Quantitative variation in leaf pocket resin composition in Hymenaea courbaril

Leaf pocket resin sesquiterpenes have been quantitatively analyzed in 22 geographic populations of the widespread Hymenaea courbaril. Highly stable quantitative resin composition in Meso-American populations of H. courbaril contrasts with greater variability in several South American populations. In some of the latter, bimodality in quantitative content of several correlated sesquiterpenes results in overall resin compositional relationships of two or three distinct types. Variance-weighted similarity coefficients between all populational pairs are single-linkage clustered to visualize chemical relationships.     

Vegetative growth and leaf resin composition in Hymenaea courbaril under photoperiodic extremes

Seedlings from five geographic populations of the widespread Hymenaea courbaril were grown for one year under two extremes of photoperiod. The short photoperiod treatment consisted of 8 hr of unsupplemented greenhouse daylight and the long photoperiod treatment of greenhouse daylight at the natural photoperiod of Santa Cruz, California (37° N) plus a 3-hr night interruption (0.25 mW/cm²). Growth was measured by total stem length and leaf resin sesquiterpene composition was quantitatively analyzed by GLC. Photoperiod had no significant effect on leaf resin chemistry but the longer photoperiod markedly promoted vegetative growth. Large population differences in overall vegetative growth and quantitative leaf resin composition were also evident. Growth patterns indicated that the low intensity night break had little or no effect on growth.     

Relationship of light intensity to leaf resin composition and yield in the tropical leguminous genera Hymenaea and Copaifera

Hymenaea and Copaifera are closely related morphologically distinct tree genera whose leaf resins appear to be composed of the same sesquiterpene hydrocarbons which occur in similar quantitative compositional patterns. The seedlings of both genera grow in varying light intensities in the understories of different lowland tropical ecosystems from desert thorn forests to equatorial evergreen rain forests; all eventually grow into high light intensity. Previous controlled environment studies of the effects of photoperiod, temperature and moisture status have shown little phenotypic plasticity in the leaf resin composition of Hymenaea seedlings. In this study, focusing on light intensity, both control chamber experiments comparing seedlings of H. courbaril var. courbaril, H. courbaril var. subsessilis, C. officinalis and C. pubiflora, grown under low and high light treatments, and field data from saplings of C. multijuga, growing under shaded and unshaded conditions, also show lack of phenotypic plasticity in resin composition. The yield of resin (mg/g leaf tissue), however, varied considerably among individuals, and increased significantly from low to high light conditions in both control chamber and field conditions. The relationship of increased synthesis is discussed with regard to photosynthetic capacity, allocation of carbon and herbivory.     

The effect of moisture stress on monoterpenoid yield and composition in Satureja douglasii

The effect of moisture stress on monoterpenoid yield and composition of Satureja douglasii was studied under controlled conditions and in the field. Large differences in monoterpenoid yield observed among field populations were closely correlated with moisture stress. In greenhouse transplants grown under uniformly moist conditions these differences were significantly reduced. In all plants studied yield per leaf dry weight decreased with development. A growth chamber study using clones grown under different soil moisture regimes showed that high moisture stress reduced leaf weight and monoterpenoid yield per leaf, but had little effect on yield per leaf dry weight. Effects on monoterpenoid composition were less striking with high moisture stress causing a small decrease in the percentage of monoterpenoids with a p-menthane carbon skeleton and perhaps accelerating the rate of developmental conversions.     

Compositional variation of leaf pocket sesquiterpenes in Trachylobium verrucosum

Greenhouse-grown plants originating from Kenyan and Madagascan populations of Trachylobium verrucosum are qualitatively identical in leaf pocket resin sesquiterpene composition, but differ quantitatively.     

Variation in leaf resin composition between parent tree and progeny in Hymenaea: Implications for herbivory in the humid tropics

Variation in the sesquiterpene hydrocarbon leaf resins in the tropical leguminous genus Hymenaea is compared between parent tree, seedling and sapling progeny. Relatively large discrete quantitative variation in the leaf resins, known experimentally to display little phenotypic plasticity, has been classified into Compositional Types. Differences in Compositional Types in the leaves between parent tree and their seedling and sapling progeny are more pronounced in rain forest and related eocystems than in savanna and dry forests. A model is presented in which it is suggested that this variation in leaf resin may play an important role in defence against lepidopteran herbivores and thus also in seedling establishment under Hymenaea parent trees in rain forest and related ecosystems.     

Quantitative variation in leaf pocket resin composition in Hymenaea

Leaf pocket resin sesquiterpenes have been quantitatively analysed in 11 species of the tropical genus Hymenaea. Variance-weighted similarity coefficients were calculated for all species and populational pairs, and chemical relationships among rainforest species and among all studied species and populations were visualized by dendrograms based on single-linkage clustering of similarity coefficients.     

