A helper NLR channels organellar calcium to trigger plant immunity
Summary
Upon activation, plant nucleotide-binding leucine-rich repeat (NLR) immune receptors are known to assemble into oligomeric resistosomes that insert into the plasma membrane, forming calcium (Ca2+)-permeable channels and triggering immunity. Here, we found that the RPW8-like coiled-coil NLR (CCR-NLR) N requirement gene 1 (NRG1) primarily targets organelles instead of the plasma membrane. Unlike canonical CC-NLRs, activated NRG1 accumulated at the chloroplast envelope and channeled stromal C
Content
# A helper NLR channels organellar calcium to trigger plant immunity
*Published: 2026 Apr 30*
Upon activation, plant nucleotide-binding leucine-rich repeat (NLR) immune
receptors are known to assemble into oligomeric resistosomes that insert into
the plasma membrane, forming calcium (Ca2+)-permeable channels and triggering
immunity. Here, we found that the RPW8-like coiled-coil NLR (CCR-NLR) N
requirement gene 1 (NRG1) primarily targets organelles instead of the plasma
membrane. Unlike canonical CC-NLRs, activated NRG1 accumulated at the
chloroplast envelope and channeled stromal Ca2+ into the cytosol. AlphaFold
modeling of the NRG1 resistosome revealed an unusually long amino-terminal
membrane-insertion structure that could span the double membrane of the
chloroplast. Nanobody-mediated relocalization showed functional membrane
specificity: Chloroplast trapping abolished activity of the canonical helper
CC-NLR NRC4 but not NRG1. NRG1 orthologs, from nonflowering lineages to
angiosperms, targeted chloroplasts, suggesting that organelle-centered defense
dates back at least ~360 million years. We propose that CC-NLR diversification
has enabled compartment-specific immune signaling to capture diverse Ca2+
stores.
DOI: 10.1126/science.aeb6690