Eliciting increased flavonoids content in Ginkgo biloba leaves through exogenous salicylic acid and methyl jasmonate treatments

Abstract

Prior to Ginkgo leaf harvest, we implemented four exogenous applications of salicylic acid (SA: 50, 80, and 100 mg·L−1) or methyl jasmonate (MJ: 20, 40, and 80 mg·L−1) as leaf spray to investigate their effect on flavonoids content and related enzyme activity. Compared with the control, a significant increase of 12% and 26% in flavonoid content was observed 7 days after the first application of 100 mg·L−1 SA and 20 mg·L−1 MJ, respectively; both were determined to be the best treatments. Operationally, administering either elicitor (SA or MJ) 1 week prior to leaf harvest is deemed to be the most practical and economic option. Additionally, enzymes activity involved in flavonoid metabolism (phenylalanine ammonia-lyase, cinnamate 4-hydroxylase, and 4-coumarate:coenzyme A ligase) and antioxidants (peroxidase, superoxide dismutase, and catalase) significantly increased in most SA and MJ treatments. The results strongly support Ginkgo leaf response to SA- or MJ-induced stress through increased nonenzymatic antioxidant compounds (flavonoids) and activity of antioxidant enzymes.