Cell wall integrity (CWI) maintenance is central for plant cells. Mechanical and chemical distortions, pH changes, and breakdown products of cell wall polysaccharides activate plasma membrane-localized receptors and induce appropriate downstream responses. Microbial interactions alter or destroy the structure of the plant cell wall, connecting CWI maintenance to immune responses. Cellulose is the major polysaccharide in the primary and secondary cell wall. Its breakdown generates short-chain cellooligomers that induce Ca²⁺-dependent CWI responses. We show that these responses require the malectin domain-containing CELLOOLIGOMER-RECEPTOR KINASE 1 (CORK1) in Arabidopsis and are preferentially activated by cellotriose (CT). CORK1 is required for cellooligomer-induced cytoplasmic Ca²⁺ elevation, reactive oxygen species (ROS) production, mitogen-associated protein kinase (MAPK) activation, cellulose synthase phosphorylation, and the regulation of CWI-related genes, including those involved in biosynthesis of cell wall material, secondary metabolites and tryptophan. Phosphoproteome analyses identified early targets involved in signaling, cellulose synthesis, the endoplasmic reticulum/Golgi secretory pathway, cell wall repair and immune responses. Two conserved phenylalanine residues in the malectin domain are crucial for CORK1 function. We propose that CORK1 is required for CWI and immune responses activated by cellulose breakdown products.

Phosphate (Pi) availability has a strong influence on the symbiotic interaction between Arabidopsis and a recently described root-colonizing beneficial Trichoderma harzianum strain. When transferred to media with insoluble Ca₃(PO₄)₂ as a sole Pi source, Arabidopsis seedlings died after 10 days. Trichoderma grew on the medium containing Ca₃(PO₄)₂ and the fungus did colonize in roots, stems, and shoots of the host. The efficiency of the photosynthetic electron transport of the colonized seedlings grown on Ca₃(PO₄)₂ medium was reduced and the seedlings died earlier, indicating that the fungus exerts an additional stress to the plant. Interestingly, the fungus initially alleviated the Pi starvation response and did not activate defense responses against the hyphal propagation. However, in colonized roots, the sucrose transporter genes SWEET11 and -12 were strongly down-regulated, restricting the unloading of sucrose from the phloem parenchyma cells to the apoplast. Simultaneously, up-regulation of SUC1 promoted sucrose uptake from the apoplast into the parenchyma cells and of SWEET2 sequestration of sucrose in the vacuole of the root cells. We propose that the fungus tries to escape from the Ca₃(PO₄)₂ medium and colonizes the entire host. To prevent excessive sugar consumption by the propagating hyphae, the host restricts sugar availability in its apoplastic root space by downregulating sugar transporter genes for phloem unloading, and by upregulating transporter genes which maintain the sugar in the root cells.

Cell wall integrity (CWI) maintenance is central for plant cells. Mechanical or chemical distortions, pH changes, or breakdown products of cell wall polysaccharides activate plasma membrane-localized receptors and induce appropriate downstream responses. Microbial interactions alter or destroy the structure of the plant cell wall, connecting CWI maintenance to immune responses. Cellulose is the major polysaccharide in the primary and secondary cell wall. Its breakdown generates short-chain cellooligomers which induce Ca ²⁺ -dependent CWI responses. We have shown here that these responses require the malectin domain-containing CELLOOLIGOMER-RECEPTOR KINASE 1 (CORK1) in Arabidopsis . CORK1 is required for cellooligomer-induced cytoplasmic Ca ²⁺ elevation, reactive oxygen species (ROS) production, mitogen associated protein kinase (MAPK) activation, cellulose synthase phosphorylation, and the regulation of CWI-related genes including those involved in biosynthesis of cell wall material, secondary metabolites and tryptophan. Phosphoproteome analyses identified early targets involved in signaling, cellulose synthesis, the endoplasmatic reticulum/Golgi secretory pathway, cell wall repair and immune responses. Two conserved phenylalanine residues in the malectin domain are crucial for CORK1 function. We propose that cellulose breakdown products bind to the malectin domain in CORK1, indicating its role as a novel receptor kinase for CWI maintenance.

Patients with chronic kidney disease (CKD) and type 2 diabetes (T2D) are vulnerable to infections. While sodium-glucose cotransporter-2 (SGLT-2) inhibitors provide established cardiorenal benefits, their effects on infection remain unclear. This study aimed to evaluate the association between SGLT-2 inhibitors and the risks of severe sepsis, infection-related complications, and mortality in this population. We conducted a real-world, active-comparator, new-user cohort study using the U.S. Collaborative Network of TriNetX. Adults with CKD and T2D who initiated SGLT-2 inhibitors or DPP-4 inhibitors between 2018 and 2024 were included. Propensity score matching was applied to balance baseline characteristics. The primary outcome was severe sepsis; secondary outcomes included septic shock, mortality, hospitalization, pneumonia, urinary tract infection (UTI), and genital infection. After matching, 25,049 patients were included in each group. During 1 year of follow-up, SGLT-2 inhibitor use was associated with a lower risk of severe sepsis than DPP-4 inhibitor use (2.7% vs. 3.3%; HR, 0.81; 95% CI, 0.73-0.90). Risks of septic shock (HR, 0.83), mortality (HR, 0.72), hospitalization (HR, 0.90), pneumonia (HR, 0.77), and UTI (HR, 0.72) were reduced, whereas the risk of genital infection (HR, 1.93) was higher. No significant differences were observed in diabetic ketoacidosis or acidosis. Among patients with CKD and T2D, SGLT-2 inhibitor initiation was associated with lower risks of severe sepsis, infection-related outcomes, hospitalization, and mortality compared with DPP-4 inhibitor initiation, despite a higher risk of genital infection. These findings support SGLT-2 inhibitors as a core therapy with potential benefits extending beyond cardiorenal protection in this high-risk population.

Microbial volatiles are important factors in symbiotic interactions with plants. Mortierella hyalina is a beneficial root-colonizing fungus with a garlic-like smell, and promotes growth of Arabidopsis seedlings. GC-MS analysis of the M. hyalina headspace and NMR analysis of the extracted essential oil identified the sulfur-containing volatile tris(methylthio)methane (TMTM) as the major compound. Its incorporation in seedlings was shown by 34S labeling experiment. Under sulfur deficiency, TMTM downregulated sulfur deficiency-responsive genes, prevented glucosinolate (GSL) and glutathione (GSH) diminishment, and sustained plant growth. However, excess TMTM led to accumulation of GSH and GSL and reduced plant growth. Since TMTM is not directly incorporated into cysteine, we propose that the volatile from M. hyalina influences the plant sulfur metabolism by interfering with the GSH metabolism, and alleviates sulfur imbalances under sulfur stress.