Characterisation of volatile sulphur-containing compounds generated in crushed leaves of Chinese chive (Allium tuberosum Rottler)

Biological features and quality comprehensive analysis of twelve germplasm resources of the genus Allium from Tibet

Introduction

Allium is important vegetables and seasonings in China, Tibet is rich in unique resources of the genus Allium, but lacks development and utilization.

Methods

We compared the biological features and comprehensively evaluating the quality of twelve germplasm resources of the genus Allium collected from Tibet.

Results

The results revealed that nine germplasm resources were bolting and bloom normally except for SC015, SC019, and SC048, all twelve germplasm resources were able to vegetative growth. The individual differences in moisture, soluble sugar, and protein content among the twelve germplasm resources were relatively small, with pyruvic acid content ranging from 0.11 to 1.12 mg/g and a large variation coefficient. A total of 8 categories and 97 volatile compounds were detected in twelve germplasm resources, the majority possessed the highest proportions of aldehydes and organosulfur compounds, but there were certain differences between the different Allium species. Additionally, 11 to 16 types of free amino acids were present in all germplasm resources, proline exhibited the highest content. The total content of essential and non-essential amino acids in SC009 was the highest. Carbon (C) accounted for the largest proportion of all elements, and the contents of other mineral elements varied greatly among the different plants.

Conclusion

In conclusion, combined with biological performance and comprehensive evaluation of quality, SC009 is the excellent germplasm resource suitable for growth and capable of reproduction with good quality. These results improved the exploitation and utilization of the genus Allium in Tibet, as well as provided germplasm resources for high-quality breeding of the genus Allium.

S-methyl cysteine sulfoxide and its potential role in human health: a scoping review

Higher intakes of cruciferous and allium vegetables are associated with a lower risk of cardiometabolic-related outcomes in observational studies. Whilst acknowledging the many healthy compounds within these vegetables, animal studies indicate that some of these beneficial effects may be partially mediated by S-methyl cysteine sulfoxide (SMCSO), a sulfur-rich, non-protein, amino acid found almost exclusively within cruciferous and alliums. This scoping review explores evidence for SMCSO, its potential roles in human health and possible mechanistic action. After systematically searching several databases (EMBASE, MEDLINE, SCOPUS, CINAHL Plus Full Text, Agricultural Science), we identified 21 original research articles meeting our inclusion criteria. These were limited primarily to animal and in vitro models, with 14/21 (67%) indicating favorable anti-hyperglycemic, anti-hypercholesterolemic, and antioxidant properties. Potential mechanisms included increased bile acid and sterol excretion, altered glucose- and cholesterol-related enzymes, and improved hepatic and pancreatic β-cell function. Raising antioxidant defenses may help mitigate the oxidative damage observed in these pathologies. Anticancer and antibacterial effects were also explored, along with one steroidogenic study. SMCSO is frequently overlooked as a potential mediator to the benefits of sulfur-rich vegetables. More research into the health benefits of SMCSO, especially for cardiometabolic and inflammatory-based pathology, is warranted. Human studies are especially needed.

Moderate Salinity of Nutrient Solution Improved the Nutritional Quality and Flavor of Hydroponic Chinese Chives (Allium tuberosum Rottler)

Sodium chloride (NaCl), as a eustressor, can trigger relevant pathways to cause plants to produce a series of metabolites, thus improving the quality of crops to a certain extent. However, there are few reports on the improvement of nutrient quality and flavor of hydroponic Chinese chives (Allium tuberosum Rottler) by sodium chloride. In this study, five NaCl concentrations were used to investigate the dose-dependent effects on growth, nutritional quality and flavor in Chinese chives. The results show that 10 mM NaCl had no significant effect on the growth of Chinese chives, but significantly decreased the nitrate content by 40% compared with 0 mM NaCl treatment, and the content of soluble protein and vitamin C was increased by 3.6% and 2.1%, respectively. In addition, a total of 75 volatile compounds were identified among five treatments using headspace solid-phase microextraction gas chromatography/mass spectrometry (HS-SPME/GC-MS). Compared with the 0 mM NaCl treatment, 10 mM NaCl had the greatest effect on the quantity and content of volatile compounds, with the total content increased by 27.8%. Furthermore, according to the odor activity values (OAVs) and odor description, there were 14 major aroma-active compounds (OAVs > 1) in Chinese chives. The “garlic and onion” odor was the strongest among the eight categories of aromas, and its highest value was observed in the 10 mM NaCl treatment (OAVs = 794).Taken together, adding 10 mM NaCl to the nutrient solution could improve the nutritional quality and flavor of Chinese chives without affecting their normal growth.

