The 2NS Chromosomal Translocation Enhances Redox Homeostasis and Mitigates Oxidative Stress during Magnaporthe oryzae Triticum Infection in Wheat

Wheat blast, caused by the hemibiotrophic fungus Magnaporthe oryzae Triticum (MoT), is a destructive disease that poses a severe threat to global wheat production. The 2NS chromosomal translocation, introgressed from Aegilops ventricosa into the Bangladeshi wheat variety BARI Gom 33 (BG33), confers moderate-to-high resistance to MoT under field conditions. Despite its widespread deployment, the molecular mechanisms underlying this 2NS-mediated resistance remain largely unknown. This study aimed to elucidate the physiological and biochemical bases of resistance in BG33, specifically regarding its capacity to counteract infection-induced oxidative stress. Comparative analysis between the resistant variety (BG33) and a susceptible variety (BARI Gom 26, BG26) revealed that BG33 maintained significantly lower accumulation of reactive oxygen species (ROS), including hydrogen peroxide (H₂O₂), and exhibited reduced lipid peroxidation (malondialdehyde, MDA) and lipoxygenase (LOX) activity post-inoculation. BG33 also retained higher photosynthetic pigment integrity (chlorophyll and carotenoids), indicating superior protection against oxidative cellular damage. Crucially, BG33 displayed enhanced constitutive and MoT-induced antioxidant activity; basal levels of catalase (CAT), peroxidase (POD), glutathione peroxidase (GPX), ascorbate peroxidase (APX), glutathione-S-transferase (GST), and proline were 1.3–2.5-fold higher in BG33 than in BG26. Upon MoT infection, BG33 further upregulated enzymatic antioxidants including superoxide dismutase (SOD), CAT, APX, GPX, glutathione reductase, dehydroascorbate reductase, and monodehydroascorbate reductase and proline by 1.2–2.0-fold, establishing a robust state of redox homeostasis that was absent in BG26. These findings establish, for the first time, that the 2NS translocation bolsters MoT resistance by potentiating a multi-tiered antioxidant defense system to mitigate the oxidative burst and preserve cellular function. This study provides a novel mechanistic framework for leveraging antioxidant pathways in the development of more durable and resilient blast-resistant wheat varieties.