TABLE 3 - uploaded by John Lokvam
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The leaves of tropical forest trees are most likely to suffer herbivore damage during the period of expansion. Herbivore selection on young leaves has given rise to a variety of leaf developmental strategies and age-specific chemical defense modes. We are studying correlations between leaf developmental types and chemical defenses in the Neotropica...
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... on the weighted averages of the individual fractions, the mDP of the entire phenolic population was estimated to be 7.2. CatechinYepicatechin ratios of the free monomers and for each of the I. goldmanii LH-20 fractions are listed in Table 3. Catechin is the predominant monomeric form and the most common procyanidin initiator unit, particularly in the higher molecular weight polymers. ...
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... Mass was received by HR-ESI-MS in negative mode. The structures of compounds 1-7, 10, 12, 14, and 16 were confirmed by comparing the NMR-spectroscopic data of the substances with the literature [14][15][16][17][18][19][20]. For substances 8 and 13, only data for the peracetylated compound can be found in the literature [21,22]. ...
Bassia longifoliaKOENIG (= Madhuca longifolia (L.) is an evergreen tree that is widely distributed throughout Nepal, India, and Sri Lanka. The bark has various traditional uses: as a paste in the treatment of cuts and wounds or internally as a decoction that is given to diabetic patients. Chemical-analytical and pharmacological investigations regarding the bark are not sufficiently available. We focused on the isolation of flavan-3-ols from the methanolic extract and their contribution to the described traditional uses in wound healing and diabetes treatment. Therefore, an antibacterial assay and an α-glucosidase assay were performed. The isolation process was performed by a combination of Sephadex®-, MCI®-Gel-, and RP-18 chromatography. The structures of the isolated compounds were elucidated by ¹H- and ¹³C-NMR-spectroscopy including COSY, ROESY, HSQC, and HMBC methods. Optical characterization was performed by polarimetry and circular dichroism. Two monomeric, seven dimeric, six trimeric, and one tetrameric flavan-3-ols were found including one dimer and three trimers with rare epiafzelechin units. Two compounds were isolated for the first time. A fraction containing higher oligomeric and polymeric proanthocyanidins (PAs) was examined by ¹³C NMR spectroscopy and revealed an average degree of polymerization of 8–9. PA with cis-configurated subunits predominated at 90 % and the presence of further monohydroxylated flavan-3-ols was revealed. Minimal inhibitory concentrations (MICs) were investigated by the serial microdilution broth assay with Staphylococcus aureus. The bacterial suspension was inoculated on agar plates for determining the MICs. The α-glucosidase assay was performed in 96 well plates with α-glucosidase from Bacillus stearothermophilus. For the detection of enzyme inhibition, p-nitrophenyl-α-d-glucopyranoside was used as a substrate and after incubation absorbance was measured at 405 nm. Antibacterial effects were only found for fractions enriched with PAs or containing higher oligomeric and polymeric flavan-3-ols. All tested substances showed high α-glucosidase inhibition. Whereby 4β→8 conjugated dimers and the monomers showed the lowest inhibition, procyanidin (PC) B5 as 4β→6 conjugated and cinnamtannin A2 as tetrameric flavan-3-ol showed the highest. PAs with epiafzelechin units are rarely found in nature but their reoccurring appearance in B. longifolia could be characteristic of this plant. For its traditional uses, the antibacterial activity of the PA-enriched fractions could contribute to the wound healing process when applied to the injured skin. Moreover, all tested substances and fractions showed α-glucosidase inhibition, which could also explain the use of a decoction in the treatment of diabetes. In conclusion, pharmacological investigations could provide scientific evidence for traditional uses of B. longifolia.
... More tannins are detected in cherry leaves or persimmon leaves infested by fungus (Niederleitner et al. 1994;Hassan, Chang, and Hossain 2020).This is a result of the plant being forced by biotic stress to produce more PCs to suppress pest-related activities (War et al. 2012). The inhibition of growth through protein precipitation may be an important mechanism, as well as oxidative stress to make inhibitory effects on pests (Lokvam and Kursar 2005). ...
