Biosynthesis Of Secondary Compounds Research Articles

Analysis of Balanites aegyptiaca wood extractives and their variation across different ecological zones

This study focuses on the analysis of extractives from the wood of Balanites aegyptiaca, an endemic and iconic species of dry African regions, and the impact of climatic and geographical conditions on these extractives. The wood samples were collected from three distinct geographical zones: the Sahelian Chadian zone, the Sudanian Chadian zone, and the Sahelian Senegalese zone. A total of nine trees were analyzed in this study. The results showed that samples from the Sahelian Chadian zone, characterized by more arid conditions, had a significantly higher extractive content compared to those from the other two regions. The extractive compounds characteristic of these samples included stereoisomers of inositol, pinnitol, diosgenin, and sesquiterpenes. These compounds were found to be identical in samples from the Sahelian Senegalese and Sudanian Chadian zones, except for disaccharides, which were additionally present in the Senegalese samples. For the same species, pinnitol remained the most dominant compound in the wood from the Sahelian Chadian zone, alongside monosaccharides. This marked difference in extractive compounds is explained as a response of the tree to local constraints, particularly water stress and high temperatures, which stimulate the production of secondary metabolites such as tannins, polysaccharides, and pinnitol. These compounds are essential for the tree's resistance to unfavorable environmental conditions. The study highlights the influence of climatic factors on the biosynthesis of secondary compounds and suggests that Balanites aegyptiaca could offer promising opportunities for pharmacological and industrial applications.

Soil microbial respiration and pH modulated by arbuscular mycorrhizal fungi influence the biosynthesis of health-promoting compounds in Anadenanthera colubrina (Vell.) Brenan

It is well-known that the formation of arbuscular mycorrhiza (AM) can impact edaphic properties by influencing enzymatic activities in the rhizosphere, pH and physical attributes of soil. In addition, AM can alter the biosynthesis of secondary compounds in plant species. Although, it is established that edaphic factors have significant effect on the production of secondary metabolites, yet there is no study relating AM-mediated effects on soil properties to the production of secondary metabolites. Anadenanthera colubrina (Vell.) Brenan, commonly known as cebil has high industrial and ethnobotanical relevance. The A. colubrina extract, which is of interest in herbal medicine production, is rich in flavanols, saponins and tannins. Thus, this study aimed to assess the effects of two arbuscular mycorrhizal fungi namely, Gigaspora albida and Acaulospora longula on the pharmaceutically valued compounds as well as some edaphic attributes. The ethanolic extracts of leaves of A. colubrina seedlings concentrated more flavanols, saponins, and exhibited outstanding antioxidant activity when inoculated with AMF. While, no significant effect was observed on concentration of tannins. Inoculation with G. albida resulted in 5-fold and 7-fold increase in flavanols and saponin respectively. Formation of AM resulted in higher CO2 evolution than non-inoculated A. colubrina. This indicates higher microbial activity (respiration) in the mycorhizosphere despite of the non-significant effect on soil microbial biomass due to formation of AM. Neverthless, microbial respiration in soil positively correlated with soil pH. The modulation of such parameters by AMF may explain the benefits in A. colubrina metabolism, as proven by correlation analysis. Therefore, AMF inoculation enhances the production of secondary metabolites in A. colubrina leaves by altering some rhizospheric parameters.

Effect of the Interaction between Elevated Carbon Dioxide and Iron Limitation on Proteomic Profiling of Soybean.

Elevated atmospheric CO2 (eCO2) and iron (Fe) availability are important factors affecting plant growth that may impact the proteomic profile of crop plants. In this study, soybean plants treated under Fe-limited (0.5 mM) and Fe-sufficient (20 mM) conditions were grown at ambient (400 μmol mol-1) and eCO2 (800 μmol mol-1) in hydroponic solutions. Elevated CO2 increased biomass from 2.14 to 3.14 g plant-1 and from 1.18 to 2.91 g plant-1 under Fe-sufficient and Fe-limited conditions, respectively, but did not affect leaf photosynthesis. Sugar concentration increased from 10.92 to 26.17 μmol g FW-1 in roots of Fe-sufficient plants and from 8.75 to 19.89 μmol g FW-1 of Fe-limited plants after exposure to eCO2. In leaves, sugar concentration increased from 33.62 to 52.22 μmol g FW-1 and from 34.80 to 46.70 μmol g FW-1 in Fe-sufficient and Fe-limited conditions, respectively, under eCO2. However, Fe-limitation decreases photosynthesis and biomass. Pathway enrichment analysis showed that cell wall organization, glutathione metabolism, photosynthesis, stress-related proteins, and biosynthesis of secondary compounds changed in root tissues to cope with Fe-stress. Moreover, under eCO2, at sufficient or limited Fe supply, it was shown an increase in the abundance of proteins involved in glycolysis, starch and sucrose metabolism, biosynthesis of plant hormones gibberellins, and decreased levels of protein biosynthesis. Our results revealed that proteins and metabolic pathways related to Fe-limitation changed the effects of eCO2 and negatively impacted soybean production.

