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Molecular Research in Plant Secondary Metabolism 2021

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A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Molecular Plant Sciences".

Deadline for manuscript submissions: closed (30 April 2021) | Viewed by 39576

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Special Issue Editors

Dr. Cha Young Kim

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Guest Editor

Biological Resource Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Jeongeup 56212, Republic of Korea
Interests: plant biotechnology; plant cell cultures; secondary metabolites; metabolite farming; elicitation technology; elicitors; healthcare biomaterials; plant metabolism; gene–metabolite; regulatory network; biological activities; plant cell and tissue cultures
Special Issues, Collections and Topics in MDPI journals

Dr. In-Cheol Jang

E-Mail Website
Guest Editor

1. Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604, Singapore
2. Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore
Interests: plant secondary metabolism/metabolites; plant metabolic engineering; terpenoids; phenylpropanoids; light signaling; phytohormone signaling; abiotic stress; plant nutrients; indoor farming
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Plants naturally produce primary and secondary metabolites. Primary metabolites are directly involved in plant growth and metabolic function. Plant secondary metabolites are not essential for a plant’s basic metabolism but still play significant roles in allowing the plant to adapt to and thrive in its environment. Plant secondary metabolites are numerous chemical compounds produced by the plant cells through metabolic pathways derived from the primary metabolic pathways. They have great application in human health and nutritional aspects. They possess various biological activities such as antimicrobial, antifungal, anticancer, anti-inflammatory, antitumoral, antiproliferative, and antihypertensive activities. Currently, these compounds can be obtained via extraction from plant raw materials, via chemical synthesis, and from plant in vitro cultures. In many cases, the chemical synthesis of these metabolites is not possible or economically feasible. Plant biotechnology methods provide new tools and strategies not only to produce bioactive secondary metabolites, but also to enhance the quantities of these important phytochemicals. To date, most attempts have been employed to increase biotechnological production using various methodologies (for example, elicitor-mediated enhancement of secondary metabolites) to enhance metabolite biosynthesis and accumulation. Plant cell and tissue culture systems are a feasible option and useful production platform for the production of secondary metabolites that are of commercial importance in pharmaceuticals, food additives, flavors, and other industrial materials.

Biotechnology offers a valuable tool to produce these secondary metabolites in plant cells, tissues, organs, and plants using plant cell and tissue cultures and genetic manipulation for enhanced production of key metabolites. Elicitors are chemical compounds from abiotic and biotic sources that can stimulate stress responses in plants or plant cell and tissue cultures, leading to the activation of biosynthetic pathways for secondary metabolites and the enhanced biosynthesis and accumulation of secondary metabolites. By employing biotechnological techniques, it is possible to regulate the biosynthetic pathways of plants in order to enhance the biosynthesis of secondary metabolites.

The present Special Issue has been conceived with the intention of discussing the various facets in light of recent advances of secondary metabolite production via plant biotechnology. Authors are invited to submit their original research articles and review papers for possible inclusion in this Special Issue.

Potential topics include but are not limited to the following:

Biosynthesis, regulation, and biotechnological approaches of plant secondary metabolites via plant cell and tissue cultures;
Functions of plant secondary metabolites both in nature and in biotechnology;
Optimizing the culture conditions and environmental and physical factors (elicitors);
Elicitor-mediated production of secondary metabolites;
Understanding of secondary metabolite biosynthesis and function;
Regulation of metabolite biosynthetic pathways;
Plant cell suspension cultures;
Plant tissue/organ cultures (adventitious or hairy root cultures, multi-shoot cultures, etc.);
Plant sprout cultures;
Scaling up the cultures for large-scale production: bioreactors, smart farming, etc.;
Biotechnological applications of plant secondary metabolites;
Identification and modification of endogenous pathways for potential molecular targets;
Metabolic engineering to improve the production of valuable plant secondary metabolites.

