Profiling of Altered Metabolomic States in Bidens pilosa Leaves in Response to Treatment by Methyl Jasmonate and Methyl Salicylate

Abstract

Bidens pilosa (Asteraceae) is an edible medicinal plant with many bioactivities reported to have a health-beneficial role in controling various diseases. Though B. pilosa contain a diverse array of natural products, these are produced in relatively low concentrations. A possible way to enhance secondary metabolite production can be through the use of elicitors. Here, the effects of exogenous treatments with two signal molecules—methyl jasmonate (MeJA) and methyl salicylate (MeSA)—on the metabolomic profiles of B. pilosa leaves were investigated. Plants were treated with 0.5 mM of MeJA or MeSA and harvested at 12 h and 24 h. Metabolites were extracted with methanol and separated on an ultra-high performance liquid chromatography system hyphenated to quadrupole time-of-flight mass spectrometry detection. Data was subjected to multivariate statistical analysis and modeling for annotation of metabolites. Hydroxycinnamic acid (HCA) derivatives, such as caffeoylquinic acids (CQAs), tartaric acid esters (chicoric acid and caftaric acid), chalcones, and flavonoids were identified as differentially regulated. The altered metabolomes in response to MeSA and MeJA overlapped to a certain extent, suggestive of a cross-talk between signaling and metabolic pathway activation. Moreover, the perturbation of isomeric molecules, especially the cis geometrical isomers of HCA derivatives by both treatments, further point to the biological significance of these molecules during physiological responses to stress. The results highlight the possibility of using phytohormones to enhance the accumulation of bioactive secondary metabolites in this plant.

Application of Plant Growth Regulators Modulates the Profile of Chlorogenic Acids in Cultured Bidens pilosa Cells

“…Changes in the metabolome of B. pilosa callus were studied with a high-throughput analytical method: UHPLC-qTOF-MS. Through visual inspection of base peak intensity (BPI) chromatograms (Figure 2A,B), HCA derivatives were a notable group of metabolites in leaf and stem callus as observed previously [5,34]. The HCA derivatives were observed to have minor intensity differences between callus grown on media with various ratios of PGRs as shown in yellow rectangles in Figure 2.…”

“…The CGA composition of methanol extracts from tissues, callus and cell suspensions from B. pilosa was previously profiled by ultra-high-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC-qTOF-MS), using an optimized in-source collision-induced dissociation (ISCID) method capable of discriminating between closely related HCA derivatives of quinic acids, based on MS fragmentation patterns [5,34]. This ISCID approach was shown to efficiently discriminate between positional isomers of CGAs.…”

“…Based on the multivariate statistical analysis, metabolites in B. pilosa callus grown on solid agar media with different ratios of PGRs, were annotated (putatively identified) to MSI-level 2 as described in [5,34] and listed in Table 3. These were annotated based on accurate mass, retention time (Rt) and mass spectrometric (MS) fragmentation patterns.…”

“…The statistical models presented here are principal component analysis (PCA) and hierarchical cluster analysis (HiCA), unsupervised models that assess the overall structure of the data and indicate trends, clusters and similarities between sample groups/experimental treatments [50]. Potential biomarkers of different sample groups were highlighted using orthogonal projection to latent structures discriminant analysis (OPLS-DA S-plots), and only significant biomarkers with correlation, (p(corr)) ≥ 0.5 and covariance, (p1) ≥ 0.05 were annotated [5,34].…”

Plant Responses to Herbivory, Wounding, and Infection

“…The artificial application of these phytohormones (e.g., JA, MeJA, and MeSA) induces SM accumulation. For example, in Bidens pilosa, the application of MeJA and MeSA as resistance elicitors enhances SM biosynthesis (e.g., caffeoylquinic acids, tartaric acid esters, chalcones, and flavonoids) [159]. Economically, SMs are one of the main factors influencing crop quality and yield.…”