Evaluation of the variations in secondary metabolite concentrations of leymus chinensis seedlings

Abstract

Limited information is available about how mammalian browsing activity influences the dynamic defense mechanisms of plants. Here, we aimed to clarify the response mechanism of a herbaceous plant (Chinese lyme grass, Leymus chinensis) to browsing by a mammalian herbivore (Brandt's vole, Lasiopodomy brandtii). We used high-performance liquid chromatography and spectrophotometry to investigate changes in the concentrations of 6-MBOA, total phenol and condensed tannin in Chinese lyme grass seedlings with respect to its ontogeny and different types of damage treatments. 6-MBOA concentrations were higher on day 7 and day 8 than on days 12 and 17 after seedling germination. The concentrations of total phenol and condensed tannin were higher on day 12 than on days 7 and 8 after seedling germination. Compared to the control, higher 6-MBOA concentrations were obtained in the salivation, gnawing and artificial cutting treatment groups. The response of 6-MBOA was delayed in the artificial cutting group compared to the salivation and gnawing groups. In contrast, the concentrations of total phenol and condensed tannin were higher in the artificial cutting and control groups compared to the salivation and gnawing groups. 6-MBOA concentration was negatively correlated with total phenol concentration. The results indicated that 6-MBOA concentration decreased with seedling ontogeny, and that it could be induced by Brandt's vole saliva. In conclusion, our study verified the hypothesis that the browsing by Brandt's vole induces the dynamic defenses of L. chinensis.