Nitric oxide, as a small active particle, is involved in many physiological activities of animals and plants. In protein posttranslational modifications, NO is mainly in the form of (NO)-based S-nitrosylation. Methylation, as another protein transcription modification, also has an important role in DNA damage and mRNA translation. Although these two areas have many published articles in recent years, there are few reports of the interaction between the two approaches. Recently, Chinese scientists have found that NO can positively regulate the activity of PRMT5, an enzyme that catalyzes Arg symmetric demethylation, through S-nitrosylation at Cys-125. The Arabidopsis prmt5-1 mutant shows severe deve- lopmental defects and hypersensitivity in stress responses. A PRMT5^C125S transgene with non-nitrosylatable mutation at Cys-125 in a prmt5-1 background shows recovered developmental defects but not the stress responses. Furthermore, S-nitrosylation at Cys-125 of PRMT5 was found involved in regulating Arg symmetric demethylation induced by NaCl. The study led to a new direction of protein S-nitrosylation and protein methylation modification, which opened up new research fields and set a new example for research in this field.