Dr. Cha Young Kim
Dr. In-Cheol Jang
Guest Editors

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. International Journal of Molecular Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

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Keywords

secondary metabolites
bioactive compounds
functional biomaterials
plant biotechnology
food additives
neutraceuticals
pharmaceuticals
plant cell and tissue cultures
metabolic pathway regulation
elicitation

Related Special Issue

Molecular Research in Plant Secondary Metabolism 2022 in International Journal of Molecular Sciences (10 articles)

Published Papers (12 papers)

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Research

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17 pages, 2116 KiB

Open AccessArticle

Assessment of the Role of PAL in Lignin Accumulation in Wheat (Tríticum aestívum L.) at the Early Stage of Ontogenesis

by Pavel Feduraev, Anastasiia Riabova, Liubov Skrypnik, Artem Pungin, Elina Tokupova, Pavel Maslennikov and Galina Chupakhina

Int. J. Mol. Sci. 2021, 22(18), 9848; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms22189848 - 12 Sep 2021

Cited by 12 | Viewed by 2480

Abstract

The current study evaluates the role of phenylalanine ammonia-lyase (PAL) and the associated metabolic complex in the accumulation of lignin in common wheat plants (Tríticum aestívum L.) at the early stages of ontogenesis. The data analysis was performed using plant samples that had reached Phases 4 and 5 on the Feekes scale—these phases are characterized by a transition to the formation of axial (stem) structures in cereal plants. We have shown that the substrate stimulation of PAL with key substrates, such as L-phenylalanine and L-tyrosine, leads to a significant increase in lignin by an average of 20% in experimental plants compared to control plants. In addition, the presence of these compounds in the nutrient medium led to an increase in the number of gene transcripts associated with lignin synthesis (PAL6, C4H1, 4CL1, C3H1). Inhibition was the main tool of the study. Potential competitive inhibitors of PAL were used: the optical isomer of L-phenylalanine—D-phenylalanine—and the hydroxylamine equivalent of phenylalanine—O-Benzylhydroxylamine. As a result, plants incubated on a medium supplemented with O-Benzylhydroxylamine were characterized by reduced PAL activity (almost one third). The lignin content of the cell wall in plants treated with O-Benzylhydroxylamine was almost halved. In contrast, D-phenylalanine did not lead to significant changes in the lignin-associated metabolic complex, and its effect was similar to that of specific substrates. Full article

(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism 2021)

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17 pages, 3929 KiB

Open AccessArticle

Molecular and Functional Evolution of the Spermatophyte Sesquiterpene Synthases

by Dongmei Liang, Weiguo Li, Xiaoguang Yan, Qinggele Caiyin, Guangrong Zhao and Jianjun Qiao

Int. J. Mol. Sci. 2021, 22(12), 6348; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms22126348 - 14 Jun 2021

Cited by 6 | Viewed by 2607

Abstract

Sesquiterpenes are important defense and signal molecules for plants to adapt to the environment, cope with stress, and communicate with the outside world, and their evolutionary history is closely related to physiological functions. In this study, the information of plant sesquiterpene synthases (STSs) with identified functions were collected and sorted to form a dataset containing about 500 members. The phylogeny of spermatophyte functional STSs was constructed based on the structural comparative analysis to reveal the sequence–structure–function relationships. We propose the evolutionary history of plant sesquiterpene skeletons, from chain structure to small rings, followed by large rings for the first time and put forward a more detailed function-driven hypothesis. Then, the evolutionary origins and history of spermatophyte STSs are also discussed. In addition, three newly identified STSs CaSTS2, CaSTS3, and CaSTS4 were analyzed in this functional evolutionary system, and their germacrene D products were consistent with the functional prediction. This demonstrates an application of the structure-based phylogeny in predicting STS function. This work will help us to understand evolutionary patterns and dynamics of plant sesquiterpenes and STSs and screen or design STSs with specific product profiles as functional elements for synthetic biology application. Full article

(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism 2021)

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21 pages, 5674 KiB

Open AccessArticle

Comparative Study of the Genetic and Biochemical Variability of Polyscias filicifolia (Araliaceae) Regenerants Obtained by Indirect and Direct Somatic Embryogenesis as a Source of Triterpenes

by Anita A. Śliwińska, Agnieszka Białek, Renata Orłowska, Dariusz Mańkowski, Katarzyna Sykłowska-Baranek and Agnieszka Pietrosiuk

Int. J. Mol. Sci. 2021, 22(11), 5752; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms22115752 - 27 May 2021

