Biological Mechanism of NO to Enhance the Quality of Radix et Caulis Acanthopanacis Senticosi

Reactive oxygen species (ROS) is an inevitable product of ecological stress, and can regulate secondary metabolism and increase secondary metabolites. The secondary metabolites, usually medicinal ingredients, in turn, eliminate ROS and reduce plant damage, and improve the adaptability of plants to unsuitable environments. Normally, nitric oxide (NO) acts upstream of ROS production and is less harmful to plants. This paper used sodium nitroprusside (SNP) of 0, 0.2, and 1.0 mmol/L as a source of NO contributor, which was sprayed on fresh stems of Acanthopanax senticosus (Rupr. & Maxim.) Harms. As a result, $${\text{O}}_{2}^{{\bullet - }}$$ , H2O2, and malondialdehyde (MDA) significantly increased, indicating a physiological state under ecological stress. The antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) were increased by 57.2, 70.0, and 67.4%. Enzymes involved in the secondary metabolites biosynthesis, such as phenylalanine ammonia-lyase (PAL), 4-coumarate coenzyme A ligase (4CL) and hydroxylated cinnamoyl transferase (HQT) showed an increase of 83.5, 60.0, and 38.6% resulting in an increase in secondary metabolites in A. senticosus, eleutheroside B increasing by 71.2%, eleutheroside E by 36.6%, isofraxidin by 137.0%, and chlorogenic acid by 63.0%. The 1,3-diphosphoglycerate (1,3-DPG) and the phosphoenolpyruvate carboxylase (PEPC) was increased by 84.5 and 46.2%, indicating that the increased secondary metabolites was mainly produced from sugars. In conclusion, SNP can construct a physiological state resembling ecological stress, and significantly improve the quality of Acanthopanacis Senticosi (AS).