An imbalance between ROS production and scavenging during stress results in oxidative bursts, which causes cellular damage. miR398 is a regulator of ROS scavenging since it targets crucial Cu/Zn superoxide dismutases (CSDs). Established functional studies aligned miR398 with plants' heat and heavy metal stress fitness. However, a knowledge gap in the dynamics of miR398-CSD interaction for redox regulation during pathogenic development impeded their use in crop improvement programmes. We use tomato, Solanum lycopersicum, plants, and necrotrophic and biotrophic pathogens to show that a complex transcriptional and post-transcriptional regulatory circuit maintains SlmiR398 and its target SlCSD genes' level. The interaction is indispensable for ROS regulation in either the pathogenic outcome, thermal stress, or a combination of both stresses, as observed in the cultivation field. The SlmiR398 knockout plants display feeble O2