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Special Issue "Molecular Research in Plant Secondary Metabolism"

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A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Biochemistry, Molecular Biology and Biophysics".

Deadline for manuscript submissions: closed (25 April 2013)

Special Issue Editor

Guest Editor
Prof. Dr. Marcello Iriti (Website)

Department of Agricultural and Environmental Sciences, Faculty of Agricultural and Food Sciences, Milan State University, Via G. Celoria 2, Milan 20133, Italy
Interests: bioactive phytochemicals; plant secondary metabolism; medicinal and food plants; environmental pollution; environmental stresses; nutraceuticals; functional foods; ethnobotany; complementary and alternative medicine

Special Issue Information

Dear Colleagues,

In plants, the ecological and functional roles of secondary metabolites range from adaptation to harsh environments, to chemical communication and pollination. In their environment, these sessile organisms have to cope with a plethora of external (potentially) stressful conditions. Pathogen challenge, adverse climate and environmental pollution are detrimental factors that plants have to overcome to survive. Therefore, on the other side of the barricade, plants mount a complex array of defence reactions to tolerate all these biotic and abiotic stresses, including the biosynthesis of antimicrobial and antioxidant phytoalexins. Similarly, plants produce and release semiochemicals and allelochemicals for intra- and interpescific communication, in order to defend themselves from phytophagy and other predators. In addition, flower colours (pigments) and scents (volatile compounds) are pivotal in attracting pollinators, the vectors of pollen grains and key player in reproduction of angiosperms. Plants spent a considerable amount of their metabolic reserves to defend themselves, balancing their available resources between primary (growth and reproduction) and secondary (defence) metabolism. These metabolic costs arise from the complex defence machinery mounted by plants at level of genes, proteins and secondary metabolites. In other terms, defence responses may have an impact on the plant fitness, thus resulting limiting for the species. In the last decades, emphasis has been paid to bioactive secondary metabolites in medicinal and food plants, possibly because of their healthy potential for humans. A huge number of in vitro and in vivo studies documented antimicrobial, antioxidant, anti-inflammatory, immunomodulatory, antitumoral, cardio- and neuroprotective activities of different phytochemicals, including phenylpropanoids, isoprenoids, alkaloids, glucosinolates, betalains and others. In this view, priming plants for improving secondary metabolite biosynthesis may represent a reliable strategy to meet plant defence and human nutrition, with a number of elicitors available in agricultural practice and able to stimulate accumulation of bioactives in plant tissues and products. We invite investigators to submit both original research and review articles that explore all the aspects of plant secondary metabolism and its regulation, at gene, protein and metabolic levels. We are also interested in contributions in the field of chemical ecology, nutraceutical and medicinal plant research. Potential topics include, but are not limited to:

  • Plant resistance mechanisms against pathogens
  • Plant tolerance strategies against abiotic stresses
  • Global climate change
  • Water, air and soil pollution
  • Fitness costs
  • Chemical ecology
  • Nutraceuticals
  • Medicinal plants
  • Essential oils

Professor Marcello Iriti
Guest Editor

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a 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 monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF.

Keywords

  • plant stress physiology and biology
  • bioactive phytochemicals
  • natural products
  • healthy plant foods
  • ethnopharmacology

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Published Papers (30 papers)

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Editorial

Jump to: Research, Review

Open AccessEditorial Plant Neurobiology, a Fascinating Perspective in the Field of Research on Plant Secondary Metabolites
Int. J. Mol. Sci. 2013, 14(6), 10819-10821; doi:10.3390/ijms140610819
Received: 3 May 2013 / Revised: 14 May 2013 / Accepted: 21 May 2013 / Published: 23 May 2013
Cited by 1 | PDF Full-text (169 KB) | HTML Full-text | XML Full-text
Abstract In this Editorial, I comment on the exciting and original topic of plant neurobiology, focusing on natural products whose biosynthesis is shared by animal and plant organisms, i.e., indoleamines (melatonin and serotonin) and catecholamines (dopamine, norepinephrine and epinephrine). Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)

