Deep Sequencing Reveals Transcriptome Re-Programming of Taxus × media Cells to the Elicitation with Methyl Jasmonate

Abstract

BackgroundPlant cell culture represents an alternative source for producing high-value secondary metabolites including paclitaxel (Taxol®), which is mainly produced in Taxus and has been widely used in cancer chemotherapy. The phytohormone methyl jasmonate (MeJA) can significantly increase the production of paclitaxel, which is induced in plants as a secondary metabolite possibly in defense against herbivores and pathogens. In cell culture, MeJA also elicits the accumulation of paclitaxel; however, the mechanism is still largely unknown.Methodology/Principal FindingsTo obtain insight into the global regulation mechanism of MeJA in the steady state of paclitaxel production (7 days after MeJA addition), especially on paclitaxel biosynthesis, we sequenced the transcriptomes of MeJA-treated and untreated Taxus × media cells and obtained ∼ 32.5 M high quality reads, from which 40,348 unique sequences were obtained by de novo assembly. Expression level analysis indicated that a large number of genes were associated with transcriptional regulation, DNA and histone modification, and MeJA signaling network. All the 29 known genes involved in the biosynthesis of terpenoid backbone and paclitaxel were found with 18 genes showing increased transcript abundance following elicitation of MeJA. The significantly up-regulated changes of 9 genes in paclitaxel biosynthesis were validated by qRT-PCR assays. According to the expression changes and the previously proposed enzyme functions, multiple candidates for the unknown steps in paclitaxel biosynthesis were identified. We also found some genes putatively involved in the transport and degradation of paclitaxel. Potential target prediction of miRNAs indicated that miRNAs may play an important role in the gene expression regulation following the elicitation of MeJA.Conclusions/SignificanceOur results shed new light on the global regulation mechanism by which MeJA regulates the physiology of Taxus cells and is helpful to understand how MeJA elicits other plant species besides Taxus.

Perfluorodecalin-supported system enhances taxane production in hairy root cultures of Taxus x media var. Hicksii carrying a taxadiene synthase transgene

“…To date, the most effective strategy for enhancing in vitro taxane production has been considered to be elicitation with methyl jasmonate (MJ), and immense effort has been invested in elucidating its molecular mechanism of action in yew cell suspension cultures, revealing the upregulation of genes engaged in the taxane biosynthetic pathway (Nims et al 2006;Onrubia et al 2010Onrubia et al , 2012Lenka et al 2012;Li et al 2012;Sun et al 2013).…”

Methyl jasmonate represses growth and affects cell cycle progression in cultured Taxus cells

“…Increased secondary metabolite accumulation upon MeJA elicitation is often accompanied with concurrent decreases in culture growth (Kim et al 2005), Thanh et al 2005, Zhang and Turner 2008, Sun et al 2013). MeJA has been shown to broadly induce defense responses and secondary metabolism in plants (Farmer and Ryan 1990, Reymond and Farmer 1998, Seo et al 2001), which diverts carbon resource allocation from primary metabolism (Logemann et al 1995, Pauwels et al 2009).…”

Methyl Jasmonate-Elicited Transcriptional Responses and Pentacyclic Triterpene Biosynthesis in Sweet Basil

“…When plants experience various biotic and abiotic stresses, biosynthesis of the secondary metabolites is triggered that helps plants adapt to the challenging environment (Gershenzon and Dudareva, 2007;Hartmann, 2007;Reichling, 2010). Consequently, transcript and metabolite profiling of stress/elicitor-treated plants or cell cultures represents a powerful approach to determine gene function in the biosynthesis of the secondary metabolites (Aerts et al, 1994;Goossens et al, 2003;Suzuki et al, 2005;Zhao et al, 2005;Naoumkina et al, 2008;De Geyter et al, 2012;Lenka et al, 2012;Yu et al, 2012;Ee et al, 2013;Mishra et al, 2013;Sun et al, 2013).…”

“…Several studies have demonstrated that MeJA treatment can trigger the biosynthesis of all three major classes of secondary metabolites (i.e. terpenoids, phenylpropanoids, and alkaloids) through an extensive transcriptional reprogramming of the plant metabolism (Gundlach et al, 1992;Cheong and Choi, 2003;Zhao et al, 2005;Pauwels et al, 2009;De Geyter et al, 2012;Sun et al, 2013). Here, we carried out transcriptome and selected metabolite analyses to identify the MeJA-responsive secondary metabolic pathways of sweet basil (Ocimum basilicum), which is a plant of the Lamiaceae family with highly valued aromatic and medicinal properties.…”