Part â… :Genome-wide Characterisation And Analysis Of BHLH Transcription Factors Related To Tanshinone Biosynthesis In Salvia Miltiorrhiza Part â…¡:Micropropagation And Adventitious Root Culture Of Valeriana Fauriei

There are two sections in this thesis. In section one, genome-wide characterisation and analysis of bHLH transcription factors related to tanshinone biosynthesis in Salvia miltiorrhiza were described. In section two, micropropagation and adventitious root culture of Valeriana fauriei were investigated.Section one:bHLH transcription factors contain basic helix-loop-helix domains and play an important role in regulating plant secondary metabolism. However, studies on bHLH transcription factors regulating tanshinone biosynthesis are limited. Based on the genome and transcriptome sequences, the bHLH transcription factors of S. miltiorrhiza were comprehensively characterised and analyzed in the current study. A total of 127 bHLH transcription factor genes were identified in the genome, and phylogenetic analysis indicated that these SmbHLHs could be classified into 25 subfamilies. Based on gene-specific expression patterns in 4 organs (root, stem, leaf and flower) and 3 tissues (periderm, phloem and xylem) and up-regulated expression patterns in response to MeJA treatment,7 bHLH genes were revealed to potentially involved in tanshinone biosynthesis. Among them, the gene expression of SmbHLH37, SmbHLH74 and SmbHLH92 perfectly matches the accumulation pattern of tanshinone biosynthesis in S. miltiorrhiza. In addition, promoter sequence analysis of enzyme-coding genes involved in tanshinone biosynthesis pathways indicated that 97% of these genes contain bHLH transcription factors binding site (E-box). Our results provide a foundation for understanding the molecular basis and regulatory mechanisms of bHLH transcription factors in tanshinone biosynthesis.Section two:Valeriana fauriei Briq. (Valerianaceae), whose roots mainly contain kessane sesquiterpenoids and iridoid glycosides and have been used for sedative and antispasmodic purposes. With the increase of market demand and decrease of wild resources, there is a need to develop a micropropagation system and an adventitious root culture method of V. fauriei. In the current study, micropropagation of the genus Valeriana was successfully established, which has been applied for China patent with an application number of 201410482874.5. The buds were used for multiple shoots induction on MS medium supplemented with 6-BA (1 mg/L) and IBA (0.02 mg/L). After 5 to 6 weeks the shoot was transferred to half strength MS medium containing IBA (0.1 mg/L) for root induction. Test-tube plantlet has been approved easy to survive in vitro. In addition, the high-frequency callus induction rate (100%) and maximum number (4±1) of adventitious roots per explants (petioles) were recorded on MS medium amplified with KT (1 mg/L) and NAA (0.2 mg/L) after 34 days. The adventitious roots were subcultured on MS medium containing KT (0.2 mg/L) and NAA (0.02 mg/L) with an average amplification rate of 8.3±0.5 after 17 days. In addition, adventitious roots were cultured in the liquid medium for 2 months before harvest. Our findings provide a foundation for the development and utilization of V.fauriei resource.