Transcriptomic analysis of genes related to alkaloid biosynthesis and the regulation mechanism under precursor and methyl jasmonate treatment in Dendrobium officinale

Abstract

Dendrobium officinale is both a traditional herbal medicine and a plant of high ornamental and medicinal value. Alkaloids, especially terpenoid indole alkaloids (TIAs), with pharmacological activities are present in the tissues of D. officinale. A number of genes involved in alkaloid biosynthetic pathways have been identified. However, the regulatory mechanisms underlying the precursor and methyl jasmonate (MeJA)-induced accumulation of alkaloids in D. officinale are poorly understood. In this study, we collected D. officinale protocorm-like bodies (PLBs) and treated them with TIA precursors (tryptophan and secologanin) and MeJA for 0 (T0), 4 (T4) and 24 h (T24); we also established control samples (C4 and C24). Then, we measured the total alkaloid content of the PLBs and performed transcriptome sequencing using the Illumina HiSeq 2,500 system. The total alkaloid content increased significantly after 4 h of treatment. Go and KEGG analysis suggested that genes from the TIA, isoquinoline alkaloid, tropane alkaloid and jasmonate (JA) biosynthetic pathways were significantly enriched. Weighted gene coexpression network analysis (WGCNA) uncovered brown module related to alkaloid content. Six and seven genes related to alkaloid and JA bisosynthetic pathways, respectively, might encode the key enzymes involved in alkaloid biosynthesis of D. officinale. Moreover, 13 transcription factors (TFs), which mostly belong to AP2/ERF, WRKY, and MYB gene families, were predicted to regulate alkaloid biosynthesis. Our data provide insight for studying the regulatory mechanism underlying TIA precursor and MeJA-induced accumulation of three types of alkaloids in D. officinale.

Uncovering the involvement of DoDELLA1-interacting proteins in development by characterizing the DoDELLA gene family in Dendrobium officinale

“…The MYB gene family is widely involved in plant growth and development, not only in model plants, but also in major crops and horticultural plants [ 85 – 88 ]. Studies on MYB in D. officinale mainly focused on polysaccharide synthesis [ 89 ], flower development [ 89 ], stress response [ 90 , 91 ], alkaloid biosynthesis [ 92 ] and terpenoid biosynthesis [ 93 ], suggesting that DoDELLA1 and DoMYBs may co-regulate one or more aspects of D. officinale , although the related functions need to be further explored and verified. WALLS ARE THIN1 (WAT1) is a plant-specific protein that regulates the secondary cell wall thickness of stem fibers and participates in the integration of auxin signaling in A. thaliana fibers [ 94 , 95 ].…”

In-depth analysis of large-scale screening of WRKY members based on genome-wide identification

“…To further clarify the roles of the WRKY genes in abiotic stress, we conducted a comparative transcriptomic analysis of MeJA-treated D. officinale at different stages ( Jiao et al, 2022 ). The results showed that WRKY family members were differentially expressed at different treatment times and showed two expression patterns ( Figure 7 ).…”

Chemical Constituents, Bioactivities, and Pharmacological Mechanisms of Dendrobium officinale: A Review of the Past Decade

“…HPLC showed that the activity of strictosidine synthase was improved, and carapanaubine (a type of TIA) levels were significantly up-regulated. 29 In addition, total alkaloid content in the D. of f icinale protocorms treated with TIA precursor substances (tryptophan and saponin) and MeJA for 4 h was significantly higher than that in the untreated group. Further transcriptome analysis revealed that alkaloid content was highly correlated with the expression of six genes involved in alkaloid biosynthesis, including DHS (Dca021396), DoADH (Dca025688), DoTYDC (Dca021379), and DoTR (Dca000522, Dca027425, and Dca000521), as well as seven genes related to jasmonate biosynthesis, including DoLOX (Dca023278), DoAOS (Dca022684), and DoOPR (newGene_9791, newGene_13686, Dca023268, Dca001807, and Dca000910), which may play important roles in the alkaloid biosynthesis of D. of f icinale.…”

“…30 Another study 31 suggested that the alkaloid content in D. off icinale samples treated with MeJA was highest at 32 days (343 μg/g), consistent with previous studies. 29 Furthermore, based on solid-phase extraction coupled with high-performance liquid chromatographytandem mass spectrometry (SPE-HPLC-LC-MS/MS), 49 compounds were identified from the MeJA-treated samples, including seven alkaloids. 31 Despite the identification of many genes related to alkaloid synthesis through multiomics analysis, most genes have not yet been confirmed by functional studies, and their mechanisms remain incompletely understood.…”

“…Further transcriptome analysis revealed that alkaloid content was highly correlated with the expression of six genes involved in alkaloid biosynthesis, including DHS ( Dca021396 ), DoADH ( Dca025688 ), DoTYDC ( Dca021379 ), and DoTR ( Dca000522 , Dca027425 , and Dca000521 ), as well as seven genes related to jasmonate biosynthesis, including DoLOX ( Dca023278 ), DoAOS ( Dca022684 ), and DoOPR ( newGene_9791 , newGene_13686 , Dca023268 , Dca001807 , and Dca000910 ), which may play important roles in the alkaloid biosynthesis of D. officinale . Weighted gene coexpression network analysis also identified 66 transcription factors, mainly belonging to the AP2/ERF, MYB, bHLH, WRKY, bZIP, and Tify families, that were positively correlated with alkaloid content, as well as transcription factors involved in the regulation of TIAs and isoquinoline alkaloid biosynthesis, including DoFPS ( Dca007721 ), DoDHQS ( Dca008449 ), DoDHS ( Dca021396 and Dca004228 ), DoCS ( Dca015447 ), DoCM ( Dca012195 ), DoTYDC ( Dca021379 ), DoADH ( Dca025688 ), DoTR ( Dca027425 ), DoAOS ( Dca022684 and Dca000659 ), and DoOPR ( Dca023268 ) . Another study suggested that the alkaloid content in D. officinale samples treated with MeJA was highest at 32 days (343 μg/g), consistent with previous studies .…”