Saposhnikovia divaricata is a valuable Chinese medicinal herb; the transformation
from vegetative growth to reproductive growth may lead to the decrease of its pharmacological
activities. Therefore, the study of bolting and flowering for Saposhnikovia divaricata
is warranted. The present study aimed to reveal differentially expressed genes (DEGs)
and regularity of expression during the bolting and flowering process, and the results
of this study might provide a theoretical foundation for the suppression of early
bolting for future research and practical application. Three sample groups, early
flowering, flower bud differentiation, and late flowering (groups A, B, and C, respectively)
were selected. Transcriptomic analysis identified 67, 010 annotated unigenes, among
which 50, 165 were differentially expressed including 16, 108 in A vs B, and 17,
459 in B vs C, respectively. Gene ontology (GO) and Kyoto Encyclopedia of Genes
and Genomes (KEGG) pathway functional classification analysis were performed on these
differentially expressed genes, and five important pathways were significantly impacted
( P ≤ 0.01): plant circadian rhythm, other glycan degradation, oxidative phosphorylation,
plant hormone signal transduction, and starch and sucrose metabolism. Plant hormone
signal transduction might play an important role in the bolting and flowering process.
The differentially expressed indole-3-acetic acid ( IAA ) gene showed significant
down-regulation during bolting and flowering, while the transport inhibitor response
1 ( TIR1 ) gene showed no significant change during the bolting process. The expression
of flowering related genes FLC, LYF, and AP1 also showed a greater difference
at different development stages. In conclusion, we speculate that the decrease in
auxin concentration is not caused by the degrading effect of TIR1 but by an alternative
mechanism.