Sterol content and gene profiling for the valorization and traceability of broad- and curly-leaved endives (Cichorium endivia var. latifolium and crispum)

Italy is a major European producer of endives. CISIA (Integrated knowledge for the Agro-food Sustainability and Innovation for made in Italy produce), a Government- and SME-supported project, aims at assessing the nutritional and economic value of varieties from Lazio shire by targeting specific metabolites and gene pathways (ref. 1, 2, 3). The overall content and profile of total sterols were determined in two curly- ('E02.7162' and 'Myrna') and two broad-leaved ('Flester' and 'Confiance') Cichorium endivia cultivars. The analysis was performed on the edible part of plants at harvesting, covering two productive cycles. GC-MS in SIM mode with isotope dilution standardisation was used for best analytical performance. The overall sterol content ranged from 155 to 208 mg kg-1of fresh weight (fw), though no significant difference was measured among the four cultivars. The content of targeted sterols (mg kg-1 fw), i.e. cholesterol (range: 1.5-4), sitostanol (0.5-3), isofucosterol (3-7.5), campesterol (9-12.5), stigmasterol (65-78) and ?-sitosterol (69-112) varied modestly among the four genotypes. Nonetheless, a significant difference resulted in sitosterol and sitostanol contents in 'Myrna' with respect to 'Confiance' and 'E02.7162', respectively. Interestingly from a nutritional value standpoint, the endive total average sterol content was ca. twice as that of crispy lettuce (ref. 4). As for the sterol pathway genes, those involved in the stigmasterol/sitosterol and campesterol syntheses (ref. 5) were analysed at the expression and structural levels by the RNA-seq approach. The expression of eleven key genes was monitored and no significant transcript variation was observed among the four cultivars except for the CYTOCHROME P450-51, FACKEL (a sterol C-14 reductase) and HYDRA1 (C-8 sterol isomerase), which skewed in the 'Flester' transcriptome. Events of single nucleotide polymorphism were identified in order to discriminate the four genotypes. References 1.Conforti F, Sosa S, Marrelli M, Menichini F, Statti GA, Uzunov D, et al. The protective ability of Mediterranean dietary plants against the oxidative damage: The role of radical oxygen species in inflammation and the polyphenol, flavonoid and sterol contents. Food Chemistry. 2009;112(3):587-94. 2.Moreau RA, Whitaker BD, Hicks KB. Phytosterols, phytostanols, and their conjugates in foods: Structural diversity, quantitative analysis, and health-promoting uses. Progress in Lipid Research. 2002;41(6):457-500. 3.Hounsome N, Hounsome B, Tomos D, Edwards-Jones G. Plant metabolites and nutritional quality of vegetables. Journal of Food Science. 2008;73(4):R48-R65. 4.Piironen V, Toivo J, Puupponen-Pimiä R, Lampi AM. Plant sterols in vegetables, fruits and berries. Journal of the Science of Food and Agriculture. 2003;83(4):330-7. 5.Benveniste P. Biosynthesis and accumulation of sterols. Annual Review of Plant Biology 2004;55:429-57.