Sesquiterpene Deterrence of a Leaf-Tying Lepidopteran, Stenoma ferrocanella, on Hymenaea stigonocarpa in Central Brazil

Study of two populations of Hymenaea stigonocarpa in the central Brazilian cerrado (savanna/woodland) shows attack by a leaf-tying lepidopteran, Steoma ferrocanella, occurred after inferred peak concentration (% of leaf dry wt) of sesquiterpene leaf resins during leaf development. Also a highly statistically significant relationship existed between leaf-tier attack and level of caryophyllene in one population and γ-muurolene in the other population. The data from one population are consistent with laboratory experiments demonstrating highly significant dose-dependent effects of caryophyllene in Hymenaea leaf resin on mortaility of the lepidopteren Spodoptera exigua. Results from both populations support other evidence that changes in the amount of single terpenes in the mixture constituting the resin may have significant antiherbivore effects and, concomitantly, that herbivory may be a source of some of the leaf resin variation.     

Implications of variation in resin composition among organs, tissues and populations in the tropical legume Hymenaea

Variation in leaf blade, petiole and primary stem resins, composed of sesquiterpene hydrocarbons, is analysed in two contrasting species of the tropical legume Hymenaea. Five populations of the New World H. courbaril, spanning a wide range of ecosystems, are compared with a population of the disjunct African H. verrucosa. Resins in petiole and primary stem tissue are similar, but differ significantly in total composition from leaf blade tissues. The major components, caryophyllene, - and β-selinene and β-copaene vary most significantly among the tissues, but all compounds vary at highly significant levels among populations. The variation patterns in resin composition among the leaf blade and petiole/primary stem tissues are put into a larger context of comparison with the primarily diterpenoid patterns in secondary stem and pod tissues. Although the comparatively minor quantitative differences in the sesquiterpene systems could be attributed solely to developmental and physiological differences among the tissues and populations, the total weight of accumulating evidence regarding quantitative variation and demonstrated toxic and deterrent properties of sesquiterpene resins to insect herbivores leads us to hypothesize a possible role of differential predator pressures.     

Sesquiterpenes in leaf pocket resins of Copaifera species

Four sesquiterpene leaf resin components were isolated and identified from Copaifera leaf resin. Additional GC and mass spectrometric evidence support the close similarity of Copaifera leaf pocket resin composition with that of the related genus, Hymenaea.     

Effects of environmental stress on leaf hair density and consequences for selection

We explored how five different environmental stresses and a benign environment affect the phenotypic expression of leaf hairs, and the potential for evolutionary response in this trait. To address these questions we planted full-sib families that had been selected for stress tolerance in a factorial design in which selection history was fully crossed with the current environment (eight families × six selection histories × six current environments × three blocks=864 plants). Our data suggest that leaf hair density is a complex character composed of two separable traits: leaf area and the number of hairs initiated per leaf. Leaf size is primarily controlled by the growth environment, whereas leaf hair initiation shows more genetically based variation. In the control and low water environments there was a negative linear relationship between leaf size and leaf hair density. However, within the low light and high boron treatments, leaf hair density remained constant across a range of leaf sizes, suggesting that these stresses disrupt normal leaf hair development. Selection gradient analysis showed that leaf hair density and leaf size were significantly positively associated with fitness in 4/6 of our environments. Our results suggest that environmental variation may diminish the ability of herbivores and pathogens to cause directional selection on leaf hair density.     

A 5, 6-dimethoxylated flavone in the leaf resin of Adenostoma sparsifolium

A new flavone 5,6-dimethoxy-3,7,4′-trihydroxyflavone was isolated from the external leaf resin of Adenostoma sparsifolium and identified by spect     

Effect of light and temperature on monoterpenoid yield and composition in Satureja douglasii

Light intensity and day temperature were identified as principal modifying factors of monoterpenoid composition and yield in individuals of Satureja douglasii. The individuals represent compositional type and clinial patterns of infraspecific compositional variation. The lack of compositional interconversion confirms the tight genetic control of biosynthesis which results in these infraspecific patterns. There was marked influence by light intensity on monoterpenoid yield per leaf dry weight and by day temperature on yield per leaf. Low light intensity reduced leaf dry weight but had little effect on the amount of monoterpenoids per leaf whereas low day temperature increased both leaf weight and yield per leaf, compared to high light and day temperature effects. Day temperature modification of yield per leaf was related to modification of composition.     

