Antioxidant enzyme reprogramming, ROS scavenging, and modulations in secondary metabolites attenuate immunity in rice against <i>Helminthosporium oryzae</i> attack

In agricultural ecosystems, plant pathogens cause devastating diseases that jeopardize global food security.This study examined the physiological and biochemical mechanisms of resistance in four rice lines and one variety against Helminthosporium oryzae.A completely randomized design experiment revealed significant shoot length reduction due to fungal toxicity, with Kharamana and Sakh showing the least damage (8.3 and 14.76%, respectively), while Binicol suffered the most.Kharamana maintained the highest chlorophyll-a levels indicating post-infection superior tolerance.Antioxidant assays showed increased superoxide dismutase (SOD) activity in Kharamana (56.19%) and Sakh (46.98%), while Binicol exhibited minimal peroxidase (POD) activity.Binicol's ascorbic acid levels dropped by 68.1%, making it highly susceptible.Secondary metabolites, including flavonoids, anthocyanins, and lignin, were significantly altered (p < 0.05), influencing resistance.Vulnerability of Binicol was due to lower metabolite levels, whereas Kharamana and Sakh exhibited reprogrammed antioxidant responses, effectively mitigating Helminthosporium oryzae effects.This comparative analysis identifies key metabolic pathways for breeding diseaseresistant rice, contributing to sustainable agriculture and improved crop management.Identification of these metabolic pathways can contribute to more sustainable and resilient agricultural practices.Additionally, these findings can be extended to rice immunity to other disease for better crop management and advancing crop production.K e y w o r d s: brown leaf spot, enzymes, Helminthosporium, immunity, oxidative stress, plants, secondary metabolites Ta b l e 1. List of rice lines and their associated codes used for the experiment (Akbar et al., 2023)