Isotope-Guided Metabolomics Reveals Divergent Incorporation of Valine into Different Flavor Precursor Classes in Chives.

Plants of the genus Allium such as chives, onions or garlic produce S-alk(en)yl cysteine sulfoxides as flavor precursors. Two major representatives are S-propenyl cysteine sulfoxide (isoalliin) and S-propyl cysteine sulfoxide (propiin), which only differ by a double bond in the C3 side chain. The propenyl group of isoalliin is derived from the amino acid valine, but the source of the propyl group of propiin remains unclear. Here, we present an untargeted metabolomics approach in seedlings of chives (Allium schoenoprasum) to track mass features containing sulfur and/or 13 C from labeling experiments with valine-13 C5 guided by their isotope signatures. Our data show that propiin and related propyl-bearing metabolites incorporate carbon derived from valine-13 C5 , but to a much lesser extent than isoalliin and related propenyl compounds. Our findings provide new insights into the biosynthetic pathways of flavor precursors in Allium species and open new avenues for future untargeted labeling experiments.

Transcriptome landscapes of multiple tissues highlight the genes involved in the flavor metabolic pathway in Chinese chive (Allium tuberosum).

The unique flavor of Allium tuberosum is primarily associated with the hydrolysis of a series of organosulfur compounds, S-alk(en)yl cysteine sulphoxides (CSOs), upon tissue bruising or maceration. To obtain the tissue-specific transcriptomes, 18 RNA-Seq libraries representing leaf, root, stem, mature flower, inflorescence, and seed tissues of A. tuberosum were sequenced, finally yielding 133.7 Gb clean reads. The de novo assembled transcriptomes enabled the identification of 223,529 unigenes, which were functionally annotated and analyzed for the gene ontology and metabolic pathways. Furthermore, to reveal the flavor metabolic pathways, a total of 205 unigenes involved in the sulfur assimilation and CSO biosynthesis were identified, and their expression profiles were analyzed by RNA-Seq and qRT-PCR. Collectively, this study provides a valuable resource for in-depth molecular and functional researches especially on flavor formation, as well as for the development of molecular markers, and other genetic studies in A. tuberosum.

Plants of the genus Allium as antibacterial agents: From tradition to pharmacy.

Plants belonging to the genus Allium are widely cultivated and used all over the world as food and medicinal plants. Since ancient times, these plants, particularly garlic (Allium sativum L.) and onion (Allium cepa L.), have represented important components of typical recipes and traditional healing systems. Not the least of which, their use as food biopreservatives is well documented, due to the relevant antibacterial activity of their extracts and essential oils. In addition to garlic and onion, this review article deals with the main members of the genus Allium, including A. ampeloprasum (Leek), A. schoenoprasum (Chive) and A. ascalonicum (Shallot), focusing both on their ethnonutritional uses and potential as promising food biopreservative agents. Noteworthy, recent research has demonstrated Allium derivatives to be novel components in active edible coatings as well as nanoformulates.

Exosome-like nanoparticles derived from Allium tuberosum prevent neuroinflammation in microglia-like cells.

OBJECTIVE: Exosome-like nanoparticles (ELNs), which are plant-derived extracellular membrane vesicles, can regulate mammalian gene expression. ELNs can cross the blood-brain barrier, making them potential therapeutic agents or drug-delivery carriers for neuroinflammation-related diseases. Here, we investigated the anti-neuroinflammatory potential of ELNs extracted from Allium tuberosum (A-ELNs). METHODS: A-ELNs were extracted, and their miRNA profile was characterized. A-ELNs were also applied to BV-2 microglial and MG-6 cells derived from C57/BL6 mice stimulated with lipopolysaccharide (LPS), followed by an examination of levels of inflammatory-related factors. To test their drug-carrying potential, A-ELNs were mixed with dexamethasone, an anti-inflammatory drug, to prepare dexamethasone-incorporated A-ELNs (Dex-A-ELNs). KEY FINDINGS: A-ELNs showed a particle size of 145 ± 2 nm and characteristic miRNAs. A-ELNs significantly decreased the LPS-induced nitric oxide (NO) and inflammatory cytokines levels in BV-2 and MG-6 cells. The mRNA expression of heme oxygenase-1 was significantly increased, and that of inducible NO synthase and inflammatory cytokines was significantly decreased by A-ELNs in BV-2 cells. Dex-A-ELNs inhibited NO production in BV-2 cells more potently than either A-ELNs or dexamethasone alone. CONCLUSION: A-ELNs can alleviate microglial inflammation. Their effects can be potentiated by incorporating anti-inflammatory drugs, such as dexamethasone, making them potential therapeutic agents or drug-delivery carriers for neuroinflammation.

