A newly identified octameric resistosome formed by the activated CCG10-NLR immune receptor WAI3 has been discovered in wheat, marking the first octameric resistosome observed in plants.

Published in Cell, the study highlights wheat as a powerful model for plant immunity and points to CC_G10-NLR pathways as promising targets for engineering durable disease resistance in crops.

The discovery leveraged expression in Nicotiana benthamiana, followed by purification and cryo-electron microscopy to resolve the activated resistosome’s structure.

A gain-of-function mutation in WAI3’s LRR domain, derived from the spontaneous wheat autoimmune mutant M3045, drives constitutive immune activation and reveals regulatory aspects of NLR activation.

Overall, the study reveals a previously unreported octameric resistosome class, offering new insights into NLR activation and calcium signaling in plant immunity.

The work positions wheat as a broader model for plant biology and immune signaling, revealing a novel octameric assembly mechanism for CC-NLR resistosomes and expanding understanding of how plant immune receptors are activated.

Functional assays show the WAI3 resistosome triggers calcium currents in plant cells but not in animal cells, implying the need for plant-specific cofactors or membrane environments.

Cryo-EM confirms the octameric structure of activated WAI3 and demonstrates activity in plant cells but not animal cells, reinforcing the role of plant-specific factors for function.

The findings also extend to Arabidopsis thaliana, where a homologous activated RPS2 protein forms an octameric resistosome and induces Ca2+ influx, suggesting conserved activation mechanisms across plant lineages.

Cross-species conservation is shown by the Arabidopsis CC_G10-NLR homolog RPS2 forming an octameric resistosome and mediating Ca2+ influx, indicating a shared immune signaling architecture in both monocots and dicots.

WAI3 assembles into an eight-subunit ring-shaped complex that functions as a calcium channel to drive Ca2+ influx and initiate plant immune signaling.

This resistosome distinctively adopts an octameric architecture, setting it apart from previously known pentameric and hexameric resistosomes while driving calcium-dependent immune responses.