Pai, H. | bioRxiv Science

bioRxiv2022

Resurrection of plant disease resistance proteins via helper NLR bioengineering

Parasites counteract host immunity by suppressing helper NLR proteins that function as central nodes in immune receptor networks. Understanding the mechanisms of immunosuppression can lead to strategies for bioengineering disease resistance. Here, we show that a cyst nematode virulence effector binds and inhibits oligomerization of the helper NLR protein NRC2 by physically preventing intramolecular rearrangements required for activation. A single amino acid polymorphism at the binding interface between NRC2 and the inhibitor is sufficient for this helper NLR to evade immune suppression, thereby restoring the activity of multiple disease resistance genes. This points to a novel strategy for resurrecting disease resistance in crop genomes. One sentence summaryA helper NLR is mutated to evade inhibition by a parasite effector.

plant biology↗

bioRxiv2022

Sensor NLR immune proteins activate oligomerization of their NRC helper

Nucleotide-binding domain and leucine-rich repeat (NLR) immune receptors are important components of plant and metazoan innate immunity that can function as individual units or as pairs or networks. Upon activation, NLRs form multiprotein complexes termed resistosomes or inflammasomes. Whereas metazoan paired NLRs, such as NAIP/NLRC4, activate into hetero-complexes, the molecular mechanisms underpinning activation of plant paired NLRs, especially whether they associate in resistosome hetero-complexes is unknown. In asterid plant species, the NLR required for cell death (NRC) immune receptor network is composed of multiple resistance protein sensors and downstream helpers that confer immunity against diverse plant pathogens. Here, we show that pathogen effector-activation of the NLR proteins Rx (confers virus resistance) and Bs2 (confers bacterial resistance) leads to oligomerization of the helper NLR NRC2. Activated Rx does not oligomerize or enter into a stable complex with the NRC2 oligomer and remains cytoplasmic. In contrast, activated NRC2 oligomers accumulate in membrane-associated puncta. We propose an activation-and-release model for NLRs in the NRC immune receptor network. This points to a distinct activation model compared to mammalian paired NLRs.

plant biology↗