Expression of putative luteolin biosynthesis genes and WRKY transcription factors in Taraxacum antungense kitag

Key message Developing flowers of Taraxacum antungense Kitag are very rich in the highly useful flavonoid luteolin. Future research may establish ways to enhance luteolin production for multiple industrial purposes. Taraxacum antungense Kitag is a wild plant used in traditional medicines, teas, functional foods, and cosmetics. Luteolin is its major secondary metabolite. However, the molecular mechanisms underlying luteolin biosynthesis in T. antungense remain largely unknown. Here, high performance liquid chromatography (HPLC) was employed to measure the luteolin content in the flowers, leaves, and roots during T. antungense flowering. The flowers accumulated significantly more luteolin than the leaves or roots. RNA-seq analysis identified 16 differentially expressed genes (DEGs) including PAL, 4CL, CHS, CHI, and F3 ' H associated with luteolin biosynthesis and they were significantly upregulated in the flowers. This observation was positively correlated with luteolin accumulation. The extremely high F3 ' H (GWHGAAAA033111) expression level detected in the flowers was also consistent with high luteolin content. Thus, F3 ' H might play a vital role in luteolin biosynthesis. We identified 44 TaWRKYs in the T. antungense transcriptome database. Relative to wild type calli, TaWRKY44 was upregulated and the luteolin content was increased in TaWRKY44-transgenic T. antungense calli. Therefore, TaWRKY44 probably regulates luteolin biosynthesis. The results of this study lay a foundation for elucidating the molecular mechanisms and pathways controlling luteolin accumulation in T. antungense.

Automated summary

The flowers of Taraxacum antungense Kitag are rich in luteolin, a flavonoid with multiple industrial purposes. Research identified 16 genes associated with luteolin biosynthesis, with F3 ' H likely playing a vital role. The results lay a foundation for elucidating the molecular mechanisms and pathways controlling luteolin accumulation in T. antungense.