Lipidomic analysis of geopropolis of Brazilian stingless bees by LC-HRMS.

Stingless bees (Meliponini) represent over than 500 species, found in tropical and sub-tropical regions of the world. They produce geopropolis, a resinous natural product containing bioactive compounds, which is commonly used in folk medicine. In the current study, LC-HRMS and bioinformatic tools were used to carry out for the first time the lipidomic analysis of geopropolis from indigenous Brazilian stingless bees. As a result, 61 compounds of several lipid classes were identified with elevated degree of confidence. Then, we demonstrated that lipids in geopropolis are not restricted to waxes and fatty acids; but fatty amides and amines, phenolic lipids, resorcinols, retinoids, abietanoids, diterpenoids, pentacyclic triterpenoids, prostaglandins, retinoids, and steroids were found. In addition, multivariate analysis, based on the lipidomic profile of extracts, reinforces the assumption that the species of stingless bees, as well as the geographical origin are relevant factors to affect geopropolis composition once that the lipidic profile allowed the discrimination of geopropolis in groups related to the geographical origin, bee specie or bee genus. The lipidic profile also suggest a selective forage habits of T. angustula, which seems to collect resins from more specific vegetal sources regardless geographic origin, while other stingless bees, such as M. marginata and M. quadrifasciata, are less selective and may adapt to collect resins from a wider variety of plants.

An integrated analysis of mRNA and sRNA transcriptional profiles in Coffea arabica L. roots: insights on nitrogen starvation responses.

Coffea arabica L. is an important agricultural commodity, accounting for 60% of traded coffee worldwide. Nitrogen (N) is a macronutrient that is usually limiting to plant yield; however, molecular mechanisms of plant acclimation to N limitation remain largely unknown in tropical woody crops. In this study, we investigated the transcriptome of coffee roots under N starvation, analyzing poly-A+ libraries and small RNAs. We also evaluated the concentration of selected amino acids and N-source preferences in roots. Ammonium was preferentially taken up over nitrate, and asparagine and glutamate were the most abundant amino acids observed in coffee roots. We obtained 34,654 assembled contigs by mRNA sequencing, and validated the transcriptional profile of 12 genes by RT-qPCR. Illumina small RNA sequencing yielded 8,524,332 non-redundant reads, resulting in the identification of 86 microRNA families targeting 253 genes. The transcriptional pattern of eight miRNA families was also validated. To our knowledge, this is the first catalog of differentially regulated amino acids, N sources, mRNAs, and sRNAs in Arabica coffee roots.

An integrated analysis of mRNA and sRNA transcriptional profiles in Coffea arabica L. roots: insights on nitrogen starvation responses

Coffea arabica L. is an important agricultural commodity, accounting for 60% of traded coffee worldwide. Nitrogen (N) is a macronutrient that is usually limiting to plant yield; however, molecular mechanisms of plant acclimation to N limitation remain largely unknown in tropical woody crops. In this study, we investigated the transcriptome of coffee roots under N starvation, analyzing poly-A+ libraries and small RNAs. We also evaluated the concentration of selected amino acids and N-source preferences in roots. Ammonium was preferentially taken up over nitrate, and asparagine and glutamate were the most abundant amino acids observed in coffee roots. We obtained 34,654 assembled contigs by mRNA sequencing, and validated the transcriptional profile of 12 genes by RT-qPCR. Illumina small RNA sequencing yielded 8,524,332 non-redundant reads, resulting in the identification of 86 microRNA families targeting 253 genes. The transcriptional pattern of eight miRNA families was also validated. To our knowledge, this is the first catalog of differentially regulated amino acids, N sources, mRNAs, and sRNAs in Arabica coffee roots.

Drought tolerance of sugarcane is improved by previous exposure to water deficit.

Under field conditions, plants are exposed to cycles of dehydration and rehydration during their lifespan. In this study, we hypothesized that sugarcane plants previously exposed to cycles of water deficits will perform better than plants that have never faced water deficits when both are subjected to low water availability. Sugarcane plants were grown in a nutrient solution and exposed to one (1WD), two (2WD) or three (3WD) water deficit cycles. As the reference, plants were grown in a nutrient solution without adding polyethylene glycol. Under water deficits, leaf gas exchange was significantly reduced in 1WD and 2WD plants. However, 3WD plants showed similar CO2 assimilation and lower stomatal conductance compared to the reference plants, with increases in intrinsic water-use efficiency. Abscisic acid concentrations were lower in 3WD plants than in 1WD plants. Our data revealed root H2O2 concentration as an important chemical signal, with the highest root H2O2 concentrations found in 3WD plants. These plants presented higher root dry matter and root:shoot ratios compared to the reference plants, as well as higher biomass production when water was available. Our data suggest that sugarcane plants were able to store information from previous stressful events, with plant performance improving under water deficits. In addition, our findings provide a new perspective for increasing drought tolerance in sugarcane plants under nursery conditions.

