Pathogen-host coevolution: a case study of Magnaporthe-rice interactions

Ryohei Terauchi (Kyoto University)

病原菌-宿主共進化：いもち病菌とイネ相互作用の例

寺内良平博士（京都大学大学院農学研究科教授）

Abstract

Pathogen-host coevolution: a case study of Magnaporthe-rice interactions

Ryohei Terauchi (Lab. Crop Evolution, Kyoto University, Kyoto, Japan; Iwate Biotechnology Research Center, Kitakami, Iwate, Japan)

In an essay titled “Disease and Evolution” (1949), J.B.S Haldane noted “I want to suggest that the struggle against disease, and particularly infectious disease, has been a very important evolutionary agent…’. Selection from pathogens has been proposed to account for the evolution of sex (Hamilton et al. 1990). In the era of genomics as ushered by the recent development of DNA sequencing technologies, we are particularly interested in how pathogen-host coevolution leaves selection signatures in the genomes of organisms.

Rice blast caused by an ascomycete fungus Magnaporthe oryzaeis the most devastating disease of rice (Oryza sativa). There are well-defined gene-for-gene interactions (Flor, 1956) between rice resistance(R-) genes and M. oryzaeavirulence(AVR) genes. Cross-breeding of R-genes has been the most economical way to control the disease. The majority of R-gene products belong to intracellular immune receptors of the NLR (Nucleotide-binding Leucine rich repeat Receptor) class. Therefore, an in-depth molecular understanding of NLR function is important. To this end, we have been studying three pairs of rice NLRs and the M. oryzaeAVRsthey detect: Pia- AVR-Pia, Pii - AVR-PiiandPik - AVR-Pik. In each case, the paired NLRs function together, with one acting as a “sensor” to detect the AVR effector and the second as a “helper” involved in transducing the immune signal. Each of the sensor NLRs contain a non-canonical integrated domain (ID): RGA5 and Pik-1 harbor an HMA integrated domain (ID), whereas Pii-2 contains a NOI ID. In this presentation, I will provide an overview of the three molecular interactions and discuss the selective forces that maybe driving molecular evolution of NLRs and AVRs in the rice/M. oryzaesystem.

この講演は英語で行われます．This lecture will be in English.