Polyphenol analysis using high-resolution mass spectrometry allows differentiation of drought tolerant peanut genotypes

Genome-wide analysis of UDP-glycosyltransferase gene family and identification of a flavonoid 7-O-UGT (AhUGT75A) enhancing abiotic stress in peanut (Arachis hypogaea L.)

BACKGROUND

Glycosylation, catalyzed by UDP-glycosyltransferase (UGT), was important for enhancing solubility, bioactivity, and diversity of flavonoids. Peanut (Arachis hypogaea L.) is an important oilseed and cash crop worldwide. In addition to provide high quality of edible oils and proteins, peanut seeds contain a rich source of flavonoid glycosides that benefit human health. However, information of UGT gene family was quite limited in peanut.

RESULTS

In present study, a total of 267 AhUGTs clustered into 15 phylogenetic groups were identified in peanut genome. Group I has greatly expanded to contain the largest number of AhUGT genes. Segmental duplication was the major driving force for AhUGT gene family expansion. Transcriptomic analysis of gene expression profiles in various tissues and under different abiotic stress treatments indicated AhUGTs were involved in peanut growth and abiotic stress response. AhUGT75A (UGT73CG33), located in mitochondria, was characterized as a flavonoid 7-O-UGT by in vitro enzyme assays. The transcript level of AhUGT75A was strongly induced by abiotic stress. Overexpression of AhUGT75A resulted in accumulating less amount of malondialdehyde (MDA) and superoxide, and enhancing tolerance against drought and/or salt stress in transgenic Arabidopsis. These results indicated AhUGT75A played important roles in conferring abiotic stress tolerance through reactive oxygen species scavenging.

CONCLUSIONS

Our research only not provides valuable information for functional characterization of UGTs in peanut, but also gives new insights into potential applications in breeding new cultivars with both desirable stress tolerance and health benefits.

Morphological and Physio-Chemical Responses to PEG-Induced Water Stress in Vanilla planifolia and V. pompona Hybrids

Vanilla planifolia is an orchid of cultural and economic value. However, its cultivation in many tropical countries is threatened by water stress. In contrast, V. pompona is a species that is tolerant of prolonged periods of drought. Due to the need for plants' resistant to water stress, the use of hybrids of these two species is considered. Therefore, the objective of this study was to evaluate the morphological and physio-chemical responses of in vitro vanilla seedlings of the parental genotype V. planifolia, and the hybrids V. planifolia × V. pompona and V. pompona × V. planifolia, which were then exposed over five weeks to polyethylene glycol-induced water stress (-0.49 mPa). Stem and root length, relative growth rate, number of leaves and roots, stomatal conductance, specific leaf area, and leaf water content were determined. Metabolites potentially associated with the response to water stress were identified in leaves, through untargeted and targeted metabolomics. Both hybrids exhibited a smaller decrease in the morphophysiological responses compared to V. planifolia and exhibited an enrichment of metabolites such as carbohydrates, amino acids, purines, phenols, and organic acids. Hybrids of these two species are considered as a potential alternative to the traditional cultivation of vanilla to face drought in a global warming scenario.

Comprehensive review of composition distribution and advances in profiling of phenolic compounds in oilseeds

A wide range of phenolic compounds participate in oilseed growth, regulate oxidative stability of corresponding vegetable oil, and serve as important minor food components with health-promoting effects. Composition distribution of phenolic compounds varied in oilseeds. Isoflavones, sinapic acid derivatives, catechin and epicatechin, phenolic alcohols, chlorogenic acid, and lignans were the main phenolic compounds in soybean, rapeseed, peanut skin, olive, sunflower seed, sesame and flaxseed, respectively. Among which, the total isoflavones content in soybean seeds reached from 1,431 to 2,130 mg/100 g; the main phenolic compound in rapeseed was sinapine, representing 70–90%; chlorogenic acid as the predominant phenolic compound in sunflower kernels, represented around 77% of the total phenolic content. With the rapid development of analytical techniques, it is becoming possible for the comprehensive profiling of these phenolic compounds from oilseeds. This review aims to provide recently developments about the composition distribution of phenolic compounds in common oilseeds, advanced technologies for profiling of phenolic compounds by the metabolomics approaches based on mass spectrometry. As there is still limited research focused on the comprehensive extraction and determination of phenolics with different bound-forms, future efforts should take into account the non-targeted, pseudo-targeted, and spatial metabolomic profiling of phenolic compounds, and the construction of phenolic compound database for identifying and quantifying new types of phenolic compounds in oilseeds and their derived products.

