CHARACTERIZATION OF AN UDP-GLYCOSYLTRANSFERASE INVOLVED IN FLAVONOID GLYCOSIDES BIOSYNTHESIS IN MAIZE

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

Congreso; Congreso SAIB 2022; 2022

Flavonoids are specialized metabolites widely distributed in plants with diverse biological functions. Inaddition, these compounds have benefits for human health. Flavonoids are accumulated in the vacuolesas O-glycosylated derivatives; however, several species including cereals synthesize flavonoid Cglycosides.The aim of this work is to characterize a maize UDP-glycosyltransferase (ZmUGT2), which maybe involved in the biosynthesis of flavonoid glycosides. First, by phylogenetic analysis of plant UGTs thataccept flavonoid as substrates, we determined that ZmUGT2 clustered with UGTs that add sugars on 5-hydroxyl group, suggesting that this enzyme may have this specificity. We then cloned the codingsequence and expressed the protein E. coli to perform in vivo and in vitro enzymatic activity assays. Theanalysis of the products formed by HPLC showed glycosylation of flavonols, flavanones and flavoneswhen tested as substrates. In order to investigate its function in planta, we generated Arabidopsisthaliana transgenic plants expressing ZmUGT2 (p35S:ZmUGT2 ). Under anthocyanin-inducing conditions,the transgenic plants showed higher levels of these compounds than wild type plants. We also studiedthe effect of UV-B radiation over the elongation of the primary root in transgenic and wild type plants.Although both genotypes showed a decrease in primary root elongation after UV-B treatment (along fourdays) compared the plants under control conditions (no UV-B), the transgenic plants showed lessinhibition of the primary root elongation in comparison with wild type plants. We are purifying ZmUGT2recombinant protein to determine its kinetic parameters for the different flavonoids as substrates. Wealso plan to analyze by LC-MS how the flavonoid glycoside accumulation patterns are altered in ZmUGT2transgenic roots with respect to WT plants and also to deepen on the studies about UV-B radiationtolerance in these transgenic plants.