Assessment of Metabolic Profiles in Florets of Carthamus Species Using Ultra-Performance Liquid Chromatography-Mass Spectrometry

Abstract

The genus Carthamus is a diverse group of plants belonging to the family Compositae. Florets of Carthamus species exhibit various colors, including white, yellow, orange, and red, which are related to their metabolite compositions. We aimed to investigate the metabolites accumulated in florets of three wild (C. lanatus, C. palaestinus, and C. turkestanicus) and one cultivated (C. tinctorius) species of safflower at three developmental stages. Metabolites were extracted from freeze-dried florets using 70% methanol; qualification and quantification were carried out using liquid chromatography quadrupole time-of-flight mass spectrometry in positive and negative ion modes followed by extraction of the peaks. Fifty-six metabolites, including phenylpropanoids, chalcones, isoflavonoids, flavanones, flavonols, flavones, and other primary metabolites, were identified for the first time in safflower wild species. The orange florets contained high abundances of safflomin A, anhydrosafflor yellow B, and baimaside, whereas white/cream and light-yellow pigmented florets had high abundances of 1,5-dicaffeoylquinic acid, luteolin 7-O-glucuronide, and apigenin 7-O-β-D-glucuronide. The principal component analysis clearly distinguished the samples based on their pigment types, indicating that color is a dominant factor dictating the identity and amount of the metabolites. Pearson correlation data based on levels of metabolites showed that orange and yellow florets were significantly correlated to each other. White and cream pigmented species were also highly correlated. Comparison between three developmental stages of safflower wild species based on their metabolite profile showed inconsistent. The findings of this study broaden the current knowledge of safflower metabolism. The wide diversity of metabolites in safflower materials also helps in efforts to improve crop quality and agronomic traits.

Distinct Effects of Seed Coat and Flower Colors on Metabolite Contents and Antioxidant Activities in Safflower Seeds

“…Despite these differences, flower color did not result in significant differences ( p < 0.05) in the values of these parameters. Several studies have shown that the metabolic profiles of safflower florets are associated with flower color, which plays an important role in their biological activities [ 31 , 50 , 51 , 52 ]. Notably, the main component of the safflower floral organ is the seeds contained inside, and the floral organ is crucial for the development of safflower seeds.…”

“…Color is an important morphological trait that can provide valuable insights into the internal quality of plant seeds [ 30 , 31 , 32 ]. Pigments, as essential secondary metabolites, play multiple roles in plant development, flower and seed coloration, and photosynthesis.…”

“…The safflower corolla exhibits varying colors, including red, yellow, white, orange, and cream [ 6 ]. Notably, the color characteristics and biological properties of safflower florets are correlated [ 31 , 33 ]. As a seed-growing organ tissue, the floral organ significantly contributes to the development of safflower seeds.…”

Integrated metabolomics and transcriptome analysis on flavonoid biosynthesis in flowers of safflower (Carthamus tinctorius L.) during colour-transition

“…Flavonoid glycosides, the main components of the pigment in safflower, are mainly detected in flowers ( Kazuma et al, 2000 ; Kim et al, 2020 ; Wang et al, 2021a ; Pu et al, 2021 ). Gene expression is closely related to its function.…”

“…However, much of the gene and chemical bases during colour transition are still unclear. There are some reports on the chemical composition of safflower, while most research uses HPLC coupled with DAD, HPLC coupled with MS, or even UHPLC-Q-TOF-MS to analyze the components of safflower ( Kazuma et al, 2000 ; Yue et al, 2013 ; Kim et al, 2020 ; Pu et al, 2021 ). However, most of these reports have some shortcomings, such as a small number of compounds.…”