Chemometric analysis of the secondary metabolite profile of Yarrow (Achillea collina Becker ex Rchb.) affected by phloem feeding Myzus persicae Sulzer aphids

Yarrow (Achillea collina Becker ex Rchb.) has a high content of secondary metabolites including phenolic acids. Among them, hydroxycinnamic acid such as chlorogenic acid and its derivatives were found to be the most abundant ones. The phloem feeding Myzus persicae Sulzer was hypothesized to affect the contents of secondary metabolites and change the metabolite profile. A high-performance liquid chromatography technique (HPLC) was used to evaluate whether there is a difference in the phenolic profile between aphid infested and non-infested yarrow leaves. M. persicae colonies composed of between 20 and 30 individuals were allowed to feed for 10 and 20 days. Preprocessing was carried out to standardize the procedures in order to obtain optimal separation of analytes, good chromatographic peak shape and robustness of the results. The methanol extracts of leaves were analyzed by means of HPLC, and the time series of peak areas obtained from each extract were evaluated through chemometric analyses. Results of the phenolic fingerprints showed a specific chromatographic profile with 58 peaks. An autoregression analysis demonstrated the absence of correlation. The discriminant analysis carried out with the data satisfying the assumption of the absence of collinearity showed a significant effect of phloem feeding on soluble phenolic compounds and identified two peaks that separate aphid infested from non-infested plants. The hydroxycinnamic acids widely found in A. collina leaves were not affected by M. persicae feeding. The results are the basis for the current studies aiming at the identification of chemical compounds that correspond to the peaks.