Elicitation of Medicinal Plants In Vivo—Is It a Realistic Tool? The Effect of Methyl Jasmonate and Salicylic Acid on Lamiaceae Species

Salicylic acid (SA) and methyl jasmonate (MeJa) are prominent phytohormones that are involved in stress reactions. Both compounds may influence the biosynthesis of secondary compounds; however, scientific experiments in vivo are rare and contradictive. This paper reports on a study on the elicitation of volatiles and total phenolics (TPC) by MeJa and SA. The subjects were four Lamiaceae species studied in open field conditions in Budapest (Hungary). According to the results, both elicitors provoked specific responses in each plant species depending on the dosage applied and the parameter studied; 2 mM of SA stimulated essential oil (EO) accumulation in marjoram and peppermint, while in hyssop 0.1 mM was optimal. MeJa proved to be effective only in marjoram and in basil. In marjoram, cis-sabinene hydrate was decreased and in hyssop, isopinocamphone was increased by both dosages of SA. In peppermint, pulegone content was reduced by 2 mM SA, but no significant change of the major components of basil EO was detected. SA was successful in increasing TPC and antioxidant activity (AC) in three of the experimental species, but not in hyssop. In marjoram, only 0.1 mM induced TPC and eventually AC, while in peppermint and basil both dosages of SA were effective. Optimalisation of the treatments is suggested in further in vivo experiments.

Axenic culture and biosynthesis of secondary compounds in lichen symbiotic fungi, the Parmeliaceae

Lichens produce unique secondary metabolites with a rich potential as bioactive compounds. In many cases, the use of these molecules is limited by the low concentration of these compounds in thalli, low growth rate in culture, and changes in chemical patterns between thalli and aposymbiotic culture. In addition, the massive collection of some species of industrial interest can cause damage to lichen diversity and the associated environment. Six lichenized fungi (Arctoparmelia centrifuga, Parmelia saxatilis, Parmelina tiliacea, Platismatia glauca, Xanthoparmelia tinctina, and Usnea ghattensis) with biotechnological interest and belonging to Parmeliaceae have been cultured in order to test culture conditions and obtain enough biomass for further studies. In addition, we analyzed the compounds synthetized in axenic conditions and they were compared with chemosyndromes identified in complete thalli. Arctoparmelia centrifuga, P. saxatilis, P. tiliacea and X. tinctina were successfully cultivated while for P. glauca and U. ghattensis we only obtained sporulation and germination of the spores. The chemical pattern of the compounds secreted into the culture media varied significantly from the chemosyndrome of the whole thallus. Phenolic compounds of pharmacological and industrial interest (usnic acid, aspicilin, α-alectoronic acid, physodic acid, lobaric acid and nordivaricatic acid) and a wide variety of potentially bioactive compounds were obtained during the culture process.

Comparative analysis of metabolite profiles from Panax herbs in specific tissues and cultivation conditions reveals the strategy of accumulation

Panax ginseng is one of the most valuable medicinal plants in the world, and wild-forest (WG) and artificial-forest (AG) ginseng are very popular in the ginseng market, with ginsenosides constituting a majority of the bioactives. Research on the biochemical and physiological patterns of metabolic accumulation in different tissues of ginseng cultivated under various conditions is relatively scarce. We profiled metabolites using GC/MS and LC/MS to explore the bioactive component changes and interrelationships that occur in 7 tissues of WG and AG. In total, 149 primary metabolites and 46 secondary compounds were found in aboveground and belowground tissues. Metabolite changes associated with primary and secondary biochemistry were observed, and the levels of ginsenoside F2 and other compounds showed a significant correlation by statistical analysis in ginseng under both cultivation methods, as observed for secondary compounds and C and N metabolites. In addition, the number of secondary components was higher in the aboveground parts than in the belowground parts, showing a different pattern, and the same accumulation pattern of compounds involved in C and N metabolism was observed in individual plant tissues, but the high rate of photosynthesis and energy metabolism in WG provided energy for the biosynthesis of secondary compounds. Furthermore, artificial neural network models explained the variation in the secondary compounds very well via the combination of several different metabolites from WG and AG. Finally, C and N metabolism plays a key role in secondary compound biosynthesis in specific tissues and cultivation conditions and highlights large-scale metabolite patterns in WG and AG.

