Effects of methyl jasmonate on specialized metabolite accumulation and phenylpropanoid pathway gene expression in Codonopsis pilosula adventitious roots

초록

Codonopsis pilosula is a traditional medicinal herb rich in phenylpropanoids and other bioactive compounds. We evaluated how methyl jasmonate (MeJA, 100 & micro;M) modulates the phenylpropanoid-flavonoid pathway in sterile adventitious root cultures of this plant. The expression of six enzyme-encoding genes in this pathway (PAL, C4H, 4CL, CHS, CHI, and F3H) was quantified by reverse transcription-quantitative PCR (RT-qPCR) from 0.5 h to 336 h, along with high-performance liquid chromatography (HPLC) profiling of representative metabolites. MeJA triggered a rapid transcriptional response in which PAL transcript levels peaked similar to 10-fold at 1 h, CHS peaked at approximately 6 h, and C4H, CHI, and F3H reached their highest levels around 12 h; 4CL changed only slightly. Metabolite accumulation followed gene induction: p-coumaric acid increased mainly during the later phase, caffeic acid increased rapidly with an early peak, and naringenin accumulated progressively during the later phase, reaching its highest level at 336 h. Quercetin showed a moderate increase around 12-24 h, rutin responded only modestly, and naringin and epicatechin also accumulated under MeJA treatment. MeJA also increased the accumulation of C. pilosula-associated glycosides, including lobetyolin and tangshenoside I. Together, these data suggest a stepwise MeJA-responsive program in which early activation of upstream genes is followed by induction of CHS/CHI and coordinated accumulation of phenolic acids and flavonoids. MeJA-elicited adventitious roots therefore provide a controllable platform for the rapid production of pharmacologically valuable compounds, complementing slow field cultivation.

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