Biochemical Defences Approaches Against Purple Blotch (Alternaria porri): Resistance in Onion Varieties

Purple blotch (Alternaria porri) cause disease in onions and reduce the yields (30-70% losses) through foliar damage, wilt and reduce the size of onion bulb. Resistant varieties over the susceptibles varities having high amounts of defence compounds like phenols, flavonoids and tannins, defense enzymes such as PAL, PO, PPO, SOD and catalase, inhibiting spore germination, fungal growth and oxidative stress while reinforcing cell walls. To understand the biochemical defence of the onion against the disease and approach ecofriendly and suitable management practices. These biochemical approaches need in onion varieties against fungicide Consequently, the farmer will require less spraying with fungicides to manage purple blotch. Breeders can target these traits for sustainable cultivars, empowering farmers with resilient, profitable, eco-friendly onion production in disease-prone tropics.