Distinctive metabolomic responses of Chlamydomonas reinhardtii to the chemical elicitation by methyl jasmonate and salicylic acid

The microalga-sourced bioactive metabolites are of particular interest related to new product strategy for medicinal, nutritional, cosmetic, and food industries. Conventional approach is to introduce physical stimuli such as pH and luminescence for the algal production. However, considering the specificity and effectiveness, it would be the best way to stimulate secondary metabolism using phytohormones if it works. Accordingly, we examine whether representative plant hormones, methyl jasmonate (MeJA) and salicylic acid (SA) trigger the signal transduction. We explore how it would be mirrored in the primary metabolic network of Chlamydomonas reinhardtii based on untargeted metabolite profiling approach. Global pathway over-representation analysis coupled to multivariate statistics-based variable mapping revealed MeJA provoked massive ranges of primary metabolism but the most profound perturbation was found in central carbon flux and saturated fatty acid metabolism with possible linkage to secondary metabolite production such as alkaloid. In contrast, the Chlamydomonas cells with SA-treatment modified relatively narrow range of metabolism where nitrogen and amino acid metabolism were selectively perturbed with putative responsive activity against reactive oxygen species (ROS). The subsequent examination on the combined application of MeJA and SA enhances unique regulatory modulation (e.g. phytol biosynthesis), and antagonistic effect of each elicitor as well.