Metabolic profiling of root exudates of Arabidopsis thaliana

In addition to accumulating biologically active chemicals, plant roots continuously produce and secrete compounds into their immediate rhizosphere. However, the mechanisms that drive and regulate root secretion of secondary metabolites are not fully understood. To enlighten two neglected areas of root biology, root secretion and secondary metabolism, an in vitro system implementing root-specific elicitation over a 48-day time course was developed. After roots of Arabidopsis thaliana had been elicited with salicylic acid, jasmonic acid, chitosan, and two fungal cell wall elicitors, the secondary metabolites subsequently secreted were profiled. High-performance liquid chromatography was used to metabolically profile compounds in the root exudates, and 289 possible secondary metabolites were quantified. The chemical structures of 10 compounds were further characterized by (1)H and (13)C NMR: butanoic acid, trans-cinnamic acid, o-coumaric acid, p-coumaric acid, ferulic acid, p-hydroxybenzamide, methyl p-hydroxybenzoate, 3-indolepropanoic acid, syringic acid, and vanillic acid. Several of these compounds exhibited a wide range of antimicrobial activity against both soil-borne bacteria and fungi at the concentration detected in the root exudates.     

Characterization of volatiles in Costa Rican guava [Psidium friedrichsthalianum (Berg) Niedenzu] fruit

Volatile compounds were isolated from Costa Rican guava fruit by simultaneous steam distillation-solvent extraction according to the Likens-Nickerson method. Compounds were identified by capillary GC-MS and sensorially characterized by sniffing-GC. One hundred and seventy-three components were identified in the aroma concentrate, from which (E)-beta-caryophyllene, alpha-terpineol, alpha-pinene, alpha-selinene, beta-selinene, delta-cadinene, 4,11-selinadiene, and alpha-copaene were found to be the major constituents. The amounts of aliphatic esters and terpenic compounds were thought to contribute to the unique flavor of this fruit.     

Soil Fertility,Sugarcane Yield Affected by Limestone,Silicate, and Gypsum Application

The aim of this study was to verify if the application of silicate or lime, in association with gypsum, on sugarcane residue can lead to amendment of subsurface soil acidity, increasing sugarcane yield and profitability. The treatments were: 1 – control (without application of amendments), 2 – gypsum, 3 – dolomitic limestone, 4 – silicate, 5 – dolomitic limestone + gypsum, and 6 – silicate + gypsum. The surface application of gypsum led to reduction in Al (aluminum) contents and Al saturation, and increase in Mg⁺², Ca⁺², K⁺, S–SO₄^?, and base saturation in deeper soil layers, as well as increased yield of stalks, sugar, trash, bagasse, and energy, and greater profit. The application of limestone and silicate, alone or in association with gypsum, amend soil acidity throughout the soil profile. It likewise leads to an increase in stalk, sugar, trash, bagasse, and energy yield, however, application of silicate in association with gypsum leads to the greatest profitability.     

Environmental risk assessment of a metal-contaminated area in the Tropics. Tier I: screening phase

Purpose  

The present study presents data on the screening phase (tier 1) of a site-specific ecological risk assessment in a former smelter area heavily contaminated with metals (Santo Amaro, Bahia, Brazil). Joining information from three lines of evidence (LoE), chemical, ecotoxicological, and ecological, integrated risk values were calculated to rank sites within the area and identify those that may need further investigation in tier 2.     

Prioritizing areas for conservation and vegetation restoration in post-agricultural landscapes: A Biosphere Reserve plan for Bioko, Equatorial Guinea

Although the conversion of natural vegetation to agriculture threatens biodiversity, post-agricultural lands may provide an opportunity to preserve biodiversity if they are allowed to regenerate. We develop a framework for incorporating abandoned agricultural fields into the design of a Biosphere Reserve using former cocoa plantations on Bioko, Equatorial Guinea, as a case study. First, we used BIOCLIM to model the potential distribution of 62 ferns, 327 monocotyledons, 749 dicotyledons, seven primates, and 104 birds on Bioko. Next, we quantitatively assessed the representation of these distributions in conservation areas proposed by the Equatoguinean administration (hereafter “EPAs”). In addition, we used an area prioritization algorithm implemented in the ResNet software package to select an initial set of sites to serve as the Biosphere Reserve’s core areas, that is, intact forest in Bioko’s montane regions. Then, to augment the beta-diversity of the Reserve, we used the area prioritization algorithm to prioritize buffer zones in lowland sites including rainforest remnants and abandoned plantations that have partially regenerated to forest. We also compared the representation of biodiversity in the EPAs to its representation in Biosphere Reserves designed with ResNet. The representation of vegetation types and species in Reserves selected by ResNet that occupy 25% of the land on Bioko is equivalent to the representation achieved by the EPAs, which would cover 42% of Bioko. To conclude, we propose a conservation plan for Bioko.     