An endophytic fungi-based biostimulant modulated lettuce yield, physiological and functional quality responses to both moderate and severe water limitation

Modulation of the water availability for the plants can be a sustainable option to reduce agricultural water demand and stimulate the synthesis and accumulation of secondary metabolites. However, information on the reduction of water availability while maintaining yield and functional quality are scarce and fragmentary. This research aimed at elucidating the agronomical, physiological and functional quality (ascorbic acid, phenolic acids and flavonoids) responses triggered by a microbial-based biostimulant containing two strains of arbuscular mychorrizal fungi (AMF) and Trichoderma koningii of greenhouse grown lettuce (Lactuca sativa L.) under well watered (WW), moderate (MDI) or severe deficit irrigation (SDI) regimes. Reducing water availability from WW to MDI did not affect yield, phenolic acids and flavonoids concentration, but reduced both AMF and Trichoderma presence in the roots and soil, respectively, along with plant Mg and Zn concentration by 12.4% and 26.8%, respectively, and almost halved net photosynthetic rate and transpiration. Further reduction in water availability also reduced yields, along with ascorbic acid, total phenols and quercetin. The biostimulant application increased a wealth of traits, including P, Mg, Fe, Mn, and Zn by 20.8%–97.4% and various phenolic acids compared to the non-inoculated control. This effect occurred irrespective of the water availability. In addition, the microbial-based biostimulant increased plant yield, Ca and Cu, and isochlorogenic acid concentrations, but such effects were evident under WW and MDI, only. Luteolin glycoside, that is frequently associated to a plant reaction to water deficit but also to a microbial stimulation, did not vary at reducing water availability in non-inoculated control and progressively increased in the biostimulant inoculated plant. These results suggest that the biostimulant effect on lettuce nutritional and functional quality was mostly independent of the water availability, whereas its effect on fresh marketable and dry yields were evident in WW and MDI, only, through a modulation of the biosynthesis of secondary compounds rather than nutrient uptake. These results have a high practical implication when aiming to improve both plant yield and product quality while reducing water availability.

THE POTENTIAL OF PLANTS TO MEDIATE THE INTERACTION BETWEEN HERBIVORY AND POLLINATION

Herbivory may affect important plant traits that mediate the interaction with floral visitors and potential pollinators with consequences to fruit and seed production. These may occur through varied mechanisms, ranging from a trade-off in resource allocation for defense and reproduction, to pleiotropic effects in the biosynthesis of secondary compounds for plant defense and floral attractiveness. The subject has been receiving attention and is leading to new perspectives in the study of ecology and evolution of insect-plant interactions. Here our main goal is to briefly review the scientific literature and discuss theoretical aspects of plant mediation of interactions between herbivores and pollinators. We conducted an extensive but non-systematic search for literature on the main theme “effects of herbivory on floral visitors and pollination”. We found experimental studies and reviews reporting that foliar and floral herbivory usually change floral traits that mediate plant-pollinator interactions. The effect of herbivores on floral visitation tend to be neutral or negative, and does not always lead to negative impacts on seed production. These results open a path for new hypotheses on how plants may avoid or compensate for possible ecological costs of herbivory. We suggest that future studies should explore finer mechanisms through which herbivory affects pollination by considering natural history, pollination effectiveness, and the chemical background upon which flowers are presented to pollinators. Such studies will improve our understanding of how indirect effects structure ecological communities and their role in the evolution of plant-animal interactions.

