Agronomic and Metabolomic Side-Effects of a Divergent Selection for Indol-3-Ylmethylglucosinolate Content in Kale (Brassica oleracea var. acephala).

Jorge Poveda,Jørgen A.B. Mølmann,Tor J. Johansen,Christian Möllers,Antonio de Haro,Elena Ordiales,Alex C. McAlvay,Pablo Velasco,Víctor M. Rodríguez

doi:10.3390/metabo11060384

Abstract

Brassica oleracea var. acephala (kale) is a cruciferous vegetable widely cultivated for its leaves and flower buds in Europe and a food of global interest as a “superfood”. Brassica crops accumulate phytochemicals called glucosinolates (GSLs) which play an important role in plant defense against biotic stresses. Studies carried out to date suggest that GSLs may have a role in the adaptation of plants to different environments, but direct evidence is lacking. We grew two kale populations divergently selected for high and low indol-3-ylmethylGSL (IM) content (H-IM and L-IM, respectively) in different environments and analyzed agronomic parameters, GSL profiles and metabolomic profile. We found a significant increase in fresh and dry foliar weight in H-IM kale populations compared to L-IM in addition to a greater accumulation of total GSLs, indole GSLs and, specifically, IM and 1-methoxyindol-3-ylmethylGSL (1MeOIM). Metabolomic analysis revealed a significant different concentration of 44 metabolites in H-IM kale populations compared to L-IM. According to tentative peak identification from MS interpretation, 80% were phenolics, including flavonoids (kaempferol, quercetin and anthocyanin derivates, including acyl flavonoids), chlorogenic acids (esters of hydroxycinnamic acids and quinic acid), hydroxycinnamic acids (ferulic acid and p-coumaric acid) and coumarins. H-IM kale populations could be more tolerant to diverse environmental conditions, possibly due to GSLs and the associated metabolites with predicted antioxidant potential.

Highlights

Crops belonging to the genus Brassica are among the top ten most agronomically and economically important vegetable species in the world
The mean fresh and dry weights were significantly higher in high in IM (H-IM) (1563 g and 172 g, respectively) than in low in IM (L-IM) (1342 g and 145 g, respectively)
We reported a higher yield of H-IM populations of kale across different environments compared to L-IM populations indicating a potentially greater adaptive capacity of the H-IM populations to varied contexts, as measured by a higher production of foliar biomass

Summary

Introduction

Crops belonging to the genus Brassica are among the top ten most agronomically and economically important vegetable species in the world These crops show high morphological and agronomic diversity and are cultivated mainly in temperate regions of the Northern Hemisphere [1]. Mainly insects, the mechanism involved in the defensive capacity of GHPs is direct toxicity by ingestion [8]. It has been described how GSLs can play a role as attractants of beneficial insects, such as pollinators [9] or parasitoids [10], as well as insect-pest of Brassica crops [11]

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Discussion

Conclusion