Genotypic Variation of Glucosinolates and Their Breakdown Products in Leaves of Brassica rapa

Abstract

An in-depth glucosinolate (GLS) profiling was performed on a core collection of 91 Brassica rapa accessions, representing diverse morphotypes of heterogeneous geographical origin, to better understand the natural variation in GLS accumulation and GLS breakdown product formation. Leaves of the 91 B. rapa accessions were analyzed for their GLS composition by UHPLC-DAD and the corresponding breakdown products by GC-MS. Fifteen different GLSs were identified, and aliphatic GLSs prevailed regarding diversity and concentration. Twenty-three GLS breakdown products were identified, among them nine isothiocyanates, ten nitriles, and four epithionitriles. Epithionitriles were the prevailing breakdown products due to the high abundance of alkenyl GLSs. The large scale data set allowed the identification of correlations in abundance of specific GLSs or of GLS breakdown products. Discriminant function analysis identified subspecies with high levels of similarity in the acquired metabolite profiles. In general, the five main subspecies grouped significantly in terms of their GLS profiles.

Identification and Characterization of Three Epithiospecifier Protein Isoforms in Brassica oleracea

“…GLS hydrolysis in Brassica vegetables often results in the release of nitriles and ETN instead of ITCs, and presence of ESP is made responsible (Petroski and Tookey, 1982;Matusheski et al, 2006;Hanschen and Schreiner, 2017;Klopsch et al, 2018). Here, we report the identification and characterization of three BoESP isoforms in B. oleracea varieties, namely kohlrabi, broccoli, white cabbage, and red cabbage and their functional characterization in A. thaliana.…”

“…Previously, we have shown that Brassica vegetables exhibit a huge variation in the pattern of intact and hydrolyzed GLS (Hanschen and Schreiner, 2017;Klopsch et al, 2018). In order to characterize the plant material with regard to those specific plant secondary compounds, seedlings of four B. oleracea varieties, namely broccoli, kohlrabi, white cabbage, and red cabbage were investigated for their GLS profile and GLS hydrolysis product formation in roots and shoots.…”

“…Occurrence and activity of the epithiospecifier protein (ESP) leads to the generation of ETNs from alkenyl-GLS aglucons as well as nitriles from non-alkenyl-GLS-aglucons (Burow et al, 2006;Matusheski et al, 2006). Many Brassica species release nitriles and ETNs upon GLS hydrolysis, among them B. oleracea and also B. campestris, B. carinata, and B. rapa (Macleod and Rossiter, 1985;Matusheski et al, 2004;Hanschen and Schreiner, 2017;Klopsch et al, 2017;Klopsch et al, 2018;Hanschen et al, 2019). So far, ESPs were characterized in A. thaliana (Lambrix et al, 2001;De Torres Zabala et al, 2005;Hanschen et al, 2018b) and in Brassica species, such as broccoli (B. oleracea var.…”

The Role of Brassica Bioactives on Human Health: Are We Studying It the Right Way?

“…Another abundant GSL present in cruciferous vegetables is glucobrassicin (GB) [24,25], whose main degradation product is ascorbigen [26]. However, its corresponding indole-3-carbinol (I3C) and its condensation product 3,3-diindolylmethane (DIM) [27] have been the main focus of medical research because they were readily commercially available.…”

“…Early authors (e.g., Bjeldanes, in the 1980s) suggested indoles to be cancer protecting; later authors noted Janus properties, being either protectors or carcinogens depending on the timing of the carcinogen and the indole, as reviewed by, e.g., Holst and Williamson [29] and Agerbirk et al [26]. Another abundant GSL present in cruciferous vegetables is glucobrassicin (GB) [24,25], whose main degradation product is ascorbigen [26]. However, its corresponding indole-3-carbinol (I3C) and its condensation product 3,3-diindolylmethane (DIM) [27] have been the main focus of medical research because they were readily commercially available.…”