Study on function of quantitative resistance gene Pid3-I1 to blast fungus in rice

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K05968
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 39010:Science in plant genetics and breeding-related
• Research Institution: Hokkaido University
• Principal Investigator: Inukai Tsuyoshi 北海道大学, 農学研究院, 講師 (90223239)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: イネ / いもち病菌 / 圃場抵抗性 / Rタンパク

Outline of Final Research Achievements

Pid3-I1 was reported as a quantitative blast resistance gene with race specificity. However, because the level of Pid3-I1 resistance was increased in an age-dependent manner and showed resistance to the blast isolate which was previously reported as a compatible race at the late growth stage, it was shown that the Pid3-I1 resistance was essentially non-race specific. Pid3-I1 is an allele at the Pid3 locus where a qualitative resistance gene Pid3-I3 was differentiated. The differences in amino acid sequences between Pid3-I1 and -I3 were only six sites and four of the six sites are occurred in the LRR domain. To determine which differences are important in the Pid3-I1 function, we made the chimeric gene Pid3-α (I3-CC-NBS + I1-LRR). The T0 transgenic plants developed HR-like lesions spontaneously, and several PR genes were also upregulated in those plants. Taken together, we concluded that the Pid3-I1 resistance was due to the autoactivated defense reaction related with the LRR function.

Free Research Field

植物育種学

Academic Significance and Societal Importance of the Research Achievements

イネのいもち病抵抗性育種において特に求められる点は抵抗性のレベルの高さとともにその持続性、安定性にある。圃場抵抗性はいもち病菌側の病原性の変異によっても抵抗性が変動しにくい安定した抵抗性であるが、しかしこの抵抗性は十分に育種には生かされているとは言えない。いもち病圃場抵抗性遺伝子を有効に利用するにはその作用機作を明らかにすることも重要であることから、本研究では圃場抵抗性遺伝子Pid3-I1を対象にその作用機作について解析を進め、Pid3-I1は抵抗性反応のautoactivationに関わる遺伝子であり、いもち病菌のレースに対して非特異的に働くことを示した。