Molecular diversity of nitrogen-fixing bacteria associated with Chrysopogon zizanioides (L.) Roberty (vetiver), an essential oil producer plant

The essential oil produced by vetiver can vary in amount and composition depending on the bacterial community associated with its roots. Some of these bacteria could also promote plant growth by fixing nitrogen. This study aimed to analyze the diversity of diazotrophic bacteria tightly associated with roots of different vetiver genotypes. nifH-based PCR-denaturing gradient gel electrophoresis (DGGE) and clone libraries were used. DGGE profiles obtained from bulk and rhizosphere soils and root DNA amplified with nifH primers showed that samples from rhizosphere soil and root were separated at 68% similarity. Twelve bands were excised from the DGGE and sequenced. High similarity with nifH sequences of Bradyrhizobium sp., Pseudacidovorax sp. and Xanthobacter sp. was observed. Moreover, three nifH clone libraries were generated using polF/polR-primers from root DNA samples obtained from vetiver genotypes UFS-VET001, UFS-VET003 and UFS-VET004. In UFS-VET001, 24.2% of 95 clones were affiliated with sequences of Mesorhizobium loti while in UFS-VET003 41.5% of 89 clones were affiliated with Sphingomonas azotifigens, and in UFS-VET004 36.4% of 85 clones were affiliated with Klebsiella pneumoniae. The data obtained can be used to guide the isolation of diazotrophic bacteria, which may contribute to plant growth promotion and improvement of the production of essential oil in vetiver.     

Mega-environment investigation based on the GGE biplot and genotype selection for high essential oil yield in vetiver grass (Chrysopogon zizanioides L. Roberty)

The genotype and genotype-environment interaction (GEI) significantly differed in the current study, demonstrating that genotype-environment (G × E) interaction heavily influenced genotype yield output. A combined analysis of variance revealed that the genotype and G × E interaction had a significant difference for all eleven characters. Except for the traits Ch1, Ch3, Ch4, Ch5, Ch9, and Ch11, a significant variance was found for all eleven characters over the years, indicating that the environment significantly influenced traits performance. The quality of vetiver essential oil is also affected by genotypic and environmental factors. The GGE biplot model shows that genotypes have a significant G × E interaction, split between the first and second IPCA/interaction principal component axis. In all three contexts, the genotypes V1, V13, and V14 in the center of the biplot graph were determined to be stable. The traits CH1-vs-CH3, CH1-vs-Ch7, and Ch4-vs-CH9 indicated significantly substantial genetic correlations among economic traits over the years. The traits Ch3-vs-Ch4, Ch3-vs-Ch9, Ch4-vs-Ch9, and Ch5-vs-Ch6 were highly significant and positively correlated, but Ch1-vs-Ch11 and CH7-vs-CH9 were negatively related. E1 and E2 were linked together to form one group, and E3 and E4 were linked together. GGE biplot analysis for environment interrelationships V1 and V7 was highly stable and well-performing for essential oil yield from a polygon perspective. Genotypes V1, V7, V10, V11, and V12 are stable and desirable genotypes arrayed in a concentric circle near the center of an ideal genotype. The genotypes V 17, V 41, V 69, and V 70 showed good photosynthetic efficiency. These genotypes might be suitable for large-scale farming.     

Preliminary comparison of vetiver root essential oils from cleansed (bacteria- and fungus-free) versus non-cleansed (normal) vetiver plants

