Genetius

The study resolves the ectodomain structure of the plant-specific LRR‑RLK CARD1 (HPCA1) and reveals a surface‑exposed copper ion coordinated by histidines that is essential for hydrogen peroxide signaling. Combined structural, genetic, and biochemical analyses show that previously identified cysteine residues are not required for signal perception, establishing CARD1 as the first copper‑dependent redox receptor.

The study evaluated the genetically encoded redox biosensor roGFP2-Orp1 for monitoring extracellular redox dynamics in diverse land plants, revealing that re‑oxidation rates in the apoplast differ between Physcomitrium patens and Arabidopsis thaliana and are accelerated by immune activation. Comparisons across tip‑growing cells showed no intracellular redox gradient but a partially reduced extracellular sensor in Nicotiana tabacum pollen tubes, indicating species‑ and cell‑type‑specific oxidative processes.

The study examined five sequential organ abscission events in two cherry species, revealing that some abscission zones form de novo while others are pre‑formed and reactivated by localized ethylene signaling, leading to cell division, lignification, ROS accumulation, and pH changes. Species‑specific differences were found in petal shedding and a post‑fertilization checkpoint that eliminates small fruits, indicating a hierarchical, multilayered reproductive filter controlling fruit set.

The study reveals that the endoplasmic reticulum‑associated degradation (ERAD) pathway governs the proteasome‑dependent turnover of PIN‑LIKES (PILS) auxin transport proteins under normal conditions, and that both internal and external cues modulate this process via the ERAD complex. These findings link ER protein homeostasis to auxin‑mediated growth regulation, highlighting a new mechanism by which plants adapt to environmental and developmental signals.

The study used chemically induced effector-triggered immunity combined with single-cell transcriptomics to map immune responses across all leaf cell types in Arabidopsis, revealing that while a core defense program is universally activated, individual cell types deploy distinct transcriptional modules. Functional assays showed that epidermis‑specific transcriptional regulators are essential for preventing pathogen penetration, indicating a spatial division of immune functions within the leaf.

The study identifies fungal effectors from Ustilago maydis that interact with plant TOPLESS corepressors and induce gall formation by hijacking maize lateral root initiation pathways, notably through upregulation of LBD transcription factors. Transgenic expression of class II effectors derepresses auxin signaling, leading to pluripotent calli without external hormones, and maize mutants in LBD genes show reduced gall development.

The study reconstitutes Papaver rhoeas self‑incompatibility (SI) in Arabidopsis thaliana by expressing the pollen S‑determinant PrpS, revealing that SI triggers a rapid Ca2+‑dependent signaling cascade that leads to mitochondrial H2O2 production, metabolic collapse, and programmed cell death. Using a genetically encoded H2O2 sensor and metabolic assays, the authors show that early mitochondrial disruption, driven by altered Ca2+, cytosolic pH, and distinct ROS sources, is central to the SI response.

The study profiled root transcriptomes of Arabidopsis wild type and etr1 gain-of-function (etr1-3) and loss-of-function (etr1-7) mutants under ethylene or ACC treatment, identifying 4,522 ethylene‑responsive transcripts, including 553 that depend on ETR1 activity. ETR1‑dependent genes encompassed ethylene biosynthesis enzymes (ACO2, ACO3) and transcription factors, whose expression was further examined in an ein3eil1 background, revealing that both ETR1 and EIN3/EIL1 pathways regulate parts of the network controlling root hair proliferation and lateral root formation.

The study compared two plasma‑activated water (PAW) solutions with different H₂O₂ levels, produced by a radio‑frequency glow discharge, on Arabidopsis thaliana growth and stress responses. PAW lacking detectable H₂O₂ promoted seedling growth and induced nitrogen‑assimilation genes, while H₂O₂‑containing PAW did not affect growth but enhanced root performance under heat stress; mature plants fertilized with H₂O₂‑free PAW performed comparably to nitrate controls. These results indicate PAW can replace NO₃⁻ fertilizers provided H₂O₂ levels are carefully managed.

The study demonstrates that Candidatus Liberibacter asiaticus induces reactive oxygen species production in chloroplasts and phloem callose deposition, leading to cell death and Huanglongbing (HLB) symptoms in citrus. Genetic manipulation—overexpressing chloroplast flavodoxin to reduce ROS, and editing callose synthase genes—along with chemical inhibition of callose formation, mitigates disease severity, while tomato‑Lpsy infection models reveal key immune regulators (Eds1, Pad4) required for these responses. These findings provide genetic evidence for a CLas‑triggered immune disease and suggest precision breeding strategies for HLB resistance.