Salvati Ascenzo, Diomaiuti Alessandra, Locci Federica, Gravino Matteo, Gramegna Giovanna, Ilyas Muhammad, Benedetti Manuel, Costantini Sara, De Caroli Monica, Castel Baptiste, Jones Jonathan D G, Cervone Felice, Pontiggia Daniela, De Lorenzo Giulia
Department of Biology and Biotechnologies, 'Charles Darwin' Sapienza University of Rome, Rome, 00185, Italy.
Department of Biological and Environmental Sciences and Technologies, University of Salento, Campus Ecotekne, Lecce, 73100, Italy.
Plant J. 2025 Apr;122(1):e70150. doi: 10.1111/tpj.70150.
Plant immunity is triggered by endogenous elicitors known as damage-associated molecular patterns (DAMPs). Oligogalacturonides (OGs) are DAMPs released from the cell wall (CW) demethylated homogalacturonan during microbial colonization, mechanical or pest-provoked mechanical damage, and physiological CW remodeling. Berberine bridge enzyme-like (BBE-l) proteins named OG oxidases (OGOXs) oxidize and inactivate OGs to avoid deleterious growth-affecting hyper-immunity and possible cell death. Using OGOX1 over-expressing lines and ogox1/2 double mutants, we show that these enzymes determine the levels of active OGs vs. inactive oxidized products (ox-OGs). The ogox1/2-deficient plants have elevated levels of OGs, while plants overexpressing OGOX1 accumulate ox-OGs. The balance between OGs and ox-OGs affects disease resistance against Pseudomonas syringae pv. tomato, Pectobacterium carotovorum, and Botrytis cinerea depending on the microbial capacity to respond to OGs and metabolize ox-OGs. Gene expression upon plant infiltration with OGs reveals that OGOXs orchestrate OG signaling in defense as well as upon mechanical damage, pointing to these enzymes as apoplastic players in immunity and tissue repair.
植物免疫由称为损伤相关分子模式（DAMPs）的内源性激发子触发。寡聚半乳糖醛酸（OGs）是在微生物定殖、机械损伤或害虫引发的机械损伤以及生理细胞壁重塑过程中从细胞壁（CW）去甲基化的同型半乳糖醛酸释放的DAMPs。名为OG氧化酶（OGOXs）的小檗碱桥酶样（BBE-l）蛋白氧化并使OGs失活，以避免有害的生长影响超免疫和可能的细胞死亡。使用过表达OGOX1的株系和ogox1/2双突变体，我们表明这些酶决定了活性OGs与无活性氧化产物（ox-OGs）的水平。缺乏ogox1/2的植物中OGs水平升高，而过表达OGOX1的植物积累ox-OGs。OGs和ox-OGs之间的平衡影响对丁香假单胞菌番茄致病变种、胡萝卜软腐果胶杆菌和灰葡萄孢的抗病性，这取决于微生物对OGs的反应和代谢ox-OGs的能力。用OGs浸润植物后的基因表达表明，OGOXs在防御以及机械损伤时协调OG信号传导，表明这些酶是免疫和组织修复中的质外体参与者。