The ‘Sunshine’ cultivar of vetiver (Vetiveria zizanioides (L.) Nash, =Chrysopogon zizanioides (L.) Roberty) was subjected to meristem tissue culture in order to produce plants that were bacteria- and fungi-free. Tissue cultured (“cleansed” or phytosanitary) vetiver was grown for five months in pots of sterilized soil, and the oil compared to non-cleansed (normal) vetiver plants grown in the same conditions except using pots of unsterilized soil. The steam distilled (24 h) oil of the roots from tissue cultured (cleansed) vetiver yielded 0.02% clear oil compared to a 0.35% yield of light yellow oil for the normal vetiver plants, a 17-fold smaller yield. GC/MS analyses of the oils revealed that the non-cleansed (normal) vetiver had the typical vetiver oil profile, whereas the tissue cultured (cleansed) vetiver produced large amounts of C₁₉–C₂₉ alkanes plus several alkanols along with typical vetiver oil compounds, but lacked presumed fungal metabolites such as β-funebrene, prezizaene, -amorphene, and β-vetispirene. An unidentified biotic factor (apparently bacteria or fungi) appears to enhance the oil production in normal vetiver by both increasing yield and by the generation of signature oil compounds. These preliminary results of endogenous microbial transformations of plant chemistry may have broader physiological implications, especially among monocotyledons (including cereals).     

Chemical composition,intraspecies variation and seasonal variation in essential oils of Calendula arvensis L.

The essential oil composition of Calendula arvensis was established for the first time using GC and GC/MS. Eighty-five essential oil components were identified, which accounted for 90.3 g/100 g of essential oil. The oil contained a high concentration of sesquiterpenes, of which δ-cadinene and α-cadinol were the main components. The chemical composition of 25 Corsican C. arvensis oils was analyzed to determine intraspecies variation in essential oil composition. A matrix linking essential oil composition to sample location was composed to identify relationships between concentrations of volatile samples and the geographical origins of samples. Two main groups of compounds were identified according to the amount of sesquiterpenic compounds (hydrocarbons and alcohols) and soil characteristics. Seasonal variation (winter vs. spring) in the concentrations of two major compounds during the flowering period was observed.     

Comparison of vetiver root essential oils from cleansed (bacteria- and fungus-free) vs. non-cleansed (normal) vetiver plants

‘Karnataka’ and ‘Malaysia’ cultivars of vetiver (Vetiveria zizanioides (L.) Nash, =Chrysopogon zizanioides (L.) Roberty) were subjected to meristem tissue culture in order to produce plants that were bacteria- and fungi-free. Tissue cultured (“cleansed” or phytosanitary) vetiver was grown for five months in sterilized soil contained in pots, and the oil content of plants grown on the medium was compared to that of non-cleansed (normal) vetiver plants grown in unsterilized soil under the same conditions. Statistical analysis of 49 of the major oil components revealed numerous significant differences between tissue culture derived and natural plants for both genotypes.     

Chemical analysis and biological activities of the essential oil of Teucrium leucocladum Boiss. (Lamiaceae)

The chemical composition of the water-distilled essential oil and n-hexane–ether extract of Teucrium leucocladum Boiss. were determined by GLC and GLC–MS. Altogether 72 compounds were identified. The sesquiterpene alcohols, patchouli alcohol (31.24% and 29.66%) and α-cadinol (9.29% and 21.54%) were the main components in the oil and the extract, respectively. α-Cadinol was isolated and characterized using MS, ¹H- and ¹³C-NMR spectral analyses. Furthermore, the oil and the extract were tested for their bacterostatic and antifungal activities; they showed broad and potent activity against Pseudomonas aeruginosa, Bacillus subtilis and Candida albicans. A marked larvicidal activity of the essential oil, n-hexane–ether extract and crude ethanolic extract was also observed against Culex pipiens, Musca domestica and Ceratitis capitata larvae.     

In Vitro Characterization and Mosquito (Aedes aegypti) Repellent Activity of Essential-Oils-Loaded Nanoemulsions

The nanoemulsions composed of citronella oil, hairy basil oil, and vetiver oil with mean droplet sizes ranging from 150 to 220 nm were prepared and investigated both in vitro and in vivo. Larger emulsion droplets (195–220 nm) shifted toward a smaller size (150–160 nm) after high-pressure homogenization and resulted in higher release rate. We proposed that thin films obtained from the nanoemulsions with smaller droplet size would have higher integrity, thus increasing the vaporization of essential oils and subsequently prolonging the mosquito repellant activity. The release rates were fitted with Avrami’s equations and n values were in the same range of 0.6 to 1.0, implying that the release of encapsulated limonene was controlled by the diffusion mechanism from the emulsion droplet. By using high-pressure homogenization together with optimum concentrations of 5% (w/w) hairy basil oil, 5% (w/w) vetiver oil (5%), and 10% (w/w) citronella oil could improve physical stability and prolong mosquito protection time to 4.7 h due to the combination of these three essential oils as well as small droplet size of nanoemulsion.     

