Glucosinolates in Diplotaxis and Eruca leaves: Diversity, taxonomic relations and applied aspects

Abstract Leaf glucosinolates of 42 Diplotaxis and 21 Eruca accessions were studied. Total content ranged from 0.25 to more than 70 g kg −1  dry wt. The 13 clusters, defined on the basis of glucosinolate composition, belonged to two glucosinolate-rich groups, characterised by the prevalence of a single component, and one low-glucosinolate group, with a profile not dominated by any individual component. A sinigrin-rich cluster ( D. ibicensis , D. berthautii , D. ilorcitana , D. siettiana , D. tenuisiliqua , D. brevisiliqua , and D. virgata ) and a gluconapin-rich cluster ( D. catholica , D.siifolia , D. virgata , and D. ollivieri ) included all the species previously classified in the nigra phylogenetic lineage. D. virgata was confirmed to be a critical taxon, with one accession slightly diverging from the others. D. siifolia subsp. vicentina was separated from the others in a glucobrassicin-rich cluster. D. harra , a rather isolated representative of sub-genus Hesperidium , clustered together D. assurgens in a sinalbin-rich cluster. Another well defined cluster was represented by D. brachycarpa (gluconasturtin). The two sub-species of D. erucoides were well differentiated by their glucosinolate profile. The low glucosinolate species: D. tenuifolia , D. viminea , D. cretacea , D. muralis (subgenus Diplotaxis ), and E. vesicaria , all previously included in the rapa/oleracea lineage, belonged to seven less defined clusters, mainly differing on the presence/absence or the relative abundance of some components (glucoraphanin, glucolepidin, 4-hydroxy-glucobrassicin, 4-phenylbutyl gls, glucoerucin and neoglucobrassicin). The data support previous taxonomic works. Glucosinolate-rich taxa, with well characterised profiles may be suitable for industrial uses, whereas the variability of edible D. tenuifolia and E. vesicaria may represent a basis for breeding horticultural types.