Safflower (Carthamus tinctorius L.) has been cultivated for over 4,500 years as a source of pigments, dyes, and traditional medicines. Its flowers are particularly valued for hydroxysafflor yellow A (HSYA) and related flavonoid glycosides that show therapeutic potential in treating cardiovascular and cerebrovascular diseases. Despite its economic and medicinal importance, the biosynthesis of these unique compounds has remained unclear. Previous studies often relied on homology comparisons or RNA-seq-based screening, which lacked a comprehensive genomic perspective. This limitation hindered precise identification of the genes controlling flavonoid pathways. Due to these challenges, more systematic research on safflowers flavonoid biosynthesis is required.
A research team from Chengdu University of Traditional Chinese Medicine has published (DOI: 10.1093/hr/uhae261) new findings on safflower's metabolic pathways in Horticulture Research on September 16, 2024. The study presents the first genome-wide analysis of cytochrome P450 and glycosyltransferase superfamilies in safflower and integrates transcriptomic and metabolomic data to pinpoint candidate genes. Among these, the team identified and functionally validated CtOGT1, a critical enzyme in flavonoid glycoside biosynthesis, offering novel insights into the genetic control of safflower’s valuable bioactive compounds.
The researchers identified 264 cataloging cytochrome P450 (CYP) and 140 uridine diphosphate glycosyltransferase (UGT) genes within the safflower genome and mapped their evolutionary relationships, conserved motifs, and promoter elements. Expression profiling across tissues, developmental stages, light intensities, and methyl jasmonate treatments revealed dynamic patterns linked to flavonoid accumulation. Metabolite analysis confirmed that HSYA is exclusively synthesized in flowers, narrowing the focus to flower-specific candidate genes. Through integrative clustering, 26 CYPs and 17 UGTs were highlighted, among which CtOGT1 emerged as the strongest candidate. Functional validation in Nicotiana benthamiana and prokaryotic systems demonstrated that CtOGT1 catalyzes glycosylation at the 7-OH position of flavonoids such as scutellarein and apigenin, producing corresponding glycosides. Kinetic analysis further confirmed its high substrate affinity, with measurable catalytic efficiency across multiple flavonoid compounds. Together, these results establish CtOGT1 as a pivotal enzyme in safflower flavonoid glycoside biosynthesis and provide the first molecular evidence linking genome-wide gene discovery to functional enzymatic activity in this crop.
“Identifying CtOGT1 fills a critical knowledge gap in understanding how safflower produces its signature flavonoid glycosides,” said Professor Jiang Chen, senior author of the study. “This work demonstrates the power of integrating genome-wide data with multi-omics approaches to uncover the hidden drivers of plant secondary metabolism. Our findings not only offer a new framework for studying complex biosynthetic pathways but also create opportunities to manipulate key genes for enhancing the medicinal value of safflower and other economically important plants.”
The discovery of CtOGT1 provides a valuable genetic tool for breeding and metabolic engineering. By targeting this enzyme, researchers and industry could enhance the production of HSYA and other pharmacologically active flavonoids, strengthening safflower's role in both traditional remedies and modern drug development. Beyond safflower, the study establishes a methodological blueprint for deciphering complex biosynthetic pathways in other medicinal plants. This opens the door to sustainable production of high-value natural compounds, advancing plant-based pharmaceuticals, functional foods, and health supplements. The integration of genome-wide and multi-omics strategies thus holds broad promise for agriculture and biotechnology.
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References
DOI
10.1093/hr/uhae261
Original Source URL
https://doi.org/10.1093/hr/uhae261
Funding information
This work was supported by grants from the National Natural Science Foundation of China (82274039; 82404792), Science and Technology Department of Sichuan Province (2021YFYZ0012-5), the Innovation Team and Talents Cultivation Program of National Administration of Traditional Chinese Medicine (ZYYCXTD-D-202209), Natural Science Foundation of Sichuan Province (2023NSFSC0660; 2023NSFSC1770) and the Xinglin Talent Program of Chengdu University of (TCMQJJJ2023010; QJRC2021011).
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.