Vetiver oil production correlates with early root growth

To gain insight into essential oil metabolism we analyzed the oil produced in Vetiver (Vetiveria zizanioides (L.) Nash) roots during early growth. Planting of Vetiver in the Campania region of southern Italy was performed in the spring using Vetiver culms with short roots and approximately 20 cm leaves. During the first two years of growth Vetiver essential oil was hydrodistilled from root samples collected at intervals of two months starting from transplantation. The production of Vetiver oil was constant during the first six months. Over the next two months there was a twofold increase in production of essential oil, which anticipated a progressive decrease during the cold months (from January to April 2003). The analysis of the Vetiver oil showed the presence of 49 constituents, mainly the tricyclic sesquiterpenes khusimol and zizanoic acid, and the bicyclic sesquiterpenes (E)-isovalencenol, junenol, juniper camphor, nootkatone and α-vetivone. These results suggest that Vetiver essential oil production is closely related to the metabolism of plant roots, which is affected by changes in environmental temperatures.     

Genetic structure and essential oil composition in wild populations of Salvia multicaulis Vahl.

The phytochemical study on ten populations of Salvia multicaulis Vahl. revealed that their essential oil qualitative profiles contained a significant amount of monoterpene hydrocarbons, which were the most abundant compounds. Besides, α-Pinene was the major constituent in all studied populations' essential oils. Significant correlations were observed between edaphic parameters and some major essential oil compounds. According to clustering analyses of the chemical data, the S. multicaulis populations were divided into three chemotypes: β-caryophyllene, camphene and camphor, and limonene. The population genetics study showed significant molecular differences among the populations. The Mantel test indicated a significant positive correlation between the geographical distances and genetic diversity, exhibiting a low amount of gene flow and a considerable genetic differentiation value. We also detected four genotypes based on the Nei's genetic distance and structure analysis. The identified chemical and genetic similarities/differences among these populations were correlated with edaphic parameters and geographic distances, suggesting that environmental factors are the primary drivers of the chemical polymorphism of essential oils in S. multicaulis populations.     

Phenological variations of secondary metabolites from Hypericum triquetrifolium Turra

The essential oils and phenolic constituents from the aerial parts of Hypericum triquetrifolium Turra, were analyzed at three developmental stages (vegetative, flowering and fruiting stages). The highest content of oil (0.12% w/w) was obtained at full flowering. Whatever the analyzed stage, n-octane, α-pinene, β-caryophyllene, 2-methyloctane, n-nonane, α-longipinene, caryophyllene oxide and β-pinene were found to be the main compounds. However, their percentages varied with the phenological cycle. Analysis by RP-HPLC-DAD of the methanolic extracts enabled us to identify 14 phenolic components and rutin, hyperoside, quercitrin and quercetin were reported as the main components. With the exception of chlorogenic acid, kaempferol and amentoflavone, the content of the remaining identified phenolic components varied with the phonological cycle.     