Photoacoustic spectroscopy applied to the direct detection of bioactive compounds in Agaricus brasiliensis mycelium.

This paper describes the application of the photoacoustic spectroscopic (PAS) for detection of bioactive compounds in Agaricus brasiliensis mycelium. The mycelium was cultivated by solid-state fermentation and by submerged fermentation. Vegetal residues from food industry were used as substrates for fermentation: apple pomace (Malus domestica), wheat (Triticum aestivum), peel and pomace of pineapple (Ananas comosus), malt (Hordeum vulgare) and grape pomace (Vitis vinifera). Dry and ground samples of biomass were directly put into the PA cell. The optical absorption spectra indicated the existence of three main absorption bands: one around 280 nm related to phytosterols (ergosterol), phenolic acids, flavonoids and aromatic amino acids, another at 340 nm, due to phenolic and flavonoid compounds, and the third one at around 550 nm associated with anthocyanins and anthocyanidins. A correlation between the PA signal and the total phenolic content was satisfactory, as well as for the analyzed spectrum region (270 nm up to 1000 nm), using multivariate methods. Our results indicated that PA technique may be considered as an analytical tool to quickly detect bioactive compounds in mushrooms without the need of sample pretreatment.

Metabolic responses of Eucalyptus species to different temperature regimes.

Species and hybrids of Eucalyptus are the world's most widely planted hardwood trees. They are cultivated across a wide range of latitudes and therefore environmental conditions. In this context, comprehensive metabolomics approaches have been used to assess how different temperature regimes may affect the metabolism of three species of Eucalyptus, E. dunnii, E. grandis and E. pellita. Young plants were grown for 53 d in the greenhouse and then transferred to growth chambers at 10°C, 20°C or 30°C for another 7 d. In all three species the leaf chlorophyll content was positively correlated to temperature, and in E. pellita the highest temperature also resulted in a significant increase in stem biomass. Comprehensive metabolomics was performed using untargeted gas chromatography mass spectrometry (GC-MS) and liquid chromatography (LC)-MS. This approach enabled the comparison of the relative abundance of 88 polar primary metabolites from GC-MS and 625 semi-polar secondary metabolites from LC-MS. Using principal components analysis, a major effect of temperature was observed in each species which was larger than that resulting from the genetic background. Compounds mostly affected by temperature treatment were subsequently selected using partial least squares discriminant analysis and were further identified. These putative annotations indicated that soluble sugars and several polyphenols, including tannins, triterpenes and alkaloids were mostly influenced.

Comparative Study of Chemical Composition and Biological Activity of Yellow, Green, Brown, and Red Brazilian Propolis.

The chemical composition and biological activity of a sample of yellow propolis from Mato Grosso do Sul, Brazil (EEP-Y MS), were investigated for the first time and compared with green, brown, and red types of Brazilian propolis and with a sample of yellow propolis from Cuba. Overall, EEP-Y MS had different qualitative chemical profiles, as well as different cytotoxic and antimicrobial activities when compared to the other types of propolis assessed in this study and it is a different chemotype of Brazilian propolis. Absence of phenolic compounds and the presence of mixtures of aliphatic compounds in yellow propolis were determined by analysing (1)H-NMR spectra and fifteen terpenes were identified by GC-MS. EEP-Y MS showed cytotoxic activity against human tumour strain OVCAR-8 but was not active against Gram-negative or Gram-positive bacteria. Our results confirm the difficulty of establishing a uniform quality standard for propolis from diverse geographical origins. The most appropriate pharmacological applications of yellow types of propolis must be further investigated.

A simple protocol to determine lignin S/G ratio in plants by UHPLC-MS.

A simple extraction protocol and an ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS) method for the determination of the syringyl/guaiacyl (S/G) ratio in lignin is reported herein. The method was entirely developed using stems of three Eucalyptus species, which were hydrolyzed with NaOH and partitioned with ethyl ether; vanillin (from the G monomer) and syringaldehyde (from S monomer) were quantified. The S/G ratios obtained were comparable to those usually reported for eucalyptus. The data for one of the eucalyptus species were compared with those obtained with a widely accepted method using thioacidolysis and gas chromatography-mass spectrometry (GC-MS). The method was also applied to sugarcane and showed to be reliable. The yield of the NaOH hydrolysis of the monolignols ranged from 89.94 to 95.69%, with more than 77.12% of recuperation in the liquid-liquid extraction. The whole analytical procedure was validated, achieving results with less than 4.38% of variation. The lowest LOD and LOQ were 0.01 and 0.05 µg/mL, respectively. In addition, the method combines reliability and a fast and direct quantification.