Targeted Metabolic and In-Silico Analyses Highlight Distinct Glucosinolates and Phenolics Signatures in Korean Rapeseed Cultivars.

Joonyup Kim,Allah Jurio Khaskheli,Min Cheol Kim,Soo In Sohn,Sang Un Park,Nam Su Kim,Ramaraj Sathasivam

doi:10.3390/plants10102027

Abstract

Rapeseed is an economically important oilseed crop throughout the world. We examined the content and composition of glucosinolates (GSLs) and phenolics in the sprouts of seven Korean cultivars. A total of eight GSLs that include four aliphatic GSLs (AGSLs) (progoitrin, gluconapin, gluconapoleiferin, and glucobrassicanapin) and four indole GSLs (IGSLs) (4-methoxyglucobrassicin, 4-hydroxyglucobrassicin, neoglucobrassicin, and glucobrassicin) were identified in these cultivars. Of the total GSLs, the highest level was detected for progoitrin, while the lowest level was identified for glucobrassicanapin in all the cultivars. Phenolics that include chlorogenic acid, catechin hydrate, 4-hydroxybenzoic acid, gallic acid, ferulic acid, p-coumaric acid, epicatechin, caffeic acid, rutin, quercetin, trans-cinnamic acid, benzoic acid, and kaempferol were present in all the cultivars. Of these, rutin was identified with the highest level while trans-cinnamic acid was identified with the lowest level in all the cultivars. Cluster analysis revealed the unique metabolic signature of eight GSLs and thirteen phenolics for the seven cultivars of rapeseed, which implies that genomic commonality and variability resulted from the previous breeding program. Further, gene expression and cis-regulatory elements suggest that the biosynthesis of GSLs and phenolics of these cultivars appears to be regulated through transcription factors associated with stress responses, phytohormones, and cellular growth.

Highlights

Rapeseed (Brassica napus L.) is one of the most important edible oil crops in the world, with high nutritional value for humans and a protein source for livestock [1,2]
The amount of GSLs was varied, the level of indole GSLs (IGSLs) (4-methoxyglucobrassicin, 4-hydroxyglucobrassicin, neoglucobrassicin, and glucobrassicin) was found to be retained at a lower level compared with progoitrin, but sustained at a relatively higher level than the rest of the aliphatic GSLs (AGSLs) in all the cultivars (Figure 1 and Supplementary Table S1)
Regarding the biosynthetic genes associated with phenolic compounds, we examined the expression of phenylalanine ammonia-lyase (PAL), sorbitol dehydrogenase (SDH), benzaldehyde dehydrogenase (BALDH), cinnamic acid 4-hydroxylase (C4H), p-coumarate 3-hydroxylase (C3H), caffeic acid 3-O-methyltransferase (COMT), 4-coumarate CoA ligase (4CL), chalcone synthase (CHS), flavanone 3-hydroxylase (F3H), flavonol synthase2 (FLS2), UDP-glucose:flavonoid 3-O-glucosyltransferase (UFGT), anthocyanidin reductase (ANR), and leucoanthocyanidin reductase (LAR) in the sprouts of seven rapeseed cultivars (Figure 5)

Summary

Introduction

Rapeseed (Brassica napus L.) is one of the most important edible oil crops in the world, with high nutritional value for humans and a protein source for livestock [1,2]. Plant secondary metabolites are derived from the structural units synthesized in primary and intermediate metabolism, such as aromatic amino acids from the shikimate pathway and isopentenyl diphosphate from the isoprenoid pathway diphosphate [5,6]. They can be divided into four major classes: terpenoids, and sulfur-containing compounds such as glucosinolates (GSLs), alkaloids, and phenolics [7,8]. Plant secondary metabolites such as GSLs have been gaining great interest because of their cancerpreventive properties for humans as well as their nutritional value [2,9,10,11], which evoked the demand for the breeding of functional cultivars and industrial applications [12]

Methods

Results

Conclusion