Levels Of Secondary Compounds Research Articles

Effect of provenance on leaf morphological traits and secondary metabolite levels in leaf extracts of Myrtle (Myrtus communis L.) in Morocco

Myrtus communis L. is widely used as an aromatic and medicinal plant. In this work, we investigate the influence of provenance on leaf morphological traits and secondary metabolite levels in leaf extracts of Myrtle. Samples of myrtle from different geographically distinct areas were measured and analysed for polyphenols, flavonoids, condensed tannins, and antioxidant activity using the DPPH test. The analysis of result reveals the significant variance among populations in terms of morphological traits and levels of secondary compounds, particularly in terms of polyphenols, flavonoids, condensed tannins, and reducing power. Correlations between certain studied traits and environmental conditions were recorded. Leaf size and methanolic leaf extract yields from Moroccan myrtle showed as good criteria for natural population selection. Precipitation, temperature, and altitude were determinants of variation in leaf morphological traits, extract yield, and their polyphenolic, tannin, and flavonoid compounds. Based on the studied traits, three major groups were identified with few clear geographical affiliations. The IZA population from the Western Rif and GHA from the Pre-Rif formed a separate group from the other populations, characterized by the highest extract yields. The BRA population from the central plateau formed a distinct isolated group from the others. This population, collected from a location with low annual rainfall values was the richest in tannins with relatively high levels of polyphenols and flavonoids compared to other populations. This means that drought affects the amount of polyphenols and flavonoids. The geographical structure of the third group is mixed, including the IKA and AGH (Pre-Rif) populations, BS and RAB from the Central Plateau, and BT from the Western Rif.

Seasonal Variation in Host Plant Chemistry Drives Sequestration in a Specialist Caterpillar

Sequestration of plant secondary metabolites by herbivores can vary across both host plant phenology and herbivore ontogeny, but few studies have explored how they concurrently change in the field. We explored variation in iridoid glycoside concentration and composition in white turtlehead, Chelone glabra, as well as sequestration of iridoid glycosides by its specialist herbivore, the Baltimore checkerspot, Euphydryas phaeton, across the development of both herbivore and host plant. In 2012 we sampled plants to describe seasonal variation in the concentrations of two iridoid glycosides, aucubin and catalpol. In 2017, we sampled both host plants and caterpillars over an entire growing season and explored the relationship between plant chemistry and herbivore sequestration. We also compared iridoid glycoside concentrations of plants with and without herbivory to gain insight into whether levels of secondary compounds were impacted by herbivory. We found that total plant iridoid glycosides varied across the season and that total sequestered iridoid glycosides in caterpillars closely mirrored concentration patterns in plants. However, the magnitude of sequestration by caterpillars ranged from 2 to 20 times the concentrations in host plants, with different proportions of aucubin and catalpol. In addition, plants with herbivory had lower iridoid glycoside concentrations than plants without herbivory, although this difference changed over time. These results suggest that while variation in host plant secondary metabolites may be a dominant factor driving sequestration, other ecological factors may mitigate the relationship between host plant chemistry and herbivore sequestration.

To bee or not to bee: The ‘raison d'être’ of toxic secondary compounds in the pollen of Boraginaceae

Abstract While the presence of secondary compounds in floral nectar has received considerable attention, much less is known about the ecological significance and evolutionary origin of secondary ‘toxic’ compounds in pollen. It is unclear whether the presence of these compounds in pollen is non‐adaptive and due to physiological ‘spillover’ from other floral tissues, or whether these compounds serve an adaptive function related to plant–pollinator interactions, such as protection of pollen against pollen thieves. Combining an experimental approach with phylogenetic comparative methods, and using western Palaearctic Boraginaceae as a model system, we investigate how pollen secondary metabolites influence, and are influenced by, relationships with bees, the main functional group of pollen‐foraging pollinators. We found a significant relationship between the levels of secondary compounds in the corollas and those in the pollen in the investigated species of Boraginaceae, suggesting that baseline levels of pollen secondary compounds may partly be due to spillover from floral tissues. At realistic levels, pollen secondary compounds showed significant detrimental effects on bee pre‐imaginal development, in agreement with previous egg‐transfer experiments showing that in some cases Boraginaceae pollen did not support pre‐imaginal development in bees not specialized on these plants. We also show that phylogenetically independent Boraginaceae taxa rewarding pollinators with pollen in addition to nectar exhibit significantly lower levels of toxic compounds in the pollen than taxa where the main reward is postulated to be nectar. Lastly, in contrast to our predictions, there was no positive association between toxin levels in the pollen of a given plant taxon and the number of bee species specialized on this taxon. We integrate all these findings and formulate an evolutionary scenario to account for the presence of toxic compounds in the pollen of Boraginaceae. We suggest that baseline levels of toxic compounds may be found in pollen due to spillover from other floral tissues and not primarily because of bee–flower interactions. Since pollen toxins can have detrimental effects on bees, we propose that selection acts to lower pollen toxin levels in plants where pollen, in addition to nectar, serves as a reward to bees. A free Plain Language Summary can be found within the Supporting Information of this article.

