Rheum tanguticum
is a perennial herb and an important medicinal
plant, with anthraquinones as its main bioactive compounds. However, the
specific pathway of anthraquinone biosynthesis in rhubarb is still unclear. The
accumulation of anthraquinones in different tissues (root, leaf, stem and seed)
of
R. tanguticum
revealed considerable variation, suggesting
possible differences in metabolite biosynthetic pathways and accumulation among
various tissues. To better illustrate the biosynthetic pathway of
anthraquinones, we assembled transcriptome sequences from the root, leaf, stem
and seed tissues yielding 157,564 transcripts and 88,142 unigenes. Putative
functions could be assigned to 56,911 unigenes (64.57%) based on BLAST searches
against annotation databases, including GO, KEGG, Swiss-Prot, NR, and Pfam. In
addition, putative genes involved in the biosynthetic pathway of anthraquinone
were identified. The expression profiles of nine unigenes involved in
anthraquinone biosynthesis were verified in different tissues of
R.
tanguticum
by qRT-PCR. Various transcription factors, including
bHLH, MYB_related, and C2H2, were identified by searching unigenes against
plantTFDB. This is the first transcriptome analysis of different tissues of
R. tanguticum
and can be utilized to describe the genes
involved in the biosynthetic pathway of anthraquiones, understanding the
molecular mechanism of active compounds in
R. tanguticum
.