Eight artichoke accessions show differences in cynarin content and Cshct and Cshqt gene expression during the growing season

In order to add-value to artichoke production for industry and fresh purposes, different artichoke accessions were evaluated in term of cynarin content (1,3-dicaffeoylquinic acid), a metabolite associated to breakdown fat, bile-stimulating effects, and reduced cholesterol production. During 2011-2012 and 2012-2013 seasons, cynarin, Cshct and Cshqt gene expression were evaluated in artichoke accessions (Cynara scolymus L. Fiori) during vegetative growth and bud yield. Eight artichoke accessions ('Francesa', 'Argentina-CAT4', 'Argentina-CAT5', 'Argentina-CAT32', 'Chilena Llay-Llay', 'Talpiot', 'Sur Temuco-3', 'Green Globe') were vegetative propagated, and cultivated under irrigation at 33°34'S and 70°38'W. Leaves and bud samples were collected in a completely randomized design, with 4 replications by accession and time course point since fall to spring for further analysis. Cynarin quantification was done by HPLC system (a quaternary pump Jasco PU-2089 PLUS with a vacuum degasser, multiple wavelength Jasco UV-2075 detector, interface modulated LC-NetII/ADC); in bud (inner bracts, outer bracts, and heart) during spring (September and October), and in leaves during fall (April and May) and also in spring (September and October). The expression of genes encoding hydroxycinnamoyl-transferase (Cshct) and hydroxycinnamoyl CoA quinate transferase (Cshqt) was also evaluated by quantitative polymerase chain reactions (qRT-PCR) in a LightCycler®96 Real-Time PCR System (Roche, Germany), using FastStart Essential DNA Green Master (Roche, Germany). All qRT-PCR data were the average of three independent biological pool samples and three technical replicates. Significant differences were observed in cynarin in leaves, among accessions and growing season (p<0.0001), leaves collected in October (spring) showed higher cynarin concentration (42.06 µg cynarin g-1 DW). In bud, the higher cynarin content was observed in 'Argentina-CAT4' accession, while bud analysis show that outer bracts have higher concentration of this metabolite (p<0.0001) with values between 9.7 to 17.9 µg cynarin g-1 DW. In relation with Cshct and Cshqt gene expression, higher hct gene expression in conjunction with higher cynarin concentration was observed in the majority of evaluated accessions (Pearson=0.896*). No significant differences were observed in hqt gene expression.