Research

Jump to: Editorial, Review

Open AccessArticle Functional Diversity of Genes for the Biosynthesis of Paeoniflorin and Its Derivatives in Paeonia
Int. J. Mol. Sci. 2013, 14(9), 18502-18519; doi:10.3390/ijms140918502
Received: 18 June 2013 / Revised: 9 August 2013 / Accepted: 19 August 2013 / Published: 9 September 2013
Cited by 4 | PDF Full-text (496 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The Paeonia root, with or without bark, are considered vital traditional Chinese medicine materials; the examples are those of Bai Shao, Chi Shao, and Dan Pi. In this study, we examine 24 genes and their expressions involved in the biosynthesis of paeoniflorin [...] Read more.
The Paeonia root, with or without bark, are considered vital traditional Chinese medicine materials; the examples are those of Bai Shao, Chi Shao, and Dan Pi. In this study, we examine 24 genes and their expressions involved in the biosynthesis of paeoniflorin and its derivatives, which are active compounds of the Paeonia root, in Paeonia lactiflora and P. suffruticosa, as well as other related plants, Punica granatum, Rhus radicans, and Coriaria nepalensis. Our phylogenetic analyses suggest that these genes have functional diversity, and analysis of the transcriptional level shows paeoniflorin and gallic acid biosynthesis-related genes exhibit different transcription profiles in flowers, carpels, bark-free roots, and bark of P. lactiflora. The correlation analysis of gene expression and active compound contents support the idea that hydroxymethylglutaryl-CoA synthase and phosphomevalonate kinase in the mevalonate pathway and 3-dehydroquinate dehydratase/shikimate dehydrogenase in shikimate biosynthesis are potentially closely related to the accumulation of paeoniflorin and benzoylpaeoniflorin. Coupling gene diversity with chemical analysis, we show that paeoniflorin and its derived aromatic amino acids are predominant in bark. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
Open AccessArticle Arbuscular Mycorrhizal Fungi and Plant Growth-Promoting Pseudomonads Increases Anthocyanin Concentration in Strawberry Fruits (Fragaria x ananassa var. Selva) in Conditions of Reduced Fertilization
Int. J. Mol. Sci. 2013, 14(8), 16207-16225; doi:10.3390/ijms140816207
Received: 3 June 2013 / Revised: 19 July 2013 / Accepted: 25 July 2013 / Published: 6 August 2013
Cited by 18 | PDF Full-text (323 KB) | HTML Full-text | XML Full-text
Abstract
Anthocyanins are a group of common phenolic compounds in plants. They are mainly detected in flowers and fruits, are believed to play different important roles such as in the attraction of animals and seed dispersal, and also in the increase of the [...] Read more.
Anthocyanins are a group of common phenolic compounds in plants. They are mainly detected in flowers and fruits, are believed to play different important roles such as in the attraction of animals and seed dispersal, and also in the increase of the antioxidant response in tissues directly or indirectly affected by biotic or abiotic stress factors. As a major group of secondary metabolites in plants commonly consumed as food, they are of importance in both the food industry and human nutrition. It is known that arbuscular mycorrhizal (AM) fungi can influence the plant secondary metabolic pathways such as the synthesis of essential oils in aromatic plants, of secondary metabolites in roots, and increase flavonoid concentration. Plant Growth-Promoting Bacteria (PGPB) are able to increase plant growth, improving plant nutrition and supporting plant development under natural or stressed conditions. Various studies confirmed that a number of bacterial species living on and inside the root system are beneficial for plant growth, yield and crop quality. In this work it is shown that inoculation with AM fungi and/or with selected and tested Pseudomonas strains, under conditions of reduced fertilization, increases anthocyanin concentration in the fruits of strawberry. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
Open AccessArticle Protein Synthesis Inhibition Activity by Strawberry Tissue Protein Extracts during Plant Life Cycle and under Biotic and Abiotic Stresses
Int. J. Mol. Sci. 2013, 14(8), 15532-15545; doi:10.3390/ijms140815532
Received: 3 May 2013 / Revised: 24 June 2013 / Accepted: 17 July 2013 / Published: 25 July 2013
Cited by 2 | PDF Full-text (738 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Ribosome-inactivating proteins (RIPs), enzymes that are widely distributed in the plant kingdom, inhibit protein synthesis by depurinating rRNA and many other polynucleotidic substrates. Although RIPs show antiviral, antifungal, and insecticidal activities, their biological and physiological roles are not completely understood. Additionally, it [...] Read more.
Ribosome-inactivating proteins (RIPs), enzymes that are widely distributed in the plant kingdom, inhibit protein synthesis by depurinating rRNA and many other polynucleotidic substrates. Although RIPs show antiviral, antifungal, and insecticidal activities, their biological and physiological roles are not completely understood. Additionally, it has been described that RIP expression is augmented under stressful conditions. In this study, we evaluated protein synthesis inhibition activity in partially purified basic proteins (hereafter referred to as RIP activity) from tissue extracts of Fragaria × ananassa (strawberry) cultivars with low (Dora) and high (Record) tolerance to root pathogens and fructification stress. Association between the presence of RIP activity and the crop management (organic or integrated soil), growth stage (quiescence, flowering, and fructification), and exogenous stress (drought) were investigated. RIP activity was found in every tissue tested (roots, rhizomes, leaves, buds, flowers, and fruits) and under each tested condition. However, significant differences in RIP distribution were observed depending on the soil and growth stage, and an increase in RIP activity was found in the leaves of drought-stressed plants. These results suggest that RIP expression and activity could represent a response mechanism against biotic and abiotic stresses and could be a useful tool in selecting stress-resistant strawberry genotypes. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
Open AccessArticle Genetic Analysis of Health-Related Secondary Metabolites in a Brassica rapa Recombinant Inbred Line Population
Int. J. Mol. Sci. 2013, 14(8), 15561-15577; doi:10.3390/ijms140815561
Received: 27 May 2013 / Revised: 9 July 2013 / Accepted: 17 July 2013 / Published: 25 July 2013
Cited by 3 | PDF Full-text (459 KB) | HTML Full-text | XML Full-text
Abstract
The genetic basis of the wide variation for nutritional traits in Brassica rapa is largely unknown. A new Recombinant Inbred Line (RIL) population was profiled using High Performance Liquid Chromatography (HPLC) and Nuclear Magnetic Resonance (NMR) analysis to detect quantitative [...] Read more.
The genetic basis of the wide variation for nutritional traits in Brassica rapa is largely unknown. A new Recombinant Inbred Line (RIL) population was profiled using High Performance Liquid Chromatography (HPLC) and Nuclear Magnetic Resonance (NMR) analysis to detect quantitative trait loci (QTLs) controlling seed tocopherol and seedling metabolite concentrations. RIL population parent L58 had a higher level of glucosinolates and phenylpropanoids, whereas levels of sucrose, glucose and glutamate were higher in the other RIL population parent, R-o-18. QTL related to seed tocopherol (α-, β-, γ-, δ-, α-⁄γ- and total tocopherol) concentrations were detected on chromosomes A3, A6, A9 and A10, explaining 11%–35% of the respective variation. The locus on A3 co-locates with the BrVTE1gene, encoding tocopherol cyclase. NMR spectroscopy identified the presence of organic/amino acid, sugar/glucosinolate and aromatic compounds in seedlings. QTL positions were obtained for most of the identified compounds. Compared to previous studies, novel loci were found for glucosinolate concentrations. This work can be used to design markers for marker-assisted selection of nutritional compounds in B. rapa. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
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Open AccessArticle Induced Production of 1-Methoxy-indol-3-ylmethyl Glucosinolate by Jasmonic Acid and Methyl Jasmonate in Sprouts and Leaves of Pak Choi (Brassica rapa ssp. chinensis)
Int. J. Mol. Sci. 2013, 14(7), 14996-15016; doi:10.3390/ijms140714996
Received: 9 May 2013 / Revised: 13 June 2013 / Accepted: 24 June 2013 / Published: 18 July 2013
Cited by 18 | PDF Full-text (370 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Pak choi plants (Brassica rapa ssp. chinensis) were treated with different signaling molecules methyl jasmonate, jasmonic acid, linolenic acid, and methyl salicylate and were analyzed for specific changes in their glucosinolate profile. Glucosinolate levels were quantified using HPLC-DAD-UV, with focus [...] Read more.
Pak choi plants (Brassica rapa ssp. chinensis) were treated with different signaling molecules methyl jasmonate, jasmonic acid, linolenic acid, and methyl salicylate and were analyzed for specific changes in their glucosinolate profile. Glucosinolate levels were quantified using HPLC-DAD-UV, with focus on induction of indole glucosinolates and special emphasis on 1-methoxy-indol-3-ylmethyl glucosinolate. Furthermore, the effects of the different signaling molecules on indole glucosinolate accumulation were analyzed on the level of gene expression using semi-quantitative realtime RT-PCR of selected genes. The treatments with signaling molecules were performed on sprouts and mature leaves to determine ontogenetic differences in glucosinolate accumulation and related gene expression. The highest increase of indole glucosinolate levels, with considerable enhancement of the 1-methoxy-indol-3-ylmethyl glucosinolate content, was achieved with treatments of sprouts and mature leaves with methyl jasmonate and jasmonic acid. This increase was accompanied by increased expression of genes putatively involved in the indole glucosinolate biosynthetic pathway. The high levels of indole glucosinolates enabled the plant to preferentially produce the respective breakdown products after tissue damage. Thus, pak choi plants treated with methyl jasmonate or jasmonic acid, are a valuable tool to analyze the specific protection functions of 1-methoxy-indole-3-carbinole in the plants defense strategy in the future. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
Figures

