Tomato SlNTRB improved excess nitrate stress tolerance by alleviating the oxidative damage in transgenic tobacco

NADPH-dependent thioredoxin reductase (NTR), which is a flavin protein family of disulfide oxidoreductases present in all living cells, reduces thioredoxin (Trx). The roles of NTR B under stress conditions have not been well characterized. In this study, a tomato NTR B (SlNTRB) gene was cloned and functionally characterized. The mRNA transcript level of SlNTRB was induced significantly after nitrate treatment. The seed germination rate of SlNTRB overexpressed transgenic tobacco was higher than wild type (WT) under nitrate stress. The growth of SlNTRB overexpressed plants was better than WT and the reactive oxygen species (ROS) accumulation were lower than WT under nitrate stress. The NTR activity, superoxide dismutase (SOD) activity, the GSH/GSSG ratio, and the expression of Trx were significantly higher than WT after nitrate stress treatment. The SlNTRB overexpressed transgenic tobacco seeds showed higher tolerance to H₂O₂ and methyl viologen (MV) treatments than WT. The above results indicated that the SlNTRB gene improved the plant nitrate stress tolerance by alleviating the oxidative damage.