POLYPHENOLIC COMPOUNDS IN ARTICHOKE CULTIVARS AND REGULATION OF THEIR SYNTHESIS IN ARTICHOKE

Abstract

The presence of health promoting compounds in artichoke, such as polyphenols, is frequently a matter of study. Particularly mono- and di-caffeoylquinic acids (e.g., chlorogenic acid, cynarin), caffeic acid and flavonoids (e.g., luteolin-7-O-glucoside, naringerin) contribute to artichoke nutraceutical qualities. A combination of genetic and biochemical analyses was used to help identify genes involved in the accumulation of polyphenols and to characterize different artichoke varietal types diffused in the Mediterranean region by polyphenolic content. Six traditionally cultivated cultivars of artichoke (‘Mola’, ‘Tondo di Paestum’, ‘Sant’Erasmo’, ‘Bianco di Ostuni’, ‘Blanca de Tudela’ and ‘Violet de Provence’) were selected, and qualitative and quantitative evaluations of phenolic profile were carried out on different artichoke tissues (three bract orders and receptacle of flower heads and leaves) in several developmental stages, by HPLC and mass spectrometry analyses. To gain insight into the mechanisms which regulate polyphenol synthesis, in silico analysis of promoter regions of genes involved in the biosynthesis of chlorogenic acid were performed. These analyses led us to detected different binding sites recognized by MYB transcription factors (TF), suggesting that, as in other plant species, this class of TF might be involved in the regulation of these artichoke genes. Two putative artichoke MYB TF genes were isolated, starting from sequences of the ortholog MYB12 from other species (e.g., Arabidopsis, tomato) used to screen artichoke EST database.