Open AccessArticle MAEWEST Expression in Flower Development of Two Petunia Species
Int. J. Mol. Sci. 2013, 14(7), 13796-13807; doi:10.3390/ijms140713796
Received: 3 May 2013 / Revised: 14 June 2013 / Accepted: 28 June 2013 / Published: 3 July 2013
PDF Full-text (1242 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Changes in flower morphology may influence the frequency and specificity of animal visitors. In Petunia (Solanaceae), adaptation to different pollinators is one of the factors leading to species diversification within the genus. This study provides evidence that differential expression patterns of MAWEWEST [...] Read more.
Changes in flower morphology may influence the frequency and specificity of animal visitors. In Petunia (Solanaceae), adaptation to different pollinators is one of the factors leading to species diversification within the genus. This study provides evidence that differential expression patterns of MAWEWEST (MAW) homologs in different Petunia species may be associated with adaptive changes in floral morphology. The Petunia × hybrida MAW gene belongs to the WOX (WUSCHEL-related homeobox) transcription factor family and has been identified as a controller of petal fusion during corolla formation. We analyzed the expression patterns of P. inflata and P. axillaris MAW orthologs (PiMAW and PaMAW, respectively) by reverse transcriptase polymerase chain reaction (RT-PCR), reverse transcription–quantitative PCR (qRT-PCR) and in situ hybridization in different tissues and different developmental stages of flowers in both species. The spatial expression patterns of PiMAW and PaMAW were similar in P. inflata and P. axillaris. Nevertheless, PaMAW expression level in P. axillaris was higher during the late bud development stage as compared to PiMAW in P. inflata. This work represents an expansion of petunia developmental research to wild accessions. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
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Open AccessArticle Early Phenylpropanoid Biosynthetic Steps in Cannabis sativa: Link between Genes and Metabolites
Int. J. Mol. Sci. 2013, 14(7), 13626-13644; doi:10.3390/ijms140713626
Received: 13 May 2013 / Revised: 13 June 2013 / Accepted: 14 June 2013 / Published: 28 June 2013
Cited by 5 | PDF Full-text (908 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Phenylalanine ammonia-lyase (PAL), Cinnamic acid 4-hydroxylase (C4H) and 4-Coumarate: CoA ligase (4CL) catalyze the first three steps of the general phenylpropanoid pathway whereas chalcone synthase (CHS) catalyzes the first specific step towards flavonoids production. This class of specialized metabolites has a wide [...] Read more.
Phenylalanine ammonia-lyase (PAL), Cinnamic acid 4-hydroxylase (C4H) and 4-Coumarate: CoA ligase (4CL) catalyze the first three steps of the general phenylpropanoid pathway whereas chalcone synthase (CHS) catalyzes the first specific step towards flavonoids production. This class of specialized metabolites has a wide range of biological functions in plant development and defence and a broad spectrum of therapeutic activities for human health. In this study, we report the isolation of hemp PAL and 4CL cDNA and genomic clones. Through in silico analysis of their deduced amino acid sequences, more than an 80% identity with homologues genes of other plants was shown and phylogenetic relationships were highlighted. Quantitative expression analysis of the four above mentioned genes, PAL and 4CL enzymatic activities, lignin content and NMR metabolite fingerprinting in different Cannabis sativa tissues were evaluated. Furthermore, the use of different substrates to assay PAL and 4CL enzymatic activities indicated that different isoforms were active in different tissues. The diversity in secondary metabolites content observed in leaves (mainly flavonoids) and roots (mainly lignin) was discussed in relation to gene expression and enzymatic activities data. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
Open AccessArticle Metabolomic-Based Study of the Leafy Gall, the Ecological Niche of the Phytopathogen Rhodococcus fascians, as a Potential Source of Bioactive Compounds
Int. J. Mol. Sci. 2013, 14(6), 12533-12549; doi:10.3390/ijms140612533
Received: 22 April 2013 / Revised: 21 May 2013 / Accepted: 4 June 2013 / Published: 14 June 2013
Cited by 4 | PDF Full-text (1126 KB) | HTML Full-text | XML Full-text
Abstract
Leafy gall is a plant hyperplasia induced upon Rhodococcus fascians infection. Previously, by genomic and transcriptomic analysis, it has been reported that, at the early stage of symptom development, both primary and secondary metabolisms are modified. The present study is based on [...] Read more.
Leafy gall is a plant hyperplasia induced upon Rhodococcus fascians infection. Previously, by genomic and transcriptomic analysis, it has been reported that, at the early stage of symptom development, both primary and secondary metabolisms are modified. The present study is based on the hypothesis that fully developed leafy gall, could represent a potential source of new bioactive compounds. Therefore, non-targeted metabolomic analysis of aqueous and chloroform extracts of leafy gall and non-infected tobacco was carried out by 1H-NMR coupled to principal component analysis (PCA) and orthogonal projections to latent structures-discriminant analysis (OPLS-DA). Polar metabolite profiling reflects modifications mainly in the primary metabolites and in some polyphenolics. In contrast, main modifications occurring in non-polar metabolites concern secondary metabolites, and gas chromatography and mass spectrometry (GC-MS) evidenced alterations in diterpenoids family. Analysis of crude extracts of leafy galls and non-infected tobacco leaves exhibited a distinct antiproliferative activity against all four tested human cancer cell lines. A bio-guided fractionation of chloroformic crude extract yield to semi-purified fractions, which inhibited proliferation of glioblastoma U373 cells with IC50 between 14.0 and 2.4 µg/mL. Discussion is focused on the consequence of these metabolic changes, with respect to plant defense mechanisms following infection. Considering the promising role of diterpenoid family as bioactive compounds, leafy gall may rather be a propitious source for drug discovery. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
Open AccessArticle Combining Hexanoic Acid Plant Priming with Bacillus thuringiensis Insecticidal Activity against Colorado Potato Beetle
Int. J. Mol. Sci. 2013, 14(6), 12138-12156; doi:10.3390/ijms140612138
Received: 25 April 2013 / Revised: 29 May 2013 / Accepted: 31 May 2013 / Published: 6 June 2013
Cited by 3 | PDF Full-text (1490 KB) | HTML Full-text | XML Full-text
Abstract
Interaction between insect herbivores and host plants can be modulated by endogenous and exogenous compounds present in the source of food and might be successfully exploited in Colorado potato beetle (CPB) pest management. Feeding tests with CPB larvae reared on three solanaceous [...] Read more.
