Up‐regulated 2‐alkenal reductase expression improves low‐nitrogen tolerance in maize by alleviating oxidative stress

Abstract In plants, cellular lipid peroxidation is enhanced under low nitrogen (LN) stress; this increases the lipid‐derived reactive carbonyl species (RCS) levels. The cellular toxicity of RCS can be reduced by various RCS‐scavenging enzymes. However, the roles of these enzymes in alleviating oxidative stress and improving nutrient use efficiency (NUE) under nutrient stress remain unknown. Here, we overexpressed maize endogenous NADPH‐dependent 2‐alkenal reductase ( ZmAER ) in maize; it significantly increased the tolerance of transgenic plants (OX‐AER) to LN stress. Under LN condition, the biomass, nitrogen accumulation, NUE, and leaf photosynthesis of the OX‐AER plants were significantly higher than those of the wild‐type (WT) plants. The leaf and root malondialdehyde and H 2 O 2 levels in the transgenic plants were significantly lower than those in WT. The expression of antioxidant enzyme‐related genes ZmCAT3 , ZmPOD5 and ZmPOD13 was significantly higher in the transgenic lines than in WT. Under LN stress, the nitrate reductase activity in the OX‐AER leaves was significantly increased compared with that in the WT leaves. Furthermore, under LN stress, ZmNRT1.1 and ZmNRT2.5 expression was upregulated in the OX‐AER plants compared with that in WT. Overall, up‐regulated ZmAER expression could enhance maize's tolerance to LN stress by alleviating oxidative stress and improve NUE.