UV-B regulation of maize ZmFLS1 and ZmFNS enzymes

JULIA EMILIANI; MA. LORENA FALCONE FERREYRA; ERICH GROTEWOLD; PAULA CASATI

Tucumán

Congreso; XLV Reunión Annual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB).; 2009

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Flavonoids are a highly diverse class of secondary plant metabolites found in vascular plants. These compounds have a significant impact in plant biology and benefits for human health. One group of these, the flavones, is synthesized from flavanones by the enzyme flavone synthase (FNS). Other flavonoids, the flavonols, are synthesized from the dihydroflavonols by the action of flavonol synthase (FLS). Here, we investigated the regulation of ZmFLS1 and a putative ZmFNS by UV-B radiation in five maize landraces from high altitudes and in the low altitude lines B73 and W23. ZmFLS1 and ZmFNS are induced by UV-B in most lines, demonstrating that these genes are under UV-B control. To relate the induction of ZmFLS1 and ZmFNS by UV-B with its regulation by the P1 or C1/PL+R/B flavonoid regulators, we investigated whether the expression of these transcription factors is also UV-B regulated. UV-B significantly increases P1 transcripts in all lines, being almost undetectable under the control conditions.  In the absence of UV-B, B and PL1 are expressed at variable levels in the different lines. After UV-B exposure for 8h, B and PL1 showed an increase in their expression in most lines. Thus, in response to UV-B, the up-regulation of ZmFLS1 and ZmFNS is possibly mediated by P1 and PL1+B, which are also induced by UV-B.