Jonathan D. G. Jones

Plant TIR domain-containing proteins exhibit NADase activity upon pathogen effector recognition, creating small molecules that activate defense via EDS1 and its associated proteins. Arabidopsis RPS4 and RRS1 comprise a TIR-NLR immune receptor pair that recognizes multiple effector proteins including AvrRps4 and PopP2. We show here that RPS4 and RRS1 acquire NADase activity upon recognition of a cognate effector. However, both in the presence and absence of effector, RPS4 and RRS1 form an oligomer that does not change in size upon effector provision. Effector-dependent defense activation by RPS4 and RRS1 requires the catalytic glutamate residue and the BB-loop motif of RPS4, which is absent in RRS1 and other RRS1-like TIR domains in Arabidopsis . Oligomerization of RPS4 and RRS1 occurs through multiple domains, but oligomerization does not require enzymatic activity. We propose that conformational changes or reconfiguration within the RPS4/RRS1 oligomer upon effector recognition derepresses the complex for immune activation.

Plant NLR immune receptors can undergo dynamic changes in subcellular localization upon effector recognition. The Arabidopsis ADR1 helper NLRs mainly act at the plasma membrane (PM) in a phospholipid-dependent manner. Whether ADR1s display nuclear translocation and how ADR1s subcellular partitioning influences their immune function remains unknown. Here, we show that ADR1s relocate from the PM to the nucleus after TNL activation and identified TRANSPORTIN1 (TRN1) as a specific nuclear transport receptor that mediates nuclear import of ADR1s through direct binding, thus enabling the formation of TNL-induced EDS1-PAD4-ADR1s complex in the nucleus. Interestingly, TRN1 suppresses the autoactivity of ADR1s through compromising their PM localization and oligomerization. Nucleus-localized ADR1s restrict their autoactivation capacity but the nuclear pool of ADR1s is required for TNL-activated transcriptional reprogramming and disease resistance. Thus, TRN1-mediated nuclear import of ADR1s coordinates the PM and as-yet-undiscovered nuclear activities of ADR1s, thus enabling plants to mount a complete immune response.

Plant nucleotide-binding, leucine-rich-repeat (NLR) immune receptors recognize pathogen effectors and activate immunity. The NLR Resistance to Pseudomonas syringae2 (RPS2) recognizes Avirulence protein interacting with RPS2 (AvrRpt2), a Pseudomonas effector that promotes virulence by proteolytically cleaving a membrane-tethered host protein, RPM1-interacting protein 4 (RIN4). RIN4 cleavage by AvrRpt2 also activates RPS2. A model in which RPS2 is activated by elimination of RIN4 is consistent with the ectopic activity of RPS2 in plants lacking RIN4 but does not explain the link between AvrRpt2's virulence activity and RPS2 activation. We found that non-membrane-tethered RIN4 derivatives are potent cytosolic activators of RPS2. Activation of RPS2 by these RIN4 derivatives, like AvrRpt2-induced activation, and unlike ectopic activation in the absence of RIN4, requires the defense signaling protein NON-RACE-SPECIFIC DISEASE RESISTANCE 1 (NDR1). Cleavage products of RIN4 produced by AvrRpt2 play contrasting roles in the activation of RPS2, with the membrane-tethered C-terminal fragment suppressing RPS2 and the non-membrane-tethered internal fragment, dependent on compatibility with the C-terminal fragment, overcoming its suppression of RPS2.

Potato leafroll virus (PLRV) is an economically important viral disease of potato ( S. tuberosum ). Genetic resistance to this phloem-limited virus is rare, and no cloned resistance ( R ) genes have been reported. Rl _adg confers resistance to PLRV in an Andean potato landrace, LOP-868 (Velásquez et al. 2007). We identified the functional Rl _adg gene as a homolog of the tomato TIR-NLR-encoding Bs4 . Rl _adg interacts with the serine protease domain of the PLRV protein P1, which is essential for virus replication. This recognition is independent of the protease’s enzymatic activity, and the Rl _adg immune receptor oligomerizes upon direct association with the protease. Like PLRV, many poleroviruses contain a serine protease. Despite their diverse amino acid sequences, these proteases are predicted to share similar structures. Rl _adg recognizes all ten tested polerovirus proteases, suggesting a conserved structural recognition mechanism. We propose that Rl _adg ’s broad recognition capacity could enable resistance to poleroviruses in many crop species. Rl _adg is the first R -gene reported to confer resistance to a phloem-limited pathogen and could provide enhanced resistance to many economically important poleroviruses.

Toll/interleukin-1 receptor (TIR) enzymes are prominent immune components in diverse organisms across the tree of life. In flowering plants, TIRs are often integrated into nucleotide binding leucine-rich repeat (NLR) receptors whose oligomerization-dependent biochemical activities create second messengers perceived by ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1)-family signaling complexes. TIR-NLRs and TIR proteins are present across the full spectrum of plant evolution, yet EDS1 signaling is a derived trait in seed plants. Here, we examined the functional dependency of diverse plant TIRs on the EDS1 pathway in the angiosperms Nicotiana benthamiana and Nicotiana tabacum . While the isolated TIR domains from non-seed plants generally required EDS1 for immune cell death activation, we also identified TIRs that functioned independent of EDS1. However, chimeric TIR-NLRs incorporating these diverse TIR domains onto the AtWRR4a receptor chassis showed a full reversion to EDS1-dependency. Extending this phenomenon further, we demonstrated that the AtWRR4a architecture enforces EDS1-dependence onto a bacterial TIR domain that is otherwise EDS1-independent. Collectively, our work demonstrates that NLR immune receptor architecture influences TIR-related immunity and provides further context to their ancient acquisition into plant immune systems.

Non-host resistance refers to the immunity of plant species to virtually all isolates of a potential pathogen and represents an underexplored avenue for breeding and engineering disease resistance. In domesticated and wild barley, cell surface-localized lectin receptor kinases (LecRKs) contribute to determining the host status to leaf rust fungi, which pose a major threat to global cereal production. Here, we identify a conserved family of leaf rust glycoside hydrolases as ligands for these barley LecRKs and show that direct ligand-receptor binding triggers immune responses. This mechanism of pathogen perception is conserved across multiple cereal species and can be functionally transferred between them. We also uncover previously uncharacterized recognition specificities among distinct LecRK variants, expanding the repertoire of LecRK-mediated rust pathogen detection. Our findings define a molecular mechanism underlying non-host resistance in cereals and provide a basis for harnessing non-host rust resistance across diverse crop-pathogen systems.

Direct air capture offers a decentralized pathway for supplying CO₂ to low-concentration utilization applications, including controlled environment agriculture, microalgae cultivation, biocatalytic conversion, and enhanced weathering. Solid sorption is favored for these applications, yet existing technologies require complex and expensive equipment to manage heat for desorption. Here we present a fluidized bed direct air capture system that uses controlled liquid water spray to drive moisture-swing desorption from a commercial ion exchange resin, eliminating the need for external high-grade heat. Breakthrough experiments revealed moisture-activated CO₂ uptake, with optimal performance at 20–40% relative humidity and capacity reaching 3 mmol g⁻¹ at 35 °C. A prototype operating cyclically on 2.8 kg of sorbent achieved productivity of 8.7 gCO₂ kgsorbent⁻¹ h⁻¹ and specific energy consumption of 2.5 kWh kgCO₂⁻¹. We demonstrate performance is strongly governed by regeneration conditions, water injection volume and inlet air conditions, with warm, dry conditions yielding the best performance.

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.