Biotransformation of Monoterpenoids by Suspension Cultures of Lavandula angustifolia

Abstract Callus and suspension cultures of Lavandula angustifolia Mill. (Lamiaceae) were established and the effect of different culture media on growth rate was investigated. Terpenoids added to suspension culture to investigate their biotransformation. All samples were analyzed by gas chromatography (GC) and GC-mass spectroscopy (MS). Octan-1-ol, citronellol, linalool, borneol and geraniol were biotransformed products of octanal, citronellal, linalyl acetate, bornyl acetate and geranyl acetate, respectively. Citronellol, linalool, borneol, and menthol didn't change by L. angustifolia suspension cultures. Blue pigment production by cultures of L. angustifolia was also studied. Ester hydrolysis and oxidation were the main reactions which occurred in biotransformation process, which may be attributed to the presence of related or bifunctional enzymes. This technique is a possible way of the production of expensive or rare compounds from cheap and plentiful substrates

Root Cultures of Linum Species Section Syllinum as Rich Sources of 6-Methoxypodophyllotoxin

professor of Pharmacognosy, Tehran Faculty of Pharmacy, Tehran on the occasion of his birthday Linum spp. from section Syllinum are promising for the production of aryltetralin lignans like podophyllotoxin (PTOX) and 6-methoxypodophyllotoxin (MPTOX). MPTOX is a PTOX congener that has cytotoxic activity comparable with PTOX. In this study root cultures of Linum Bungei from section Dasyllinum, L. strictum from section Linastrum, L. album, L. mucronatum ssp. mucronatum and L. nodiflorum from section Syllinum were established and their MPTOX levels were investigated in 1000 ml flasks. Root cultures of L. mucronatum ssp. mucronatum and L. nodiflorum were used to examine cell growth and production of MPTOX during a culture period of 36 days in 250 ml flasks. Considerable amounts of MPTOX in root cultures (1000 ml flasks) of L. album (6 mg/100 g DW), L. mucronatum ssp. mucronatum (770 mg/100 g DW) and L. nodiflorum (91 mg/100 g DW) were detected while it wasn't detected in root cultures of L. Bungei and L. strictum. In time course experiments, the maximum amount of MPTOX in L. nodiflorum root culture was at day 16 with 480 mg/ 100 g DW and the maximum amount of MPTOX in L. mucronatum ssp. mucronatum root culture was at day 12 with 130 mg/100 g DW. The results showed that root cultures of Linum species from section Syllinum are rich sources of MPTOX and since this lignan has remarkable cytotoxic activity, it can be used as a precursor for the production of antitumor agents

Transcriptional machineries in jasmonate-elicited plant secondary metabolism

Jasmonates (JAs) act as conserved elicitors of plant secondary metabolism. JA perception triggers extensive transcriptional reprogramming leading to the concerted activation of entire metabolic pathways. This observation inspired numerous quests for 'master' regulators capable of enhancing the production of specific sets of valuable plant metabolites. Many transcription factors (TFs), often JA-activated themselves, with a role in the JA-modulated regulation of metabolism were discovered. At the same time, it became clear that metabolic reprogramming is subject to complex control mechanisms integrated in robust cellular networks. In this review, we discuss current knowledge of the effect of JA-modulated TFs in the elicitation of secondary metabolism in the model plant Arabidopsis (Arabidopsis thaliana) and a range of medicinal plant species with structurally divergent secondary metabolites. We draw parallels with the regulation of secondary metabolism in fungi and consider the remaining challenges to map and exploit the transcriptional machineries that drive JA-mediated elicitation of plant secondary metabolism

Natural product biosynthesis in Medicago species

The genus Medicago, a member of the legume (Fabaceae) family, comprises 87 species of flowering plants, including the forage crop M. sativa (alfalfa) and the model legume M. truncatula (barrel medic). Medicago species synthesize a variety of bioactive natural products that are used to engage into symbiotic interactions but also serve to deter pathogens and herbivores. For humans, these bioactive natural products often possess promising pharmaceutical properties. In this review, we focus on the two most interesting and well characterized secondary metabolite classes found in Medicago species, the triterpene saponins and the flavonoids, with a detailed overview of their biosynthesis, regulation, and profiling methods. Furthermore, their biological role within the plant as well as their potential utility for human health or other applications is discussed. Finally, we give an overview of the advances made in metabolic engineering in Medicago species and how the development of novel molecular and omics toolkits can influence a better understanding of this genus in terms of specialized metabolism and chemistry. Throughout, we critically analyze the current bottlenecks and speculate on future directions and opportunities for research and exploitation of Medicago metabolism

Biotransformation of Monoterpenoids by Suspension Cultures ofLavandula angustifolia: Monoterpenoid biotransformation