Proanthocyanidins (PAs) are a class of polymers composed of flavan-3-ol units that have a variety of bioactivities, and could be applied as natural biologics in food, pharmaceuticals, and cosmetics. PAs are widely found in fruit and vegetables (F&Vegs) and are generally extracted from their flesh and peel. To reduce the cost of extraction and increase the number of commercially viable sources of PAs, it is possible to exploit the by-products of plants. Leaves are major by-products of agricultural production of F&Vegs, and although their share has not been accurately quantified. They make up no less than 20% of the plant and leaves might be an interesting resource at different stages during production and processing. The specific structural PAs in the leaves of various plants are easily overlooked and are notably characterized by their stable content and degree of polymerization. This review examines the existing data on the effects of various factors (e.g. processing conditions, and environment, climate, species, and maturity) on the content and structure of leaf PAs, and highlights their bioactivity (e.g. antioxidant, anti-inflammatory, antibacterial, anticancer, and anti-obesity activity), as well as their interactions with gut microbiota and other biomolecules (e.g. polysaccharides and proteins). Future research is also needed to focus on their precise extraction, bioactivity of high-polymer native or modified PAs and better application type.
... Each compound can vary independently, leading to an almost infinite number of potential niche axes for herbivore species to occupy (Coley and Kursar 2014). We have catalogued over 9,000 compounds from Inga, including non-protein amino acids, flavonoids, flavan-3-ols, and saponins (Lokvam et al. 2004;Lokvam and Kursar 2005;Brenes-Arguedas et al. 2006;Lokvam et al. 2007). Inga also overexpresses L-tyrosine, an essential amino acid, which is toxic to herbivores at the elevated concentrations found in young Inga leaves Lokvam et al. 2006). ...
... Bioassays using artificial diets were conducted in Utah with Heliothis virescens (Noctuidae), a generalist herbivore of tropical origin, and in Panama with Phoebis philea (Pieridae), which feeds on Cassia (Fabaceae) but not on Inga. Bioassays showed that all extracts and fractions (Coley et al. 2005;Lokvam and Kursar 2005;Lokvam et al. 2006;Coley et al. 2018). In addition to secondary metabolites, one clade of 17 species overexpresses tyrosine in young expanding leaves . ...
In forests, insect herbivores and their host plants are major components of the community. The study of their interactions is essential for understanding the mechanisms promoting and maintaining species diversity and niche differentiation in both trophic levels (Becerra 2015). Theory has long predicted that the evolution of plant anti-herbivore defenses and insect counter-adaptations is the driver of trait diversification and coevolution (Ehrlich and Raven 1964). This arms race has also been implicated in mechanisms of coexistence (Becerra 1997; Lewinsohn and Roslin 2008; Kursar et al. 2009; Marquis et al. 2016; Maron et al. 2019). For example, recent work suggests that herbivores play a key role in maintaining the high local diversity of rainforests by preventing most plant species from becoming abundant (Comita et al. 2014). Species with different defenses do not share herbivores and therefore can coexist, promoting high local diversity (Janzen 1970; Becerra 2007, Fine et al. 2013; Comita et al. 2014; Coley and Kursar 2014, Salazar et al. 2016a, b; Vleminckx et al. 2018; Forrister et al. 2019). For herbivores, host plant specialization has been regarded as one of the main mechanisms promoting insect diversity, as specialized partitioning of plant resources may allow more herbivore species to coexist (Novotny et al. 2006; Lewinsohn and Roslin 2008). Thus, there is an intricate relationship between plant traits and host plant choice, yet we still do not fully understand the impacts of plant defenses on host choice nor the consequences at ecological and evolutionary time scales for herbivorous insects. In this chapter, we will review the relative effect of different plant defenses on host plant choice by Lepidoptera caterpillars. We will focus on insect herbivores associated with the Neotropical tree genus Inga (Fabaceae) in the rainforests of Central and South America, a region where the diversity of plants and invertebrates is among the highest in the terrestrial world and where the arms race coevolution may be particularly pronounced.KeywordsCommunity structureCoevolutionEcological trackingHost use
Inga
Insect herbivorePlant defensesExtrafloral nectariesSecondary metabolitesTrichomesTropical forestsYoung leavesLepidopteraGelechioideaErebidaeRiodinidaeLycaenidaeNoctuidaeSaponinsPhenolicsPanamaPeruEcuadorFrench Guiana
... Our analysis yielded 6,217 compounds from 91 Inga species and one species in its sister genus, Zygia mediana (156 accessions including the same species from different sites). In order to annotate compounds, we performed MS/MS spectral matching to all publicly available datasets in GNPS as well as in silico fragmentation of the Universal Natural Products Database (Allard et al., 2016;Gu et al., 2013) and our own in-house database built from compounds found in Inga (Lokvam & Kursar, 2005). We further enumerated the library using in silico combinatorial chemistry to generate ~75,000 plausible structures using the 'scaffold' and 'building block' structures within the CLEVER application (Song et al., 2009). ...