Cited by 8 | Viewed by 2608

Abstract

Polyscias filicifolia (Araliaceae) is broadly used in traditional medicine in Southeast Asia due to its antimicrobial, immunomodulating and cytotoxic activities. The main groups of compounds responsible for pharmacological effects are believed to be oleanolic triterpene saponins. However, Polyscias plants demonstrate relatively slow growth in natural conditions, which led to applying a developing sustainable source of plant material via primary (PSE), secondary (DSE) and direct somatic embryogenesis from DSE (TSE). The AFLP and metAFLP genotyping resulted in 1277 markers, amplified by a total of 24 pairs of selective primers. Only 3.13% of the markers were polymorphic. The analysis of variance showed that the PSE and TSE regenerants differed only in terms of root number, while the DSE plantlets differed for all studied morphological characteristics. Further, the chemical analysis revealed that oleanolic acid (439.72 µg/g DW), ursolic acid (111.85 µg/g DW) and hederagenin (19.07 µg/g DW) were determined in TSE regenerants. Our results indicate that direct somatic embryogenesis ensures the production of homogeneous plant material, which can serve as a potential source of triterpene compounds. Plants obtained via somatic embryogenesis could also be reintroduced into the natural environment to protect and preserve its biodiversity. Full article

(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism 2021)

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15 pages, 3316 KiB

Open AccessArticle

Synergistic Effect of Methyl Jasmonate and Abscisic Acid Co-Treatment on Avenanthramide Production in Germinating Oats

by Soyoung Kim, Tae Hee Kim, Yu Jeong Jeong, Su Hyun Park, Sung Chul Park, Jiyoung Lee, Kwang Yeol Yang, Jae Cheol Jeong and Cha Young Kim

Int. J. Mol. Sci. 2021, 22(9), 4779; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms22094779 - 30 Apr 2021

Cited by 9 | Viewed by 2588

Abstract

The oat (Avena sativa L.) is a grain of the Poaceae grass family and contains many powerful anti-oxidants, including avenanthramides as phenolic alkaloids with anti-inflammatory, anti-oxidant, anti-itch, anti-irritant, and anti-atherogenic activities. Here, the treatment of germinating oats with methyl jasmonate (MeJA) or abscisic acid (ABA) resulted in 2.5-fold (582.9 mg/kg FW) and 2.8-fold (642.9 mg/kg FW) increase in avenanthramide content, respectively, relative to untreated controls (232.6 mg/kg FW). Moreover, MeJA and ABA co-treatment synergistically increased avenanthramide production in germinating oats to 1505 mg/kg FW. Individual or combined MeJA and ABA treatment increased the expression of genes encoding key catalytic enzymes in the avenanthramide-biosynthesis pathway, including hydroxycinnamoyl-CoA:hydrocyanthranilate N-hydroxycinnamoyl transferase (HHT). Further analyses showed that six AsHHT genes were effectively upregulated by MeJA or ABA treatment, especially AsHHT4 for MeJA and AsHHT5 for ABA, thereby enhancing the production of all three avenanthramides in germinating oats. Specifically, AsHHT5 exhibited the highest expression following MeJA and ABA co-treatment, indicating that AsHHT5 played a more crucial role in avenanthramide biosynthesis in response to MeJA and ABA co-treatment of germinating oats. These findings suggest that elicitor-mediated metabolite farming using MeJA and ABA could be a valuable method for avenanthramide production in germinating oats. Full article

(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism 2021)

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10 pages, 3011 KiB

Open AccessArticle

Effect of Light and Dark on the Phenolic Compound Accumulation in Tartary Buckwheat Hairy Roots Overexpressing ZmLC

by Chang Ha Park, Ye Eun Park, Hyeon Ji Yeo, Nam Il Park and Sang Un Park

Int. J. Mol. Sci. 2021, 22(9), 4702; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms22094702 - 29 Apr 2021

