Cloning and characterization of a glucosyltransferase from <it>Crocus sativus </it>stigmas involved in flavonoid glucosylation

• Main Authors: Ahrazem Oussama, Mozos Almudena, Moraga Ángela, Gómez-Gómez Lourdes
• Format: Article
• Language: English
• Published: BMC 2009-08-01
• Series: BMC Plant Biology
• Online Access: http://www.biomedcentral.com/1471-2229/9/109

<p>Abstract</p> <p>Background</p> <p>Flavonol glucosides constitute the second group of secondary metabolites that accumulate in <it>Crocus sativus </it>stigmas. To date there are no reports of functionally characterized flavonoid glucosyltransferases in <it>C. sativus</it>, despite the importance of these compounds as antioxidant agents. Moreover, their bitter taste makes them excellent candidates for consideration as potential organoleptic agents of saffron spice, the dry stigmas of <it>C. sativus</it>.</p> <p>Results</p> <p>Using degenerate primers designed to match the plant secondary product glucosyltransferase (PSPG) box we cloned a full length cDNA encoding CsGT45 from <it>C. sativus </it>stigmas. This protein showed homology with flavonoid glucosyltransferases. <it>In vitro </it>reactions showed that CsGT45 catalyses the transfer of glucose from UDP_glucose to kaempferol and quercetin. Kaempferol is the unique flavonol present in <it>C. sativus </it>stigmas and the levels of its glucosides changed during stigma development, and these changes, are correlated with the expression levels of CsGT45 during these developmental stages.</p> <p>Conclusion</p> <p>Findings presented here suggest that CsGT45 is an active enzyme that plays a role in the formation of flavonoid glucosides in <it>C. sativus</it>.</p>