The outstanding diversity of Amazonian forests is predicted to be the result of several processes. While tree lineages have dispersed repeatedly across the Amazon, interactions between plants and insects may be the principal mechanism structuring the communities at local scales.
Using metabolomic and phylogenetic approaches, we investigated the patterns of historical assembly of plant communities across the Amazon based on the Neotropical genus of trees Inga (Leguminosae) at four, widely separated sites.
Our results show a low degree of phylogenetic structure and a mixing of chemotypes across the whole Amazon basin, suggesting that although biogeography may play a role, the metacommunity for any local community in the Amazon is the entire basin. Yet, local communities are assembled by ecological processes, with the suite of Inga at a given site more divergent in chemical defences than expected by chance
Synthesis. To our knowledge, this is the first study to present metabolomic data for nearly 100 species in a diverse Neotropical plant clade across the whole Amazonia. Our results demonstrate a role for plant–herbivore interactions in shaping the clade's community assembly at a local scale, and suggest that the high alpha diversity in Amazonian tree communities must be due in part to the interactions of diverse tree lineages with their natural enemies providing a high number of niche dimensions.
... In the leaves of I. umbellifera, flavonoids and proanthocyanidins derived from catechin were isolated (Lokvam et al., 2004). From I. goldmani, a trimeric proanthocyanidin and trans-4-methoxypipecolic acid was isolated from I. paterno (Lokvam and Kursar, 2005;Morton et al., 1991). From the leaves and barks of I. edulis metabolites derived from catechin, myricetin, quercetin, and terpenes derived from stigmasterol were isolated (Tchuenmogne et al., 2013). ...
The Inga genus comprises approximately 300 species that can be found from Mexico to northern Argentina. In folk medicine, Inga species are used to treat various diseases. The species Inga laurina is widely found in the Brazilian flora; however, there are few studies about its biological activity and chemical composition. The main purpose of this study was to identify and isolate the chemical constituents of Inga laurina barks and to evaluate the antifungal and cytotoxic activities. The total content of phenolics, proanthocyanidins, and flavonoids from the barks of Inga laurina were performed by spectrophotometric methods and the ethyl acetate (EAF) and n-butanol (BF) fractions showed the best results. Eleven compounds were identified in EAF by HPLC-ESI(−)-MS/MS, which showed good antifungal activity with MIC values of 23.4 and 46.8 μg mL⁻¹, evaluated by broth microdilution method. Five new compounds of the genus Inga were isolated for the first time. Three of these compounds were isolated and reported on the literature for the first time: a proanthocyanidin B-type, gallocatechin-(4α→8)-4’-O-methylgallocatechin (XI) and two proanthocyanidins A-type, gallocatechin-(2→O→7,4→8)-4’-O-methylgallocatechin (XII) and gallocatechin-3-O-galloyl-(2→O→7,4→8)-4’-O-methylgallocatechin (XIII). The chemical study of the plant bark showed that this species is rich in phenolic compounds and it has great potential for the discovery of new bioactive compounds.
... Both of these factors have previously been shown to influence protein precipitation capacity generally (e.g. Jones et al., 1976;Porter & Woodruffe, 1984;Kumar & Horigome, 1986;Osborne & McNeill, 2001;Lokvam & Kursar, 2005;Huang et al., 2011;Saminathan et al., 2014), which made it surprising that there was a negative relationship between the protein precipitation capacity of eucalypt samples and the mDP of PAs. Nevertheless, this could be due to a negative correlation between the mDP of PAs and the concentration of late-eluting HHDP derivatives (data not shown). ...
Although tannins have been an important focus of studies of plant–animal interactions, traditional tannin analyses cannot differentiate between the diversity of structures present in plants. This has limited our understanding of how different mixtures of these widespread secondary metabolites contribute to variation in biological activity.
We used UPLC‐MS/MS to determine the concentration and broad composition of tannins and polyphenols in 628 eucalypt (Eucalyptus, Corymbia and Angophora) samples, and related these to three in vitro functional measures believed to influence herbivore defence: protein precipitation capacity, oxidative activity at high pH and capacity to reduce in vitro nitrogen (N) digestibility.
