Effects of Foliar Spraying Salicylic Acid on the Content of Chlorogenic Acid and Expression of Key Enzyme Gene in Solanum tuberosum Leaves

The diploid Solanum tuberosum CIP−65 was used as the test material in this study, and the S. tuberosum leaves were sprayed with 3 different concentrations of salicylic acid(SA) solutions of 0.01, 0.10, and 1.00 mmol/L. Then, the content of chlorogenic acid(CGA) and the expression level of hydroxycinnamoyl CoA quinate hydroxycinnamoyl transferase(HQT) gene were detected by UV spectrophotometry and qRT-PCR. The effects of SA on CGA content and the expression of key enzyme gene in S. tuberosum leaves were analyzed. The results showed that the content of CGA and the expression of HQT gene in S. tuberosum leaves were significantly increased after low concentration of SA(0.01 mmol/L), and the expression of HQT gene was also activated, which was consistent with the change trend of CGA; the expression of HQT and CGA content in S. tuberosum leaves were significantly increased by SA treatment with medium concentration(0.1 mmol/L), but the increase of CGA content was lower than that of 0.01 mmol/L SA treatment; high concentration(0.1 mmol/L) of SA solution promoted the expression of HQT gene, but the content of CGA was not significantly different from that before treatment. In conclusion, SA treatment with lower concentration could promote the expression of HQT gene and the accumulation of CGA in S. tuberosum leaves.