Determination of reliable reference genes for gene expression studies in Chinese chive (Allium tuberosum) based on the transcriptome profiling.

Chinese chive (Allium tuberosum) is widely cultivated around the world for its unique flavor, nutrient, and medicinal values, yet its molecular mechanism on flavor formation and other metabolic pathways remains intangible. The elucidation of these complex processes begins with investigating the expression of the genes of interest, however the appropriate reference genes (RGs) for normalizing the gene expression are still unavailable in A. tuberosum. To fill this lacuna, transcriptome-wide screening was undertaken to identify the most stable genes according to the analysis of their FPKM values. The expression stability of the RGs was further evaluated using geNorm, NormFinder, BestKeeper, and RefFinder algorithms. The comprehensive analysis showed that GLY1 and SKP1, instead of two traditionally used RGs (eIF1α and ACT2), were the most stable genes across diverse A. tuberosum tissues, indicating the necessity to carefully validate the stability of RGs prior to their use for normalizations. As indicated by geNorm, the normalizations with at least two RGs could give more accurate results. qRT-PCR experiments were conducted with randomly selected genes, demonstrating that normalization with a combination of GLY1 and SKP1 resulted in reliable normalization results. Our finding represents the first attempt toward establishing a standardized qRT-PCR analysis in this economically important vegetable.

A novel potent inhibitor of 2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine (PhIP) formation from Chinese chive: Identification, inhibitory effect and action mechanism.

Differential solvent extraction and phytochemical profiling of Chinse chive were employed to identify its principal PhIP-formation inhibitory constituents. Six compounds (mangiferin, isorhamnetin, luteolin, rosmarinic acid, 6-methylcoumarin, and cyanidin-3-glucoside) were further analyzed in a PhIP-producing chemical model to identify the dominant inhibitor. Its inhibitory mechanism was investigated by assessing the contribution of antioxidation and scavenging of key PhIP precursor/intermediate. No significant correlation was observed between PhIP inhibition rates and antioxidant activities. Further evaluation of the novel potent inhibitor mangiferin revealed a highly significant correlation between its dose-dependent inhibition of PhIP formation and phenylacetaldehyde scavenging. Finally, the proposed mechanism was corroborated through organic synthesis and structural elucidation of the mangiferin-phenylacetaldehyde adduct. This study has identified a potent novel inhibitor of the most abundant HA in heat-processed food and characterized its action mechanism. These findings may provide insight for future studies on mitigation of dietary exposure to toxic Maillard products by polyphenolic phytochemicals.

Therapeutic potential of garlic chive-derived vesicle-like nanoparticles in NLRP3 inflammasome-mediated inflammatory diseases.

Aberrant activation of the nucleotide-binding domain and leucine-rich repeat related (NLR) family, pyrin domain containing 3 (NLRP3) inflammasome drives the development of many complex inflammatory diseases, such as obesity, Alzheimer's disease, and atherosclerosis. However, no medications specifically targeting the NLRP3 inflammasome have become clinically available. Therefore, we aim to identify new inhibitors of the NLRP3 inflammasome in this study. Methods: Vesicle-like nanoparticles (VLNs) were extracted from garlic chives and other Allium vegetables and their effects on the NLRP3 inflammasome were evaluated in primary macrophages. After garlic chive-derived VLNs (GC-VLNs) were found to exhibit potent anti-NLRP3 inflammasome activity in cell culture, such function was further assessed in a murine acute liver injury disease model, as well as in diet-induced obesity. Finally, GC-VLNs were subjected to omics analysis to identify the active components with anti-NLRP3 inflammasome function. Results: GC-VLNs are membrane-enclosed nanoparticles containing lipids, proteins, and RNAs. They dose-dependently inhibit pathways downstream of NLRP3 inflammasome activation, including caspase-1 autocleavage, cytokine release, and pyroptotic cell death in primary macrophages. The inhibitory effects of GC-VLNs on the NLRP3 inflammasome are specific, considering their marginal impact on activation of other inflammasomes. Local administration of GC-VLNs in mice alleviates NLRP3 inflammasome-mediated inflammation in chemical-induced acute liver injury. When administered orally or intravenously, GC-VLNs accumulate in specific tissues and suppress activation of the NLRP3 inflammasome and chronic inflammation in diet-induced obese mice. The phospholipid 1,2-dilinoleoyl-sn-glycero-3-phosphocholine (DLPC) in GC-VLNs has been identified to inhibit NLRP3 inflammasome activation. Conclusions: Identification of GC-VLNs and their active component DLPC as potent inflammasome inhibitors provides new therapeutic candidates in the treatment of NLRP3 inflammasome-driven diseases.