Determination of phenolic compounds and their antioxidant activity of Iranian Allium sativum controversum extracts and their antimicrobial properties in fresh sausages

In this study, Iranian Allium sativum controversum extracts, as a valuable source of bioactive compounds such as antioxidants, extracted by solvents were analyzed. Based on the analysis of total phenolic content (TPC) and total flavonoid content (TFC) and radical scavenging activity (1,1-diphenyl-2-picrylhydrazyl (DPPH)) of each extract, ethanol extracts were finally added to the sausage formulation at 0.5 and 1.5%w/v. Treatments were kept at refrigerated temperature (4-5°C) for 1, 15, and 30 days, and DPPH and microbial assays were performed on the treatments and the control samples. Experimental data were performed in a completely randomized design with the factorial arrangement. Hydroalcoholic extract had the highest total phenols and the aqueous extract of Allium sativum controversum showed the highest radical scavenging activity (11.85 ± 0.81 mg/g). No colony counts were observed on the first day of the coliform count. On 15 to 30 days, the control sample showed the highest count and the treatment containing Allium sativum controversum extract (1.5%) had the lowest coliform count. During the first month, the control sample had the highest count of Staphylococcus aureus. Regarding mold and yeast, a treatment containing Allium sativum controversum extract (1.5%) and the control sample had the lowest and highest count, respectively. The results showed that using Allium sativum controversum extracts and increased radical scavenging activity reduced microbial growth during the storage period.

Antimicrobial activity, chemical composition and mechanism of action of Chinese chive (Allium tuberosum Rottler) extracts

Chinese chive (Allium tuberosum Rottler) is a popular food from Allium species in East and Southeast Asia. Most Allium species possess characteristic aromas and have antimicrobial activity. In this study, the antimicrobial activities of root, leaf, and scape extracts of Chinese chive at different pH levels (3.0, 5.0, 7.0, 9.0, and 10.7) were compared. The most pronounced activity was produced by the scape extract, and the greatest activity was obtained at pH 5.0. HPLC and GC-MS analysis showed that the major active ingredient was 2-amino-5-methylbenzoic acid. The mechanism of action of Chinese chive scape extracts may involve the depression or disruption of cell membrane integrity, according to our results of the leakage of electrolytes and protein, as well as scanning electron microscopy and transmission electron microscopy observations.

Insight into drug sensitizing effect of diallyl disulfide and diallyl trisulfide from Allium sativum L. on paclitaxel-resistant triple-negative breast cancer cells

ETHNOPHARMACOLOGICAL RELEVANCE

Ayurvedic practitioners and herbal healers in India and China have extensively used garlic (Allium sativum L.) to treat cancers. Diallyl disulfide (DADS) and diallyl trisulfide (DATS) are major volatile organosulfur phytochemical constituents found in garlic.

AIM OF THE STUDY

To find new insight into the drug sensitizing effect of DADS and DATS on paclitaxel (PTX)-resistant triple-negative breast cancer cells (TNBC/PR).

MATERIALS AND METHODS

This study estimates the non-toxic concentration of DADS and DATS against normal healthy breast epithelial cell line (MCF-12A) by using a trypan blue viability assay. Also, it evaluates the effect of DADS and DATS on the sensitization of established stable TNBC/PR cell clones (MDA-MB 231 PR and MDA-MB 468 PR) by MTT, BrdU incorporation, intracellular ROS, cell cycle, and apoptosis assays.

RESULTS

The results show that DADS and DATS are non-cytotoxicity against MCF-12A cells. Nevertheless, DADS and DATS have shown significantly high cytotoxicity against MDA-MB 231 PR and MDA-MB 468 PR cells. They also inhibited PTX-resistant cell proliferation by blocking the cell cycle. Further, they induced apoptosis by activation of caspase 3 and 9. N-acetyl cysteine pre-treatment inhibited DADS and DATS-induced intracellular ROS release. In silico study shows that DADS and DATS interact with a large extracellular loop (LEL) of CD151 with a binding energy of -4.0 kcal/mol and transmembrane domain (TM) with a binding affinity of 11.7 and 13.6 kcal/mol, respectively. They also inhibited the surface expression of CD151 in TNBC/PR cells.