Ethnobotany,leaf anatomy,essential oil composition and antibacterial activity of Pteronia onobromoides (Asteraceae)

Available ethnobotanical information on Pteronia onobromoides (first recorded in 1685) indicates that the plant was once of considerable cultural and commercial importance and that it was powdered, mixed with fat, and applied to the skin for cosmetic and/or medicinal purposes. Sâb, as well as Son or San, are considered to be the original Nama names for this aromatic bush and also the origin of various names for San people, such as Sonqua and Bushman. A study of the leaf anatomy showed that essential oil is produced in globose oil glands situated below some of the vascular bundles in the spongy parenchyma, adjacent to the palisade parenchyma. The oil is relatively complex but contains a combination of myrcene, limonene, 1,8-cineole and p-cymene as main compounds, with smaller amounts of sabinene, trans-linalooloxide, linalool, terpinen-4-ol, α-terpineol, eugenol, thymol and α-phellandrene. Dichloromethane extracts exhibited antibacterial activity (especially against Staphylococcus epidermidis) with MIC values as low as 0.83 mg/ml. Other solvent extracts and the essential oil itself were less active. The results show that the traditional method of mixing powdered leaves with fat and applying it to the skin may have had deodorant, disinfectant and medicinal benefits.     

Castor and camphor essential oils alter hemocyte populations and induce biochemical changes in larvae of Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae)

Two plant essential oils; camphor and castor were tested for insecticidal and antifeedant activity against the 4th instar larvae of Spodoptera littoralis, a serious pest on cotton in Egypt. Also the impact of LC₁₀ of both oils on some physiological parameters in larvae was studied by using leaf dipping technique. Analysis of both oils using GC–MS revealed several insecticidal and antifeedant compounds. Our results showed higher insecticidal activity and antifeedant index of camphor oil against S. littoralis. The LC₅₀ and the antifeedant indices were 163.1, 246.8?mg/ml and 12.69, 6.62% for camphor and castor bean oil, respectively. The total hemocyte count (THC) and differential hemocyte count (DHC) were reduced significantly after 48?h of treatment compared to controls. Both oils reduced all types of hemocytes except plasmatocytes which were reduced only by castor oil. Camphor oil decreased total proteins and carbohydrates while castor oil targeted only carbohydrate content. Both oils didn't affect the amount of total lipids. Lipase, α-amylase and glucose-6-phosphate dehydrogenase (G6PD) enzyme activities were increased significantly in larvae treated with camphor oil than other treatments. These results clearly indicate that castor and camphor oils can affect the nutritional status in S. littoralis larvae, thereby changing the internal metabolic processes in the larvae which make them as potential control agents in IPM programs against S. littoralis.     

Essential oils of Phlomis leucophracta,Phlomis chimerae and Phlomis grandiflora var. grandiflora from Turkey

The essential oils of three species of Phlomis from Turkey, Phlomis leucophracta, Phlomis chimerae and Phlomis grandiflora var. grandiflora have been studied. The main constituents of P. leucophracta essential oil were β-caryophyllene (20.2%), α-pinene (19.2%) and limonene (11.0%). This species also contained three diterpene derivatives, 15-isopimaradiene, manoyl oxide and epi-13-manoyl oxide that summed 1.4%. In P. chimerae the principal compounds were β-caryophyllene (31.6%), α-pinene (11.0%), germacrene D (6.1%), limonene (5.5%) and linalool (4.7%). In P. grandiflora var. grandiflora, germacrene D (45.4%), β-caryophyllene (22.8%) and bicyclogermacrene (4.9%) were among the principal derivatives.     

Caraway essential oil composition and morphology: The role of location and genotype

Caraway (Carum carvi) is used as a vegetable; more commonly, the fruits are used to flavour foods or as a preservative. Quality is a key issue; however, little is known about the respective influences of type of material and location and the interaction of these factors on essential oil composition. In this study, wild populations and commercial cultivars from the Nordic germplasm collection were examined. Plants were grown in two locations (Iceland and Sweden) and essential oil composition and phenotypic characteristics identified. Carvone and limonene were the two major compounds detected at levels around 14 and 70% of total peak area, respectively. Also p-cymene, trans-β-ocimene, α-Terpinolene and myrcene each were detected at levels above or around 2%. In total, 47 compounds were detected of which 40 were identified. The effects of material type and location were established, where location had a greater impact than genotype. In 15 out of the 35 compounds detected at levels below 2%, significant location-dependent differences were detected. For morphological traits, genotype had a more significant effect than location.     

