Expression and Regulation of flavonol synthases from maize.

MA LORENA FALCONE FERREYRA; JULIA I. QÜESTA; MA. ISABEL CASAS; AL HERRERA; ERICH GROTEWOLD; PAULA CASATI

Congreso; XLVII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2011

Flavonoids are specialized compounds widely distributed throughout the plant kingdom with diverse functions in plants and benefits for human health. In particular, flavonols, synthesized by flavonol synthase (FLS), protect plants against UV-B radiation and are essential for male fertility in maize. We have recently characterized a UV-B inducible ZmFLS1 which was the first enzyme to be described in monocot plants. Interestingly, the new assembly of the B73 genome revealed the presence of a second putative FLS gene (ZmFLS2) with extremely high similarity both at the nucleotide and amino acid level. Expression analysis showed that both genes are UV-B regulated in inbred lines and high altitude landraces. By combining EMSA assays and transient expression experiments, we were able to show that both genes are direct targets of the transcription factors P1, C1 and R involved in flavonoid biosynthesis regulation. Moreover, the high sequence conservation of the ZmFLS promoters between maize lines would indicate that the differences observed in ZmFLS expression could be explained by allelic variations in the transcription factor activities. Finally, the presence of two FLS genes in maize and sorghum, and one in rice and Brachypodium, in addition to the evolutionary distances across the grasses suggest that duplication of the FLS gene occurred early in evolution.