CONCLUSION

This study implies that DADS and DATS could be considered for sensitizing drug-resistant breast cancers.

Effect of Methyl Jasmonate Treatment on Primary and Secondary Metabolites and Antioxidant Capacity of the Substrate and Hydroponically Grown Chinese Chives

Hydroponic culture has become a commercial planting model for leafy vegetables, herbs, and other plants with medicinal value. Methyl jasmonate (MeJA) is involved in primary and secondary plant metabolism; moreover, it regulates plant bioactive compounds and enhances the nutritional and medicinal value of plants. We performed targeted metabolomic analysis of the primary and secondary metabolites in substrate-grown and hydroponic Chinese chive leaves sprayed with MeJA (0, 300, 500, and 800 μM). Using ultra-performance liquid chromatography (UPLC), UPLC tandem mass spectrometry, and chemometric tools, and analyzed the antioxidant activity of these plants. We identified the biomarkers of amino acids (serine, proline, lysine, and arginine) and phenolic compounds (4-coumaric acid and protocatechuic acid) using chemometric tools to distinguish between substrate-grown and hydroponic Chinese chives treated with MeJA. MeJA (500 μM) treatment significantly increased the total sugar and amino acid (essential and non-essential amino acids and sulfur-containing amino acids) contents of hydroponically grown Chinese chives. However, the changes in total sugar and amino acid contents in Chinese chive grown in substrates showed the opposite trend. The organic acid content of hydroponically grown Chinese chives treated with MeJA decreased significantly, whereas that of substrate-grown plants treated with 300 μM MeJA increased significantly. Further, MeJA treatment significantly increased the phenolic content of substrate-grown Chinese chives. Treatment with 800 μM MeJA significantly increased the carotenoid content of substrate-grown Chinese chives and the phenolic content of hydroponic Chinese chives. In addition, the 500 μM MeJA treatment significantly increased the antioxidant activity of Chinese chives in both substrate-grown and hydroponic cultures, and promoted the accumulation of nutrients and bioactive substances. This treatment also improved the flavor quality of these plants and their nutritional and medicinal value. Thus, the results suggested that MeJA-treated plants could be used as value-added horticultural products.

Optimization of Headspace Solid-Phase Micro-Extraction Conditions (HS-SPME) and Identification of Major Volatile Aroma-Active Compounds in Chinese Chive (Allium tuberosum Rottler)

In order to rapidly and precisely identify the volatile compounds in Chinese chive (Allium tuberosum Rottler), seven key parameters of headspace solid-phase micro-extraction conditions (HS-SPME) from Chinese chive were optimized. A total of 59 volatile compounds were identified by using the optimized method, including 28 ethers, 15 aldehydes, 6 alcohols, 5 ketones, 2 hydrocarbons, 1 ester, and 2 phenols. Ethers are the most abundant, especially dimethyl trisulfide (10,623.30 μg/kg). By calculating the odor activity values (OAVs), 11 volatile compounds were identified as the major aroma-active compounds of Chinese chive. From the analysis of the composition of Chinese chive aroma, the “garlic and onion” odor (OAV = 2361.09) showed an absolute predominance over the other 5 categories of aroma. The results of this study elucidated the main sources of Chinese chive aroma from a chemical point of view and provided the theoretical basis for improving the flavor quality of Chinese chive.

Phytotoxic effects on chloroplast and UHPLC-HRMS based untargeted metabolomic responses in Allium tuberosum Rottler ex Sprengel (Chinese leek) exposed to antibiotics

