Transcriptome Sequencing and Chemical Analysis Reveal the Formation Mechanism of White Florets in Carthamus tinctorius L.

Abstract

<jats:p>Carthamus tinctorius L. (safflower), an economic crop and herb, has been extensively studied for its diverse chemical constituents and pharmacological effects, but the mechanism of safflower pigments (SP) leading to different colors of florets has not been clarified. In the present study, we compared the contents of SP in two varieties of safflower with white and red florets, named Xinhonghua No. 7 (WXHH) and Yunhong No. 2 (RYH). The results showed the contents of SP in RYH were higher than WXHH. To investigate genes related to SP, we obtained six cDNA libraries of florets from the two varieties by transcriptome sequencing. A total of 225,008 unigenes were assembled and 40 unigenes related to safflower pigment biosynthesis were annotated, including 7 unigenes of phenylalanine ammonia-lyase (PAL), 20 unigenes of 4-coumarate-CoA ligase (4CL), 1 unigene of trans-cinnamate 4-monooxygenase (C4H), 7 unigenes of chalcone synthase (CHS), 4 unigenes of chalcone isomerase (CHI), and 1 unigene of flavanone 3-hydroxylase (F3H). Based on expression levels we selected 16 differentially expressed unigenes (DEGs) and tested them using reverse transcription-quantitative real-time polymerase chain reaction (RT-qPCR), which was consistent with the sequencing results. Consequently, we speculated that in WXHH, 3 PALs, 3 4CLs, 1 C4H, 1 CHS, and 1 CHI, which were down-regulated, and 1 F3H, which was up-regulated, may play a key role in the formation of white florets.</jats:p>

Integrated Metabolomics and Transcriptome Analysis of Flavonoid Biosynthesis in Safflower (Carthamus tinctorius L.) With Different Colors

“…In safflower, studies have used different types of safflower to elucidate the details on color biosynthesis. Qiang et al (2020) used transcriptome sequencing and chemical analysis to reveal the formation mechanism of white florets in safflower. However, the pigment contents of red and white flowers were determined only using a spectrophotometer.…”

Integrated transcriptome and metabolome analyses revealed regulatory mechanisms of flavonoid biosynthesis in Radix Ardisia

“…CHS in flavonoid biosynthesis can catalyze one molecule of p-cinnamoyl-CoA and three molecules of malonyl-CoA to produce naringenin chalcone. CHI can convert naringenin chalcone into naringenin, which can be converted by F3H into dihydrokaempferol ( Qiang et al, 2020 ; He et al, 2018 ; Fig. 5 ).…”

Integrated Proteomics and Metabolomics of Safflower Petal Wilting and Seed Development

“…Pigments missing in our dataset were HSYA, safflor yellow A, and isosafflomin C; their water-solubility might have prohibited their extraction under our organic conditions [1]. Safflower pigments were reported to be more abundant in red inflorescences than white inflorescences [27]. Safflower flowers are known adulterants of saffron and detection methods have been devised [8,9].…”

“…Furthermore, 4CL is a key phenylpropanoid pathway enzyme by biosynthesising monolignol through the production of flavonoid precursor p-coumaroyl-CoA. In addition, 4CL safflower transcripts were down-regulated in white flowers relative to red flowers [27].…”

“…Metabolomics was applied to monitor the changes in pigment composition during the blooming period [25] and to assess how betaine salvage seedling growth suppression under salt stress [26]. The integration of several post-genomics workflows as a multi-omics strategy has successfully advanced the understanding of safflower capitula biology, in particular, white floret formation [27], as well as flavonoid profiling during colour transition [28], colour variation [29], or methyl jasmonate treatment [30]. An integrated proteome and lipidome analysis of naturally aged safflower seeds varying in vitality indicated that enzymes involved in glycerolipid metabolism and FA degradation contributed to the degradation of oil bodies and membrane lipids and are thus responsible for a decline in seed vigour during natural seed ageing [31].…”