Cited by 15 | Viewed by 2343

Abstract

Fagopyrum tataricum ‘Hokkai T10′ is a buckwheat cultivar capable of producing large amounts of phenolic compounds, including flavonoids (anthocyanins), phenolic acids, and catechin, which have antioxidant, anticancer, and anti-inflammatory properties. In the present study, we revealed that the maize transcription factor Lc increased the accumulation of phenolic compounds, including sinapic acid, 4-hydroxybenzonate, t-cinnamic acid, and rutin, in Hokkai T10 hairy roots cultured under long-photoperiod (16 h light and 8 h dark) conditions. The transcription factor upregulated phenylpropanoid and flavonoid biosynthesis pathway genes, yielding total phenolic contents reaching 27.0 ± 3.30 mg g⁻¹ dry weight, 163% greater than the total flavonoid content produced by a GUS-overexpressing line (control). In contrast, when cultured under continuous darkness, the phenolic accumulation was not significantly different between the ZmLC-overexpressing hairy roots and the control. These findings suggest that the transcription factor (ZmLC) activity may be light-responsive in the ZmLC-overexpressing hairy roots of F. tataricum, triggering activation of the phenylpropanoid and flavonoid biosynthesis pathways. Further studies are required on the optimization of light intensity in ZmLC-overexpressing hairy roots of F. tataricum to enhance the production of phenolic compounds. Full article

(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism 2021)

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14 pages, 3114 KiB

Open AccessArticle

A Novel WRKY Transcription Factor HmoWRKY40 Associated with Betalain Biosynthesis in Pitaya (Hylocereus monacanthus) through Regulating HmoCYP76AD1

by Lulu Zhang, Canbin Chen, Fangfang Xie, Qingzhu Hua, Zhike Zhang, Rong Zhang, Jianye Chen, Jietang Zhao, Guibing Hu and Yonghua Qin

Int. J. Mol. Sci. 2021, 22(4), 2171; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms22042171 - 22 Feb 2021

Cited by 24 | Viewed by 2815

Abstract

Betalains are water-soluble nitrogen-containing pigments with multiple bioactivities. Pitaya is the only large-scale commercially grown fruit containing abundant betalains for consumers. However, the upstream regulators in betalain biosynthesis are still not clear. In this study, HmoWRKY40, a novel WRKY transcription factor, was obtained from the transcriptome data of pitaya (Hylocereus monacanthus). HmoWRKY40 is a member of the Group IIa WRKY family, containing a conserved WRKY motif, and it is located in the nucleus. The betalain contents and expression levels of HmoWRKY40 increased rapidly during the coloration of pitaya and reached their maximums on the 23rd day after artificial pollination (DAAP). Yeast one-hybrid and transient expression assays showed that HmoWRKY40 could bind and activate the promoter of HmoCYP76AD1. Silencing the HmoWRKY40 gene resulted in a significant reduction of betacyanin contents. These results indicate that HmoWRKY40 transcriptionally activates HmoCYP76AD, which is involved in the regulation of pitaya betalain biosynthesis. The results of the present study provide new regulatory networks related to betalain biosynthesis in pitaya. Full article

(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism 2021)

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22 pages, 4497 KiB

Open AccessArticle

Sweet Basil Has Distinct Synthases for Eugenol Biosynthesis in Glandular Trichomes and Roots with Different Regulatory Mechanisms

by Vaishnavi Amarr Reddy, Chunhong Li, Kumar Nadimuthu, Jessica Gambino Tjhang, In-Cheol Jang and Sarojam Rajani

Int. J. Mol. Sci. 2021, 22(2), 681; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms22020681 - 12 Jan 2021

Cited by 6 | Viewed by 2630

Abstract

Production of a volatile phenylpropene; eugenol in sweet basil is mostly associated with peltate glandular trichomes (PGTs) found aerially. Currently only one eugenol synthase (EGS), ObEGS1 which belongs to PIP family is identified from sweet basil PGTs. Reports of the presence of eugenol in roots led us to analyse other EGSs in roots. We screened for all the PIP family reductase transcripts from the RNA-Seq data. In vivo functional characterization of all the genes in E. coli showed their ability to produce eugenol and were termed as ObEGS2-8. Among all, ObEGS1 displayed highest expression in PGTs and ObEGS4 in roots. Further, eugenol was produced only in the roots of soil-grown plants, but not in roots of aseptically-grown plants. Interestingly, eugenol production could be induced in roots of aseptically-grown plants under elicitation suggesting that eugenol production might occur as a result of environmental cues in roots. The presence of ObEGS4 transcript and protein in aseptically-grown plants indicated towards post-translational modifications (PTMs) of ObEGS4. Bioinformatics analysis showed possibility of phosphorylation in ObEGS4 which was further confirmed by in vitro experiment. Our study reveals the presence of multiple eugenol synthases in sweet basil and provides new insights into their diversity and tissue specific regulation. Full article

(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism 2021)