Insilico Structural 3D Modelling of Novel Cry1Ib9 and Cry3A Toxins from Local Isolates of Bacillus thuringiensis

Three-dimensional (3D) models for the 79.2 kDa activated Cry1Ib9 and 77.4 kDa activated Cry3A δ-endotoxins from Bacillus thuringiensis (Bt) native isolates that are specifically toxic to Coleopteran insect pests were constructed by utilizing homology modeling online tool. Evidences presented here, based on the identification of structural equivalent residues of Cry1Ib9 and Cry3A toxin through homology modelling indicate that, they share a common Bt toxin tridimensional structure. The main differences observed in Cry1I9 domain I at positions α2b (S56-I60), α4 (F78-l93) and additionally β0 (Q10-L12), α8a (T280-V282) were observed, in domain II at positions α9b (P333-L339), β6(T390-Q393), β7(V398-W404), β8 (V418-W425), β9 (E453-N454), β10 (S470-I479) where as in domain III the changes were observed at positions β19 (R601-F607), β20 (609-L613), β21 (S618-F627) and α11a (K655-F664), α13, α14 components present at downstream sites, where as in Cry3A main differences observed in domain I is at the position of α4 (P105-I152), α5 (Q163-A185), β1A(E190-L192), α6 (F193-Y217), Domain II is not consevered and main variations were observed at β2 (E292-L295), β3(V299-L308), β4(I340-F347), β5(D356-P368), β6(I375-T377), β7(V389-F394), β8(K398-N405), β9(Y416-Y427), β10 (T436-Y439), β12(G476-H495), β12A (M503-I504) where as in domain III main variations observed at positions of β18 (P583-I593), β19(F604-S610), β20(P611-L615), β21(N619-G626). Cry1Ib9 and Cry3A contain the most variable regions in the loops of domain II, which determine the specificity of these toxins. These are the first models of Coleopteran-active protein from native isolates of Bt and its importance can be perceived since members of this group of toxins are potentially important candidates for coleoptera insect pest control programs.     

Composition and variability of essential oils of Platycladus orientalis growing in China

Essential oils were isolated from the leaves of Platycladus orientalis growing in 16 areas of China. The essential oils were analyzed by gas chromatography and gas chromatography-mass spectrometry. In total, 98 volatile compounds were identified. Chemical variability in essential oil composition was evaluated using cluster analysis and principal component analysis. The two analyses led to the identification of four chemotypes: α-pinene, α-pinene/3-carene, cedrol, and cedrol/terpinyl acetate. Geographically, the populations growing in close proximity had similar essential oil composition. The chemical variability could possibly be attributed to genetic and environmental factors.     

Effect of calcium on growth performance and essential oil of vetiver grass (Chrysopogon zizanioides) grown on lead contaminated soils

The aim of this study was to investigate effect of calcium on growth, survival, essential oil yield and chemical compositions of vetiver grass grown on lead contaminated soils. Calcium inform of CaCO3 (0, 2000, 4000, 6000 mg Ca kg(-1)) was added to river sand soils containing 4000 mg Pb kg(-1) dry soil. Results showed that, in the absence of calcium treatment, no plants survived after 2 weeks of cultivation, while the rest grew well to the end of the experimental period (42 weeks). Calcium treatments generally resulted in a slight decrease in biomass. Interestingly, an increase in calcium over 2000 mg kg(-1) did not result in a decrease in accumulation of lead in vetiver roots and shoots. The levels of lead in roots and shoots under calcium treatments were around 2000 and 90 mg kg(-1) dry weight, respectively. The addition of CaCO3 did not improve vetiver essential oil yield and chemical composition compared to the control. A level of applied CaCO3 about half of the lead concentration in soils was sufficient to improve vetiver growth and survival, and accumulate high concentrations of lead in the roots. This finding can be applied for re-vegetation of lead contaminated soils using vetiver.     