Phenolic compounds induced by Bemisia tabaci and Trialeurodes vaporariorum in Nicotiana tabacum L. and their relationship with the salicylic acid signaling pathway

Changes in the levels of secondary compounds can trigger plant defenses. To identify phenolic compounds induced by Bemisia tabaci Middle East-Asia Minor 1 (MEAM1) in tobacco (Nicotiana tobacco L.), the content changes of 11 phenolic compounds in plants infested by B. tabaci MEAM1 or Trialeurodes vaporariorum were compared. The chlorogenic acid, catechin, caffeic acid, p-coumaric acid, rutin, and ferulic acid contents in B. tabaci MEAM1-infested tobacco plants increased significantly, having temporal and spatial effects, compared with uninfested control and T. vaporariorum infested plants. The contents were 4.10, 2.84, 2.25, 3.81, 1.46, and 1.91 times higher, respectively, than those in the control. However, a T. vaporariorum nymphal infestation just caused smaller chlorogenic acid, catechin, caffeic acid, and rutin contents increase, which were 2.33, 2.13, 1.59, and 3.19 times higher, respectively, than those in the control. In B. tabaci MEAM1 third-instar nymph-infested plants, chlorogenic acid, catechin, caffeic acid, and rutin increased more significantly in systemic than in local leaves. Salicylate-deficient plants inhibited the induction of the content of 10 phenolic compounds, but not caffeic acid, after a B. tabaci MEAM1 nymphal infestation. Thus, the elevated levels of phenolic compounds induced by B. tabaci MEAM1 were correlated with the salicylic acid signaling pathway and induced the responses of defense-related phenolic compounds.

How lichens impact on terrestrial community and ecosystem properties.

Lichens occur in most terrestrial ecosystems; they are often present as minor contributors, but in some forests, drylands and tundras they can make up most of the ground layer biomass. As such, lichens dominate approximately 8% of the Earth's land surface. Despite their potential importance in driving ecosystem biogeochemistry, the influence of lichens on community processes and ecosystem functioning have attracted relatively little attention. Here, we review the role of lichens in terrestrial ecosystems and draw attention to the important, but often overlooked role of lichens as determinants of ecological processes. We start by assessing characteristics that vary among lichens and that may be important in determining their ecological role; these include their growth form, the types of photobionts that they contain, their key functional traits, their water-holding capacity, their colour, and the levels of secondary compounds in their thalli. We then assess how these differences among lichens influence their impacts on ecosystem and community processes. As such, we consider the consequences of these differences for determining the impacts of lichens on ecosystem nutrient inputs and fluxes, on the loss of mass and nutrients during lichen thallus decomposition, and on the role of lichenivorous invertebrates in moderating decomposition. We then consider how differences among lichens impact on their interactions with consumer organisms that utilize lichen thalli, and that range in size from microfauna (for which the primary role of lichens is habitat provision) to large mammals (for which lichens are primarily a food source). We then address how differences among lichens impact on plants, through for example increasing nutrient inputs and availability during primary succession, and serving as a filter for plant seedling establishment. Finally we identify areas in need of further work for better understanding the role of lichens in terrestrial ecosystems. These include understanding how the high intraspecific trait variation that characterizes many lichens impacts on community assembly processes and ecosystem functioning, how multiple species mixtures of lichens affect the key community- and ecosystem-level processes that they drive, the extent to which lichens in early succession influence vascular plant succession and ecosystem development in the longer term, and how global change drivers may impact on ecosystem functioning through altering the functional composition of lichen communities.

