In this study, both ABA and NO seemed to participate in SA03-induced saline–alkaline tolerance of plants. This raised the question how ABA interacted with NO to regulate the adaptive responses of SA03-inoculated plants to saline–alkaline stress. Since ABA has been shown to regulate the NO accumulation in plants under salt stress (Zhang et al., 2009), we wondered if SA03-induced a great increase of ABA resulted in promoting NO biosynthesis. Indeed, we found that cellular NO levels were markedly higher in the inoculated roots compared with the non-inoculated plants under non-stress condition. Moreover, saline–alkaline treatment strikingly enhanced the NO biosynthesis in plants, whereas the inoculated plants accumulated more NO than the non-inoculated plants. Intriguingly, FLU exposure did not remarkably affect endogenous NO content in the inoculated plants under non-stress condition, whereas a marked decrease of NO levels was observed in the FLU-treated inoculated plants under the stress compared with the untreated inoculated plants (Supplementary Figure S2).