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15 pages, 7078 KiB

Open AccessArticle

Lipopolysaccharide Enhances Tanshinone Biosynthesis via a Ca²⁺-Dependent Manner in Salvia miltiorrhiza Hairy Roots

by Bin Zhang, Xueying Li, Xiuhong Li, Zhigang Lu, Xiaona Cai, Qing Ou Yang, Pengda Ma and Juane Dong

Int. J. Mol. Sci. 2020, 21(24), 9576; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms21249576 - 16 Dec 2020

Cited by 10 | Viewed by 1974

Abstract

Tanshinones, the major bioactive components in Salvia miltiorrhiza Bunge (Danshen), are synthesized via the mevalonic acid (MVA) pathway or the 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway and the downstream biosynthesis pathway. In this study, the bacterial component lipopolysaccharide (LPS) was utilized as a novel elicitor to induce the wild type hairy roots of S. miltiorrhiza. HPLC analysis revealed that LPS treatment resulted in a significant accumulation of cryptotanshinone (CT) and dihydrotanshinone I (DTI). qRT-PCR analysis confirmed that biosynthesis genes such as SmAACT and SmHMGS from the MVA pathway, SmDXS and SmHDR from the MEP pathway, and SmCPS, SmKSL and SmCYP76AH1 from the downstream pathway were markedly upregulated by LPS in a time-dependent manner. Furthermore, transcription factors SmWRKY1 and SmWRKY2, which can activate the expression of SmDXR, SmDXS and SmCPS, were also increased by LPS. Since Ca²⁺ signaling is essential for the LPS-triggered immune response, Ca²⁺ channel blocker LaCl₃ and CaM antagonist W-7 were used to investigate the role of Ca²⁺ signaling in tanshinone biosynthesis. HPLC analysis demonstrated that both LaCl₃ and W-7 diminished LPS-induced tanshinone accumulation. The downstream biosynthesis genes including SmCPS and SmCYP76AH1 were especially regulated by Ca²⁺ signaling. To summarize, LPS enhances tanshinone biosynthesis through SmWRKY1- and SmWRKY2-regulated pathways relying on Ca²⁺ signaling. Ca²⁺ signal transduction plays a key role in regulating tanshinone biosynthesis in S. miltiorrhiza. Full article

(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism 2021)

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17 pages, 2615 KiB

Open AccessArticle

Identification and Functional Characterization of Tissue-Specific Terpene Synthases in Stevia rebaudiana

by Savitha Dhandapani, Mi Jung Kim, Hui Jun Chin, Sing Hui Leong and In-Cheol Jang

Int. J. Mol. Sci. 2020, 21(22), 8566; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms21228566 - 13 Nov 2020

Cited by 6 | Viewed by 2417

Abstract

In addition to the well-known diterpenoid steviol glycosides, Stevia rebaudiana (Stevia) produces many labdane-type diterpenoids and a wide range of mono- and sesquiterpenoids. However, biosynthesis of mono- and sesquiterpenoids in Stevia remains unknown. Here we analyzed the extracts of Stevia leaves, flowers, stems, and roots by Gas Chromatography–Mass Spectrometry and putatively identified a total of 69 volatile organic compounds, most of which were terpenoids with considerably varied quantities among the four tissues of Stevia. Using Stevia transcriptomes, we identified and functionally characterized five terpene synthases (TPSs) that produced major mono- and sesquiterpenoids in Stevia. Transcript levels of these Stevia TPSs and levels of corresponding terpenoids correlated well in Stevia tissues. Particularly, the root-specific SrTPS4 and SrTPS5 catalyzed the formation of γ-curcumene/zingiberene/β-sesquiphellandrene and α-longipinene/β-himachalene/himachalol as multifunctional sesqui-TPSs, respectively. Most of the SrTPSs were highly responsive to various environmental stresses in a tissue-specific manner. Taken together, our results provide new insights into how Stevia produces diverse terpenoids to confer differential responses to various environmental factors in each tissue. Full article

(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism 2021)

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27 pages, 4395 KiB

Open AccessArticle

Integrated Analysis of the Transcriptome and Metabolome of Cecropia obtusifolia: A Plant with High Chlorogenic Acid Content Traditionally Used to Treat Diabetes Mellitus

by Jorge David Cadena-Zamudio, Pilar Nicasio-Torres, Juan Luis Monribot-Villanueva, José Antonio Guerrero-Analco and Enrique Ibarra-Laclette

