Identification and Expression Analysis of Glucosinolate Biosynthetic Genes and Estimation of Glucosinolate Contents in Edible Organs of Brassica oleracea Subspecies

Abstract

Abstract:Glucosinolates are anti-carcinogenic, anti-oxidative biochemical compounds that defend plants from insect and microbial attack. Glucosinolates are abundant in all cruciferous crops, including all vegetable and oilseed Brassica species. Here, we studied the expression of glucosinolate biosynthesis genes and determined glucosinolate contents in the edible organs of a total of 12 genotypes of Brassica oleracea: three genotypes each from cabbage, kale, kohlrabi and cauliflower subspecies. Among the 81 genes analyzed by RT-PCR, 19 are transcription factor-related, two different sets of 25 genes are involved in aliphatic and indolic biosynthesis pathways and the rest are breakdown-related. The expression of glucosinolate-related genes in the stems of kohlrabi was remarkably different compared to leaves of cabbage and kale and florets of cauliflower as only eight genes out of 81 were expressed in the stem tissues of kohlrabi. In the stem tissue of kohlrabi, only one aliphatic transcription factor-related gene, Bol036286 (MYB28) and one indolic transcription factor-related gene, Bol030761 (MYB51), were expressed. The results indicated the expression of all genes is not essential for glucosinolate biosynthesis. Using HPLC analysis, a total of 16 different types of glucosinolates were OPEN ACCESSMolecules 2015, 20 13090 identified in four subspecies, nine of them were aliphatic, four of them were indolic and one was aromatic. Cauliflower florets measured the highest number of 14 glucosinolates. Among the aliphatic glucosinolates, only gluconapin was found in the florets of cauliflower. Glucoiberverin and glucobrassicanapin contents were the highest in the stems of kohlrabi. The indolic methoxyglucobrassicin and aromatic gluconasturtiin accounted for the highest content in the florets of cauliflower. A further detailed investigation and analyses is required to discern the precise roles of each of the genes for aliphatic and indolic glucosinolate biosynthesis in the edible organs.

Glucosinolates in Food

“…2). In white cauliflower, the total GLSs content varied from 91 mg/100 g FW to 109 mg/100 g FW (mean value of 78 mg/100 g FW) [78][79][80][81][82] (Table 2). Glucoiberin is the predominant GLS ranging from 3 to 43 mg/100 g FW (mean value of 23 mg/100 g FW), followed by sinigrin (mean value of 22 mg/100 g FW) and glucobrassicin (mean value of 14 mg/100 g FW) [80,81] (Fig.…”

CRISPR-Cas9-mediated editing ofmyb28impairs glucoraphanin accumulation ofBrassica oleraceain the field

“…This includes direct regulation of expression of glucosinolate biosynthesis genes involved in every step of glucosinolate production (Gigolashvili et al, 2007;Hirai et al, 2007;Sonderby et al, 2007) in addition to regulating primary sulphur assimilation genes and partitioning of methionine, vital precursors for aliphatic glucosinolates (Frerigmann and Gigolashvili, 2014;Sonderby et al, 2007;Yatusevich et al, 2010). This regulatory role is conserved within the Brassica genus, with homologues characterised in Brassica napus (Li et al, 2014), B. juncea (Augustine et al, 2013) and B. rapa (Kim et al, 2013;Seo et al, 2016).This includes studies to a lesser extent in B. oleracea varieties kohlrabi (Yi et al, 2015) and Chinese kale (Yin et al, 2017), which generated RNAi lines to study the function of this transcription factor. To date no stable MYB28 knockout has been published in this species.…”

The Effect of Introgression of an R2R3 MYB Transcription Factor on Sulphur Metabolism inBrassica oleracea

“…MYB28 mediates this effect through direct regulation of expression of glucosinolate biosynthesis genes involved in every step of glucosinolate production [7][8][9] in addition to regulating primary sulphur assimilation genes and partitioning of methionine; a vital precursor for aliphatic glucosinolates [9][10][11]. MYB28 has also been repeatedly and independently well characterised as a regulator of aliphatic glucosinolate biosynthesis across the Brassica genus, including homologues in B. napus [12], B. juncea [13] and B. rapa [14,15] as well as B. oleracea varieties, kohlrabi [16] and Chinese kale [17]. However, the role of MYB28 in broccoli (Brassica oleracea var italica) has yet to be fully characterised.…”