Protein precipitation capacity was most strongly correlated with concentrations of procyanidin subunits in proanthocyanidins (PAs), and late‐eluting ellagitannins. Capacity to reduce in vitro N digestibility was affected most by the subunit composition and mean degree of polymerisation (mDP) of PAs. Finally, concentrations of ellagitannins and prodelphinidin subunits of PAs were the strongest determinants of oxidative activity.
The results illustrate why measures of total tannins rarely correlate with animal feeding responses. However, they also confirm that the analytical techniques utilised here could allow researchers to understand how variation in tannins influence the ecology of individuals and populations of herbivores, and, ultimately, other ecosystem processes.
... Given that plant chemical defenses can mediate attacks from natural enemies, they represent important plant traits that could determine the abundance and distribution of plant species. Moreover, secondary metabolites (hereafter: SM) can represent 30-50% of a plant's dry weight (Lokvam and Kursar, 2005), emphasizing the potential importance of selective pressures experienced by plants in response to natural enemies. Indeed, most species express dozens of metabolites that function to defend against natural enemies, and these metabolites exhibit important quantitative and qualitative variation across species (Agrawal and Weber, 2015). ...
Little is known about the mechanisms promoting or limiting the coexistence of functionally divergent species in hyperdiverse tropical tree genera. Density-dependent enemy attacks have been proposed to be a major driver for the local coexistence of chemically divergent congeneric species. At the same time, we expect local soil conditions to favor the coexistence of species sharing similar functional traits related to resource use strategies, while environmental heterogeneity would promote the diversity of these traits at both local and large spatial scales. To test how these traits mediate species coexistence, we used functional trait data for 29 species from the tree genus Protium (Burseraceae), collected in 19 plots (2 ha each) in the Peruvian Amazon. We characterized the presence-absence of 189 plant secondary metabolites (SM) for 27 of these species, and 14 functional traits associated with resource use strategies (RUT) for 16 species. Based on these data, we found that SM were significantly more dissimilar than null expectations for species co-occurring within plots, whereas RUT were significantly more similar. These results were consistent with the hypothesis that density-dependent enemy attacks contribute to the local coexistence of congeneric species displaying divergent chemical defenses, whereas local habitat conditions filter species with similar RUT. Using measurements of nine soil properties in each plot, we also found a significant turnover of RUT traits with increasing dissimilarity of soil texture and nutrient availabilities, providing support for the hypothesis that soil heterogeneity maintains functional diversity at larger spatial scales (from 500 m up to ca. 200 km) in Protium communities. Our study provides new evidence suggesting that density-dependent enemy attacks and soil heterogeneity both contribute to maintaining high species richness in diverse tropical forests.
... For case i in Fig. 1, we expect traits related to anti-herbivore defence to diverge more at low elevation, where ecological conditions are mainly characterized by strong biotic interactions (Coley and Aide 1991;Rasmann and Agrawal 2011;Rasmann et al. 2014). That herbivore pressure forces defence trait divergence has been corroborated in the tropics, on several systems (Kursar et al. 2009;Lokvam and Kursar 2005;Salazar et al. 2016). For case ii in Fig. 1, we expect that if a trait is principally affecting plant tolerance against abiotic stresses, we expect this trait to diverge more at high elevation. ...
Predicting variation in plant functional traits related to anti-herbivore defences remains a major challenge in ecological research, considering that multiple traits have evolved in response to both abiotic and biotic conditions. Therefore, understanding variation in plant anti-herbivore defence traits requires studying their expression along steep environmental gradients, such as along elevation, where multiple biotic and abiotic factors co-vary. We expand on plant defence theory and propose a novel conceptual framework to address the sources of variations of plant resistance traits at the community level. We analysed elevation patterns of within-community trait dissimilarity using the RaoQ index, and the community-weighted-mean (CWM) index, on several plant functional traits: plant height, specific leaf area (SLA), leaf-dry-matter-content (LDMC), silicium content, presence of trichomes, carbon-to-nitrogen ratio (CN) and total secondary metabolite richness. We found that at high elevation, where harsh environmental conditions persist, community functional convergence is dictated by traits relating to plant growth (plant height and SLA), while divergence arises for traits relating resource-use (LDMC). At low elevation, where greater biotic pressure occurs, we found a combination of random (plant height), convergence (metabolite richness) and divergence patterns (silicium content). This framework thus combines community assembly rules of ecological filtering and niche partition with plant defence hypotheses to unravel the relationship between environmental variations, biotic pressure and the average phenotype of plants within a community.
