Continuous Inflorescence Removal Changes Parameters, Lignin and Saponin a Content and Alters the Transcriptome of Root of Bupleurum Chinense DC

Abstract BackgroundBupleurum chinense DC. is an important traditional medicinal plant, and its root as the only medicinal part named Radix Bupleuri is used widely for the treatments of influenza, fever, inflammation, etc. in China, Japan and Korea. As a bulk herb, this herbal medicine occupies a comparatively big market share and is widely cultivated. However, because of the vigorous flowering and fruiting, the root growth is influenced seriously. ResultsWe assessed the effect of the continuous inflorescence removal (CIR) on improving the yield and quality of Radix Bupleuri. The results showed that the taproot length, root head diameter, and lateral root numbers were significantly elevated by CIR. We also found an average 1.71-fold increase in root biomass, and the lower lignin and higher saponin a content were detected in roots of CIR-treated plants. Based on a comparative transcriptome analysis, 172, 243, 1974 and 3024 differentially expressed genes (DEGs) were respectively identified in the CIR-treated roots. Gene Ontology and KEGG pathway functional annotation analysis of the DEGs showed that multiple genes were involved sugars metabolism pathway, lignin and terpenoids biosynthesis pathway, and the plant hormones signal transduction pathway. In addition, 295 genes encoding transcription factors (TFs), including members of the ERF, MYB-related, bHLH, NAC, MYB, AUX/IAA and bZIP families etc, were identified as CIR responsive. ConclusionThe CIR treatment could improve the yield, quality and market value of B. chinense DC. medicine, and the first transcriptome profile of CIR-treated roots of B. chinense DC. provides a series of clues of the molecular mechanisms of these phenotype changes induced by CIR.