The effects of AgNO3 combined with temperature stress on the transcriptome of Gentiana rigescens and the accumulation of gentiopicroside

The root and rhizome of Gentiana rigescens are used as important traditional Chinese medicine and ethno medicine, with gentiopicroside is the major bioactive compounds. In order to explore the effects of temperature and heavy metals stress on the gentiopicroside, we investigated the accumulation of gentiopicroside and the transcriptional response of G. rigescens when exposed to a combination of AgNO 3 and temperature stress. AgNO 3 (100 µmol/L) was sprayed onto sterile Gentiana rigescens seedlings and cultured at three temperatures (22°C, 10°C and 34°C); control plants were sprayed with sterile water and cultured at 22°C. Gentiopicroside levels were determined by high-performance liquid chromatography (HPLC), and the differential expression of genes in the gentiopicroside biosynthesis pathway in response to different treatments was analyzed by an IIIumina Hiseq 6000 system. Analysis showed that the levels of gentiopicroside in response to a combination of AgNO 3 and temperature treatment were significantly higher than that of those in the control; the 100µmol/L AgNO 3 and 10°C treatment group had the highest levels of gentiopicroside. A total of 135 197 unigenes were identified by transcriptome sequencing, with an average length of 1351 base pairs (bp). A total of 238 unigenes, encoding 19 key enzymes, were identified in the gentiopicroside biosynthesis pathway. The combination of 100µmol/L AgNO 3 and 10°C treatment led to the largest number of differentially expressed transcription factors when compared with the control. Our research provides key biological information for elucidating the molecular mechanisms underlying the biosynthesis of gentiopicroside in response to the combination of AgNO 3 and temperature stress.