... One clade with 17 species overexpresses tyrosine, an essential amino acid that is highly toxic at 5-19% of dry weight (DW) found in expanding leaves . Expanding leaves invest substantial resources in these soluble secondary metabolites, averaging 45% DW (Lokvam and Kursar 2005;Wiggins et al. 2016). ...
... We have bioassayed the chemical fractions in Inga with a generalist caterpillar (Heliothis virescens; Coley et al. 2005;Lokvam and Kursar 2005;Lokvam et al. 2006;Brenes-Arguedas et al. 2008;Bixenmann et al. 2016;and unpublished). We found high toxicity of the phenolic and saponin fractions, and of tyrosine, even at concentrations considerably lower than what are found naturally in expanding leaves. ...
... This suggests that several distinct classes of compounds found in Inga (phenolics, saponins, non-protein amino acids and tyrosine) have a defensive role. An additional 20% of DW is covalently bound to cell walls, and bioassays with H. virescens show that this fraction is also highly toxic (Lokvam and Kursar 2005). Most studies ignore cell wall-bound compounds, yet this fraction contains a Only trichomes (length and density) showed a phylogenetic signal. ...
We summarize work on a speciose Neotropical tree genus, Inga (Fabaceae), examining how interspecific variation in anti-herbivore defenses may have evolved, how defenses shape host choice by herbivores and how they might regulate community composition and influence species radiations. Defenses of expanding leaves include secondary metabolites, extrafloral nectaries, rapid leaf expansion, trichomes, and synchrony and timing of leaf production. These six classes of defenses are orthogonal, supporting independent evolutionary trajectories. Moreover, only trichomes show a phylogenetic signature, suggesting evolutionary lability in nearly all defenses. The interspecific diversity in secondary metabolite profiles does not arise from the evolution of novel compounds, but from novel combinations of common compounds, presumably due to changes in gene regulation. Herbivore host choice is determined by plant defensive traits, not host phylogeny. Neighboring plants escape each other’s pests if their defenses differ enough, thereby enforcing the high local diversity typical of tropical forests. Related herbivores feed on hosts with similar defenses, implying that there are phylogenetic constraints placed on the herbivore traits that are associated with host use. Divergence in defensive traits among Inga appears to be driven by herbivore pressure. However, the lack of congruence between herbivore and host phylogeny suggests that herbivores are tracking defenses, choosing hosts based on traits for which they already have adaptations. There is, therefore, an asymmetry in the host–herbivore evolutionary arms race.
... T ropical plant species contain dozens of diverse secondary metabolites comprising up to half of their dry weight 1 . The current understanding of the mechanisms involved in the origin and maintenance of the vast diversity of plant secondary chemistry is based on the escape and radiate hypothesis (E&R) 2 , which links the rise of new plant species to the escape from herbivores via novel plant secondary metabolites. ...
... To characterize the maximum number of secondary compounds, we performed separate analyses for high-and low-molecular-weight metabolites. All extraction and chromatographic methods were developed de novo using as a starting point the work of D.S.37,38 and J.L.1,39,40 . ...
Plant secondary metabolites play important ecological and evolutionary roles, most notably in the deterrence of natural ene-mies. The classical theory explaining the evolution of plant chemical diversity is that new defences arise through a pairwise co-evolutionary arms race between plants and their specialized natural enemies. However, plant species are bombarded by dozens of different herbivore taxa from disparate phylogenetic lineages that span a wide range of feeding strategies and have distinctive physiological constraints that interact differently with particular plant metabolites. How do plant defence chemi-cals evolve under such multiple and potentially contrasting selective pressures imposed by diverse herbivore communities? To tackle this question, we exhaustively characterized the chemical diversity and insect herbivore fauna from 31 sympatric species of Amazonian Protieae (Burseraceae) trees. Using a combination of phylogenetic, metabolomic and statistical learning tools, we show that secondary metabolites that were associated with repelling herbivores (1) were more frequent across the Protieae phylogeny and (2) were found in average higher abundance than other compounds. Our findings suggest that generalist herbi-vores can play an important role in shaping plant chemical diversity and support the hypothesis that chemical diversity can also arise from the cumulative outcome of multiple diffuse interactions.
