Environmentally-driven metabolite and lipid variations correspond to altered bioactivities of black wolfberry fruit

Determination and comparison of lipid profiles of Chinese green tea varieties using untargeted lipidomics analysis combined with chemometrics

Tea is the most widely consumed drink in the world. Lipids as important chemical components are closely related to the flavor and quality of tea. However, the information about the lipidomic fingerprints of different Chinese green tea varieties was limited. Therefore, an untargeted lipidomics analysis combined with chemometrics was applied for discriminating Chinese green tea varieties. A total of 147 molecular species belonging to 16 lipid classes were identified. And the green tea samples exhibited high levels of phospholipids, glycolipids, linoleic acid, and linolenic acid. They play important roles in metabolic processes that could influence flavor formation. Furthermore, combined with multivariate data analysis, 8 molecular species were screened out for discriminating green tea varieties, such as PC 16:0/18:3, MGDG 18:3/18:3, PC 18:2/18:2, etc. This study offers a reference for the guarantee of quality and the prevention of fraud within the Chinese green tea market.

The authentication of Yanchi tan lamb based on lipidomic combined with particle swarm optimization-back propagation neural network

This study successfully combined widely targeted lipidomic with a back propagation (BP) neural network optimized based on a particle swarm algorithm to identify the authenticity of Yanchi Tan lamb. An electronic nose and gas chromatography-olfactometry-mass spectrometry (GC-O-MS) were used to explore the flavor differences in Tan lamb from various regions. Among the 17 identified volatile compounds, 16 showed significant regional differences (p < 0.05). Lipidomic identified 1080 molecules across 41 lipid classes, with 11 lipids, including Carnitine 15:0, Carnitine 17:1, and Carnitine C8:1-OH, serving as potential markers for Yanchi Tan lamb. In addition, a stepwise linear discriminant model and three types of BP neural networks were used to identify the origin of Tan lamb. The results showed that particle swarm optimization-back propagation (PSO-BP) neural network had the best prediction effect, with 100 % prediction accuracy in both the training and test sets. The established PSO-BP model was able to achieve effective discrimination between Yanchi and non-Yanchi Tan lamb. These results provide a comprehensive perspective on the discrimination of Yanchi Tan lambs and improve the understanding of Tan lamb flavor and lipid composition in relation to origin.

Metabolite-based genome-wide association studies enable the dissection of the genetic bases of flavonoids, betaine and spermidine in wolfberry (Lycium)

Wolfberry is a plant with medicinal and food values. However, its bioactive ingredients and the corresponding genetic bases have not been determined. Here, we de novo generated a chromosome-level genome assembly for wolfberry, yielding a genome sequence of ~1.77 Gb with contig N50 of 50.55 Mb and 39 224 predicted gene models. A variation map, using 307 re-sequenced accessions, was called based on this genome assembly. Furthermore, the fruit metabolome of these accessions was profiled using 563 annotated metabolites, which separated Lycium barbarum L. and non-L. barbarum L. The flavonoids, coumarins, alkaloids and nicotinic acid contents were higher in the former than in the latter. A metabolite-based genome-wide association study mapped 156 164 significant single nucleotide polymorphisms corresponding to 340 metabolites. This included 19 219 unique lead single nucleotide polymorphisms in 1517 significant association loci, of which three metabolites, flavonoids, betaine and spermidine, were highlighted. Two candidate genes, LbUGT (evm.TU.chr07.2692) and LbCHS (evm.TU.chr07.2738), with non-synonymous mutations, were associated with the flavonoids content. LbCHS is a structural gene that interacts with a nearby MYB transcription factor (evm.TU.chr07.2726) both in L. barbarum and L. ruthenicum. Thus, these three genes might be involved in the biosynthesis/metabolism of flavonoids. LbSSADH (evm.TU.chr09.627) was identified as possibly participating in betaine biosynthesis/metabolism. Four lycibarbarspermidines (E-G and O) were identified, and only the lycibarbarspermidines O content was higher in L. barbarum varieties than in non-L. barbarum varieties. The evm.TU.chr07.2680 gene associated with lycibarbarspermidines O was annotated as an acetyl-CoA-benzylalcohol acetyltransferase, suggesting that it is a candidate gene for spermidine biosynthesis. These results provide novel insights into the specific metabolite profile of non-L. barbarum L. and the genetic bases of flavonoids, betaine and spermidine biosynthesis/metabolism.

