After reading this article you will learn about the UV-B radiation and the evolution of Polyphenolics. Solar UV-B radiation is known to stimulate the enzymes phenylalanine amonialyase (PAL) and chalcone synthase (CHS) and other branch-point enzymes of the phenylpropanoid pathway (Fig. 17.3). PAL catalyzes the transformation of phenylalanine into transcinnamic acid, which may eventually lead […]