Glucosinolate profile of Eruca sativa, Diplotaxis tenuifolia and Diplotaxis erucoides grown in soil and soilless systems

A B S T R A C T Soilless cultivation systems (SCS) are increasingly used to produce high quality baby-leaf arugula, appreciated by consumers for its pungent taste, due to the content of glucosinolates (GLS). Given all of the health benefits attributed to GLSs, there is great interest in understanding whether and how soilless growing systems may affect the GLS profile of arugula. For this purpose, a study was conducted to compare the GLS profile of Diplotaxis erucoides, D. tenuifolia, and Eruca sativa grown side-by-side under protected environment in a conventional soilsystem (CSS) and in a SCS. Genotype and growing-system resulted in a significant effect on GLS content, while the resulting qualitative GLS profile was species-specific. Despite the growing-system, six different GLSs were identified from plants of D. tenuifolia and E. sativa, while only sinigrin was detected in plants of D. erucoides. Total GLS content was on average 9.85, 8.23, and 7.96 mg g−1 of dry weight in D. erucoides, D. tenuifolia, and E. sativa, grown in CSS, respectively. The same three species grown in SCS synthesized 36%, 51%, and 41% more GLSs than plants grown in CSS, respectively. Soilless cultivation may be adopted to increase the GLS content and enhance the nutritional quality of brassicas leafy vegetables. 1. Introduction Brassicaceae are among the oldest cultivated crops (Schmidt and Bancroft, 2011) with a production across Europe estimated at approximately 70 million tons/annum, and are considered a rich source of health-promoting phytochemicals (Avato and Argentieri, 2015). They are commonly referred to as the “mustard” (from the Latin mustum ardens) plant family, due to the sharp, potent flavour attributable to their main sulphur metabolites, the glucosinolates (GLSs) (Björkman et al., 2011; Petropoulos et al., 2017). When plant tissues are crushed or powdered, they are hydrolysed releasing the typical hot, pungent mustard components that are associated with the botanical family. While Brassicaceae contain several phytonutrients, GLSs are their most commonly studied constituents (Argentieri et al., 2012; Argentieri et al., 2011; Björkman et al., 2011; D’Antuono et al., 2008). Although anti-nutritional effects, resulting in goitre and liver damage in animals have been reported for GLSs (Cartea and Velasco, 2008; Tripathi and Mishra, 2007), several epidemiological studies have shown that in humans, high consumption of Brassica vegetables is inversely linked to cancer risk (Fimognari and Hrelia, 2007; Petropoulos et al., 2017). Moreover, it has been shown that GLSs and their breakdown products