Co-evolution of virulence and recognition in rice blast disease
J. MAIDMENT (1), A. Maqbool (1), H. Saitoh (2), H. Kanzaki (2), M. Franceschetti (1), C. Stevenson (1), S. Kamoun (3), R. Terauchi (2), M. Banfield (1) (1) John Innes Centre, United Kingdom; (2) Iwate Biotechnology Research Center, Japan; (3) The Sainsbury Laboratory, United Kingdom

As the causative agent of rice blast disease, the fungus Magnaporthe oryzae represents a major threat to global food security. During infection, M. oryzae secretes effector proteins which manipulate host targets to enhance the virulence of the pathogen. A subset of these, termed avirulence (AVR) proteins, can be recognised by specific NLR receptors in rice to trigger plant defences. Recognition of AVR-Pik is mediated by the paired NLRs Pik-1 and Pik-2. Previous work identified an integrated heavy metal associated (HMA) domain in Pikp-1, and biochemical/structural studies revealed that AVR-PikD directly binds to the Pikp-HMA domain. It is posited that the integrated Pikp-HMA domain originated from the host target of AVR-PikD. Recently, it was shown that AVR-PikD directly interacts with a number of small HMA-domain containing proteins (sHMAs) in rice. Using biochemical and structural approaches, we are characterising the interactions between the allelic series of AVR-Pik effectors and these putative targets. We have expressed sHMA proteins in E. coli and purified the proteins. Using analytical gel filtration and surface plasmon resonance, we have established that the four AVR-Pik alleles each bind sHMA1 with nanomolar affinity. In contrast, Pikp-1 does not bind AVR-PikC, suggesting that AVR-PikC may have evolved to evade host recognition while maintaining its virulence function.

Abstract Number: P9-287
Session Type: Poster