Biochar reduced Chinese chive (Allium tuberosum) uptake and dissipation of thiamethoxam in an agricultural soil.

Information about the effect of biochar on the environmental fate of pesticide thiamethoxam (THI) in soil-vegetable ecosystems is limited. Therefore, the influence of a wood-derived biochar produced at 450 °C (BC450) on the uptake of THI by Chinese chive (Allium tuberosum) and its dissipation in soil was investigated using a 42-day pot experiment. BC450 addition decreased THI uptake and its metabolite clothianidin (CLO) by 22.8 % and 37.6 %, respectively. However, the half-life of THI in soil rose from 89.4-120 days, indicating that BC450 increased soil THI's persistence. The decreased bioavailability and increased persistence of THI resulted mainly from the higher sorption capacity of BC450 to THI and CLO, which, in turn, enhanced the soil sorption capacity. Consequently, the application of BC450 increased the soil microbial diversity and altered the structure of the microbial community. Although the abundance of Actinobacteria associated with the biodegradation of THI, increased the persistence of THI in the BC450-amended soil, mainly due to the decrease in bioavailable THI. Our findings provide valuable information about the effect of biochar on the fate of THI and its metabolites in agricultural soil and will help to guide the practical application of biochar to remediate soils contaminated with neonicotinoid pesticides.

Host plant nutrient contents influence nutrient contents in Bradysia cellarum and Bradysia impatiens.

The chive maggot Bradysia cellarum and the fungus gnat B. impatiens are two primary root pests of plants, which can coexist on the same host plants and are the devastating pests on liliaceous crops and edible fungi. Their growth and development are affected by the nutrient contents of their host plants. In this study, we assessed the effects of different host plant nutrients on the nutrient contents of these two Bradysia species. The nutrients of the chive (Allium tuberosum Rottl. ex Spreng.), board bean (Vicia faba L.), lettuce (Lactuca sativa L. var. ramosa Hort.), cabbage (Brassica oleracea L.), wild cabbage (Brassica oleracea var. capitata rubra) and pepper (Capsicum annuum L.) roots were determined, and their effect on nutrient content of the two Bradysia species after feeding on the host plant for three continuous generations were evaluated. The results show that chive and B-bean contained higher levels of protein, free amino acid, soluble sugar and starch than others. As a result, the soluble sugar, fat and protein contents were significantly higher in both Bradysia species reared on chive and B-bean than on cabbage, lettuce, W-cabbage and pepper, suggesting nutritional preference of these insects. Based on our results, we concluded that the two Bradysia species displayed nutrient preference toward chive and B-bean, which provides a reference for understanding their host plant range and for control of the insect species via field crop rotations.

Chive (Allium schoenoprasum L.) response as a phytoextraction plant in cadmium-contaminated soils.

Cadmium (Cd) soil contamination poses a major hazard to safe food production throughout the world, calling upon actions for decontamination using environmentally friendly methods, such as phytoextraction. In this study, the capability of chive (Allium schoenoprasum L.) for phytoextracting Cd from contaminated soils was tested. Growth of chive was studied in a soil spiked with 0, 15, 30, 60, and 120 mg Cd/kg soil, and then, concentrations of Cd in soil, plant shoots, and roots were measured after harvest. Chive dry matter production was not affected significantly by the different Cd levels in soil, except from the maximum Cd concentration (120 mg Cd/kg soil), where dry matter was reduced by 77%. Cadmium accumulation occurred mostly in roots rather than in shoots, with maximum Cd concentrations 482.48 and 26.65 mg/kg of dry matter, respectively. Translocation factor (the proportion of Cd concentration in the aerial plant parts to that in the roots) was below 1 in all contaminated levels and decreased with increasing Cd concentrations in soil, indicating low Cd reallocation from roots to shoots. Maximum amount of Cd absorption (Cd concentration in shoots), maximum contaminant uptake rate, and minimum clean-up time were all observed in Cd concentration 60 mg/kg soil. Based on chive potential to acquire Cd in its roots and shoots, it can be designated as a convenient species for reducing Cd from contaminated soils up to concentrations of 60 mg Cd/kg soil.