Interaction between insect herbivores and host plants can be modulated by endogenous and exogenous compounds present in the source of food and might be successfully exploited in Colorado potato beetle (CPB) pest management. Feeding tests with CPB larvae reared on three solanaceous plants (potato, eggplant and tomato) resulted in variable larval growth rates and differential susceptibility to Bacillus thuringiensis Cry3Aa toxin as a function of the host plant. An inverse correlation with toxicity was observed in Cry3Aa proteolytic patterns generated by CPB midgut brush-border membrane vesicles (BBMV) from Solanaceae-fed larvae, being the toxin most extensively proteolyzed on potato, followed by eggplant and tomato. We found that CPB cysteine proteases intestains may interact with Cry3Aa toxin and, in CPB BBMV from larvae fed all three Solanaceae, the toxin was able to compete for the hydrolysis of a papain substrate. In response to treatment with the JA-dependent plant inducer Hexanoic acid (Hx), we showed that eggplant reduced OPDA basal levels and both, potato and eggplant induced JA-Ile. CPB larvae feeding on Hx-induced plants exhibited enhanced Cry3Aa toxicity, which correlated with altered papain activity. Results indicated host-mediated effects on B. thuringiensis efficacy against CPB that can be enhanced in combination with Hx plant induction. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
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Open AccessArticle Versatile Redox Chemistry Complicates Antioxidant Capacity Assessment: Flavonoids as Milieu-Dependent Anti- and Pro-Oxidants
Int. J. Mol. Sci. 2013, 14(6), 11830-11841; doi:10.3390/ijms140611830
Received: 26 April 2013 / Revised: 17 May 2013 / Accepted: 22 May 2013 / Published: 4 June 2013
Cited by 9 | PDF Full-text (629 KB) | HTML Full-text | XML Full-text
Abstract
Some antioxidants have been shown to possess additional pro-oxidant effects. Diverse methodologies exist for studying redox properties of synthetic and natural chemicals. The latter are substantial components of our diet. Exploration of their contribution to life-extending or -compromising effects is mandatory. Among [...] Read more.
Some antioxidants have been shown to possess additional pro-oxidant effects. Diverse methodologies exist for studying redox properties of synthetic and natural chemicals. The latter are substantial components of our diet. Exploration of their contribution to life-extending or -compromising effects is mandatory. Among reactive oxygen species (ROS), hydroxyl radical (OH) is the most damaging species. Due to its short half-life, the assay has to contain a specific generation system. Plants synthesize flavonoids, phenolic compounds recognized as counter-agents to coronary heart disease. Their antioxidant activities are affected by their hydroxylation patterns. Moreover, in the plant, they mainly occur as glycosides. We chose three derivatives, quercetin, luteolin, and rutin, in attempts to explore their redox chemistry in contrasting hydrogen peroxide environments. Initial addition of hydrogen peroxide in high concentration or gradual development constituted a main factor affecting their redox chemical properties, especially in case of quercetin. Our study exemplifies that a combination of a chemical assay (deoxyribose degradation) with an electrochemical method (square-wave voltammetry) provides insightful data. The ambiguity of the tested flavonoids to act either as anti- or pro-oxidant may complicate categorization, but probably contributed to their evolution as components of a successful metabolic system that benefits both producer and consumer. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
Open AccessArticle Use of Heat Stress Responsive Gene Expression Levels for Early Selection of Heat Tolerant Cabbage (Brassica oleracea L.)
Int. J. Mol. Sci. 2013, 14(6), 11871-11894; doi:10.3390/ijms140611871
Received: 24 April 2013 / Revised: 21 May 2013 / Accepted: 21 May 2013 / Published: 4 June 2013
Cited by 4 | PDF Full-text (1153 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Cabbage is a relatively robust vegetable at low temperatures. However, at high temperatures, cabbage has disadvantages, such as reduced disease tolerance and lower yields. Thus, selection of heat-tolerant cabbage is an important goal in cabbage breeding. Easier or faster selection of superior [...] Read more.
Cabbage is a relatively robust vegetable at low temperatures. However, at high temperatures, cabbage has disadvantages, such as reduced disease tolerance and lower yields. Thus, selection of heat-tolerant cabbage is an important goal in cabbage breeding. Easier or faster selection of superior varieties of cabbage, which are tolerant to heat and disease and have improved taste and quality, can be achieved with molecular and biological methods. We compared heat-responsive gene expression between a heat-tolerant cabbage line (HTCL), “HO”, and a heat-sensitive cabbage line (HSCL), “JK”, by Genechip assay. Expression levels of specific heat stress-related genes were increased in response to high-temperature stress, according to Genechip assays. We performed quantitative RT-PCR (qRT-PCR) to compare expression levels of these heat stress-related genes in four HTCLs and four HSCLs. Transcript levels for heat shock protein BoHsp70 and transcription factor BoGRAS (SCL13) were more strongly expressed only in all HTCLs compared to all HSCLs, showing much lower level expressions at the young plant stage under heat stress (HS). Thus, we suggest that expression levels of these genes may be early selection markers for HTCLs in cabbage breeding. In addition, several genes that are involved in the secondary metabolite pathway were differentially regulated in HTCL and HSCL exposed to heat stress. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
Open AccessArticle The Physiological Importance of Glucosinolates on Plant Response to Abiotic Stress in Brassica
Int. J. Mol. Sci. 2013, 14(6), 11607-11625; doi:10.3390/ijms140611607
Received: 27 April 2013 / Revised: 14 May 2013 / Accepted: 20 May 2013 / Published: 30 May 2013
Cited by 26 | PDF Full-text (372 KB) | HTML Full-text | XML Full-text
Abstract
Glucosinolates, a class of secondary metabolites, mainly found in Brassicaceae, are affected by the changing environment. This review is focusing on the physiological significance of glucosinolates and their hydrolysis products in the plant response to different abiotic stresses. Special attention is paid [...] Read more.
