Nitric oxide (NO) regulates several biological and physiological processes in plants. This study investigated the role ofArabidopsis thaliana Negative Immune and Growth Regulator 1(AtNIGR1), encoding an NAD(P)-binding Rossmann-fold superfamily, in the growth and immunity ofArabidopsis thaliana.AtNIGR1was pooled from the CySNO transcriptome as a NO-responsive gene. Seeds of the knockout (atnigr1) and overexpression plants were evaluated for their response to oxidative [(hydrogen peroxide (H2O2) and methyl viologen (MV)] or nitro-oxidative [(S-nitroso-L-cysteine (CySNO) and S-nitroso glutathione (GSNO)] stress. Results showed that the root and shoot growth ofatnigr1(KO) andAtNIGR1(OE) exhibited differential phenotypic responses under oxidative and nitro-oxidative stress and normal growth conditions. To investigate the role of the target gene in plant immunity, the biotrophic bacterial pathogenPseudomonas syringaepv.tomatoDC3000 virulent (PstDC3000vir) was used to assess the basal defense, while thePstDC3000 avirulent (avrB) strain was used to investigateR-gene-mediated resistance and systemic acquired resistance (SAR). Data revealed thatAtNIGR1negatively regulated basal defense,R-gene-mediated resistance, and SAR. Furthermore, theArabidopsiseFP browser indicated that the expression ofAtNIGR1is detected in several plant organs, with the highest expression observed in germinating seeds. All results put together suggest thatAtNIGR1could be involved in plant growth, as well as basal defense and SAR, in response to bacterial pathogens inArabidopsis.