De Novo Assembly and Annotation of the Chinese Chive (Allium tuberosum Rottler ex Spr.) Transcriptome Using the Illumina Platform.

Chinese chive (A. tuberosum Rottler ex Spr.) is one of the most widely cultivated Allium species in China. However, minimal transcriptomic and genomic data are available to reveal its evolution and genetic diversity. In this study, de novo transcriptome sequencing was performed to produce large transcript sequences using an Illumina HiSeq 2000 instrument. We produced 51,968,882 high-quality clean reads and assembled them into 150,154 contigs. A total of 60,031 unigenes with an average length of 631 bp were identified. Of these, 36,523 unigenes were homologous to existing database sequences, 35,648 unigenes were annotated in the NCBI non-redundant (Nr) sequence database, and 23,509 unigenes were annotated in the Swiss-Prot database. A total of 26,798 unigenes were assigned to 57 Gene Ontology (GO) terms, and 13,378 unigenes were assigned to Cluster of Orthologous Group categories. Using the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway database, we mapped 21,361 unigenes onto 128 pathways. Furthermore, 2,125 sequences containing simple sequence repeats (SSRs) were identified. This new dataset provides the most comprehensive resource currently available for gene expression, gene discovery, and future genomic research on Chinese chive. The sequence resources developed in this study can be used to develop molecular markers that will facilitate further genetic research on Chinese chive and related species.

Cadmium accumulation in Allium schoenoprasum L. grown in an aqueous medium.

The ability of Allium schoenoprasum L. (chives) to accumulate and tolerate cadmium in aqueous Hoagland medium at 50microM and 250microM was tested under continuous growth or several successive harvests of shoots. After 28 days of continuous growth, chives accumulated the metal up to 0.2% and 0.5% of its dry weight, when grown in 50microM and 250microM, respectively. In experiments that the leaves were successively harvested every 16 days, there were no obvious stress symptoms after six harvests during a period of 96 days at 50microM Cd. At 250microM, after 64 days and four harvests, inhibition of growth occurred. In each treatment, a total of 1.2g kg(-1) DW and 2.4g kg(-1) DW was accumulated in the leaves, respectively. Total SH compounds concentration in leaf was found significantly higher by 3 and 7.4 times in plants treated with Cd at 50microM and 250microM in comparison to the control, respectively, while no difference in the concentration of glutathione (GSH+GSSG) was found. Thus, it is assumed that sulphur-containing compounds, yet unknown, are involved in defensive mechanisms against heavy metals in chives. The results presented, point to chives phytoremediation potential, but also on the potential risk in accumulation of heavy metals in a commonly edible plant.

[Residue of chlorpyrifos and its degradation dynamics in Chinese chive (Allium tuberosum) plant and soil].

This paper studied the residue of chlorpyrifos and its degradation dynamics in Chinese chive (Allium tuberosum) plant and soil after irrigating different concentrations of this pesticide into A. tuberosum root zone under plastic greenhouse and open-field cultivated conditions. The chlorpyrifos in A. tuberosum plant had a faster degradation rate than that in soil, with an average half-life of the pesticide being 3.41 and 7.40 days in the plant and soil, respectively. Under the conditions of plastic greenhouse and open-field cultivation, the degradation rate of chlorpyrifos in A. tuberosum plant had less difference, with the average half-life of chlorpyrifos being 3.37 and 3.44 days, respectively. 21 days after irrigating into root zone, the chlorpyrifos (0.021-0.102 mg x kg(-1)) in A. tuberosum plant did not exceed the maximum residue limit (< or = 0.01 mg x kg(-1), GB 2763-2005). A few chlorpyrifos residue was found in the new growth parts of A. tuberosum, but the residue concentration was obviously lower than that in the first harvested plant after irrigating this pesticide. The chlorpyrifos residue in soil had significant effects on the residue of the pesticide in A. tuberosum plant.

Influence of biochars on plant uptake and dissipation of two pesticides in an agricultural soil.

