Curcumin: An innovative approach for postharvest control of Alternaria alternata induced black rot in cherry tomatoes

Curcumin, a natural bioactive compound derived from Curcuma longa, has been widely recognized for its antifungal properties. In this study, we investigated the effects of curcumin on the phytopathogenic fungus Alternaria alternata and its pathogenicity in cherry tomato fruit. The results demonstrated that curcumin treatment significantly inhibited mycelial growth and spore germination of A. alternata in a dose-dependent manner. Scanning electron microscopy revealed alterations in the morphology of A. alternata mycelia treated with curcumin. Furthermore, curcumin treatment led to an increase in malondialdehyde and hydrogen peroxide contents, indicating cell membrane damage in A. alternata. Moreover, curcumin exhibited a remarkable inhibitory effect on the incidence and lesion diameters of black rot caused by A. alternata in cherry tomato fruit. Gene expression analysis revealed upregulation of defense-related genes (POD, SOD, and CAT) in tomato fruit treated with curcumin. Additionally, curcumin treatment resulted in decreased activity of exocellular pathogenic enzymes (polygalacturonase, pectin lyase, and endo-1,4-β-d-glucanase) in A. alternata. Overall, our findings highlight the potential of curcumin as an effective antifungal agent against A. alternata, providing insights into its inhibitory mechanisms on mycelial growth, spore germination, and pathogenicity in cherry tomato fruit.