Margarita Yaber Grass

Constituents of the root exudate of Avena fatua grown under far-infrared-enriched light.

The constituents of the root exudate of plantlets of wild oats (Avena fatua) grown in the greenhouse under far-IR-enriched radiation were analysed for the first time by HPTLC and capillary GC, and further separated by medium-pressure liquid chromatography (MPLC; monitored by TLC) and characterised by GC-EIMS and 1H-NMR. This combination of methodologies permitted the study of root exudates under controlled conditions and is appropriate for examining a variety of ecophysiological/environmental effects in a short time period. In this instance, the response compounds of the irradiated plantlets were identified as linear and branched alcohols, linear and branched alkanes, a bicyclic monoterpene, mono- and bicyclic sesquiterpenes, and free and esterified fatty acids. An ester, isopropyl myristate, was the main component present, although the unusual occurrence of branched compounds, sesquiterpenoids and related compounds of isoprenoid metabolism is noteworthy. The effect of far-IR-enriched light on the production of these compounds is discussed. Copyright

Response of winter crops differing in grain yield and essential oil production to some agronomic practices and environmental gradient in the Rolling Pampa, Argentina

Abstract Intensive land use in the Rolling Pampa of Argentina generates heterogeneous environmental and ecological conditions associated with agronomic practices. The yields of crops with different resource allocation to the production of primary or secondary metabolites could vary with the environment. Crops that mainly produce primary metabolites would have high yields under favorable environments, and crops that produce high quantities of secondary metabolites would have high essential oil yield under unfavorable environments. To test whether this hypothesis is applicable under the Rolling Pampa conditions, field experiments were conducted with the following objectives: (1) to compare biomass and grain yield in three winter crops: wheat (Triticum aestivum L.), coriander (Coriandrum sativum L.) landrace with high essential oil content (HEO) and coriander landrace with low essential oil content (LEO), grown at different levels of N fertilization and weed control; and (2) to determine relative changes in grain yield, essential oil production and harvest index with environment in the coriander landraces. The crops were grown at two locations differing in physical and chemical soil degradation due to the intensity of land use. Wheat allocated resources mainly to the production of primary metabolites, producing higher biomass and grain yield in the favorable environments. The HEO coriander landrace, which allocates resources to the production of both primary and secondary metabolites, produced similar biomass and grain yield in both locations, but resource partitioning to the production of essential oils was high under unfavorable environmental conditions. The LEO coriander landrace which allocates resources mainly to the production of primary metabolites and, in a minor proportion, to secondary metabolites, produced high biomass and grain yield in intermediate environments and high essential oil yield under unfavorable environments. The environmental conditions of the Rolling Pampa that curtailed the allocation of resources to the production of grain yield promoted the production of essential oils. Based on these results, under poor soil environments, one option is to produce crops with essential oils as marketable yields, instead of adding inputs to improve soil condition and produce traditional crops, where yield is very sensitive to environmental variations.

Changes in Eucalyptus camaldulensis essential oil composition as response to drought preconditioning

Abstract Water deficit, a common constraint in forestry, is the main cause of plant stress during plantation. The survival and growth of seedlings is also compromised by herbivory during establishment. The potential of nursery preconditioning to enhance survival chances of future trees by reducing palatability or attracting beneficial insects as a result of changes in chemical defences may be an answer to overcome this situation. Changes in essential oil production and composition were evaluated by GC and GC-MS in Eucalytus camaldulensis seedlings submitted to drought during four weeks at the last stage of nursery period (20 weeks). Significant changes in essential oil relative composition were found. Seedlings (young leaves) submitted to drought developed a terpenoid blend, which has been previously associated to mature leaves and related to their higher resistance towards herbivory. Total amount of non-oxygenated terpenes decreased by 44%, whereas some oxygenated sesquiterpenes (globulol, epiglobulol and ledol) were doubled, and 1,8-cineole content was enhanced by 28.3%.

Changes in Senecio grisebachii pyrrolizidine alkaloids abundances and profiles as response to soil quality.

Abstract Senecio grisebachii Baker is an invasive weed considered to be toxic due to the presence of pyrrolizidine alkaloids (PA) in its tissues. The PA production by S. grisebachii aerial parts was evaluated in samples grown in two Argentinean Rolling Pampa fields with the same kind of soil but differing in the length of their exploitation period by conventional tillage practices and, consequently, in their deterioration level. We found significant differences in the relative concentrations of seven alkaloids between samples taken from the two fields. Seneciphylline was the most abundant alkaloid in inflorescences from less deteriorated soil (LD) while senecionine was the major one in those from highly deteriorated soil (D) being followed by seneciphylline, integerrimine, and minor amounts of spartiodine, jacobine, jacozine and retrorsine. A significant increase in total alkaloid content (TAC) was observed in inflorescences from samples growing in D soil (3.52±0.20 mg/g DW) when comparing with those from samples grown in LD one (3.23±0.26).

Nucleocyclitols. Coupling of Heterocyclic Bases to Cyclitol Oxiranes

Abstract Several nucleocyclitols were synthesized in good yield from an inositol epoxide and some activated purine derivatives (adenine, 6-methylmercaptopurine). The reaction was also carried out with other more basic, nitrogen heterocycles such as imidazole and piperidine, although side reactions can then became significant.

Efecto de extractos de Chenopodium album L. sobre los estados larval y adulto de Oryzaephilus surinamensis L. (Coleoptera:Silvanidae)

espanolPara evaluar el efecto biologico de los metabolitos secundarios polares y no polares de la parte aerea (hojas e inflorescencias) de Chenopodium album L. (quinoa blanca) en la alimentacion de Oryzaephilus surinamensis L. (Coleoptera: Silvanidae) se desarrollo un ensayo donde material vegetal previamente secado y triturado se sometio a extraccion continua primero con eter de petroleo y luego con metanol, finalmente se realizo una extraccion con agua en �batch� del material remanente dando origen a los correspondientes extractos. Se impregnaron 2 g de dieta base con solucion de los extractos etereo, metanolico y acuoso, en una concentracion de 66 mg/ml. En los tratamientos control se utilizo eter de petroleo metanol y agua, respectivamente. Se realizaron seis tratamientos en un diseno completamente aleatorizado, con cuatro repeticiones, analizandose el comportamiento y evolucion de los insectos y el ciclo biologico de las larvas resultantes de los mismos. Cada siete dias se determino el numero de individuos adultos y larvas vivas. Todos los datos fueron evaluados por ANOVA y las diferencias entre medias fueron verificadas por el test de Tukey (p EnglishThe present assay was performed in order to evaluate the biological effects of polar and non-polar metabolites form the aerial parts of (leaves and inflorescences) Chenopodium album L. (white quinoa) on Oryzaephilus surinamensis L (Coleoptera: Silvanidae) feeding. Previously dried and ground plant material was submitted to sequential continuous extraction with petroleum ether and then with methanol; the remaining plant material was finally extracted in batch with water, giving rise to the corresponding extracts. 2 g of basic diet were impregnated with 66 mg/ml solutions of ether, methanol or aqueous extracts. Petroleum ether, methanol and distilled water were used respectively as control treatments. Six treatments were performed in a completely randomized design with four repetitions, analyzing insect behavior and the evolution of the biological cycle of the resulting larvae. The number of living adults and larvae was determined every seven days. All treatments were evaluated by means of ANOVA, and differences between mean values using Tukey`s test. (p