Essential oil from leaves of Cryptocarya mandioccana Meisner (Lauraceae): Composition and intraspecific chemical variability

The composition of the essential oil from leaves of Cryptocarya mandioccana has been determined by chromatographic fractionation and GC–FID, GC–MS and ¹³C NMR analyses, yielding the identification of 64 compounds with predominance of isomeric sesquiterpenes with molecular weights of 204. The main components of the oil obtained by hydrodistillation were β-caryophyllene, spathulenol, caryophyllene oxide, δ-cadinene, germacrene D, benzaldehyde and bicyclogermacrene. However, the oil obtained by steam distillation contained higher levels of sesquiterpene hydrocarbons, with predominance of β-caryophyllene (C), germacrene D (G) and bicyclogermacrene (B), and was considered to be more representative of the composition of the oil in its natural state. The intraspecific chemical variability of the essential oil obtained by steam distillation was evaluated within populations of trees growing at three separate locations in the state of São Paulo, Brazil. Three distinct chemical groups could be characterised due to differences in the relative percentages of the three main sesquiterpenes from essential oil: CGB [relative contents of C (14–34%), G (5–28%), B (8–15%)], BCG [B (17–34%), C (9–24%), G (12–25%)] and GCB [G (22–42%), C (4–17%), B (7–15%)]. Individuals from groups CGB and BCG were found to be more frequent at south locations while group GCB is predominant in north location.     

Identification of drought tolerant Chickpea genotypes through multi trait stability index

Drought is a major and constantly increasing abiotic stress factor, thus limiting chickpea production. Like other crops, Kabuli Chickpea genotypes are screened for drought stress through Multi-environment trials (METs). Although, METs analysis is generally executed taking into account only one trait, which provides less significant reliability for the recommendation of genotypes as compared to multi trait-based analysis. Multi trait-based analysis could be used to recommend genotypes across diverse environments. Hence, current research was conducted for selection of superior genotypes through multi-trait stability index (MTSI) by using mixed and fixed effect models under six diverse environments. The genotypic stability was computed for all traits individually using the weighted average of absolute scores from the singular value decomposition of the matrix of best linear unbiased predictions for the genotype vs environment interaction (GEI) effects produced by a linear mixed-effect model index. A superiority index, WAASBY was measured to reflect the MPS (Mean performance and stability). The selection differential for the WAASBY index was 11.2%, 18.49% and 23.30% for grain yield (GY), primary branches per plant (PBP) and Stomatal Conductance (STOMA) respectively. Positive selection differential (0.80% ≤ selection differential ≤ 13.00%) were examined for traits averaged desired to be increased and negative (-0.57% ≤ selection differential ≤ -0.23%) for those traits desired to be reduced. The MTSI may be valuable to the plant breeders for the selection of genotypes based on many characters as being strong and simple selection process. Analysis of MTSI for multiple environments revealed that, the genotypes G20, G86, G31, G28, G116, G12, G105, G45, G50, G10, G30, G117, G81, G48, G85, G17, G32, G4, and G37 were the most stable and high yielding out of 120 chickpea genotypes, probably due to high MPS of selected traits under various environments. It is concluded that identified traits can be utilized as genitors in hybridization programs for the development of drought tolerant Kabuli Chickpea breeding material.     

Essential oil variability within and among populations of Cunila incisa Benth.

To evaluate the intra- and interpopulational variability of volatile compounds in Cunila incisa, 72 samples representing 12 populations, were collected all over the distribution area of the species in Rio Grande do Sul State. The samples were extracted by steam distillation and analyzed using GC and GC–MS. A total of 19 volatile compounds were detected and identified. In average, the main compounds were 1,8-cineole, α-terpineol, p-cymene, sabinene, terpinene-4-ol, and γ-terpinene. Negative correlation was detected between the concentrations of 1,8-cineole and α-terpineol. Significant variation in the concentration of volatile compounds was detected within and among populations. Multivariate analysis of volatile oil composition identified three groups. Most populations exhibited low intra-populational variation indicating foundation effect. Relation between geographic distribution and chemical composition was observed.