Int. J. Mol. Sci. 2020, 21(20), 7572; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms21207572 - 14 Oct 2020

Cited by 11 | Viewed by 2674

Abstract

This investigation cultured Cecropia obtusifolia cells in suspension to evaluate the effect of nitrate deficiency on the growth and production of chlorogenic acid (CGA), a secondary metabolite with hypoglycemic and hypolipidemic activity that acts directly on type 2 diabetes mellitus. Using cell cultures in suspension, a kinetics time course was established with six time points and four total nitrate concentrations. The metabolites of interest were quantified by high-performance liquid chromatography (HPLC), and the metabolome was analyzed using directed and nondirected approaches. Finally, using RNA-seq methodology, the first transcript collection for C. obtusifolia was generated. HPLC analysis detected CGA at all sampling points, while metabolomic analysis confirmed the identity of CGA and of precursors involved in its biosynthesis. Transcriptome analysis identified differentially expressed genes and enzymes involved in the biosynthetic pathway of CGA. C. obtusifolia probably expresses a key enzyme with bifunctional activity, the hydroxycinnamoyl-CoA quinate hydroxycinnamoyl transferase and hydroxycinnamoyl-CoA shikimate/quinate hydroxycinnamoyl transferase (HQT/HCT), which recognizes shikimic acid or quinic acid as a substrate and incorporates either into one of the two routes responsible for CGA biosynthesis. Full article

(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism 2021)

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13 pages, 1620 KiB

Open AccessArticle

Metabolism of Gallic Acid and Its Distributions in Tea (Camellia sinensis) Plants at the Tissue and Subcellular Levels

by Xiaochen Zhou, Lanting Zeng, Yingjuan Chen, Xuewen Wang, Yinyin Liao, Yangyang Xiao, Xiumin Fu and Ziyin Yang

Int. J. Mol. Sci. 2020, 21(16), 5684; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms21165684 - 08 Aug 2020

Cited by 21 | Viewed by 5352

Abstract

In tea (Camellia sinensis) plants, polyphenols are the representative metabolites and play important roles during their growth. Among tea polyphenols, catechins are extensively studied, while very little attention has been paid to other polyphenols such as gallic acid (GA) that occur in tea leaves with relatively high content. In this study, GA was able to be transformed into methyl gallate (MG), suggesting that GA is not only a precursor of catechins, but also can be transformed into other metabolites in tea plants. GA content in tea leaves was higher than MG content—regardless of the cultivar, plucking month or leaf position. These two metabolites occurred with higher amounts in tender leaves. Using nonaqueous fractionation techniques, it was found that GA and MG were abundantly accumulated in peroxisome. In addition, GA and MG were found to have strong antifungal activity against two main tea plant diseases, Colletotrichum camelliae and Pseudopestalotiopsis camelliae-sinensis. The information will advance our understanding on formation and biologic functions of polyphenols in tea plants and also provide a good reference for studying in vivo occurrence of specialized metabolites in economic plants. Full article

(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism 2021)

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19 pages, 1438 KiB

Open AccessReview

The Biochemistry of Phytocannabinoids and Metabolic Engineering of Their Production in Heterologous Systems

by Kaitlyn Blatt-Janmaat and Yang Qu

Int. J. Mol. Sci. 2021, 22(5), 2454; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms22052454 - 28 Feb 2021

Cited by 19 | Viewed by 6795

Abstract

The medicinal properties of cannabis and the its legal status in several countries and jurisdictions has spurred the massive growth of the cannabis economy around the globe. The value of cannabis stems from its euphoric activity offered by the unique phytocannabinoid tetrahydrocannabinol (THC). However, this is rapidly expanding beyond THC owing to other non-psychoactive phytocannabinoids with new bioactivities that will contribute to their development into clinically useful drugs. The discovery of the biosynthesis of major phytocannabinoids has allowed the exploration of their heterologous production by synthetic biology, which may lead to the industrial production of rare phytocannabinoids or novel synthetic cannabinoid pharmaceuticals that are not easily offered by cannabis plants. This review summarizes the biosynthesis of major phytocannabinoids in detail, the most recent development of their metabolic engineering in various systems, and the engineering approaches and strategies used to increase the yield. Full article

(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism 2021)

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