CHARACTERIZATION OF A MAIZE FLAVONE SYNTHASE II

SILVANA RIGHINI ARAMBURU; PAULA CASATI; MA. LORENA FALCONE FERREYRA

Congreso; Reunión Conjunta de Sociedades de Biociencias; 2017

Flavones, a subtype of flavonoid, are widespread among the higher plants and have diverse physiological functions. There are two classes of flavone synthase (FNS) enzymes that catalyze the conversion of flavanones into flavones. The flavone synthase II comprises oxygen- and NADPH-dependent cytochrome P450 membrane-bound monooxygenases. We identified a gene encoding a putative FNSII in maize named ZmCYP93G7. In order to examine whether this enzyme participates in flavone biosynthesis, we cloned the open reading frame in a yeast expression vector, transformed the WATT11 yeast strain and cultures of transformed yeast cells were fed with the flavanones substrates. LC-MS/MS analyses showed that ZmCYP93G7 is able to catalyze the conversion of flavanones (naringenin and eriodictyol) into the corresponding flavones (apigenin and luteolin, respectively). The coding sequence was expressed from the constitutive 35S promoter in Arabidopsis plants. Total flavonoid extracts of Arabidopsis transgenic plants expressing ZmCYP93G7 in dmr6 mutant background (lacking a FNSI enzyme) analyzed by LC-MS showed apigenin accumulation demonstrating FNS functionality in planta. Moreover, when transgenic Arabidopsis lines (35Spro::ZmCYP93G7) were infected with the pathogen Pseudomonas syringae, we found that maize CYP93G7 restores pathogen susceptibility compared to dmr6 mutant plants (p