Comparative metabolomic profiling of secondary metabolites in different tissues of Euryale ferox and functional characterization of phenylalanine ammonia-lyase

Secondary active substances have been extensively applied in several industrial fields because of their unique biological activities. Euryale ferox Salisb. (Nymphaeaceae), commonly known as prickly waterlily, as an important commercial crop, have a lot of health functions, however, information on secondary metabolites is largely un-available. In our study, 589 secondary active substance were obtained from five tissues of E. ferox by UHPLC-MS/ MS technique, with polyphenols occupying 87%. Among these, leaves accumulated significantly flavonoids with widespread glycosylation, seed shell was abundant in polyphenols, and fruit peel was rich in phenolic acids. Flavonoids ("flavone and flavonol biosynthesis", p < 0.05) were the most variable among the five tissues. Total polyphenols and flavonoids content in five tissues supported the metabolomic findings. Furthermore, the anti-oxidant evaluation demonstrated that the seed shell was excellent antioxidant materials. And finally, in vitro enzyme activity assays and overexpression in Arabidopsis evidenced the remarkable activity of EfPAL4 in the biosynthesis of polyphenols and flavonoids. Our study provides important guideline for the future application of E. ferox in the field of industrial medicine.