The Flavor Characteristics and Metabolites of Three Commercial Dried Jujube Cultivars

To understand the flavor and metabolite differences between the three commercial dried jujube cultivars Huizao (HZ), Hamazao 1 (HMZ), and Qiyuexian (QYX), their soluble sugars, organic acids, volatiles, and metabolites were systematically investigated. The results show that sucrose and malic acid were the main soluble sugar and organic acids contained in these dried jujubes, respectively. Sucrose (573.89 mg/g DW) had the highest presence in HZ, and the total sugar content (898.33 mg/g DW) was the highest in QYX. Both of these had a low total acid content, resulting in relatively high sugar-acid ratios (105.49 and 127.86, respectively) compared to that of HMZ (51.50). Additionally, 66 volatile components were detected in the 3 jujubes. These mainly included acids, aldehydes, esters, and ketones (90.5-96.49%). Among them, (E)-2-nonenal, (E)-2-decenal, heptanal, decanal, nonanal, and octanal were identified as the key aromatic substances of the dried jujubes, and their contents were the highest in HMZ. Moreover, 454 metabolites were identified, including alkaloids, amino acids, flavonoids, lipids, nucleotides, and terpenoids. The highest contents of flavonoids (5.6%) and lipids (24.9%) were detected in HMZ, the highest contents of nucleotides (10.2%) and alkaloids (27%) were found in QYX, and the contents of saccharides (5.7%) and amino acids (23.6%) were high in HZ. Overall, HZ, HMZ, and QYX significantly differ in their flavor and nutrition. HZ tastes better, HMZ is more fragrant, and QYX and HMZ possess higher nutritional values.

Major quality regulation network of flavonoid synthesis governing the bioactivity of black wolfberry

Black wolfberry (Lycium ruthenicum Murr.) contains various bioactive metabolites represented by flavonoids, which are quite different among production regions. However, the underlying regulation mechanism of flavonoid biosynthesis governing the bioactivity of black wolfberry remains unclear. Presently, we compared the bioactivity of black wolfberry from five production regions. Multi-omics were performed to construct the regulation network associated with the fruit bioactivity. The detailed regulation mechanisms were identified using genetic and molecular methods. Typically, Qinghai (QH) fruit exhibited higher antioxidant and anti-inflammatory activities. The higher medicinal activity of QH fruit was closely associated with the accumulation of eight flavonoids, especially Kaempferol-3-O-rutinoside (K3R) and Quercetin-3-O-rutinoside (rutin). Flavonoid biosynthesis was found to be more active in QH fruit, and the upregulation of LrFLS, LrCHS, LrF3H and LrCYP75B1 caused the accumulation of K3R and rutin, leading to high medicinal bioactivities of black wolfberry. Importantly, transcription factor LrMYB94 was found to regulate LrFLS, LrCHS and LrF3H, while LrWRKY32 directly triggered LrCYP75B1 expression. Moreover, LrMYB94 interacted with LrWRKY32 to promote LrWRKY32-regulated LrCYP75B1 expression and rutin synthesis in black wolfberry. Transgenic black wolfberry overexpressing LrMYB94/LrWRKY32 contained higher levels of K3R and rutin, and exhibited high medicinal bioactivities. Importantly, the LrMYB94/LrWRKY32-regulated flavonoid biosynthesis was light-responsive, showing the importance of light intensity for the medicinal quality of black wolfberry. Overall, our results elucidated the regulation mechanisms of K3R and rutin synthesis, providing the basis for the genetic breeding of high-quality black wolfberry.