Callus and suspension cultures of Lavandula angustifoliaMill. (Lamiaceae)were established and the effect of different culture media on growth rate wasinvestigated. Terpenoids added to suspension culture to investigate their biotrans-formation. All samples were analyzed by gas chromatography (GC) and GC-massspectroscopy (MS). Octan-1-ol, citronellol, linalool, borneol and geraniol werebiotransformed products of octanal, citronellal, linalyl acetate, bornyl acetate andgeranyl acetate, respectively. Citronellol, linalool, borneol, and menthol didn'tchange by L. angustifoliasuspension cultures. Blue pigment production by culturesof L. angustifoliawas also studied. Ester hydrolysis and oxidation were the main reactions which occurred in biotransformation process, which may be attributed tothe presence of related or bifunctional enzymes. This technique is a possible wayof the production of expensive or rare compounds from cheap and plentiful substrates

The MYB transcription factor emission of methyl anthranilate 1 stimulates emission of methyl anthranilate from Medicago truncatula hairy roots

Plants respond to herbivore or pathogen attacks by activating specific defense programs that include the production of bioactive specialized metabolites to eliminate or deter the attackers. Volatiles play an important role in the interaction of a plant with its environment. Through transcript profiling of jasmonate-elicited Medicago truncatula cells, we identified Emission of Methyl Anthranilate (EMA) 1, a MYB transcription factor that is involved in the emission of the volatile compound methyl anthranilate when expressed in M. truncatula hairy roots, giving them a fruity scent. RNA sequencing (RNA-Seq) analysis of the fragrant roots revealed the upregulation of a methyltransferase that was subsequently characterized to catalyze the O-methylation of anthranilic acid and was hence named M. truncatula anthranilic acid methyl transferase (MtAAMT) 1. Given that direct activation of the MtAAMT1 promoter by EMA1 could not be unambiguously demonstrated, we further probed the RNA-Seq data and identified the repressor protein M. truncatula plant AT-rich sequence and zinc-binding (MtPLATZ) 1. Emission of Methyl Anthranilate 1 binds a tandem repeat of the ACCTAAC motif in the MtPLATZ1 promoter to transactivate gene expression. Overexpression of MtPLATZ1 in transgenic M. truncatula hairy roots led to transcriptional silencing of EMA1, indicating that MtPLATZ1 may be part of a negative feedback loop to control the expression of EMA1. Finally, application of exogenous methyl anthranilate boosted EMA1 and MtAAMT1 expression dramatically, thus also revealing a positive amplification loop. Such positive and negative feedback loops seem to be the norm rather than the exception in the regulation of plant specialized metabolism.NDG, TM, YB and AGh are indebted to the Agency for Innovation by Science and Technology, the VIB International PhD Fellowship Program, the Chinese Scholarship Council (CSC), and the Iranian Ministry for Health and Medical Education, respectively, for pre-doctoral fellowships, and the Research Foundation Flanders (FWO) with a research project grant to AG (G004515N) and a postdoctoral fellowship to JP

The MYB transcription factor Emission of Methyl Anthranilate 1 stimulates emission of methyl anthranilate from Medicago truncatula hairy roots

Plants respond to herbivore or pathogen attacks by activating specific defense programs that include the production of bioactive specialized metabolites to eliminate or deter the attackers. Volatiles play an important role in the interaction of a plant with its environment. Through transcript profiling of jasmonate‐elicited Medicago truncatula cells we identified Emission of Methyl Anthranilate (EMA) 1, a MYB transcription factor that is involved in the emission of the volatile compound methyl anthranilate when expressed in M. truncatula hairy roots, giving them a fruity scent. RNA‐Seq analysis of the fragrant roots revealed the upregulation of a methyltransferase that was subsequently characterized to catalyze the O‐methylation of anthranilic acid and was hence named M. truncatula Anthranilic Acid Methyl Transferase (MtAAMT) 1. Given that direct activation of the MtAAMT1 promoter by EMA1 could not be unambiguously demonstrated, we further probed the RNA‐Seq data and identified the repressor protein M. truncatula Plant AT‐rich sequence and Zinc‐binding (MtPLATZ) 1. EMA1 binds a tandem repeat of the ACCTAAC motif in the MtPLATZ1 promoter to transactivate gene expression. Overexpression of MtPLATZ1 in transgenic M. truncatula hairy roots led to transcriptional silencing of EMA1, indicating that MtPLATZ1 may be part of a negative feedback loop to control the expression of EMA1. Finally, exogenous methyl anthranilate application boosted EMA1 and MtAAMT1 expression dramatically, thus also revealing a positive amplification loop. Such positive and negative feedback loops seem to be a norm rather than an exception in the regulation of plant specialized metabolism