# The Carthamus tinctorius L. genome sequence provides insights into synthesis of unsaturated fatty acids

## TL;DR

The safflower genome sequence reveals how unsaturated fatty acids are synthesized, offering insights for improving oil quality in this important crop.

## Contribution

The study provides a high-quality genome assembly and identifies key genes involved in linoleic acid biosynthesis in safflower.

## Key findings

- The genome assembly of Carthamus tinctorius variety Jihong01 is 1,061.1 Mb with 32,379 protein-coding genes.
- FAD2 and FAD6 genes play pivotal roles in linoleic acid biosynthesis in safflower seeds.
- Comparative genomic analysis shows a recent whole genome duplication event in safflower evolution.

## Abstract

Domesticated safflower (Carthamus tinctorius L.) is a widely cultivated edible oil crop. However, despite its economic importance, the genetic basis underlying key traits such as oil content, resistance to biotic and abiotic stresses, and flowering time remains poorly understood. Here, we present the genome assembly for C. tinctorius variety Jihong01, which was obtained by integrating Oxford Nanopore Technologies (ONT) and BGI-SEQ500 sequencing results. The assembled genome was 1,061.1 Mb, and consisted of 32,379 protein-coding genes, 97.71% of which were functionally annotated. Safflower had a recent whole genome duplication (WGD) event in evolution history and diverged from sunflower approximately 37.3 million years ago. Through comparative genomic analysis at five seed development stages, we unveiled the pivotal roles of fatty acid desaturase 2 (FAD2) and fatty acid desaturase 6 (FAD6) in linoleic acid (LA) biosynthesis. Similarly, the differential gene expression analysis further reinforced the significance of these genes in regulating LA accumulation. Moreover, our investigation of seed fatty acid composition at different seed developmental stages unveiled the crucial roles of FAD2 and FAD6 in LA biosynthesis. These findings offer important insights into enhancing breeding programs for the improvement of quality traits and provide reference resource for further research on the natural properties of safflower.

The online version contains supplementary material available at 10.1186/s12864-024-10405-z.