A novel elicitor confers apple resistance to Glomerella cingulata through modulation of flavonoid metabolic pathways

Abstract BACKGROUND Apple is a globally vital economic crop severely damaged by Glomerella leaf spot (GLS) caused by Glomerella cingulata . Current disease management relies heavily on chemical fungicides, but long‐term intensive application has triggered pathogen resistance, weakened control efficacy, aggravated pesticide residues and environmental contamination, and severely restricted the sustainable development of the apple industry. This study systematically investigated the disease resistance‐inducing potential of 3,6‐bis(1‐methylpropyl)‐2,5‐piperazinedione (BMP), a functional metabolite from plant endophytes. RESULTS BMP induced strong resistance against G. cingulata in detached apple leaves. Exogenous application of 0.1 μg mL −1 BMP reduced leaf lesion counts by 58.46% at the early GLS stage, persistently alleviated fruit disease severity and simultaneously promoted seedling root development and biomass accumulation. It functions by enhancing core defense enzyme activities and defense‐related gene expression, boosting flavonoid synthesis via down‐regulating MdMYB16 and establishing a multi‐layered defense system. CONCLUSION This work provides a novel strategy for apple disease management. It can reduce pesticide use, lower environmental impact, and improve fruit quality and safety, which fits the development concept of green agriculture and holds favorable application prospects. © 2026 Society of Chemical Industry.