Variation in Hydrogen Isotope Composition Among Salt Marsh Plant Organic Compounds Highlights Biochemical Mechanisms Controlling Biosynthetic Fractionation

AbstractHydrogen isotopes of plant‐derived biomarkers can vary by >100‰ at a single location. Isotope fractionation associated with the movement of water in plant leaves cannot account for this variability alone. Biochemical processes therefore must play a fundamental role in controlling hydrogen isotope fractionation during secondary compound biosynthesis. Different biosynthetic pathways utilize discrete hydrogen pools and occur within distinct cell compartments. We analyzed hydrogen isotope compositions of C16 and C18 fatty acids and phytol from seven salt marsh plants and compared these data with (i) leaf water and n‐alkane δ2H, (ii) leaf carbon and nitrogen contents, and (iii) nitrogen isotopes of bulk tissue, to evaluate the relationship between biochemical processes, cellular compartmentalization, and hydrogen isotope fractionation. Interspecies variation in chloroplastic fatty acids and phytol δ2H exceeds leaf water δ2H, indicating that different commitments of metabolites among species at branching points in chloroplast metabolic processes may be important determinants of lipid δ2H values. Dominant osmoregulatory strategies, in particular, show strong correlation with leaf wax n‐alkane δ2H. Species that preferentially produce nitrogenous compounds (dicots/shrubs) as protective solutes have 2H‐enriched n‐alkanes relative to species that produce mainly carbohydrates (monocots). n‐Alkane δ2H values, in combination with δ15N data and elemental (C, N) composition, together provide information about biochemical environmental adaptations exhibited by different higher plant species in response to environmental stresses. Thus, while spatial and temporal integration of biomarkers may produce an isotopic record of ecosystem function, biomarkers from individual plant or microbial remains may hold additional details into biologic function and adaptation to ancient environments.

Mycobiont and Whole Thallus Cultures of Roccella Montagnei Bél. For the Biosynthesis of Secondary Compounds

The mycobiont and whole thallus cultures of Roccella montagnei Bel. were established using soredia as an inoculum.The mycobiont cultures showed optimum growth, biomass and biosynthesis of compounds in Lilly and Barnett medium with glucose as a carbon source, micronutrients and vitamins. After the incubation period of 180 days, the cultures were harvested, and their biomass and secondary compound profiles were analysed. The HPTLC chromatogram of the acetone extract of the NT and mycobiont cultures revealed erythrinas the major biosynthesized compound in both and identified as a key biosynthate by R. montagnei. Further, the NT biosynthesized 5 additional compounds and themycobiont cultures biosynthesized 6 additional compounds. The molecular identity of the cultured mycobiont was confirmed using nuclear ribosomal Internal Transcribed Spacer (ITS) as well as the secondary chemistry. Lichen compound erythrin was identified as a key biosynthate by the cultures.

Mycobiont and Whole Thallus Cultures of Roccella Montagnei Bél. For the Biosynthesis of Secondary Compounds

<p>The mycobiont and whole thallus cultures of Roccella montagnei Bel. were established using soredia as an inoculum.The mycobiont<br />cultures showed optimum growth, biomass and biosynthesis of compounds in Lilly and Barnett medium with glucose as a carbon source,<br />micronutrients and vitamins. After the incubation period of 180 days, the cultures were harvested, and their biomass and secondary<br />compound profiles were analysed. The HPTLC chromatogram of the acetone extract of the NT and mycobiont cultures revealed erythrin<br />as the major biosynthesized compound in both and identified as a key biosynthate by R. montagnei. Further, the NT biosynthesized 5<br />additional compounds and the mycobiont cultures biosynthesized 6 additional compounds. The molecular identity of the cultured<br />mycobiont was confirmed using nuclear ribosomal Internal Transcribed Spacer (ITS) as well as the secondary chemistry. Lichen<br />compound erythrin was identified as a key biosynthate by the cultures.<br />Key word:-Roccella montagnei, Mycobiont, Whole thallus culture, Soredia, Erythrin.<br />Abbreviation: - NT, Natural thallus; MYC, Mycobiont culture; WTC, Whole thallus culture; UV, Ultra violet wave length; HPTLC,<br />High performance thin layer chromatography; ITS, Internal transcribed spacer.</p><p> </p><p><a id="pub-id::doi" href="http://dx.doi.org/10.21756/cba.v0i.11014">http://dx.doi.org/10.21756/cba.v0i.11014</a></p>

Developmental stages and secondary compound biosynthesis of mycobiont and whole thallus cultures of Buellia subsororioides

