Identification and characterization of major constituents in different-colored rapeseed petals by UPLC-HESI-MS/MS.

Abstract

Oilseed rape (Brassica napus L.) is the second highest yielding oil crop worldwide. In addition to being used as an edible oil and a feed for livestock, rapeseed has high ornamental value. In this study, we identified and characterized the main floral major constituents, including phenolic acids and flavonoids components, in rapeseed accessions with different-colored petals. A total of 144 constituents were identified using ultrahigh-performance liquid chromatography-HESI-mass spectrometry (UPLC-HESI-MS/MS), 57 of which were confirmed and quantified using known standards, mainly contained phenolic acids, flavonoids and glucosinolates compounds. Most of epicatechin, quercetin and isorhamnetin derivates were found in red and pink petals of B. napus, while kaempferol derivates were in yellow and pale white petals. Moreover, petal-specific compounds, including putative hydroxycinnamic acid derivative, sinapoyl malate 1-O-sinapoyl-beta-D-glucose, feruloyl glucose, naringenin-7-O-glucoside, cyanidin 3-glucoside, cyanidin 3,5-di-O-glucoside, petunidin-3-O-beta-glucopyranoside, is-3-O-glucoside, km-3-O-glucoside-7-O-glucoside, qn-3,4 -O-di-beta-glucopyranoside, qn-3-O-glucoside, and delphinidin-3-O-glucoside, which might contribute to a variety of petal colors in B. napus. In addition, bound phenolics were tentatively identified and contained three abundant compounds (p-coumaric acid, ferulic acid and 8-O-4 diferulic acid). These results provide insight into the molecular mechanisms underlying petal color and suggest strategies for breeding rapeseed with a specific petal color in the future.