Glucosinolates, a class of secondary metabolites, mainly found in Brassicaceae, are affected by the changing environment. This review is focusing on the physiological significance of glucosinolates and their hydrolysis products in the plant response to different abiotic stresses. Special attention is paid to the crosstalk between some of the physiological processes involved in stress response and glucosinolate metabolism, with the resulting connection between both pathways in which signaling mechanisms glucosinolate may act as signals themselves. The function of glucosinolates, further than in defense switching, is discussed in terms of alleviating pathogen attack under abiotic stress. The fact that the exogenous addition of glucosinolate hydrolysis products may alleviate certain stress conditions through its effect on specific proteins is described in light of the recent reports, but the molecular mechanisms involved in this response merit further research. Finally, the transient allocation and re-distribution of glucosinolates as a response to environmental changes is summarized. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
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Open AccessArticle Oxidative and Molecular Responses in Capsicum annuum L. after Hydrogen Peroxide, Salicylic Acid and Chitosan Foliar Applications
Int. J. Mol. Sci. 2013, 14(5), 10178-10196; doi:10.3390/ijms140510178
Received: 16 February 2013 / Revised: 24 April 2013 / Accepted: 2 May 2013 / Published: 15 May 2013
Cited by 14 | PDF Full-text (2706 KB) | HTML Full-text | XML Full-text
Abstract
Hydrogen peroxide (H2O2) is an important ROS molecule (Reactive oxygen species) that serves as a signal of oxidative stress and activation of signaling cascades as a result of the early response of the plant to biotic stress. This [...] Read more.
Hydrogen peroxide (H2O2) is an important ROS molecule (Reactive oxygen species) that serves as a signal of oxidative stress and activation of signaling cascades as a result of the early response of the plant to biotic stress. This response can also be generated with the application of elicitors, stable molecules that induce the activation of transduction cascades and hormonal pathways, which trigger induced resistance to environmental stress. In this work, we evaluated the endogenous H2O2 production caused by salicylic acid (SA), chitosan (QN), and H2O2 elicitors in Capsicum annuum L. Hydrogen peroxide production after elicitation, catalase (CAT) and phenylalanine ammonia lyase (PAL) activities, as well as gene expression analysis of cat1, pal, and pathogenesis-related protein 1 (pr1) were determined. Our results displayed that 6.7 and 10 mM SA concentrations, and, 14 and 18 mM H2O2 concentrations, induced an endogenous H2O2 and gene expression. QN treatments induced the same responses in lesser proportion than the other two elicitors. Endogenous H2O2 production monitored during several days, showed results that could be an indicator for determining application opportunity uses in agriculture for maintaining plant alert systems against a stress. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
Open AccessArticle Characterization, Purification of Poncirin from Edible Citrus Ougan (Citrus reticulate cv. Suavissima) and Its Growth Inhibitory Effect on Human Gastric Cancer Cells SGC-7901
Int. J. Mol. Sci. 2013, 14(5), 8684-8697; doi:10.3390/ijms14058684
Received: 20 January 2013 / Revised: 2 April 2013 / Accepted: 17 April 2013 / Published: 24 April 2013
Cited by 7 | PDF Full-text (290 KB) | HTML Full-text | XML Full-text
Abstract
Poncirin is a bitter flavanone glycoside with various biological activities. Poncirin was isolated from four different tissues (flavedo, albedo, segment membrane, and juice sac) of Ougan fruit (Citrus reticulate cv. Suavissima). The highest content of poncirin was found in the albedo [...] Read more.
Poncirin is a bitter flavanone glycoside with various biological activities. Poncirin was isolated from four different tissues (flavedo, albedo, segment membrane, and juice sac) of Ougan fruit (Citrus reticulate cv. Suavissima). The highest content of poncirin was found in the albedo of Ougan fruit (1.37 mg/g DW). High speed counter-current chromatography (HSCCC) combined with D101 resin chromatography was utilized for the separation and purification of poncirin from the albedo of Ougan fruit. After this two-step purification, poncirin purity increased from 0.14% to 96.56%. The chemical structure of the purified poncirin was identified by both HPLC-PDA and LC-MS. Poncirin showed a significant in vitro inhibitory effect on the growth of the human gastric cancer cells, SGC-7901, in a dose-dependent manner. Thus, poncirin from Ougan fruit, may be beneficial for gastric cancer prevention. The purification method demonstrated here will be useful for further studies on the pharmacological mechanism of poncirin activity, as well as for guiding the consumption of Ougan fruit. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
Open AccessArticle Identifying Differentially Expressed Genes in Pollen from Self-Incompatible “Wuzishatangju” and Self-Compatible “Shatangju” Mandarins
Int. J. Mol. Sci. 2013, 14(4), 8538-8555; doi:10.3390/ijms14048538
Received: 14 January 2013 / Revised: 2 March 2013 / Accepted: 7 April 2013 / Published: 17 April 2013
Cited by 3 | PDF Full-text (552 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Self-incompatibility (SI) is one of the important factors that can result in seedless fruit in Citrus. However, the molecular mechanism of SI in Citrus is not yet clear. In this study, two suppression subtractive hybridization (SSH) libraries (forward, F and reverse, [...] Read more.
Self-incompatibility (SI) is one of the important factors that can result in seedless fruit in Citrus. However, the molecular mechanism of SI in Citrus is not yet clear. In this study, two suppression subtractive hybridization (SSH) libraries (forward, F and reverse, R) were constructed to isolate differentially expressed genes in pollen from “Wuzishatangju” (SI) and “Shatangju” (self-compatibility, SC) mandarins. Four hundred and sixty-eight differentially expressed cDNA clones from 2077 positive clones were sequenced and identified. Differentially expressed ESTs are possibly involved in the SI reaction of “Wuzishatangju” by regulating pollen development, kinase activity, ubiquitin pathway, pollen-pistil interaction, and calcium ion binding. Twenty five SI candidate genes were obtained, six of which displayed specific expression patterns in various organs and stages after self- and cross-pollination. The expression level of the F-box gene (H304) and S1 (F78) in the pollen of “Wuzishatangju” was 5-fold higher than that in “Shatangju” pollen. The F-box gene, S1, UBE2, UBE3, RNaseHII, and PCP were obviously up-regulated in pistils at 3 d after self-pollination of “Wuzishatangju”, approximately 3-, 2-, 10-, 5-, 5-, and 2-fold higher, respectively than that at the same stage after cross-pollination of “Wuzishatangju” × “Shatangju” pistils. The potential involvement of these genes in the pollen SI reaction of “Wuzishatangju” is discussed. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)

