Identification of bacterial wilt-resistance gene using Ralstonia solanacearum effector proteins

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K18659
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Plant protection science
• Research Institution: 岡山県農林水産総合センター生物科学研究所
• Principal Investigator: Nakano Masahito 岡山県農林水産総合センター生物科学研究所, その他部局等, JSPS特別研究員 (60756708)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 青枯病 / 病害抵抗性 / エフェクター / 活性酸素種

Outline of Final Research Achievements

Ralstonia solanacearum is the causal agent of bacterial wilt in solanaceous crops. This pathogen injects approximately 70 effector proteins into plant cells via the Hrp type III secretion system. To identify an as-yet-unidentified avirulence factor possessed by R. solanacearum, we transiently expressed R. solanacearum effectors in Nicotiana benthamiana leaves and monitored their ability to induce effector-triggered immunity. The expression of RipB strongly induced the production of reactive oxygen species and the expressions of defense-related genes in N. benthamiana. The ripB mutant of R. solanacearum caused wilting symptoms in N. benthamiana. RipB shares homology with Pseudomonas HopQ1, which is recognized by the resistant protein Roq1. The RipB-induced resistance against R. solanacearum was abolished in Roq1-silenced plants. These findings indicate that RipB acts as a major avirulence factor in N. benthamiana and that Roq1 is involved in the recognition of RipB.

Free Research Field

植物保護科学

Academic Significance and Societal Importance of the Research Achievements

ベンサミアナタバコは青枯病菌のRipP1とRipAAを認識することで抵抗性を発揮すると従来考えられてきた。しかしながら、ripAA ripP1二重変異株はベンサミアナタバコに病原性を示さなかった。一方、ripB変異株は萎凋症状を誘導したことから、ベンサミアナタバコに認識される主要なフェクターはRipBであることが明らかになった。この発見は従来の定説に対して再考を促す新知見といえる。