Selection of Leguminous Trees Associated with Symbiont Microorganisms for Phytoremediation of Petroleum-Contaminated Soil

Leguminous trees have a potential for phytoremediation of oil-contaminated areas for its symbiotic association with nitrogen-fixing bacteria and arbuscular mycorrhizal fungi (AMF). This study selects leguminous tree associated with symbiotic microorganisms that have the potential to remediate petroleum-contaminated soil. Seven species of trees were tested: Acacia angustissima, Acacia auriculiformis, Acacia holosericea, Acacia mangium, Mimosa artemisiana, Mimosa caesalpiniifolia, and Samanea saman. They were inoculated with AMF mix and nitrogen-fixing bacteria mix and cultivated over five oil levels in soils, with five replicates. The decreasing of total petroleum hydrocarbons (TPH) values occurred especially with S. saman and its symbiotic microorganisms on highest oil soil contamination. Despite the large growth of A. angustissima and M. caesalpiniifolia on the highest level of oil, these species and its inoculated microorganisms did not reduce the soil TPH. Both plants were hydrocarbon tolerant but not able to remediate the polluted soil. In contrast were significative hydrocarbon decrease with M. artemisiana under high oil concentrations, but plant growth was severely affected. Results suggest that the ability of the plants to decrease the soil concentration of TPH is not directly related to its growth and adaptation to conditions of contamination, but the success of the association between plants and its symbionts that seem to play a critical role on remediation efficiency.     

Optimization of the isoelectric precipitation method to obtain protein isolates from amaranth (Amaranthus cruentus) seeds

This research was conducted to evaluate the effect of extraction pH (7.8-9.2) and precipitation pH (4.3-5.7) on four selected quality attributes of protein isolates from amaranth seeds (Amaranthus cruentus) such as protein content (PC), whiteness index (WI), enthalpy of transition (EN), and denaturation temperature (DT). Ten different treatments involving extraction and precipitation pH combinations were analyzed by a central composite design; the experimental data were fitted by a second-order model using a least-squares method for each one of the four dependent variables. Response surface methodology was used for the optimization process; in addition, a common optimum value for the four dependent variables was obtained utilizing the desirability method. A confirmatory test showed that the generated regression equations could adequately predict performance of this isoelectric precipitation method. The results indicate that extraction pH and precipitation pH showed an important effect on PC, WI, and EN. However, the different combinations did not significantly affect the DT. Values of 9.2 and 8.0 for extraction pH and 5.7 for precipitation pH produced the best overall result for all responses. Finally, the results have shown that it is possible to obtain protein isolates from A. cruentus seeds at optimized values of extraction pH and precipitation pH, which presented a high protein content and good physicochemical properties.     

Chemical characterization of Citrus sinensis grafted on C. limonia and the effect of some isolated compounds on the growth of Xylella fastidiosa

Citrus sinensis grafted on C. limonia produces a considerable number of compounds that are not common in both plants developed from germination of seeds. The chemical profile of scion and rootstock differ notably for absence in the form of flavonoids and coumarins containing C5 prenyl groups attached to the carbon atoms of aromatic and heterocyclic systems or to oxygen. Only linear pyranocoumarins xanthyletin and xanthoxyletin were found in scion. This observation indicates that the prenylated compounds once biosynthesized in the roots could have been translocated to other organs. Xylella fastidiosa colonizes the xylem of plants causing diseases on several economically important crops such as citrus variegated chlorosis (CVC). A number of flavonoids, coumarins, alkaloids, dihydrocinnamic acid derivative, anacardic acid, triterpenes, and limonoids were tested for in vitro activity on the growth of Xylella fastidiosa. Azadirachtin A was the most active. Hesperidin, which occurs in great amounts in cells of the mesophyll of the affected leaves with CVC, showed a moderate activity suggesting that it can act as a good barrier for small-size colonies from X. fastidiosa.     

Organic residues and their impact on soil health,crop production and sustainable agriculture: A review including bibliographic analysis

Despite their potential as a sustainable source of soil nutrients and organic matter, waste organic residues are often discarded rather than utilized in agriculture. This review examines the current state-of-the-art in the application of organic residues in agricultural production systems by analysing trends and results in published research conducted on their use for soil health and crop production purposes. For this, a bibliographic analysis was conducted on 81 papers collected from the Web of Science database. Our research shows a growing trend in the field, particularly in recent years, with articles from India, China and the United States at the forefront. The most commonly evaluated organic residues were compost, animal manure, crop residues, municipal solid waste and biochar. Soil pH, bulk density and especially organic matter/total organic carbon (TOC) were the chemical, physical and biological attributes most frequently evaluated, respectively. This review indicates that the application of organic residues improves soil health, positively affecting crop productivity in crops such as maize, wheat and rice. However, further research is needed to address the potential risk of soil contamination from potentially toxic metals (PTMs) associated with organic residues, as well as to identify best practices to guarantee food safety and environmental preservation.