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Open AccessReview Advanced Knowledge of Three Important Classes of Grape Phenolics: Anthocyanins, Stilbenes and Flavonols
Int. J. Mol. Sci. 2013, 14(10), 19651-19669; doi:10.3390/ijms141019651
Received: 17 July 2013 / Revised: 11 September 2013 / Accepted: 12 September 2013 / Published: 27 September 2013
Cited by 44 | PDF Full-text (319 KB) | HTML Full-text | XML Full-text
Abstract
Grape is qualitatively and quantitatively very rich in polyphenols. In particular, anthocyanins, flavonols and stilbene derivatives play very important roles in plant metabolism, thanks to their peculiar characteristics. Anthocyanins are responsible for the color of red grapes and wines and confer organoleptic [...] Read more.
Grape is qualitatively and quantitatively very rich in polyphenols. In particular, anthocyanins, flavonols and stilbene derivatives play very important roles in plant metabolism, thanks to their peculiar characteristics. Anthocyanins are responsible for the color of red grapes and wines and confer organoleptic characteristics on the wine. They are used for chemotaxonomic studies and to evaluate the polyphenolic ripening stage of grape. They are natural colorants, have antioxidant, antimicrobial and anticarcinogenic activity, exert protective effects on the human cardiovascular system, and are used in the food and pharmaceutical industries. Stilbenes are vine phytoalexins present in grape berries and associated with the beneficial effects of drinking wine. The principal stilbene, resveratrol, is characterized by anticancer, antioxidant, anti-inflammatory and cardioprotective activity. Resveratrol dimers and oligomers also occur in grape, and are synthetized by the vine as active defenses against exogenous attack, or produced by extracellular enzymes released from pathogens in an attempt to eliminate undesirable toxic compounds. Flavonols are a ubiquitous class of flavonoids with photo-protection and copigmentation (together with anthocyanins) functions. The lack of expression of the enzyme flavonoid 3',5'-hydroxylase in white grapes restricts the presence of these compounds to quercetin, kaempferol and isorhamnetin derivatives, whereas red grapes usually also contain myricetin, laricitrin and syringetin derivatives. In the last ten years, the technological development of analytical instrumentation, particularly mass spectrometry, has led to great improvements and further knowledge of the chemistry of these compounds. In this review, the biosynthesis and biological role of these grape polyphenols are briefly introduced, together with the latest knowledge of their chemistry. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
Open AccessReview Biochemistry and Molecular Biology of Carotenoid Biosynthesis in Chili Peppers (Capsicum spp.)
Int. J. Mol. Sci. 2013, 14(9), 19025-19053; doi:10.3390/ijms140919025
Received: 13 June 2013 / Revised: 29 July 2013 / Accepted: 17 August 2013 / Published: 16 September 2013
Cited by 9 | PDF Full-text (602 KB) | HTML Full-text | XML Full-text
Abstract
Capsicum species produce fruits that synthesize and accumulate carotenoid pigments, which are responsible for the fruits’ yellow, orange and red colors. Chili peppers have been used as an experimental model for studying the biochemical and molecular aspects of carotenoid biosynthesis. Most reports [...] Read more.
Capsicum species produce fruits that synthesize and accumulate carotenoid pigments, which are responsible for the fruits’ yellow, orange and red colors. Chili peppers have been used as an experimental model for studying the biochemical and molecular aspects of carotenoid biosynthesis. Most reports refer to the characterization of carotenoids and content determination in chili pepper fruits from different species, cultivars, varieties or genotypes. The types and levels of carotenoids differ between different chili pepper fruits, and they are also influenced by environmental conditions. Yellow-orange colors of chili pepper fruits are mainly due to the accumulation of α- and β-carotene, zeaxanthin, lutein and β-cryptoxanthin. Carotenoids such as capsanthin, capsorubin and capsanthin-5,6-epoxide confer the red colors. Chromoplasts are the sites of carotenoid pigment synthesis and storage. According to the most accepted theory, the synthesis of carotenoids in chili peppers is controlled by three loci: c1, c2 and y. Several enzymes participating in carotenoid biosynthesis in chili pepper fruits have been isolated and characterized, and the corresponding gene sequences have been reported. However, there is currently limited information on the molecular mechanisms that regulate this biosynthetic pathway. Approaches to gain more knowledge of the regulation of carotenoid biosynthesis are discussed. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
Open AccessReview Berry Phenolics of Grapevine under Challenging Environments
Int. J. Mol. Sci. 2013, 14(9), 18711-18739; doi:10.3390/ijms140918711
Received: 11 July 2013 / Revised: 27 July 2013 / Accepted: 15 August 2013 / Published: 11 September 2013
Cited by 35 | PDF Full-text (1191 KB) | HTML Full-text | XML Full-text
Abstract
Plant phenolics have been for many years a theme of major scientific and applied interest. Grape berry phenolics contribute to organoleptic properties, color and protection against environmental challenges. Climate change has already caused significant warming in most grape-growing areas of the world, [...] Read more.
Plant phenolics have been for many years a theme of major scientific and applied interest. Grape berry phenolics contribute to organoleptic properties, color and protection against environmental challenges. Climate change has already caused significant warming in most grape-growing areas of the world, and the climatic conditions determine, to a large degree, the grape varieties that can be cultivated as well as wine quality. In particular, heat, drought and light/UV intensity severely affect phenolic metabolism and, thus, grape composition and development. In the variety Chardonnay, water stress increases the content of flavonols and decreases the expression of genes involved in biosynthesis of stilbene precursors. Also, polyphenolic profile is greatly dependent on genotype and environmental interactions. This review deals with the diversity and biosynthesis of phenolic compounds in the grape berry, from a general overview to a more detailed level, where the influence of environmental challenges on key phenolic metabolism pathways is approached. The full understanding of how and when specific phenolic compounds accumulate in the berry, and how the varietal grape berry metabolism responds to the environment is of utmost importance to adjust agricultural practices and thus, modify wine profile. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
Open AccessReview Green Leaf Volatiles: A Plant’s Multifunctional Weapon against Herbivores and Pathogens
Int. J. Mol. Sci. 2013, 14(9), 17781-17811; doi:10.3390/ijms140917781
Received: 26 June 2013 / Revised: 6 August 2013 / Accepted: 13 August 2013 / Published: 30 August 2013
Cited by 44 | PDF Full-text (790 KB) | HTML Full-text | XML Full-text
Abstract
Plants cannot avoid being attacked by an almost infinite number of microorganisms and insects. Consequently, they arm themselves with molecular weapons against their attackers. Plant defense responses are the result of a complex signaling network, in which the hormones jasmonic acid (JA), [...] Read more.
Plants cannot avoid being attacked by an almost infinite number of microorganisms and insects. Consequently, they arm themselves with molecular weapons against their attackers. Plant defense responses are the result of a complex signaling network, in which the hormones jasmonic acid (JA), salicylic acid (SA) and ethylene (ET) are the usual suspects under the magnifying glass when researchers investigate host-pest interactions. However, Green Leaf Volatiles (GLVs), C6 molecules, which are very quickly produced and/or emitted upon herbivory or pathogen infection by almost every green plant, also play an important role in plant defenses. GLVs are semiochemicals used by insects to find their food or their conspecifics. They have also been reported to be fundamental in indirect defenses and to have a direct effect on pests, but these are not the only roles of GLVs. These volatiles, being probably one of the fastest weapons exploited, are also able to directly elicit or prime plant defense responses. Moreover, GLVs, via crosstalk with phytohormones, mostly JA, can influence the outcome of the plant’s defense response against pathogens. For all these reasons GLVs should be considered as co-protagonists in the play between plants and their attackers. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
Open AccessReview Plant Flavonoids—Biosynthesis, Transport and Involvement in Stress Responses
Int. J. Mol. Sci. 2013, 14(7), 14950-14973; doi:10.3390/ijms140714950
Received: 24 April 2013 / Revised: 11 July 2013 / Accepted: 11 July 2013 / Published: 17 July 2013
Cited by 44 | PDF Full-text (836 KB) | HTML Full-text | XML Full-text
Abstract
This paper aims at analysing the synthesis of flavonoids, their import and export in plant cell compartments, as well as their involvement in the response to stress, with particular reference to grapevine (Vitis vinifera L.). A multidrug and toxic compound extrusion [...] Read more.