Introduction of antibiotics into agricultural fields poses serious health risks to humans. This study investigated the uptake of antibiotics, their effects on metabolic pathways, and chloroplast structure changes of Allium tuberosum exposed to norfloxacin (NFL), oxytetracycline (OTC), and tetracycline (TC). Among all the antibiotic treatments, the highest accumulation of antibiotics in roots (4.15 mg/kg) and leaves (0.29 mg/kg) was TC, while in bulbs it was NFL (5.94 mg/kg). OTC was with the lowest accumulation in roots: 0.19 mg/kg, bulbs: 0.18 mg/kg, and leaves: 0.11 mg/kg. The number of mitochondira and the number of plastoglobulli increased. The chloroplast structure was disturbed under the stress of NFL, OTC, and TC. Disturbance in the chloroplast ultrastructure leads to altered chlorophyll fluorescence variables. Simultaneously, metabolomic profiling of leaves demonstrated that NFL stress regulated more of metabolic pathways than OTC and TC. Differences in metabolic pathways among the antibiotic treatments showed that each antibiotic has different impact even under the same experimental conditions. TC and NFL have more toxic effects than OTC antibiotic. Metabolic variations induced by antibiotics stress highlighted pools of metabolites that affect the metabolic activities, chlorophyll fluorescence, ultrastructural adjustments, and stimulate defensive impact in A. tubersoum. These findings provide an insight of metabolic destabilization as well as metabolic changes in defensive mechanism and stress response of A. tuberosum to different antibiotics.

Microbiota Analysis and Microbiological Hazard Assessment in Chinese Chive (Allium tuberosum Rottler) Depending on Retail Types

Chinese chive (Allium tuberosum Rottler) has potential risks associated with pathogenic bacterial contamination as it is usually consumed raw. In this study, we investigated the microbiota of Chinese chives purchased from traditional markets and grocery stores in March (Spring) and June (Summer) 2017. Differences in bacterial diversity were observed, and the microbial composition varied across sampling times and sites. In June, potential pathogenic genera, such as Escherichia, Enterobacter, and Pantoea, accounted for a high proportion of the microbiota in samples purchased from the traditional market. A large number of pathogenic bacteria (Acinetobacter lwoffii, Bacillus cereus, Klebsiella pneumoniae, and Serratia marcescens) were detected in the June samples at a relatively high rate. In addition, the influence of the washing treatment on Chinese chive microbiota was analyzed. After storage at 26°C, the washing treatment accelerated the growth of enterohemorrhagic Escherichia coli (EHEC) because it caused dynamic shifts in Chinese chive indigenous microbiota. These results expand our knowledge of the microbiota in Chinese chives and provide data for the prediction and prevention of food-borne illnesses.

Effects of Preharvest Methyl Jasmonate and Salicylic Acid Treatments on Growth, Quality, Volatile Components, and Antioxidant Systems of Chinese Chives

Methyl jasmonate (MeJA) and salicylic acid (SA) regulate the production of biologically active compounds in plants and stimulate the accumulation of plant aromatic substances. However, the underlying mechanisms of how MeJA and SA influence characteristic flavor compounds and the antioxidant activity of vegetables are poorly understood. Five MeJA and SA concentrations were used to investigate the dose-dependent effects of these phytohormones on the dry and fresh weight; chlorophyll abundance; the contents of vitamin C, soluble protein, and sugar, nitrate, total phenols, flavonoids, volatile components, and enzymatically produced pyruvic acid; and antioxidant activity in Chinese chive. We found that MeJA and SA at concentrations of 500 and 150 μM, respectively, significantly increased the levels of total chlorophyll, phenols and flavonoids, vitamin C, and volatile components and significantly reduced the accumulation of nitrate. In addition, compared with the control, 500 μM of MeJA significantly increased the soluble sugar and protein content, and 150 μM SA significantly increased the dry and fresh weight of Chinese chive. Furthermore, these concentrations of MeJA and SA significantly increased the enzymatic pyruvate content and the amount of sulfide and aromatic volatile compounds and improved the characteristic flavor compounds. The 2,2-diphenyl-1-picrylhydrazyl radical scavenging capacity, Trolox-equivalent antioxidant capacity, and ferric-reducing antioxidant capacity were significantly improved after a preharvest treatment with 500 μM MeJA and 150 μM SA, which could improve the antioxidant activity, thus improving the postharvest quality and preservation characteristics of Chinese chives. Taken together, a preharvest treatment with 500 μM MeJA and 150 μM SA is optimal to improve the growth, quality, antioxidant activity, and flavor of Chinese chive, thereby enhancing its commercial value.

