Copper-based nanoformulation stimulates host defense response in maize against Bipolaris maydis

Maydis leaf blight (MLB) is a dreadful disease caused by Bipolaris maydis, rendering a loss of up to 70%. Conventional fungicides have significant drawbacks, prompting a pressing demand for alternative approaches to disease management. Nanotechnology offers sustainable solutions for plant disease management, providing precision targeting, enhanced efficacy, reduced environmental impact, and improved plant immunity. In the present investigation, B. maydis was identified using morpho-molecular approaches. In vitro efficacy evaluation of copper-based nanoformulations called essential oil-grafted copper nanoparticles (EGC) resulted in a significant reduction in radial growth of B. maydis at concentrations above 20 µg ml⁻¹, and at 120 µg ml⁻¹, complete inhibition was observed. The pathogenesis-related (PR) protein genes viz., β-1, 3-glucanases, PR-1, and Chitinase2 at 250 µg ml⁻¹ of EGC application were significantly up-regulated, suggesting that EGC can act as abiogenic elicitors, reducing the percent disease index (PDI). In addition, detached leaf inoculation assay confirmed that loss of melanin in B. maydis treated with EGC rendered loss of virulence. Our study demonstrates the significant potential and promise of EGC through its antifungal properties and ability to activate plant defense, contributing to sustainable disease management practices.