This study investigated the influence of two types of biochars on the bioavailability of two soil-applied insecticides (chlorpyrifos and fipronil) to Chinese chives ( Allium tuberosum ) and dissipation of the pesticides in the biochar-amended soils. The biochars (BC450 and BC850) prepared from the burning of cotton ( Gossypium spp.) straw chips at two different temperatures (450 and 850 degrees C) were thoroughly mixed into a soil to achieve 0, 0.1, 0.5, and 1% by soil dry weight. Chinese chives were grown for 5 weeks in the biochar-amended soils spiked with 50 mg kg(-1) of each pesticide. The loss of both pesticides in soils decreased significantly with increasing amounts of the biochars in the soil. After 35 days of incubation, 58-68% of the pesticides was lost from the control soil, whereas in the soil amended with 1.0% BC850 only 34% of chlorpyrifos and 32% of fipronil were dissipated. More losses of the pesticides were found in the soils with plants due to plant uptake and enhanced microbial degradation. Despite greater persistence of the two pesticide residues in the biochar-amended soils, plant uptake of the two pesticides from the amended soils decreased markedly with increasing biochar content in the soil. With the amendment of 1% of BC850 in the soil, the total chlorpyrifos and fipronil residues in plant biomass decreased to 19 and 48% of those in the control treatment, respectively. Thus, biochar BC850 was found to be effective in reducing the bioavailability of both pesticides from the soil. Biochar could be applied to sequester pesticide residues in contaminated soils and to reduce plant uptake.

Bioavailability of selenium from selenium-enriched green onions (Allium fistulosum) and chives (Allium schoenoprasum) after 'in vitro' gastrointestinal digestion.

Three sample preparation methods--proteolysis to determine the initial species distribution, and an in vitro gastric and gastrointestinal digestion to assess the bioavailability of selenium--were applied to extract the selenium from selenized green onion and chive samples. Ion exchange chromatography was coupled to a high-performance liquid chromatography-ICP-MS system to analyze the selenium species of Allium samples. The difference in the selenium accumulation capability of green onions and chives was significant. Chive accumulated a one order of magnitude higher amount of selenium than did green onion. After proteolysis of both types of Allium plants, high amounts of organic selenium species such as MeSeCys, SeCys2 and SeMet became accessible. In the case of Se(VI)-enrichment, selenate was the main species in the proteolytic extract. After simulating the human digestion, the organic species were just slightly bioavailable compared with the results from proteolysis. The inorganic selenium content of the selenized samples increased significantly and SeOMet could be detected from the extracts. As an effect of the significant pH change between the gastric and the intestinal tracts, two oxidation processes took place: selenite oxidized to selenate, while SeMet oxidized to SeOMet.

[Degradation of methyl parathion in soil and Chinese chive by strain DLL-1].

Degradation of methyl parathion in soil and Chinese chive by strain DLL-1 was studied. Usage of methyl parathion at 7.5, 15, and 22.5 kg(a.i.).hm-2 resulted in the average amount of residue of 0.663, 1.270, and 1.901 mg.kg-1 in Chinese chive respectively. The natural degradation rate was 98.94%, 96.44%, and 96.04% corresponding to the 3 levels of usage. The amount of pesticide residue could be significantly decreased through the application of high effective degrading microbial agents. The amount of pesticide residue in Chinese chive and soil was 0.269 and 0.099 mg.kg-1 with the usage of 75 kg.hm-2 of degradation bacterium, which was decreased by 78.82% and 98.68% compared with the control. Increasing the bacterium usage led to the increase of degradation rate. Usage of degradation bacterium more than 75 kg.hm-2 did not increase the degradation rate further. The best time of the application of the degrading microbe was 3 days after the application of the pesticide.

A monomeric mannose-binding lectin from inner shoots of the edible chive (Allium tuberosum).

A mannose-binding lectin was isolated from the inner shoots of the chive Allium tuberosum. The procedure involved aqueous extraction, (NH4)2SO4 precipitation, dialysis to remove (NH4)2SO4, affinity chromatography on mannose-agarose, ion exchange chromatography on SP-Sepharose, gel filtration on Superdex 75, and ion exchange chromatography on Mono S. Lectin activity was adsorbed on mannose-agarose, SP-Sepharose, and Mono S. The lectin demonstrated a molecular weight of 13 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration, indicating that it is a single-chain protein. N-terminal sequence analysis revealed its remarkable homology to Allium cepa lectin and similarity to a lesser extent to lectins from members of the Amaryllidaceae, Orchidaceae, and Liliaceae. The lectin manifested mitogenic activity in murine splenocytes and inhibitory activity against human immunodeficiency virus type 1 reverse transcriptase.