Salinity stress effects on direct and indirect defence metabolites in maize

In nature, plants are often exposed to multiple stress factors at the same time. The effects of single biotic or abiotic stresses on plant metabolism are well documented but how plants respond to a combination of these is little researched. Here we studied the effects of high salinity and herbivory on levels of secondary compounds and gene expression associated with defences against insects. Hydroponically grown maize plants were subjected to sodium chloride (1, 50, 100mM NaCl) and/or damage by caterpillars of Spodoptera exigua. Salt-stressed plants showed stunted growth, reduced chlorophyll fluorescence and enhanced levels of reactive oxygen species and 1,4-benzoxazin-3-one aglycones (aBX). Herbivory induced higher transcript levels of the Zm-Bx1 gene involved in aBX biosynthesis and of the Zm-SerPIN gene coding for a serine proteinase inhibitor which might affect plant feeding insects. Herbivory also triggered the emission of volatile organic compounds (VOCs) that are attractive signals for parasitoids and predators and thus regarded as an indirect defence. Herbivore-induced metabolites were differentially affected in salt-stressed plants. High salinity resulted in transient priming of jasmonic acid while aBX levels were reduced in double-stressed plants. Salt stress led to lower herbivore-induced VOC emission per plant but not per unit biomass. However, quantitative shifts in individual compounds were found in both cases. Our study confirms the notion that combined stresses produce a unique phenotype that cannot be derived from single-stress effects. The ecological implications of these changes for organisms from different trophic levels and for plant fitness remain to be tested.

Can polycultural manipulation effectively control rice planthoppers in rice-based ecosystems?

Rice planthoppers (mainly Nilaparvata lugens (Stål) and Sogatella furcifera Horvath) are the most destructive rice pests throughout southeastern and eastern Asia. Planthopper feeding often causes “hopper burn” and reduces rice yields. Currently, insecticide use is the sole pest management option available to most Chinese farmers. Because pesticide use may have undesirable effects, environmentally sound and sustainable management alternatives are urgently needed. In a two-year field study at the Wuyishan Experimental Station of the Institute of Applied Ecology (IAE), Fujian Agriculture and Forestry University (FAFU), we evaluated the effects of polycultural manipulation on the abundance, sexual differentiation and wing dimorphism of rice planthoppers. The polycultural manipulation was arranged in mosaic patterns of paddy plots intercropped with non-paddy plots including chili pepper, ginger, maize and peanut plants. Monocultural fields of paddy plants were used as controls. Polycultural manipulation significantly reduced the abundance of total planthoppers and nymphs of N. lugens and S. furcifera. The number of overall planthoppers decreased on average by 49% and 55% in 2007 and 2008, respectively. However, polycultural manipulation had no impact on the proportions of female or macropterous planthoppers. The resource concentration and associational resistance hypotheses may explain these results. In polycultural fields, non-rice species may mask the chemical or visual attractants of rice, making them less apparent, and microhabitat differences in the levels of secondary compounds or in plant quality may also disrupt planthopper orientation.

Biodiversity of wild strains of Saccharomyces cerevisiae as tool to complement and optimize wine quality

The principal agent in winemaking is the yeast Saccharomyces cerevisiae, which is characterized by a significant strain biodiversity. Here we report the characterization of 80 wild S. cerevisiae strains, isolated from grapes of different varieties in southern Italy, for genetic and technological variability. By PCR amplification with M13 primer a significant polymorphism was recorded and 12 different biotypes were identified among the strains. The specific strain-pattern could be used to follow the dynamics of different biotypes during the fermentation process. The analysis of experimental wines obtained by inoculated fermentations with the 80 strains showed significant differences among the wines. The level of each compound was a function of the strain performing the fermentative process. The main variables for the strain differentiation were the production of acetaldehyde and acetic acid, which ranged from 53 to 282 mg/l and from 0.20 to 1.88 g/l, respectively. Selected strains were tested in fermentation with two different grape musts, yielding experimental wines differing in the levels of secondary compounds and polyphenol content, in function of the interaction “grape must composition/yeast strain”. This finding has an applicative value for the potentiality of utilizing the resource of strain variability as a tool to individuate suitable starter cultures, which are able to complement and optimize grape quality.

