Transcriptional responses for biosynthesis of ginsenoside in arbuscular mycorrhizal fungi-treated Panax quinquefolius L. seedlings using RNA-seq

Panax quinquefolius L. has been considered as an important traditional Chinese medicine with a history of more than 300 years in China. Ginsenoside is the main bioactive component. Our research group has found that the accumulation of ginsenoside is affected by arbuscular mycorrhizal fungi (AMF). However the underlying mechanism how AMF affected the biosynthesis of ginsenoside in P. quinquefolius is still unclear. In this study, the RNA-seq analysis was used to evaluate the effects of AMF (Rhizophagus intraradices, R. intraradices) on the expression of ginsenoside synthesis related genes in P. quinquefolius root. The result indicated that a symbiotic relationship between R. intraradices and P. quinquefolius was established. RNA-seq achieved approximately 48.62 G reads of all samples. Assembly of all the reads involved in all samples produced 63,420 transcripts and 24,137 unigenes. Differential expression analysis was performed between the control and AMF group. A total of 111 differentially expressed genes (DEGs) in response to AMF vs. control were identified, 78 and 33 transcripts were upregulated and downregulated, respectively. Based on the functional analysis, Gene ontology (GO) analysis revealed that most DEGs were related to stress responses and cellular metabolic processes. The Kyoto Encyclopedia of Genes and Genomes enrichment analysis identified transduction, plant hormone signal transduction and terpenoids and polyketides biosynthesis pathways. Furthermore, the expression of glycolysis-related genes and ginsenoside synthesis related genes was largely induced by AMF. In conclusion, our results comprehensively elucidated the molecular mechanism how AMF affected the biosynthesis of ginsenoside in P. quinquefolius by transcriptome profiling.