Lichen species have unique culture media preferences, and established cultures are known for the synthesis of secondary metabolites. This paper reports observations on the developmental stages and secondary compound biosynthesis by the mycobiont and whole thallus cultures of Buellia subsororioides. It also investigates the suitable media compositions for the culture growth, the role (nutrient or stressor) of sucrose concentrations on the growth stages, biomass, secondary compound profiles, and the quantity of biosynthesized known compounds/g of culture biomass for each treatment using mycobiont cultures. The ascospore-derived mycobiont cultures and thallus macerate-derived whole thallus cultures of B. subsororioides were established and grown using malt yeast extract (MY) medium. Mycobiont cultures were subcultured in MY medium supplemented with sucrose and its concentrations ranging from 0 to 30 % (with 2 % increment between treatments) for 120 days. The molecular identity of cultures was confirmed using nuclear ribosomal Internal transcribed spacer (ITS) DNA sequences obtained from the cultured mycobiont and from the natural thallus. The ITS DNA sequences of the mycobiont showed 99 % similarity with the sequences of the natural thallus. The mycobiont cultures under varying sucrose concentrations initiated as white cottony stages and transformed to brown compact mycelia, with optimum biomass and biosynthesis of nine secondary compounds in MY 10 %. The number of compounds (1–9) varies according to treatments. The whole thallus cultures (MY 0 %) showed a profile of secondary compounds similar to that of the natural thalli along with a trace of one unknown compound. The obtained results are encouraging for the synthesis of the desired quantities of lichen secondary compounds through cultures for relevant applications.

Identification of drought-responsive genes in a drought-tolerant cotton (Gossypium hirsutum L.) cultivar under reduced irrigation field conditions and development of candidate gene markers for drought tolerance

Cotton productivity is affected by water deficit, and little is known about the molecular basis of drought tolerance in cotton. In this study, microarray analysis was conducted to identify drought-responsive genes in the third topmost leaves of the field-grown drought-tolerant cotton (Gossypium hirsutum L.) cultivar Acala 1517-99 under drought stress conditions. Water stress was imposed by withholding irrigation for 9 days in the early squaring stage, which resulted in 10–15 % reduction in plant growth compared to the well-watered plants. A total of 110 drought-responsive genes (0.5 % of the total genes) were identified, 79 % (88 genes) of which were drought-repressed and 21 % (22 genes) were drought-induced. The drought-induced genes were grouped into six functional categories including stress-related (ten genes, nine of which encode heat shock proteins), metabolism (three genes) and one gene each for transcription factor, proline biosynthesis and cellular transport. The drought-repressed genes were classified into 14 functional categories, comprising metabolism (20 genes), cellular transport (12 genes), stress-related (12 genes), regulation of gene expression (nine genes), transcription factor (four genes), signal transduction (seven genes) and two genes each for biosynthesis of secondary compounds, cell wall, fatty acids/lipids and chlorophyll, and protein degradation. Most of the genes have been reported in other plants as drought-tolerant/responsive. The responsiveness of 19 selected drought-responsive genes was validated by quantitative RT-PCR. Furthermore, primers were developed and assayed for all the drought-responsive genes to develop single-strand conformation polymorphic markers, many of which were found to be correlated with drought tolerance. This report represents the first study on integration of a transcriptome analysis to develop molecular markers that are associated with drought tolerance in cotton.

Isolation of Viable Multicellular Glands from Tissue of the Carnivorous Plant, <i>Nepenthes</i>

Many plants possess specialized structures that are involved in the production and secretion of specific low molecular weight compounds and proteins. These structures are almost always localized on plant surfaces. Among them are nectaries or glandular trichomes. The secreted compounds are often employed in interactions with the biotic environment, for example as attractants for pollinators or deterrents against herbivores. Glands that are unique in several aspects can be found in carnivorous plants. In so-called pitcher plants of the genus Nepenthes, bifunctional glands inside the pitfall-trap on the one hand secrete the digestive fluid, including all enzymes necessary for prey digestion, and on the other hand take-up the released nutrients. Thus, these glands represent an ideal, specialized tissue predestinated to study the underlying molecular, biochemical, and physiological mechanisms of protein secretion and nutrient uptake in plants. Moreover, generally the biosynthesis of secondary compounds produced by many plants equipped with glandular structures could be investigated directly in glands. In order to work on such specialized structures, they need to be isolated efficiently, fast, metabolically active, and without contamination with other tissues. Therefore, a mechanical micropreparation technique was developed and applied for studies on Nepenthes digestion fluid. Here, a protocol is presented that was used to successfully prepare single bifunctional glands from Nepenthes traps, based on a mechanized microsampling platform. The glands could be isolated and directly used further for gene expression analysis by PCR techniques after preparation of RNA.

