A helper NLR channels organellar calcium to trigger plant immunity
- Tarhan Ibrahim
- Freddie J. King
- AmirAli Toghani
- Luyao Wang
- Saskia Jenkins
- Enoch Lok Him Yuen
- Hung-Yu Wang
- Cristina Vuolo
- Nick Eilmann
- Vanda Adamkova
- Khong-Sam Chia
- Baptiste Castel
- Jonathan D. G. Jones
- Philip Carella
- Chih-Hang Wu
- Jiorgos Kourelis
- Sophien Kamoun
- Tolga O. Bozkurt
2026-04-30
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 (Ca 2+ )–permeable channels and triggering immunity. Here, we found that the RPW8-like coiled-coil NLR (CC R -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 Ca 2+ 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 Ca 2+ stores.