Temporal transcriptome profiling of developing seeds reveals candidate genes involved in oil accumulation in safflower (Carthamus tinctorius L.)

Dandan Li,Jingsheng Yu,Wei Wu,Bo Wei,Xin Xu,Zhiyu Chen,Qing Wang

doi:10.1186/s12870-021-02964-0

Dandan Li, Jingsheng Yu + Show 5 more

Open Access

https://doi.org/10.1186/s12870-021-02964-0

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Abstract

BackgroundThe investigation of molecular mechanisms involved in lipid metabolism plays a critical role for the genetic engineering of safflower (Carthamus tinctorius L.) to increase the oil accumulation level or to change the oil composition. Although transcript sequences are currently available for the leaves and flowers of safflower, a wide range scan of temporal transcripts at different stages of seed development has not been conducted for safflower.ResultsIn this study, temporal transcriptome sequencing was executed at 10, 14, 18, and 22 days after flowering (DAF) to uncover the molecular networks concerned in the biosynthesis of unsaturated fatty acids (USFAs). The results revealed that the biosynthesis of fatty acids is a dominant cellular process from 10 to 14 DAF, while degradation mainly happens after 18 DAF. Significant expression changes of two genes, stearoyl-[acyl-carrier-protein] 9-desaturase gene (SAD) from 10 to 14 DAF and oleate desaturase (FAD2–1) from 14 to 18 DAF, were detected at the transcriptomic levels, and the temporal expression patterns revealed by the transcriptomic analysis were confirmed using quantitative real-time PCR experiments. In addition, 13 candidate transcription factors (TFs) involved in regulating the expression level of the FAD2–1 gene were identified.ConclusionsThese results create a link between fatty acid biosynthesis and gene expression at different developmental stages of the seeds, provide insight into the underlying lipid metabolism, and meanwhile lay an important foundation for the genetic engineering of safflower varieties. We have identified novel candidate genes, including TFs, that are worthy of further exploration.

Highlights

The investigation of molecular mechanisms involved in lipid metabolism plays a critical role for the genetic engineering of safflower (Carthamus tinctorius L.) to increase the oil accumulation level or to change the oil composition
The accumulation of the major fatty acids was detected during seed development, and the results showed that fatty acids content continuously changed until the seeds matured
During the early seed developmental process, the cells differentiated and expanded rapidly, and abundant membrane lipids were synthesized in large quantities

Summary

Introduction

The investigation of molecular mechanisms involved in lipid metabolism plays a critical role for the genetic engineering of safflower (Carthamus tinctorius L.) to increase the oil accumulation level or to change the oil composition. Safflower (Carthamus tinctorius L.) is a multipurpose plant with excellent medicinal and oil value. To date, complete genome information is not available, and most safflower researchers have concentrated on studies of the molecular mechanisms of the flowers [14] and different tissues [15], including the flowers, leaves and roots involved in flavonoids compounds biosynthesis. It is essential to explore the expression of RNA transcripts at the whole gene expression level in safflower seeds to further the study above the molecular mechanism of polyunsaturated fatty acids biosynthesis

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