Transcriptional Profiling and Molecular Characterization of Astragalosides, Calycosin, and Calycosin-7‑<i>O</i>‑β‑d‑glucoside Biosynthesis in the Hairy Roots of <i>Astragalus membranaceus</i> in Response to Methyl Jasmonate

We used the next-generation Illumina/Solexa HiSeq2000 platform on RNA analysis to investigate the transcriptome of Astragalus membranaceus hairy roots in response to 100 μM methyl jasmonate (MeJA). In total, 77 758 230 clean reads were assembled into 48 636 transcripts (average length of 1398 bp), which were clustered into 23 658 loci (genes). Of these, 19 940 genes were annotated by BLASTx searches. In addition, DESeq analysis showed that 2127 genes were up-regulated, while 1247 genes were down-regulated by MeJA. Seventeen novel astragaloside (AST) biosynthetic genes and seven novel calycosin and calycosin-7-O-β-d-glucoside (CG) biosynthetic genes were isolated. The accumulation of ASTs, calycosin, and CG increased significantly in MeJA-treated hairy roots compared with control hairy roots. Our findings will provide a valuable resource for molecular characterization of AST, calycosin, and CG biosynthetic pathways and may lead to new approaches to maximize their production and biomass productivity in the hairy roots of A. membranaceus.