Molecular coevolution of Magnaporthe oryzae pathogen and rice: defense by evolutionary bricolage mediated by genetic recombination

Microbial pathogens generally have larger population sizes and shorter generation time, making natural selection effective to evolve mechanisms to invade and exploit host organisms. On the other hand, hosts have smaller population sizes and longer generation time, making evolution of defense inefficient. How the plants without acquired immunity cope with rapid pathogen evolution? In this talk, I focus on the roles of genetic recombination in plant defense taking example of rice-Magnaporthe oryzae interactions. First, I show a case of host defense evolution in which a rice HMA domain ectopically recombined to Pik-1 sensor NLR, leading to an integrated domain (ID) functioning as bait for pathogen effector AVR-Pik. Next I show the hypervariability of rice Pia/Pias locus sensor NLRs with multiple integrated host domains, which is possibly maintained by a long-term balancing selection. Third, using recombinant lines of both pathogens and host plants, their gene-for-gene interactions and coevolution may be addressed at the genome-wide scale (GxGome). Finally, I will present a high-throughput genetic approach to identify novel AVRs and cognate NLRs from rice, which enables us to explore the functional NLRome of rice.