Identification and characterization of core abscisic acid (ABA) signaling components and their gene expression profile in response to abiotic stresses in Setaria viridis.

Abscisic acid (ABA) is an essential phytohormone that regulates growth, development and adaptation of plants to environmental stresses. In Arabidopsis and other higher plants, ABA signal transduction involves three core components namely PYR/PYL/RCAR ABA receptors (PYLs), type 2C protein phosphatases (PP2Cs) and class III SNF-1-related protein kinase 2 (SnRK2s). In the present study, we reported the identification and characterization of the core ABA signaling components in Setaria viridis, an emerging model plant for cereals and feedstock crops presenting C4 metabolism, leading to the identification of eight PYL (SvPYL1 to 8), twelve PP2C (SvPP2C1 to 12) and eleven SnRK2 (SvSnRK2.1 through SvSnRK2.11) genes. In order to study the expression profiles of these genes, two different S. viridis accessions (A10.1 and Ast-1) were submitted to drought, salinity and cold stresses, in addition to application of exogenous ABA. Differential gene expression profiles were observed in each treatment and plant genotype, demonstrating variations of ABA stress responses within the same species. These differential responses to stresses were also assessed by physiological measurements such as photosynthesis, stomatal conductance and transpiration rate. This study allows a detailed analysis of gene expression of the core ABA signaling components in Setaria viridis submitted to different treatments and provides suitable targets for genetic engineering of C4 plants aiming tolerance to abiotic stresses.

Correction to: Silencing of a BAHD acyltransferase in sugarcane increases biomass digestibility.

[This corrects the article DOI: 10.1186/s13068-019-1450-7.].

Silencing of a BAHD acyltransferase in sugarcane increases biomass digestibility.

BACKGROUND: Sugarcane (Saccharum spp.) covers vast areas of land (around 25 million ha worldwide), and its processing is already linked into infrastructure for producing bioethanol in many countries. This makes it an ideal candidate for improving composition of its residues (mostly cell walls), making them more suitable for cellulosic ethanol production. In this paper, we report an approach to improving saccharification of sugarcane straw by RNAi silencing of the recently discovered BAHD01 gene responsible for feruloylation of grass cell walls. RESULTS: We identified six BAHD genes in the sugarcane genome (SacBAHDs) and generated five lines with substantially decreased SacBAHD01 expression. To find optimal conditions for determining saccharification of sugarcane straw, we tried multiple combinations of solvent and temperature pretreatment conditions, devising a predictive model for finding their effects on glucose release. Under optimal conditions, demonstrated by Organosolv pretreatment using 30% ethanol for 240 min, transgenic lines showed increases in saccharification efficiency of up to 24%. The three lines with improved saccharification efficiency had lower cell-wall ferulate content but unchanged monosaccharide and lignin compositions. CONCLUSIONS: The silencing of SacBAHD01 gene and subsequent decrease of cell-wall ferulate contents indicate a promising novel biotechnological approach for improving the suitability of sugarcane residues for cellulosic ethanol production. In addition, the Organosolv pretreatment of the genetically modified biomass and the optimal conditions for the enzymatic hydrolysis presented here might be incorporated in the sugarcane industry for bioethanol production.

Effect of the environment on the secondary metabolic profile of Tithonia diversifolia: a model for environmental metabolomics of plants.

Tithonia diversifolia is an invasive weed commonly found in tropical ecosystems. In this work, we investigate the influence of different abiotic environmental factors on the plant's metabolite profile by multivariate statistical analyses of spectral data deduced by UHPLC-DAD-ESI-HRMS and NMR methods. Different plant part samples of T. diversifolia which included leaves, stems, roots, and inflorescences were collected from two Brazilian states throughout a 24-month period, along with the corresponding monthly environmental data. A metabolomic approach employing concatenated LC-MS and NMR data was utilised for the first time to study the relationships between environment and plant metabolism. A seasonal pattern was observed for the occurrence of metabolites that included sugars, sesquiterpenes lactones and phenolics in the leaf and stem parts, which can be correlated to the amount of rainfall and changes in temperature. The distribution of the metabolites in the inflorescence and root parts were mainly affected by variation of some soil nutrients such as Ca, Mg, P, K and Cu. We highlight the environment-metabolism relationship for T. diversifolia and the combined analytical approach to obtain reliable data that contributed to a holistic understanding of the influence of abiotic environmental factors on the production of metabolites in various plant parts.

Influence of abiotic environmental factors on the main constituents of the volatile oils of Tithonia diversifolia

ABSTRACT Tithonia diversifolia (Hemsl.) A. Gray, Asteraceae, commonly known as Mexican sunflower, is a wide distributed invasive species encountered around the world. We proposed herein to establish the relationship between different abiotic environmental factors and the variation in the production of volatile compounds in T. diversifolia, during a period of one year. Samples of leaf and inflorescence volatile oils obtained from individuals located at two different regions of Brazil were analyzed by GC-MS and the data were submitted to chemometric analysis. Based on the main constituents, the analysis allowed us to classify the volatile oils into two chemotypes, according to their geographical origin. The influence of soil nutrients, mainly Ca and P, was also observed in the composition of the volatile oils. Climate also seems to affect the constituents of the volatile oils, mainly the contents of leaf sesquiterpenes of individuals growing in areas with higher average temperatures and solar radiation levels. We can therefore highlight that the appropriate multivariate statistical analysis allowed us to propose for the first time the existence of chemotypes for the volatile oils of T. diversifolia, as well as reporting the main abiotic environmental factors related to the accumulation of the discriminant compounds in these oils.

Antinociceptive effect of Lafoensia pacari A. St.-Hil. independent of anti-inflammatory activity of ellagic acid.

This study was performed to determine the antinociceptive and anti-inflammatory activities of ethanolic extract of Lafoensia pacari A. St.-Hil. (PEtExt) stem bark and its fractions using various animal models such as acetic acid-induced abdominal writhing, formalin-induced pain and croton oil-induced ear edema tests. The PEtExt inhibited the acetic acid-induced abdominal writhing, reduced the pain reaction time on both phases of the formalin test and decreased the edema in a dose-dependent manner. Pre-treatment with naloxone did not reverse the antinociceptive effect. Only the ethyl acetate fraction showed antinociceptive and anti-inflammatory effects. Our results also showed that this extract contains compounds with analgesic action independent of anti-inflammatory activity.

Influence of environmental factors on the concentration of phenolic compounds in leaves of Lafoensia pacari

Lafoensia pacari A. St.-Hil., Lythraceae, a plant from the Cerrado known as pacari or dedaleiro, is widely used as an antipyretic, wound healing, anti-inflammatory, antidiarrheal and in the treatment of gastritis and cancer. Notable among the metabolite groups identified in leaves of L. pacari are the polyphenols, such as tannins and flavonoids, related to the pharmacological activities of pacari. Studies on the influence of environmental factors over production of major groups of secondary metabolites in pacari are important because they contribute data for its cultivation and harvest, and establish quantitative parameters of secondary metabolites in the plant drug. The objective of this study was to evaluate the influence of environmental factors on concentrations of phenolic metabolites in the leaves of L. pacari. Compounds quantified in the leaves were: total phenols, tannins by protein precipitation, hydrolysable tannins, total flavonoids, ellagic acid and mineral nutrients, while soil fertility was also analyzed, all over a period of one year. The data were analyzed using multivariate analysis, and the results suggest that metabolite concentrations in the leaves of this plant are influenced by seasonal factors, in particular the temperature and foliar micronutrients (Cu, Fe, Mn, Zn).