The allelic rice immune receptor Pikh confers extended resistance to strains of the blast fungus through a single polymorphism in the effector binding interface

DOI: 10.1371/journal.ppat.1009368

Authors: Juan Carlos De La Concepcion (John Innes Centre) , Josephine H. R. Maidment (John Innes Centre) , Apinya Longya (John Innes Centre; Kasetsart University) , Gui Xiao (John Innes Centre; International Rice Research Institute, Philippines) , Marina Franceschetti (John Innes Centre) , Mark J. Banfield (John Innes Centre)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Plos Pathogens , VOL 17

State: Published (Approved)
Published: March 2021
Diamond Proposal Number(s): 13467

Abstract: Arms race co-evolution drives rapid adaptive changes in pathogens and in the immune systems of their hosts. Plant intracellular NLR immune receptors detect effectors delivered by pathogens to promote susceptibility, activating an immune response that halts colonization. As a consequence, pathogen effectors evolve to escape immune recognition and are highly variable. In turn, NLR receptors are one of the most diverse protein families in plants, and this variability underpins differential recognition of effector variants. The molecular mechanisms underlying natural variation in effector recognition by NLRs are starting to be elucidated. The rice NLR pair Pik-1/Pik-2 recognizes AVR-Pik effectors from the blast fungus Magnaporthe oryzae, triggering immune responses that limit rice blast infection. Allelic variation in a heavy metal associated (HMA) domain integrated in the receptor Pik-1 confers differential binding to AVR-Pik variants, determining resistance specificity. Previous mechanistic studies uncovered how a Pik allele, Pikm, has extended recognition to effector variants through a specialized HMA/AVR-Pik binding interface. Here, we reveal the mechanistic basis of extended recognition specificity conferred by another Pik allele, Pikh. A single residue in Pikh-HMA increases binding to AVR-Pik variants, leading to an extended effector response in planta. The crystal structure of Pikh-HMA in complex with an AVR-Pik variant confirmed that Pikh and Pikm use a similar molecular mechanism to extend their pathogen recognition profile. This study shows how different NLR receptor alleles functionally converge to extend recognition specificity to pathogen effectors.

Journal Keywords: Rice; Plant pathogens; Rice blast fungus; Immune receptors; Immune response; Alleles; Crystal structure; Hydrogen bonding

Subject Areas: Biology and Bio-materials


Instruments: I04-Macromolecular Crystallography

Discipline Tags:

Plant science Pathogens Biotechnology Agriculture & Fisheries Structural biology Life Sciences & Biotech

Technical Tags:

Diffraction Macromolecular Crystallography (MX)