Effect of soil moisture stress on legume-rhizobium symbiosis in soybeans

Summary In a pot culture experiment, the influence of soil moisture stress at different physiological stages of soybean, cv. Hark, on nodulation, symbiosis and nitrogen accumulation was studied. Moisture stress reduced leghemoglobin content of root nodules and nitrogen uptake by plants. It had no effect on number of bacteroids. Stress at mid bloom and rapid pod filling stages reduced yield and seed protein content. However, these parameters were not affected by stress at nodule initiation and early flowering stages, though, flower initiation and maturity of the plant were delayed. Moisture stress at any stage did not alter nitrogen status of roots.     

Inhibitory effects of Hymenaea and Copaifera leaf resins on the leaf fungus, Pestalotia subcuticularis

Leaf resins in the leguminous genera Hymenaea and Copaifera may play a role in restricting infection by the associated leaf fungus, Pestalotia. We tested this hypothesis by assessing growth of the geographically widespread Pestalotia subcuticularis presented with different compositions of resins. Leaf resins of Hymenaea and Copaifera are composed of the same suite of sesquiterpene hydrocarbons, but these vary quantitatively to form discrete compositional patterns among individuals and populations. Leaf resins may also contain sesquiterpene oxides; caryophyllene oxide, which may have been formed from the caryophyllene precursor common in these resins, inhibited fungal growth in vitro.     

Intra- and interplant leaf sesquiterpene variability in Copaifera langsdorfii: relation to microlepidopteran herbivory

Oecophorid herbivory in Copaifera langsdorfii leaves along with sesquiterpene composition, concentration of most of the individual sesquiterpenes and total yield did not significantly differ between the lower and upper portions of tree canopies. Although sesquiterpene variation in leaves collected throughout individual tree canopies was less than variation among trees, leaves which were eaten by oecophorid larvae had slightly lower yields than those unattacked. Individual C. langsdorfii trees within the population were significantly different from one another in sesquiterpene yield, oecophorid herbivory and in the concentration of seven out of the 11 sesquiterpene compounds. Leaf sesquiterpenes appear to be more important in inhibiting herbivory by Stenoma aff. assignata than leaf moisture and nitrogen content and toughness.     

The impact of plasticity and maternal effect on the evolution of leaf resin production in Diplacus aurantiacus

Our previous quantitative genetic study of leaf resin production in Diplacus aurantiacus revealed large environmental and maternal effects on variation in resin production, which suggests the possibility of a genotype×environment interaction for this trait when plants grow in heterogeneous environments. Our objectives in this study were to observe the genetic variation in plasticity of resin production under field and chamber conditions, compare phenotypic correlations of resin content with growth traits under these two environmental conditions, and distinguish the possible basis of the maternal effect on resin production using parents and half-sib progeny. A significant genotype×environment interaction (P<0.0001) in leaf resin production was found, which suggests a potential for the evolution of plasticity of these secondary metabolites under heterogeneous environments. The phenotypic correlation between resin content and growth rate also exhibited plasticity. In addition, the resin content of dam half-sib families grown in the chamber had a closer relationship with their maternal parents in the field (r=0.65, P=0.059) than in the chamber (r=0.39, P=0.34), suggesting an environmentally based maternal effect on the secondary chemicals. We suggest that the maternal environmental effect may act as a contributor to plasticity of resin production and, while it may not diminish the appearance of the genotype×environment interaction, the heritable variation of plasticity of resin production may be confounded.     

Analyses of the volatile leaf oils of Juniperus deppeana and its infraspecific taxa: Chemosystematic implications

Eight OTUs of Juniperus deppeana were collected and their volatile leaf oils analysed by GC/GCMS. The volatile oils are dominated by oxygenated terpenes such as camphor, linalool, cis-verbenol, 4-terpineol, verbenone, borneol and trans-sabinene hydrate. The major monoterpene found was α-pinene. Sesquiterpenoids were minor components of the volatile leaf oils. The six named taxa were only distinguished by combinations of terpenoid characters. The differentiation of the Arizona J. deppeana (var. pachyphlaea ?) and J.d. forma sperryi from the other taxa in Mexico was the major subdivision found. Juniperus deppeana forma sperryi was clearly distinguished as were J.d. var. robusta and J.d. var. patoniana.     

Biosynthesis of sesquiterpenes in Hymenaea inferred from their quantitative co-occurrence

Leaf pocket resins of 11 species of the tropical arborescent genus Hymenaea are virtually identical qualitatively, but of widely varying quantitative proportions. Within this large range of variability, several strong positive quantitative correlations between resin constituents were found, especially between caryophyllene and β-humulene and between γ-muurolene and δ-cadinene. These data lead to clarification of sesquiterpene biosynthetic routes in Hymenaea. In addition, quantitative relationships found among caryophyllene, α- and β-selinene, γ-muurolene and δ-cadinene are explained only with difficulty by long accepted biosynthetic pathways, and the intermediacy of germacrenes is suggested.