three JRLs with N-terminal secretion signal peptides in Nicotiana benthamiana enhanced the virulence of the pathogen Phytophthora palmivora inoculated onto the same leaves. INF1-mediated induction of defense-related genes was suppressed by co-expression of JRL. These findings suggest that JRLs are novel apoplastic effectors that contribute to pathogenicity by suppressing plant defense responses.

Free Research Field

植物病理学

Academic Significance and Societal Importance of the Research Achievements

本研究では、アワしらが病菌が感染し、葉化病徴を誘導する機構を解析した。葉化組織では感染によるMADS-boxの撹乱が示唆された一方で、詳細な機構解明には至らなかった。病原菌因子の解析では、JRLが病原性エフェクターとして機能する可能性を示した。これまでに、JRLが病原性に関わることを明確に示した報告はなく、しらが病菌を含む卵菌類の感染機構を明らかにする上で、新しい成果と言える。