A Chickpea NCR Peptide Suppresses Postharvest Alternaria alternata Infection by Disrupting Fungal Membranes, Mitochondria and Respiration.

Postharvest fungal diseases cause substantial losses in horticultural crops and are commonly managed using chemical fungicides, which raise concerns regarding resistance development and environmental impact. Plant-derived antifungal peptides represent a promising alternative for sustainable disease control. Here, we evaluated the antifungal activity and mode of action of three nodule-specific cysteine-rich (NCR) peptides-NCR044, NCR192 and NCR13_PFV2-against major postharvest fungal pathogens. Among the peptides tested, NCR13_PFV2 exhibited the strongest inhibitory activity against Alternaria alternata, Colletotrichum gloeosporioides, Lasiodiplodia theobromae and Penicillium expansum, although activity against C. gloeosporioides was predominantly fungistatic rather than fungicidal. Mechanistic analyses using A. alternata as a model pathogen revealed that NCR13_PFV2 rapidly associates with fungal membranes, induces membrane permeabilization and exhibits selective binding to anionic phospholipids and phosphoinositides. Peptide treatment was associated with mitochondrial depolarization, elevated reactive oxygen species accumulation, reduced cellular respiration and disruption of vacuolar integrity. These intracellular effects were accompanied by loss of turgor pressure and hyphal collapse. Importantly, application of NCR13_PFV2 to wounded bell pepper fruit significantly reduced lesion development caused by A. alternata in a concentration-dependent manner. Together, these findings demonstrate that NCR13_PFV2 suppresses postharvest fungal infection through a multi-target mechanism that disrupts fungal cellular homeostasis, highlighting its potential as a peptide-based alternative to synthetic fungicides.