Transcriptomic and physiological analysis reveal phytohormone and phenylpropanoid biosynthesis in root of Cynanchum auriculatum

Baishouwu (Cynanchum auriculatum), a medicinal and food dual-use plant, has been cultivated for centuries is favored by consumers. C. auriculatum tuberous roots contain enormous amounts of flavonoids, lignin, other nutrients. However, the developmental characteristics phenylpropanoid metabolic mechanism in have not clarified. Here, phenotypes at three stages were observed, compared with root forming stage (S1), there significant morphological differences expanding (S2) harvest (S3). Through next-generation sequencing (NGS) on Illumina HiSeq2500 platform, nine transcriptomic libraries constructed analysis. A total 28,926 DEGs identified during development root, many enriched GO terms/ KEGG pathways ‘phytohormone signal transduction’ ‘phenylpropanoid biosynthesis’. The analysis phytohormone content gene expression revealed that auxin cytokinin acted concert to regulate development, while biosynthesis signaling ethylene inhibited. Phloroglucinol staining results showed lignified cells mainly distributed central xylem S1, followed ring-like structure formation S2, finally formed connecting rays between phloem S3. Lignin increased S2 then decreased S3, lignin synthesis genes also presented similar trend. Total flavonoids gradually increasing trend, flavonoid was up-regulated. pathway enhanced reducing activity key enzymes auriculatum. This study provided basis further utilization roots.