Characterization of two maize flavone synthases class II from maize

SILVANA RIGHINI ARAMBURU; JULIA EMILIANI; EDUARDO JOSE RODRIGUEZ; PAULA CASATI, MA. LORENA FALCONE FERREYRA

Mar del Plata

Congreso; LI Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2015

Flavones are found extensively in plants and have diverse physiological functions. There are two classes of flavone synthase (FNS) enzymes that catalyze the conversion of flavanones into flavones. The FNS class II comprises oxygen- and NADPH-dependent cytochrome P450 membrane-bound monooxygenases. We identified two genes encoding putative FNSIIs in maize named ZmCYP93G6 (G6) and ZmCYP93G7 (G7). Relative expression was assessed in different maize tissues. G6 showed higher relative expression levels than G7 in roots, hypocotyls and radicles, while G7 transcripts were predominant in pericarps, silks and anthers. To examine whether these enzymes could participate in flavone biosynthesis, we cloned the open reading frames in a yeast expression vector, transformed the WAT11 yeast strain and cultures of transformed yeast cells were fed with the flavanones substrates. LC-MS/MS analyses showed that yeast expressing G6 or G7 accumulated the corresponding flavones. Interestingly, the analysis did not detect 2-hydroxinaringenin as an intermediate product, indicating that the reaction mechanism is not similar to that of flavanone 2-hydroxilases. Moreover, so as to determine their activities in planta, we generated Arabidopsis transgenic plants expressing G6 or G7 and the levels of flavones accumulated will be analyzed by HPLC. Together, our results provide evidence that G6 and G7 are FNSII enzymes.