Neighbor species differentially alter resistance phenotypes in Plantago

In this study, we investigated how neighbors (i.e., competitors) altered resistance phenotypes, namely plant size and levels of secondary compounds (iridoid glycosides), of individual plants and specifically tested whether neighbor identity mattered. We conducted a greenhouse experiment with Plantago lanceolata and Plantago major (Plantaginaceae) in which each species served as focal plants as well as neighbors in a factorial design. In addition, we harvested plants six and nine weeks after transplantation to test whether effects changed as plants grew. In both species, competition reduced plant size, and this effect increased over time. Plantago lanceolata neighbors suppressed growth of both focal plant species more than P. major neighbors. Effects of competition on levels of secondary compounds were more complex. Concentrations of iridoid glycosides were increased by competition in both species at harvest one. By the second harvest, an effect of competition on iridoid glycosides was found only in P. major. Neighbor identity influenced levels of iridoid glycosides in P. lanceolata at harvest one; concentrations were higher in plants grown with P. lanceolata neighbors than in plants grown with P. major neighbors. We also tested whether there was a trade-off between growth (biomass) and defense (levels of iridoid glycosides). Biomass and iridoid glycoside content were significantly correlated only in plants grown with competition and harvested at nine weeks, and this relationship was positive in both species, indicating that there was no trade-off between growth and defense. This study suggests that neighbor identity could play an important role in interspecific interactions, including the interactions of plants with other trophic levels.

The influence of different yeasts on the fermentation, composition and sensory quality of cachaça

Cachaca (sugarcane wine) was produced using different yeast strains, six being strains of Saccharomyces cerevisiae and one each of Candida apicola, Hanseniaspora occidentalis, Pichia subpelliculosa and Schizosaccharomyces pombe. The ethanol yields (%) of the non-Saccharomyces strains were similar to those of the Saccharomyces strains. The following determinations were carried out on the cachaca: acetaldehyde, ethyl acetate, propanol, isobutyl alcohol, isoamyl alcohol, volatile acidity. The cachacas showed variations in the levels of secondary compounds, but these variations did not result in differences (P ≤ 0.05) in the sensory attributes of aroma and flavour and overall impression. Of the volatile compounds quantified in the cachacas, only propanol showed a positive correlation (P ≤ 0.05) with the flavour attributes and overall impression. The S. pombe strain was considered inadequate for the production of cachaca. The cachacas were classified into five groups in an exploratory Hierarchical Cluster Analysis as a function of the volatile compounds. Principal Component Analysis showed that 93% of the variation (PC 1) occurred among the samples, and was explained by the individual volatile compounds and the total secondary compounds, with the exception of isoamyl alcohol only 7% (PC 2) was associated with the volatile acidity. The negative correlations shown between the volatile compounds of the cachacas and the ethanol content of the sugarcane wine, with the exception of acetaldehyde, showed that the variation in ethanol content of the sugarcane wine is an important factor for standardization of the ethanol/volatiles ratio and the beverage quality.

Dietary and Feeding Differences Between Sympatric Propithecus diadema diadema and Indri indri

We analyzed the dietary profiles and feeding behaviors of Propithecus diadema diadema and Indri indri in a community of animals that reside in midaltitude rain forest within Madagascar's Mantadia National Park. Propithecus diadema diadema ate a diverse mixture of fruits, seeds, flowers and young leaves, while the bulk of the diet of Indri indri consisted of young leaves, which resulted in significantly higher levels of fat and water-soluble carbohydrates in foods eaten by Propithecus diadema diadema. Fiber values of items eaten are high (54% NDF) for both species, though not significantly different between them. The preference for immature foliage by Indri indri suggests that their overall intake of fiber is greater than that of Propithecus diadema diadema, which had a high proportion of non-leaf material in their diet. We propose that differences in gut morphology between the two indriids contribute to their disparate diets. Levels of secondary compounds were high in certain food items, but overall they are also not significantly different between the two indriid diets. Propithecus diadema diadema exhibited a strong preference for 2 alkaloid-containing seed species, while no food of Indri indri contained alkaloids. In addition, Propithecus diadema diadema consumed a higher diversity of plant species on a daily/yearly basis, exhibited more feeding bouts on a daily basis, and their feeding bouts (on young leaves, fruit and flowers) are significantly shorter in duration than those of Indri indri. Furthermore, Propithecus diadema diadema had twice the number of geophagic episodes of Indri indri.