Chemical constituents and medicinal properties of Allium species

Allium species, belonging to Alliaceae family, are among the oldest cultivated vegetables used as food. Garlic, onions, leeks and chives, which belong to this family, have been reported to have medicinal properties. The Allium species constituents have been shown to have antibacterial and antioxidant activities, and, in addition, other biological properties. These activities are related to their rich organosulfur compounds. These organosulfur compounds are believed to prevent the development of cancer, cardiovascular, neurological, diabetes, liver diseases as well as allergy and arthritis. There have also been reports on toxicities of these compounds. The major active compounds of Allium species includes, diallyl disulfide, diallyl trisulfide, diallyl sulfide, dipropyl disulfide, dipropyl trisulfide, 1-propenylpropyl disulfide, allyl methyl disulfide and dimethyl disulfide. The aim of this review is to focus on a variety of experimental and clinical reports on the effectiveness, toxicities and possible mechanisms of actions of the active compounds of garlic, onions, leek and chives.

Hepatoprotective Activity of Yellow Chinese Chive against Acetaminophen-Induced Acute Liver Injury via Nrf2 Signaling Pathway

Glutathione, the most abundant intracellular antioxidant, protects cells against reactive oxygen species induced oxidative stress and regulates intracellular redox status. We previously demonstrated that yellow Chinese chive (ki-nira) increased the intracellular glutathione levels. Acetaminophen (APAP) is a commonly used analgesic. However, an overdose of APAP causes severe hepatotoxicity via depletion of the hepatic glutathione. In this study, we investigated the hepatoprotective effects of yellow Chinese chive extract (YCE) against APAP-induced hepatotoxicity in mice. YCE (25 or 100 mg/kg) was administered once daily for 7 d, and then APAP (700 mg/kg) was injected at 6 h before the mice were sacrificed. APAP treatment markedly increased the serum biological markers of liver injury such as alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, and alkaline phosphatase. Pretreatment with YCE significantly prevented the increases in the serum levels of these enzymes. Histopathological evaluation of the livers also revealed that YCE prevented APAP-induced centrilobular necrosis. Pretreatment with YCE dose-dependently elevated glutathione levels, but the difference was not significant. Nuclear factor erythroid 2-related factor 2 (Nrf2) plays a critical role in APAP-induced hepatotoxicity by regulating the antioxidant defense system. Therefore, we investigated the expression of Nrf2 and its target antioxidant enzyme. YCE led to an increased expression of Nrf2 and its target antioxidant enzymes, NAD(P)H quinone oxidoreductase 1 (NQO1), glutathione peroxidase (GPx), cystine uptake transporter (xCT), especially hemeoxygenase-1 (HO-1) in mice livers. These results suggest that YCE could induce HO-1 expression via activation of the Nrf2 antioxidant pathway, and protect against APAP-induced hepatotoxicity in mice.

Controlled Fermentation Using Autochthonous Lactobacillus plantarum Improves Antimicrobial Potential of Chinese Chives against Poultry Pathogens

Chinese chives (CC) are rich in several antimicrobial constituents including organosulfur compounds, phenolics, and saponins, among others. Herein, we fermented CC juice using an autochthonous isolate, Lactobacillus plantarum having antimicrobial effects against poultry pathogens toward formulating an antimicrobial feed additive. Following 24 h of fermentation, the antimicrobial and antiviral activities of CC juice were significantly enhanced against poultry pathogens. However, the antioxidant activity of CC juice was significantly decreased following fermentation. Meanwhile, the compositional changes of CC juice following fermentation were also investigated. The total polyphenol, thiol, and allicin contents were significantly decreased in L. plantarum 24 h-fermented CC juice (LpCC) extract; however, total flavonoids increased significantly following fermentation. The untargeted metabolite profiling of nonfermented CC juice (NCC) and LpCC extracts was carried out using the ultra-high-performance liquid chromatography-linear trap quadrupole-orbitrap-tandem mass spectrometry (UHPLC-LTQ-Orbitrap-MS/MS) followed by multivariate analyses. The score plots of principal component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA) based on UHPLC-LTQ-Orbitrap-MS/MS datasets displayed a clear segregation between the LpCC and NCC samples, which suggests their marked metabolomic disparity. Based on the multivariate analysis, we selected 17 significantly discriminant metabolites belonging to the different chemical classes including alkaloid, flavonols, saponins, fatty acids, amino acids, and organic acids. Notably, the flavonols including the glycosides of quercetin, kaempferol, and isorhamnetin as well as the saponins displayed significantly higher relative abundance in LpCC as compared with NCC. This study provides useful insights for the development of a fermented CC juice based antimicrobial feed additive to combat poultry infections.