Olive phenolic compounds: metabolic and transcriptional profiling during fruit development

BackgroundOlive (Olea europaea L.) fruits contain numerous secondary metabolites, primarily phenolics, terpenes and sterols, some of which are particularly interesting for their nutraceutical properties. This study will attempt to provide further insight into the profile of olive phenolic compounds during fruit development and to identify the major genetic determinants of phenolic metabolism.ResultsThe concentration of the major phenolic compounds, such as oleuropein, demethyloleuropein, 3–4 DHPEA-EDA, ligstroside, tyrosol, hydroxytyrosol, verbascoside and lignans, were measured in the developing fruits of 12 olive cultivars. The content of these compounds varied significantly among the cultivars and decreased during fruit development and maturation, with some compounds showing specificity for certain cultivars. Thirty-five olive transcripts homologous to genes involved in the pathways of the main secondary metabolites were identified from the massive sequencing data of the olive fruit transcriptome or from cDNA-AFLP analysis. Their mRNA levels were determined using RT-qPCR analysis on fruits of high- and low-phenolic varieties (Coratina and Dolce d’Andria, respectively) during three different fruit developmental stages. A strong correlation was observed between phenolic compound concentrations and transcripts putatively involved in their biosynthesis, suggesting a transcriptional regulation of the corresponding pathways. OeDXS, OeGES, OeGE10H and OeADH, encoding putative 1-deoxy-D-xylulose-5-P synthase, geraniol synthase, geraniol 10-hydroxylase and arogenate dehydrogenase, respectively, were almost exclusively present at 45 days after flowering (DAF), suggesting that these compounds might play a key role in regulating secoiridoid accumulation during fruit development.ConclusionsMetabolic and transcriptional profiling led to the identification of some major players putatively involved in biosynthesis of secondary compounds in the olive tree. Our data represent the first step towards the functional characterisation of important genes for the determination of olive fruit quality.

Seasonal changes in nitrogen availability, and root and microbial uptake of 15N 13C 9-phenylalanine and 15N-ammonium in situ at a temperate heath

In the plant biosynthesis of secondary compounds, phenylalanine is a precursor of condensed tannins. Tannins are deposited into the soil in plant root exudates and dead plant material and have been suggested to precipitate some soil nutrients and hence reduce nutrient availability for plants. Free amino acid, inorganic and microbial N concentration during the growing season was investigated in an ecosystem with a natural tannin chemosphere. The influence of tannins on the uptake of nitrogen in plants and microbes was followed by injecting tannic acid (TA), ammonium- 15N and phenylalanine- 15N/ 13C 9. Plants preferred ammonium over phenylalanine, while microbes had no preference. Soil microbes had a 77% uptake of intact phenylalanine. Phenylalanine was acquired intact by both grasses and Calluna, with 63% and 38% uptake of intact phenylalanine in grass fine roots and Calluna roots, respectively. Inorganic N and amino acid concentrations were lowest in the period with highest plant activity and grass root biomass but were unaffected by TA addition.

Transcriptional Profiling of Mature Arabidopsis Trichomes Reveals That NOECK Encodes the MIXTA-Like Transcriptional Regulator MYB106

Leaf hairs (trichomes) of Arabidopsis (Arabidopsis thaliana) have been extensively used as a model to address general questions in cell and developmental biology. Here, we lay the foundation for a systems-level understanding of the biology of this model cell type by performing genome-wide gene expression analyses. We have identified 3,231 genes that are up-regulated in mature trichomes relative to leaves without trichomes, and we compared wild-type trichomes with two mutants, glabra3 and triptychon, that affect trichome morphology and physiology in contrasting ways. We found that cell wall-related transcripts were particularly overrepresented in trichomes, consistent with their highly elaborated structure. In addition, trichome expression maps revealed high activities of anthocyanin, flavonoid, and glucosinolate pathways, indicative of the roles of trichomes in the biosynthesis of secondary compounds and defense. Interspecies comparisons revealed that Arabidopsis trichomes share many expressed genes with cotton (Gossypium hirsutum) fibers, making them an attractive model to study industrially important fibers. In addition to identifying physiological processes involved in the development of a specific cell type, we also demonstrated the utility of transcript profiling for identifying and analyzing regulatory gene function. One of the genes that are differentially expressed in fibers is the MYB transcription factor GhMYB25. A combination of transcript profiling and map-based cloning revealed that the NOECK gene of Arabidopsis encodes AtMYB106, a MIXTA-like transcription factor and homolog of cotton GhMYB25. However, in contrast to Antirrhinum, in which MIXTA promotes epidermal cell outgrowth, AtMYB106 appears to function as a repressor of cell outgrowth in Arabidopsis.

