Effects of salicylic acid on acteoside accumulation and gene expression in tuberous roots of Rehmannia glutinosa Libosch.

The Rehmannia glutinosa ‘Wen 85-5’ cultivar was used to analyze the effects of spraying salicylic acid (SA) on the leaf surface on acteoside content and molecular regulation characteristics. The plants were grown for 180 days, then sprayed with SA (100 μmol/L). The leaves and tuberous roots of R. glutinosa were collected at 0, 1, 3, and 6 h after treatment to determine the content of acteoside. Transcriptome sequencing of the tuberous roots at different times after SA treatment was also performed. Results showed that, compared with the controls, acteoside content in the leaves and tuberous roots increased by 11.2% - 19.3%, and 0.9 - 1.4 times, respectively, after SA treatment. Transcriptome analysis showed that most differentially expressed genes (DEGs) were obtained 3 h after SA treatment, with more down-regulated genes than up-regulated genes. Most DEGs were significantly enriched in the phenylpropanoid biosynthesis pathway, while several catalytic enzyme genes of the acteoside synthesis pathway, such as ALDH, UGT, and PPO, were up-regulated in the tuberous roots. Many AP2-EREBP, WRKY, and MYB transcription factor genes were differentially expressed after SA treatment. This study provides theoretical support for the use of elicitors to treat R. glutinosa plants in the field to increase acteoside content.