Recognition of rice blast effectors by paired immune receptors

De La Concepcion, Juan (2019) Recognition of rice blast effectors by paired immune receptors. Doctoral thesis, University of East Anglia.

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Plant diseases are a major burden for global agriculture. Pathogens deliver an array of molecules, termed effectors, to successfully colonize the host. Effectors can be recognized by intracellular immune receptors from the Nucleotide-binding Leucine-rich Repeat (NLR) family, activating immune responses that restrict pathogen growth. Engineering NLR receptors to enhance disease resistance has been a major biotechnological goal for over two decades. However, this has proven challenging as we still lack mechanistic knowledge on pathogen recognition and immune activation by NLRs. Recently, unconventional domains integrated in NLRs have been found to bind pathogen effectors and mediate immunity, opening new possibilities to engineer pathogen recognition.

Here, I combined molecular and structural biology to understand how integrated Heavy Metal Associated (HMA) domains in the rice NLR Pik mediate recognition to the rice blast pathogen Magnaporthe oryzae, and how they co-adapt with their acceptor NLR following integration. By obtaining the crystal structure of five complexes between HMA domains from allelic Pik resistance proteins and the AVR-Pik effectors from the rice blast pathogen, I could define the mechanistic basis of the arms-race co-evolution between plants and pathogens. Moreover, I showed that structural information can guide the engineering of disease resistance by the extending the pathogen recognition specificity of the Pikp NLR using structure-informed mutagenesis.

I also investigated the co-evolutionary dynamics between Pik receptors and how integrated HMA domains play a crucial role in regulation of immune responses. This uncovered unprecedent details on the co-adaptation between integrated domains and their NLR chassis, with broad implications from plant immunity. Altogether, my results advance the understanding on how integrated domains mediate pathogen recognition, their role in immune activation and the co-evolutionary events that underpin immune regulation. Finally, I applied the techniques developed here to a different rice blast effector, AVR-Pii, paving the way for new discoveries in effector biology and plant immunity.

The findings presented in this thesis link mechanistic and evolutionary research in plant immunity and have the potential to inform the design of immune receptors with enhanced capabilities, an important goal in global agriculture.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Chris White
Date Deposited: 24 Oct 2022 10:48
Last Modified: 24 Oct 2022 10:48

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