This paper aims at analysing the synthesis of flavonoids, their import and export in plant cell compartments, as well as their involvement in the response to stress, with particular reference to grapevine (Vitis vinifera L.). A multidrug and toxic compound extrusion (MATE) as well as ABC transporters have been demonstrated in the tonoplast of grape berry, where they perform a flavonoid transport. The involvement of a glutathione S-transferase (GST) gene has also been inferred. Recently, a putative flavonoid carrier, similar to mammalian bilitranslocase (BTL), has been identified in both grape berry skin and pulp. In skin the pattern of BTL expression increases from véraison to harvest, while in the pulp its expression reaches the maximum at the early ripening stage. Moreover, the presence of BTL in vascular bundles suggests its participation in long distance transport of flavonoids. In addition, the presence of a vesicular trafficking in plants responsible for flavonoid transport is discussed. Finally, the involvement of flavonoids in the response to stress is described. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
Open AccessReview Modulation of Phytoalexin Biosynthesis in Engineered Plants for Disease Resistance
Int. J. Mol. Sci. 2013, 14(7), 14136-14170; doi:10.3390/ijms140714136
Received: 25 April 2013 / Revised: 19 June 2013 / Accepted: 25 June 2013 / Published: 8 July 2013
Cited by 28 | PDF Full-text (2081 KB) | HTML Full-text | XML Full-text
Abstract
Phytoalexins are antimicrobial substances of low molecular weight produced by plants in response to infection or stress, which form part of their active defense mechanisms. Starting in the 1950’s, research on phytoalexins has begun with biochemistry and bio-organic chemistry, resulting in the [...] Read more.
Phytoalexins are antimicrobial substances of low molecular weight produced by plants in response to infection or stress, which form part of their active defense mechanisms. Starting in the 1950’s, research on phytoalexins has begun with biochemistry and bio-organic chemistry, resulting in the determination of their structure, their biological activity as well as mechanisms of their synthesis and their catabolism by microorganisms. Elucidation of the biosynthesis of numerous phytoalexins has permitted the use of molecular biology tools for the exploration of the genes encoding enzymes of their synthesis pathways and their regulators. Genetic manipulation of phytoalexins has been investigated to increase the disease resistance of plants. The first example of a disease resistance resulting from foreign phytoalexin expression in a novel plant has concerned a phytoalexin from grapevine which was transferred to tobacco. Transformations were then operated to investigate the potential of other phytoalexin biosynthetic genes to confer resistance to pathogens. Unexpectedly, engineering phytoalexins for disease resistance in plants seem to have been limited to exploiting only a few phytoalexin biosynthetic genes, especially those encoding stilbenes and some isoflavonoids. Research has rather focused on indirect approaches which allow modulation of the accumulation of phytoalexin employing transcriptional regulators or components of upstream regulatory pathways. Genetic approaches using gain- or less-of functions in phytoalexin engineering together with modulation of phytoalexin accumulation through molecular engineering of plant hormones and defense-related marker and elicitor genes have been reviewed. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
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Open AccessReview Biosynthetic Pathway and Health Benefits of Fucoxanthin, an Algae-Specific Xanthophyll in Brown Seaweeds
Int. J. Mol. Sci. 2013, 14(7), 13763-13781; doi:10.3390/ijms140713763
Received: 12 April 2013 / Revised: 18 June 2013 / Accepted: 25 June 2013 / Published: 2 July 2013
Cited by 17 | PDF Full-text (537 KB) | HTML Full-text | XML Full-text
Abstract
Fucoxanthin is the main carotenoid produced in brown algae as a component of the light-harvesting complex for photosynthesis and photoprotection. In contrast to the complete elucidation of the carotenoid biosynthetic pathways in red and green algae, the biosynthetic pathway of fucoxanthin in [...] Read more.
Fucoxanthin is the main carotenoid produced in brown algae as a component of the light-harvesting complex for photosynthesis and photoprotection. In contrast to the complete elucidation of the carotenoid biosynthetic pathways in red and green algae, the biosynthetic pathway of fucoxanthin in brown algae is not fully understood. Recently, two models for the fucoxanthin biosynthetic pathway have been proposed in unicellular diatoms; however, there is no such information for the pathway in brown seaweeds to date. Here, we propose a biosynthetic pathway for fucoxanthin in the brown seaweed, Ectocarpus siliculosus, derived from comparison of carotenogenic genes in its sequenced genome with those in the genomes of two diatoms, Thalassiosira pseudonana and Phaeodactylum tricornutum. Currently, fucoxanthin is receiving attention, due to its potential benefits for human health. Therefore, new knowledge regarding the medical and nutraceutical properties of fucoxanthin from brown seaweeds is also summarized here. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
Open AccessReview Sesquiterpenoids Lactones: Benefits to Plants and People
Int. J. Mol. Sci. 2013, 14(6), 12780-12805; doi:10.3390/ijms140612780
Received: 26 April 2013 / Revised: 24 May 2013 / Accepted: 31 May 2013 / Published: 19 June 2013
Cited by 53 | PDF Full-text (539 KB) | HTML Full-text | XML Full-text
Abstract
Sesquiterpenoids, and specifically sesquiterpene lactones from Asteraceae, may play a highly significant role in human health, both as part of a balanced diet and as pharmaceutical agents, due to their potential for the treatment of cardiovascular disease and cancer. This review highlights [...] Read more.
Sesquiterpenoids, and specifically sesquiterpene lactones from Asteraceae, may play a highly significant role in human health, both as part of a balanced diet and as pharmaceutical agents, due to their potential for the treatment of cardiovascular disease and cancer. This review highlights the role of sesquiterpene lactones endogenously in the plants that produce them, and explores mechanisms by which they interact in animal and human consumers of these plants. Several mechanisms are proposed for the reduction of inflammation and tumorigenesis at potentially achievable levels in humans. Plants can be classified by their specific array of produced sesquiterpene lactones, showing high levels of translational control. Studies of folk medicines implicate sesquiterpene lactones as the active ingredient in many treatments for other ailments such as diarrhea, burns, influenza, and neurodegradation. In addition to the anti-inflammatory response, sesquiterpene lactones have been found to sensitize tumor cells to conventional drug treatments. This review explores the varied ecological roles of sesquiterpenes in the plant producer, depending upon the plant and the compound. These include allelopathy with other plants, insects, and microbes, thereby causing behavioural or developmental modification to these secondary organisms to the benefit of the sesquiterpenoid producer. Some sesquiterpenoid lactones are antimicrobial, disrupting the cell wall of fungi and invasive bacteria, whereas others protect the plant from environmental stresses that would otherwise cause oxidative damage. Many of the compounds are effective due to their bitter flavor, which has obvious implications for human consumers. The implications of sesquiterpenoid lactone qualities for future crop production are discussed. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
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Open AccessReview Putative Genes Involved in Saikosaponin Biosynthesis in Bupleurum Species
Int. J. Mol. Sci. 2013, 14(6), 12806-12826; doi:10.3390/ijms140612806
Received: 22 April 2013 / Revised: 13 June 2013 / Accepted: 14 June 2013 / Published: 19 June 2013
Cited by 6 | PDF Full-text (869 KB) | HTML Full-text | XML Full-text
Abstract
Alternative medicinal agents, such as the herb Bupleurum, are increasingly used in modern medicine to supplement synthetic drugs. First, we present a review of the currently known effects of triterpene saponins-saikosaponins of Bupleurum species. The putative biosynthetic pathway of saikosaponins in Bupleurum [...] Read more.
Alternative medicinal agents, such as the herb Bupleurum, are increasingly used in modern medicine to supplement synthetic drugs. First, we present a review of the currently known effects of triterpene saponins-saikosaponins of Bupleurum species. The putative biosynthetic pathway of saikosaponins in Bupleurum species is summarized, followed by discussions on identification and characterization of genes involved in the biosynthesis of saikosaponins. The purpose is to provide a brief review of gene extraction, functional characterization of isolated genes and assessment of expression patterns of genes encoding enzymes in the process of saikosaponin production in Bupleurum species, mainly B. kaoi. We focus on the effects of MeJA on saikosaponin production, transcription patterns of genes involved in biosynthesis and on functional depiction. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
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Open AccessReview Towards a Molecular Understanding of the Biosynthesis of Amaryllidaceae Alkaloids in Support of Their Expanding Medical Use
Int. J. Mol. Sci. 2013, 14(6), 11713-11741; doi:10.3390/ijms140611713
Received: 28 April 2013 / Revised: 26 May 2013 / Accepted: 27 May 2013 / Published: 31 May 2013
Cited by 6 | PDF Full-text (896 KB) | HTML Full-text | XML Full-text
Abstract