Reveal the kernel dehydration mechanisms in maize based on proteomic and metabolomic analysis

BACKGROUND

Kernel dehydration is an important factor for the mechanized harvest in maize. Kernel moisture content (KMC) and kernel dehydration rate (KDR) are important indicators for kernel dehydration. Although quantitative trait loci and genes related to KMC have been identified, where most of them only focus on the KMC at harvest, these are still far from sufficient to explain all genetic variations, and the relevant regulatory mechanisms are still unclear. In this study, we tried to reveal the key proteins and metabolites related to kernel dehydration in proteome and metabolome levels. Moreover, we preliminarily explored the relevant metabolic pathways that affect kernel dehydration combined proteome and metabolome. These results could accelerate the development of further mechanized maize technologies.

RESULTS

In this study, three maize inbred lines (KB182, KB207, and KB020) with different KMC and KDR were subjected to proteomic analysis 35, 42, and 49 days after pollination (DAP). In total, 8,358 proteins were quantified, and 2,779 of them were differentially expressed proteins in different inbred lines or at different stages. By comparative analysis, K-means cluster, and weighted gene co-expression network analysis based on the proteome data, some important proteins were identified, which are involved in carbohydrate metabolism, stress and defense response, lipid metabolism, and seed development. Through metabolomics analysis of KB182 and KB020 kernels at 42 DAP, 18 significantly different metabolites, including glucose, fructose, proline, and glycerol, were identified.

CONCLUSIONS

In sum, we inferred that kernel dehydration could be regulated through carbohydrate metabolism, antioxidant systems, and late embryogenesis abundant protein and heat shock protein expression, all of which were considered as important regulatory factors during kernel dehydration process. These results shed light on kernel dehydration and provide new insights into developing cultivars with low moisture content.

ERF5.1 modulates carotenoid accumulation by interacting with CCD4.1 in Lycium

Carotenoids are important natural pigments and have medical and health functions for humans. Carotenoid cleavage dioxygenase 4 (CCD4) and ethylene responsive factor (ERF) participate in carotenoid metabolism, but their roles in Lycium have not been discovered. Here, we annotated LbCCDs from the Lycium reference genome and found that LbCCD4.1 expression was significantly correlated with the carotenoid metabolites during Lycium five fruit developmental stages. Over-expression of LbCCD4.1 in NQ's leaves resulted in a series of significantly lower contents of carotenoid metabolites, including β-carotene and β-cryptoxanthin. Moreover, LbERF5.1, a transcription factor belonging to the ERF family that was located in the nucleus, was isolated. Significant reductions in the carotenoids, especially lutein, violaxanthin and their derivatives, were observed in over-expressing ERF5.1 transgenic NQ's leaves. Over-expression or virus-induced gene silencing of LbERF5.1 in NQ's leaves induced a consistent up- or down-expression, respectively, of LbCCD4.1. Furthermore, yeast one-hybrid and dual-luciferase reporter assays showed that ERF5.1 interacted with the promoter of CCD4.1 to increase its expression, and LbERF5.1 could bind to any one of the three predicted binding sites in the promoter of LbCCD4.1. A transcriptome analysis of LbERF5.1 and LbCCD4.1 over-expressed lines showed similar global transcript expression, and geranylgeranyl diphosphate synthase, phytoene synthase, lycopene δ-cyclase cytochrome, cytochrome P450-type monooxygenase 97A, cytochrome P450-type monooxygenase 97C, and zeaxanthin epoxidase in the carotenoid biosynthesis pathway were differentially expressed. In summary, we uncovered a novel molecular mechanism of carotenoid accumulation that involved an interaction between ERF5.1 and CCD4.1, which may be used to enhance carotenoid in Lycium.

