Iron homeostasis and fire blight resistance in the Asian and European pear cultivars: Desferal (Deferoxamine) modulates plant pathogen interactions

Iron is an essential cofactor for plant metabolism during host-pathogen interactions. Erwinia amylovora , the causal agent of fire blight, exploits high-affinity siderophores to acquire iron from host tissues, enhancing virulence. This study investigated whether targeted manipulation of iron availability with the iron chelator Desferal (Des) can alter the outcome of E. amylovora infection in pears. Two cultivars with contrasting susceptibility to fire blight, Pyrus communis cultivar ʻDargaziʼ and Pyrus serotina cv. ʻKS13ʼ were inoculated with E. amylovora and monitored at multiple time points for disease progression, iron speciation (Fe 2+ /Fe 3+ ), enzymatic antioxidants (peroxidase, superoxide dismutase, catalase, polyphenol oxidase), non-enzymatic antioxidant capacity (FRAP), secondary metabolites (phenolics, flavonoids), pigments (chlorophyll, carotenoids), and total carbohydrates. Des treatment was applied 24 h before inoculation. Across two experimental seasons, Des consistently reduced internode and shoot necrosis in both cultivars, with the largest absolute reduction observed in the susceptible ʻKS13ʼ cultivar and the strongest overall tolerance in ʻDargaziʼ. Des treated tissues showed lower activities of several antioxidant enzymes, preserved photosynthetic pigments, and cultivar-specific shifts in secondary metabolites (e.g., elevated late-stage flavonoids in ʻDargaziʼ). Des altered iron speciation, with treated plants showing higher Fe 3+ and Fe 2+ relative to untreated controls. Multivariate analyses revealed that Des reorganized the biochemical landscape (shifting ʻKS13ʼ toward a profile more similar to resistant ʻDargaziʼ) and clustering Des-treated samples separately from controls. Correlation analyses supported a model in which necrosis associates with strong inducible antioxidant responses and pigment loss in untreated ʻKS13ʼ, while resistance in ʻDargaziʼ is linked to a stable phenolic (pigment) iron module that buffers oxidative damage. Further studies are suggested on other pear cultivars under commercial pear orchard conditions.