Characterization of a maize UDP-glucosyltransferase involved in flavonoid biosynthesis

JULIETA PETRICH; PAULA CASATI; ERICH GROTEWOLD; FALCONE FERREYRA, MARÍA LORENA

Congreso; LVIV Reunión Anual de SAIB; 2023

Flavonoids are specialized metabolites widely distributed in plants. These compounds not only havephysiological functions during growth and development, but also have protective roles against biotic andabiotic stressful conditions, such as pathogen infections, UV B radiation, high white light, drought, cold andsalinity. One important step in the flavonoids biosynthesis is their glycosylation, which enhances the stabilityand solubility of these compounds. As a result, plants typically accumulate flavonoids as C- and O- mono or diglycosylated derivatives. Maize is a major crop used for human and animal consumption, however, someenzymes involved in the flavonoid biosynthetic pathway has not been elucidated. Our aim is to functionallycharacterize a novel UDP-sugar glycosyltransferase, named ZmUGT2, which catalyzes the O-glucosylation offlavonoids in maize plants. Previous studies showed that ZmUGT2 expression is induced by Pericarp Color1, thetranscription factor involved in the regulation of flavonoid biosynthesis. Phylogenetic analysis suggests thatZmUGT2 belongs to family 1 glycosyltransferases, which includes other UGTs involved in flavonoid Oglycosylation. Here, the recombinant protein ZmUGT2 was purified and kinetically characterized. HPLC and LCMS analysis showed that ZmUGT2 is able to accept different flavonoids as substrate acceptors (flavanones,flavone and flavonols), and notably, both mono and di-glucoside derivatives are formed. To analyze ZmUGT2functionality in planta, we generated Arabidopsis transgenic plants expressing ZmUGT2 from the 35S promoterin background WT and mutant in genes encoding enzymes of flavonoid biosynthesis. Now, we are evaluatingthe accumulation pattern profiles of glycosylated flavonoids in transgenic plants in comparison to WT indifferent plant tissues and growth conditions.