Enzymatic Suppression of Postharvest Fungi in Tomato Fruits: In-vitro and In-silico Evidence of Chitinase and β-1,3-Glucanase Efficacy

Abstract

Spoiled tomato fruits exhibited fungal infections, and the isolates were identified as Penicillium expansum, Alternaria alternata, Aspergillus terreus, and Fusarium oxysporum. Varying doses of chitinase, β-1,3-glucanase, and a chemical fungicide were tested against four fungal pathogens. All treatments showed dose-dependent inhibition of fungal growth. The chemical fungicide caused complete inhibition at the highest dose, while chitinase and β-1,3-glucanase significantly reduced colony size, especially in P. expansum and A. alternata, though they were less effective against A. terreus and F. oxysporum. This study rigorously investigated the molecular docking interactions of chitinase (PDB ID: 1CTN) and β-1,3-glucanase (PDB ID: 4M80), with target proteins of F. oxysporum (PDB ID: 7T69). Molecular simulations revealed compelling binding affinities, with chitinase demonstrating a docking score of -82.67 kcal/mol and β-1,3-glucanase exhibiting a score of -78.1 kcal/mol. Detailed interaction analyses revealed distinct binding mechanisms: Chitinase forms a stable complex through multiple hydrogen bonds and significant π-π stacking with key residues such as TRP210, while β-1,3-glucanase employs extensive hydrogen bonding and strong ionic interactions, notably with GLU121, for electrostatic stabilization. These findings provide critical molecular insights into the antifungal capabilities of these enzymes, highlighting their potential as agents to combat postharvest fungal pathogens.