Modulation of heterophyllin B biosynthesis and transcription of key transcription factor genes in Pseudostellaria heterophylla by methyl jasmonate

Abstract

Heterophyllin B (HB) is a small molecule cyclic peptide (CP) compound with important pharmacological activities. This CP is specifically produced in Chinese herb Pseudostellaria heterophylla. However, the production of HB in P. heterophylla is often limited, and fails to meet market demands. Phytohormones play regulatory roles in medicinal plant secondary metabolism. We treated P. heterophylla tuberous roots with various concentrations of methyl jasmonate (MeJA) and observed a higher HB content at 200 μM MeJA treatment. Subsequently, we collected the tuberous roots exposed to 200 μM MeJA for 0, 6, and 12 h (MeJA-0 h, MeJA-6 h, and MeJA-12 h) and subjected them to transcriptome sequencing. A total of 82,363 unigenes were identified and categorized according to publicly available data. KEGG analysis indicated that the differentially expressed genes (DEGs) were significantly associated with metabolic pathways such as plant hormone signaling pathways, phenylpropanoid biosynthesis, and the MAPK signal transduction-plant. Notably, MeJA also significantly promoted the expression of the precursor gene (prePhHB) of HB biosynthesis. Six transcription factors (TFs) were chosen as candidate genes for regulating HB biosynthesis. qRT-PCR further demonstrated that PhNAC1 and PhMYB2 exhibited a similar expression pattern to prePhHB. In summary, the transcriptome of P. heterophylla seedlings treated with MeJA was analyzed, and potential regulatory genes related to HB biosynthesis of P. heterophylla were obtained, establishing a foundation for further investigation into the biosynthesis and regulation of CPs.