Zinc priming enhances Capsicum annuum immunity against infection by Botrytis cinerea– From the whole plant to the molecular level

• Published in: Plant science (Limerick) Vol. 343; p. 112060
• Main Authors: Kuvelja, Anđela, Morina, Filis, Mijovilovich, Ana, Bokhari, Syed Nadeem Hussain, Konik, Peter, Koloniuk, Igor, Küpper, Hendrik
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier B.V 01-06-2024
• Subjects: Fungal pathogen; Gray mold disease; Metabolites; Metalloproteins; Micronutrients; Pepper; Plant immunity; Fungal pathogen; Gray mold disease; Micronutrients; Metabolites; Pepper; Plant immunity; Metalloproteins
• ISSN: 0168-9452; 1873-2259
• DOI: 10.1016/j.plantsci.2024.112060

Micronutrient manipulation can enhance crop resilience against pathogens, but the mechanisms are mostly unknown. We tested whether priming Capsicum annuum plants with zinc (5 μM Zn) or manganese (3 μM Mn) for six weeks increases their immunity against the generalist necrotroph Botrytis cinerea compared to deficient (0.1 μM Zn, 0.02 μM Mn) and control conditions (1 μM Zn, 0.6 μM Mn). Zinc priming reduced the pathogen biomass and lesion area and preserved CO2 assimilation and stomatal conductance. Zinc mobilization at the infection site, visualized by micro-X-ray fluorescence, was accompanied by increased Zn protein binding obtained by size exclusion HPLC-ICP/MS. A common metabolic response to fungal infection in Zn- and Mn-primed plants was an accumulation of corchorifatty acid F, a signaling compound, and the antifungal compound acetophenone. In vitro tests showed that the binding of Zn2+ increased, while Mn2+ binding decreased acetophenone toxicity against B. cinerea at concentrations far below the toxicity thresholds of both metals in unbound (aquo complex) form. The metal-specific response to fungal infection included the accumulation of phenolics and amino acids (Mn), and the ligand isocitrate (Zn). The results highlight the importance of Zn for pepper immunity through direct involvement in immunity-related proteins and low molecular weight Zn-complexes, while Mn priming was inefficient.
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•Zinc priming promotes resistance in Capsicum annuum against Botrytis cinerea.•Zn-binding proteins and low MW Zn ligands accumulate in infected Zn-primed plants.•Zn priming mechanisms include local Zn accumulation at the infection site.•Zn-acetophenone has higher antifungal activity than the ligand or the Mn-complex.•Mn priming was not efficient.