The alkaloids characteristically produced by the subfamily Amaryllidoideae of the Amaryllidaceae, bulbous plant species that include well know genera such as Narcissus (daffodils) and Galanthus (snowdrops), are a source of new pharmaceutical compounds. Presently, only the Amaryllidaceae alkaloid galanthamine, an acetylcholinesterase inhibitor [...] Read more.
The alkaloids characteristically produced by the subfamily Amaryllidoideae of the Amaryllidaceae, bulbous plant species that include well know genera such as Narcissus (daffodils) and Galanthus (snowdrops), are a source of new pharmaceutical compounds. Presently, only the Amaryllidaceae alkaloid galanthamine, an acetylcholinesterase inhibitor used to treat symptoms of Alzheimer’s disease, is produced commercially as a drug from cultivated plants. However, several Amaryllidaceae alkaloids have shown great promise as anti-cancer drugs, but their further clinical development is restricted by their limited commercial availability. Amaryllidaceae species have a long history of cultivation and breeding as ornamental bulbs, and phytochemical research has focussed on the diversity in alkaloid content and composition. In contrast to the available pharmacological and phytochemical data, ecological, physiological and molecular aspects of the Amaryllidaceae and their alkaloids are much less explored and the identity of the alkaloid biosynthetic genes is presently unknown. An improved molecular understanding of Amaryllidaceae alkaloid biosynthesis would greatly benefit the rational design of breeding programs to produce cultivars optimised for the production of pharmaceutical compounds and enable biotechnology based approaches. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
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Open AccessReview Integrated -Omics: A Powerful Approach to Understanding the Heterogeneous Lignification of Fibre Crops
Int. J. Mol. Sci. 2013, 14(6), 10958-10978; doi:10.3390/ijms140610958
Received: 26 April 2013 / Revised: 15 May 2013 / Accepted: 17 May 2013 / Published: 24 May 2013
Cited by 12 | PDF Full-text (286 KB) | HTML Full-text | XML Full-text
Abstract
Lignin and cellulose represent the two main components of plant secondary walls and the most abundant polymers on Earth. Quantitatively one of the principal products of the phenylpropanoid pathway, lignin confers high mechanical strength and hydrophobicity to plant walls, thus enabling erect [...] Read more.
Lignin and cellulose represent the two main components of plant secondary walls and the most abundant polymers on Earth. Quantitatively one of the principal products of the phenylpropanoid pathway, lignin confers high mechanical strength and hydrophobicity to plant walls, thus enabling erect growth and high-pressure water transport in the vessels. Lignin is characterized by a high natural heterogeneity in its composition and abundance in plant secondary cell walls, even in the different tissues of the same plant. A typical example is the stem of fibre crops, which shows a lignified core enveloped by a cellulosic, lignin-poor cortex. Despite the great value of fibre crops for humanity, however, still little is known on the mechanisms controlling their cell wall biogenesis, and particularly, what regulates their spatially-defined lignification pattern. Given the chemical complexity and the heterogeneous composition of fibre crops’ secondary walls, only the use of multidisciplinary approaches can convey an integrated picture and provide exhaustive information covering different levels of biological complexity. The present review highlights the importance of combining high throughput -omics approaches to get a complete understanding of the factors regulating the lignification heterogeneity typical of fibre crops. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
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Open AccessReview Plant Defense against Insect Herbivores
Int. J. Mol. Sci. 2013, 14(5), 10242-10297; doi:10.3390/ijms140510242
Received: 2 April 2013 / Revised: 27 April 2013 / Accepted: 2 May 2013 / Published: 16 May 2013
Cited by 49 | PDF Full-text (1044 KB) | HTML Full-text | XML Full-text
Abstract
Plants have been interacting with insects for several hundred million years, leading to complex defense approaches against various insect feeding strategies. Some defenses are constitutive while others are induced, although the insecticidal defense compound or protein classes are often similar. Insect herbivory [...] Read more.
Plants have been interacting with insects for several hundred million years, leading to complex defense approaches against various insect feeding strategies. Some defenses are constitutive while others are induced, although the insecticidal defense compound or protein classes are often similar. Insect herbivory induce several internal signals from the wounded tissues, including calcium ion fluxes, phosphorylation cascades and systemic- and jasmonate signaling. These are perceived in undamaged tissues, which thereafter reinforce their defense by producing different, mostly low molecular weight, defense compounds. These bioactive specialized plant defense compounds may repel or intoxicate insects, while defense proteins often interfere with their digestion. Volatiles are released upon herbivory to repel herbivores, attract predators or for communication between leaves or plants, and to induce defense responses. Plants also apply morphological features like waxes, trichomes and latices to make the feeding more difficult for the insects. Extrafloral nectar, food bodies and nesting or refuge sites are produced to accommodate and feed the predators of the herbivores. Meanwhile, herbivorous insects have adapted to resist plant defenses, and in some cases even sequester the compounds and reuse them in their own defense. Both plant defense and insect adaptation involve metabolic costs, so most plant-insect interactions reach a stand-off, where both host and herbivore survive although their development is suboptimal. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
Open AccessReview Agriculture and Bioactives: Achieving Both Crop Yield and Phytochemicals
Int. J. Mol. Sci. 2013, 14(2), 4203-4222; doi:10.3390/ijms14024203
Received: 27 November 2012 / Revised: 8 January 2013 / Accepted: 29 January 2013 / Published: 20 February 2013
Cited by 10 | PDF Full-text (256 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Plants are fundamental elements of the human diet, either as direct sources of nutrients or indirectly as feed for animals. During the past few years, the main goal of agriculture has been to increase yield in order to provide the food that [...] Read more.
Plants are fundamental elements of the human diet, either as direct sources of nutrients or indirectly as feed for animals. During the past few years, the main goal of agriculture has been to increase yield in order to provide the food that is needed by a growing world population. As important as yield, but commonly forgotten in conventional agriculture, is to keep and, if it is possible, to increase the phytochemical content due to their health implications. Nowadays, it is necessary to go beyond this, reconciling yield and phytochemicals that, at first glance, might seem in conflict. This can be accomplished through reviewing food requirements, plant consumption with health implications, and farming methods. The aim of this work is to show how both yield and phytochemicals converge into a new vision of agricultural management in a framework of integrated agricultural practices. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)
Open AccessReview Flavonoids as Antioxidants and Developmental Regulators: Relative Significance in Plants and Humans
Int. J. Mol. Sci. 2013, 14(2), 3540-3555; doi:10.3390/ijms14023540
Received: 11 January 2013 / Revised: 30 January 2013 / Accepted: 31 January 2013 / Published: 7 February 2013
Cited by 46 | PDF Full-text (347 KB) | HTML Full-text | XML Full-text
Abstract
Phenylpropanoids, particularly flavonoids have been recently suggested as playing primary antioxidant functions in the responses of plants to a wide range of abiotic stresses. Furthermore, flavonoids are effective endogenous regulators of auxin movement, thus behaving as developmental regulators. Flavonoids are capable of [...] Read more.
Phenylpropanoids, particularly flavonoids have been recently suggested as playing primary antioxidant functions in the responses of plants to a wide range of abiotic stresses. Furthermore, flavonoids are effective endogenous regulators of auxin movement, thus behaving as developmental regulators. Flavonoids are capable of controlling the development of individual organs and the whole-plant; and, hence, to contribute to stress-induced morphogenic responses of plants. The significance of flavonoids as scavengers of reactive oxygen species (ROS) in humans has been recently questioned, based on the observation that the flavonoid concentration in plasma and most tissues is too low to effectively reduce ROS. Instead, flavonoids may play key roles as signaling molecules in mammals, through their ability to interact with a wide range of protein kinases, including mitogen-activated protein kinases (MAPK), that supersede key steps of cell growth and differentiation. Here we discuss about the relative significance of flavonoids as reducing agents and signaling molecules in plants and humans. We show that structural features conferring ROS-scavenger ability to flavonoids are also required to effectively control developmental processes in eukaryotic cells. Full article
(This article belongs to the Special Issue Molecular Research in Plant Secondary Metabolism)

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