Chemical defense of embryos and larvae of a West Indian gorgonian coral,Briareum asbestinum

Summary The complex life cycles of colonial marine invertebrates provide an unusual opportunity to examine potential constraints in chemical defense because colonies are of ten chemically well defended, and the multiple developmental stages are accessible. Briareum asbestinum is unique among Caribbean gorgonians in surface brooding newly fertilized, conspicuously colored eggs and larvae; therefore, all developmental stages can be collected from the surface of a colony. In St. Croix, US Virgin Islands, maternal colonies and their embryos, larvae and newly metamorphosed juveniles have high levels of asbestinane diterpenoids. Although the embryos are brooded for approximately 8 months, and the four major compounds are present in adult colonies and their early embryonic progeny in similar concentrations, there is not a significant correlation between the levels of secondary compounds in embryos and their natal colonies. Levels of compounds did not vary significantly with stage nor change linearly through deve...

Preservation of salicaceae leaves for phytochemical analyses: Further assessment

The chemistry of the plant family Salicaceae has been of interest to researchers as diverse as chemical ecologists, chemosystematists, and paper chemists. Continuing the debate on proper methods for preservation of plant material prior to analysis, vacuum-drying was recently advocated, because freeze-drying may cause degradation of phenolic glycosides. This study was conducted to clarify the consequences of freeze-drying for foliar secondary chemicals and to evaluate the consequences of vacuum-drying for primary compounds (protein and carbohydrates). Leaves of quaking aspen (Populus tremuloides) were flash-frozen in liquid nitrogen and freeze-dried or vacuum-dried at room temperature. We then analyzed samples for levels of salicortin and tremulacin (phenolic glycosides), condensed tannins, nitrogen, soluble protein, sugars, and starch. Freeze-drying did not alter the concentrations of phenolic glycosides or tannins, relative to vacuum-drying. Freeze-drying did cause a small and inexplicable decline in nitrogen and soluble protein. Vacuum-drying, however, reduced starch concentrations by 38%. We suggest that the vacuum-drying method be used in studies in which carbohydrates are of no interest. For studies measuring carbohydrates, however, freeze-drying is a better alternative, and should effect no changes in levels of secondary compounds if samples are not allowed to thaw during the drying process.

Seasonal changes in secondary compounds in the phloem sap of cassava in relation to plant genotype and infestation byPhenacoccus manihoti(Homoptera: Pseudococcidae)

AbstractA previous study on the population dynamics of the cassava mealybug,Phenacoccus manihoti(Matile-Ferrero), on cassava has shown that populations increase during the dry season. The aim of the present studies was to determine whether these important changes in the pest population observed throughout the seasons in the field in the Congo, could be correlated with seasonal variations in the level of secondary compounds in the phloem, implicated in cassava plant resistance toP. manihoti. Our results showed that cassava was in drought stress conditions during the dry season (foliar area decreased). The combination of infestation and dry stress factors was clearly visible during the dry season. In fact, the decrease in leaf water potential together with infestation byP. manihotiwas clearly observed at the end of the rainy season and during the dry season. The levels of the secondary compounds, rutin (an unfavourable substance toP. manihoti) decreased in the less resistant genotype, and cyanide (a phagostimulant substance) increased in each genotype in the dry season. These results may partially explain the important population changes inP. manihotiduring the seasons.

Changes in Saponins and Tannins in Ripening Holly Fruits and Effects of Fruit Consumption on Nonadapted Insect Herbivores

-Secondary compounds in fruits are thought to be a defense against invertebrates or pathogens which might otherwise damage or destroy the fruits or seeds without contributing to seed dispersal. We incorporated ground, nonripe green or ripe red fruits of American holly Ilex opaca into standard diets of two species of polyphagous caterpillars to test the hypothesis that nonripe fruits are better defended than ripe fruits. Fall armyworm Spodoptera frugiperda larvae grew more slowly on diet augmented with 10% (dry wt) ripe fruits than on control diet with 10% cellulose powder, and slower still on diet with nonripe fruits. However, survival, pupal weight and length of the pupal period were not affected by either treatment. Growth rates and survival of fall webworms HIyphantria cunea were reduced to a similar degree by both nonripe and ripe fruits. Methanolic extracts of nonripe fruits brushed on leaf disks of sassafras, a preferred host, deterred feeding by Japanese beetles Popillia japonica Newman, a highly polyphagous species. Extracts of ripe fruits were not repellent. Saponin content was highest in nonripe green fruits, while tannin levels were highest in ripening fruits. In choice tests, red holly fruits were removed from bird feeders at a faster rate than nonripe green fruits. Levels of secondary compounds in fruits of I. opaca may be a compromise between the continued need to protect the seeds from predispersal damaging agents without deterring potential vertebrate dispersers.