The octadecanoic pathway: signal molecules for the regulation of secondary pathways.

Plant defense against microbial pathogens and herbivores relies heavily on the induction of defense proteins and low molecular weight antibiotics. The signals between perception of the aggression, gene activation, and the subsequent biosynthesis of secondary compounds are assumed to be pentacylic oxylipin derivatives. The rapid, but transient, synthesis of cis-jasmonic acid was demonstrated after insect attack on a food plant and by microbial elicitor addition to plant suspension cultures. This effect is highly specific and not caused by a number of environmental stresses such as light, heavy metals, or cold or heat shock. Elicitation of Eschscholtzia cell cultures also led to a rapid alkalinization of the growth medium prior to jasmonate formation. Inhibition of this alkalinization process by the protein kinase inhibitor staurosporine also inhibited jasmonate formation. The induction of specific enzymes in the benzo[c]phenanthridine alkaloid pathway leading to the antimicrobial sanguinarine was induced to a qualitatively and quantitatively similar extent by fungal elicitor, methyl jasmonate, and its linolenic acid-derived precursor 12-oxophytodienoic acid. It is herein proposed that a second oxylipid cascade may exist in plants starting from linoleic acid via 15,16-dihydro-12-oxophytodienoic acid to 9,10-dihydrojasmonate. Experiments with synthetic trihomojasmonate demonstrated that beta-oxidation is not a prerequisite for biological activity and that 12-oxophytodienoic acid and derivatives are most likely fully active as signal transducers. Octadecanoic acid-derived compounds are essential elements in modulating the synthesis of antibiotic compounds and are thus integral to plant defense.

The applications of hydrophobic interaction chromatography to the purification of plant proteins

Protein separation by hydrophobic interaction chromatography (HIC) depends on the differences in surface hydrophobicity of the constituent proteins and is hence complementary to chromatographic techniques based on the charge or the size of the macromolecule. This review summarises some of the recent developments in HIC supports and discusses the parameters that must be considered in designing an efficient chromatographic system. The application of HIC to the purification of enzymes of secondary compound biosynthesis that cannot be obtained in pure form by size-exclusion and ion-exchange techniques alone is exemplified by reference to recent studies on tryptophan decarboxylase, strictosidine synthase and geraniol-10-hydroxylase.

Pesticide effects on secondary metabolism of higher plants

AbstractSecondary compounds serve both endogenous and exogenous functions in higher plants because they are involved in plant growth and development as well as intraspecies and interspecies interactions. Documentation of the effects of pesticides on secondary compound biosynthesis in higher plants is increasing. While several herbicides have been reported to reduce levels of secondary compounds by non‐specific mechanisms, a few herbicides, such as alachlor and glyphosate, directly affect specific biosynthetic steps. Alachlor reduces flavonoid synthesis at a step late in the biosynthetic pathway, and glyphosate blocks synthesis of all cinnamate derivatives by inhibiting 5‐enolpyruvyl shikimate‐3‐phosphate (EPSP) synthase. Inhibition of EPSP synthase also leads to the accumulation of high levels of shikimate, benzoic acids and benzoic acid derivatives. The sulfonylureas and p‐nitro‐substituted diphenylether (DPE) herbicides can cause increases in the level of cinnamatederived phenolic compounds and the DPEs can cause dramatic increases in terpenoid stress metabolites. Certain fungicides are thought to act through enhancing the capacity of plants to produce phytoalexins. These and other data suggest that sublethal effects of pesticides on target and non‐target plants can significantly affect agricultural ecosystems by altering the synthesis of compounds important in inter‐ and intraspecies interactions.