T42 induces local defense against pv. under nitrate and ammonium nutrients in tobacco.

has been explored and found to play a vital role in the defense mechanism of plants. However, its effects on host disease management in the presence of N nutrients remains elusive. The present study aimed to assess the latent effects of T42 on oxidative burst-mediated defense mechanisms against pv. () in tobacco plants fed 10 mM NO and 3 mM NH nutrients. The nitrate-fed tobacco plants displayed an increased HR when infected, which was enhanced in the -treated plants. This mechanism was enhanced by the involvement of , which elicited NO production and enhanced the expression pattern of NO-modulating genes (, and ). The real-time NO fluorescence intensity was alleviated in the NH -fed tobacco plants compared to that fed NO nutrient, suggesting the significant role of -elicited NO. The nitrite content and NR activity demonstration further confirmed that nitrate metabolism led to NO generation. The production of ROS (HO) in the plant leaves well-corroborated that the disease resistance was mediated through the oxidative burst mechanism. Nitrate application resulted in greater ROS production compared to NH nutrient after infection at 12 h post-infection (hpi). Additionally, the mechanism of enhanced plant defense under NO and NH nutrients mediated by involved NO, ROS production and induction of and antioxidant enzyme transcription level. Moreover, the use of sodium nitroprusside (100 μM) with suspension in the leaves matched the disease resistance mediated NO burst. Altogether, this study provides novel insights into the fundamental mechanism behind the role of in the activation of plant defense against non-host pathogens under N nutrients.