Optimizing Procedures for Antioxidant Phenolics Extraction from Skin and Kernel of Peanuts with Contrasting Levels of Drought Tolerance

Peanut is an affordable legume known for its nutritional value and phenolic content. The kernel and skin of 14 peanut genotypes contrasting in drought tolerance had their phenolic profiles determined and reactive oxygen species (ROS) scavenging activity evaluated. Firstly, temperature and % EtOH to extract antioxidant phenolic compounds were optimized using response surface methodology (RSM). The optimized extraction conditions, 60 °C and 35% EtOH for kernels and 40 °C and 60% EtOH for skins, were further adopted, and phenolic compounds were identified and quantified using high-performance liquid chromatography coupled with electrospray ionization-quadrupole-time of flight-mass spectrometry (HPLC-ESI-QTOF-MS) and high-performance liquid chromatography with photodiode array detector (HPLC-PDA). As a result, phenolic acids and glycosidic/non-glycosidic flavonoids were found. Principal component analysis was conducted, and the pairwise score plot of the skin extracts based on individual phenolic compounds showed a trend of genotype clustering based not only on drought tolerance but also on botanical type of germplasm. Therefore, our results demonstrate the status quo for antioxidant phenolic compounds of peanut genotypes contrasting in drought tolerance grown under natural field conditions.

Crosstalk between phytohormones and secondary metabolites in the drought stress tolerance of crop plants: A review

Drought stress negatively affects crop performance and weakens global food security. It triggers the activation of downstream pathways, mainly through phytohormones homeostasis and their signaling networks, which further initiate the biosynthesis of secondary metabolites (SMs). Roots sense drought stress, the signal travels to the above-ground tissues to induce systemic phytohormones signaling. The systemic signals further trigger the biosynthesis of SMs and stomatal closure to prevent water loss. SMs primarily scavenge reactive oxygen species (ROS) to protect plants from lipid peroxidation and also perform additional defense-related functions. Moreover, drought-induced volatile SMs can alert the plant tissues to perform drought stress mitigating functions in plants. Other phytohormone-induced stress responses include cell wall and cuticle thickening, root and leaf morphology alteration, and anatomical changes of roots, stems, and leaves, which in turn minimize the oxidative stress, water loss, and other adverse effects of drought. Exogenous applications of phytohormones and genetic engineering of phytohormones signaling and biosynthesis pathways mitigate the drought stress effects. Direct modulation of the SMs biosynthetic pathway genes or indirect via phytohormones' regulation provides drought tolerance. Thus, phytohormones and SMs play key roles in plant development under the drought stress environment in crop plants.

Phenolic profile and potential beneficial effects of underutilized Brazilian native fruits on scavenging of ROS and RNS and anti-inflammatory and antimicrobial properties

Brazilian native fruits (BNF) have aroused interest of researchers and consumers for their great human health benefits. In this study, five BNF (Byrsonima lancifolia, Campomanesia phaea, Jacaratia spinosa, Solanum alternatopinnatum and Acnistus arborescens) were tested for their polyphenolic compounds by LC-ESI-MS/MS, reactive species deactivation (ROO˙, O2˙-, HOCl and NO˙), anti-inflammatory properties in vivo, and in vitro antimicrobial activity - with determination of putative mechanism(s) of action. Eighty-one polyphenols were identified, which exhibited a significant capacity to deactivate both ROS and RNS. C. phaea extract had the highest capacity to scavenge ROO˙ (68.94 μmol TE per g), O2˙- (IC50: 575.36 μg mL-1) and NO˙ (IC50: 16.96 μg mL-1), which may be attributed to the presence of ellagitanins. B. lancifolia decreased neutrophil influx into the peritoneal cavity of mice by 50% as compared to carrageenan and reduced Candida albicans biofilm viability by 3 log10 possibly due to complexation with cell membrane ergosterol. In summary, the BNF presented herein are good sources of bioactive compounds with positive effects on deactivation of biological reactive species, as well as with anti-inflammatory and antimicrobial activities, which can be altogether highly beneficial to human health.