Quantitative analysis and hepatoprotective mechanism of Cistanche deserticola Y. C. Ma against alcohol-induced liver injury in mice

Cistanche deserticola Y. C. Ma (CD), known as "desert ginseng", has been found to have hepatoprotective effect. This research aimed to investigate the quality control and its alleviating effect on alcoholic liver injury in mice. In this study, for the first time, a sensitive and efficient ultra-high-performance liquid chromatography with quadrupole ion-trap mass spectrometry (UPLC-Q-TRAP/MS) method was developed to rapidly characterize nine representative phenylethanoid glycosides (PhGs) in the CD extract within 14 min, offering a reference for the quality control standard of this plant. In addition, we found that the CD extract significantly inhibited the weight loss, decreased the liver index, and attenuated excessive lipid deposition, inflammatory and oxidative stress in the mice liver. With the help of the high-throughput lipidomics technique, we discovered that CD markedly reversed 17 lipid metabolites and their involved linoleic acid, arachidonic acid and glycerophospholipid metabolic pathways. As these metabolites are mainly associated with lipid metabolism and liver damage, we further used molecular biological tests to found that CD could regulate the upstream genes and proteins of the lipid metabolism pathway, including adenosine 5'-monophosphate-activated protein kinase (AMPK), sterol regulatory element binding protein-1c (SREBP-1c), fatty acid synthase (FAS), and peroxidase proliferators activate receptors α (PPARα). In conclusion, this study elucidates the modulatory effects of CD on lipid metabolism disorders in alcoholic fatty liver from holistic system and provides a reference for further research and development of CD as a therapeutic agent.

Metabolic Variations in Brown Rice Fertilised with Different Levels of Nitrogen

Nitrogen is a necessary element for plant growth; therefore, it is important to study the influence of N fertilisers on crop metabolites. In this study, we investigate the variability of endogenous metabolites in brown rice fertilised with different amounts of nitrogen. We identified 489 metabolites in brown rice. Compared to non-nitrogen fertilised groups, there were 59 differentially activated metabolic pathways in the nitrogen-fertilised groups. Additionally, there were significantly differential secondary metabolites, especially flavonoids, between groups treated with moderate (210 kg N/hm2) and excessive amounts of nitrogen (420 kg N/hm2). Nitrogen fertilisation upregulated linoleic acid metabolism and most steroids, steroid derivatives, and flavonoid compounds, which have antioxidant activity. The DPPH, ABTS, and hydroxyl radical scavenging rates were higher in fertilised groups than in the non-fertilised group. These findings provide a theoretical basis to enhance the health benefits of brown rice by improving fertilisation.

Spatially resolved metabolomics reveals variety-specific metabolic changes in banana pulp during postharvest senescence

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Both post-ripening stages and banana varieties contribute to metabolite variation.

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AuNP-assisted LDI-MSI was firstly used in mapping functional metabolites in pulps.

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AAs and monoamines exclusively accumulated in the middle region near the seed zone.

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Monosaccharides locate in whole pulps but enrich in the intermediate microregion.

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Di/trisaccharides exhibit different accumulation patterns as monosaccharides.

Banana is one of most popular fruits globally due to health-promoting and disease-preventing effects, yet little is known about in situ metabolic changes across banana varieties. Here, we integrated gold nanoparticle (AuNP)-assisted laser desorption/ionization mass spectrometry imaging (LDI-MSI) and metabolomics to investigate the spatiotemporal distribution and levels of metabolites within Brazil and Dongguan banana pulps during postharvest senescence. Metabolomics results indicated that both postripening stages and banana varieties contribute to metabolite levels. Benefiting from improved ionization efficiency of small-molecule metabolites and less peak interference, we visualized the spatiotemporal distribution of sugars, amino acids (AAs) and monoamines within pulps using AuNP-assisted LDI-MSI for the first time, revealing that AAs and monoamines exclusively accumulated in the middle region near the seed zone. Monosaccharides and di/trisaccharides were generally distributed across entire pulps but exhibited different accumulation patterns. These findings provide a guide for breeding new varieties and improving extraction efficiency of bioactive compounds.