Fitness costs in chlorfenapyr-resistant populations of the chive maggot, Bradysia odoriphaga

The chive maggot, Bradysia odoriphaga (Yang and Zhang) is an economically important insect pest, affecting many key vegetables, including Chinese chive, especially in northern China. Chlorfenapyr, a halogenated pyrrole insecticide that interferes with mitochondrial oxidative phosphorylation is widely used against B. odoriphaga. In this study, we evaluated selection-induced resistance to chlorfenapyr and fitness costs in B. odoriphaga. The results showed that B. odoriphaga developed 43.32-fold resistance after continuous exposure to chlorfenapyr for over 10 consecutive generations. The life-history traits of chlorfenapyr-resistant and susceptible strains were compared using age-stage, two-sex life table approach. No significant effects were observed on the longevity and pre-adult period. However, reduction in the total pre-oviposition period (TPOP) and fecundity (eggs/female) were observed in the resistant strain. Moreover, the demographic parameters such as intrinsic rate of increase (r), net reproductive rate (R₀) and finite rate of increase (λ) were also decreased significantly in the resistant strain compared to the susceptible strain. These results showed the potential of B. odoriphaga to develop resistance against chlorfenapyr under continuous selection pressure. Furthermore, there was a fitness cost linked with chlorfenapyr resistance in B. odoriphaga. We conclude that a better knowlegde on the trade-off at play between resistance degree and fitness cost could be crucial for developing further management of B. odoriphaga in China.

Electrophysiological and behavioral responses of Bradysia odoriphaga (Diptera: Sciaridae) to volatiles from its Host Plant, Chinese Chives (Allium tuberosum Rottler ex Spreng)

Bradysia odoriphaga Yang et Zhang is a serious belowground pest of Chinese chives (Allium tuberosum). Our previous studies have indicated that B. odoriphaga females prefer to oviposit near the roots of Chinese chives rather than the roots of other plants, and that the performance (longevity and fecundity) of B. odoriphaga offspring was better on Chinese chives than on Lettuce (var. ramosa Hort.), Onion (Allium cepa) and Potato (Solanum tuberosum) but little is known about how the volatiles released by Chinese chives affect the host-finding and oviposition behaviors of B. odoriphaga. Here, we used gas chromatography-mass spectrometry and determined that Chinese chives releases the following volatiles: methyl allyl disulfide, β-myrcene, cis-ocimene, diallyl disulfide, nonane, n-dodecane, n-tetradecane, and n-hexadecane; quantities released were highest for methyl allyl disulfide and diallyl disulfide. In addition to eliciting strong responses in females in electroantennography assays, the latter two sulfur compounds and their mixtures attracted females in Y-tube olfactometer assays. The addition of methyl allyl disulfide, diallyl disulfide, or a mixture of the two compounds at a 1:5 ratio to chive plants increased oviposition when compared to control plants. These results indicate that methyl allyl disulfide and diallyl disulfide, either alone or in combination, influence the host-seeking behavior of B. odoriphaga.

Chinese chives and garlic in intercropping in strawberry high tunnels for Neopamera bilobata Say (Hemiptera: Rhyparochromidae) control

Strawberry is affected by several pests and diseases. Neopamera bilobata is an emerging pest that has been reported by several strawberry growers, usually associated with catfacing symptoms in fruits. We evaluated intercropping garlic or Chinese chives on N. bilobata populations on strawberry crops grown in high tunnels in two experiments. In the first experiment, we evaluated N. bilobata populations on strawberry intercropping with garlic plants (three densities: 8, 16, 24 GP - garlic plant per plot) on the bags by taking 12 samples from December 2015 to April 2017. N. bilobata populations on strawberry were also assessed when Chinese chives were grown under the suspended wooden structures in which strawberry plants are grown ('undercropping') (14 samples), in two high tunnels, from November 2016 to March 2017. The number of nymphs and adults on 14 randomly selected fruits per plot were assessed. During the garlic intercropping experiment, the treatments of three densities of garlic reduced N. bilobata populations; however, the 24 GP treatment caused a greater reduction than the 8 GP treatment. Garlic densities reduced N. bilobata populations by 35, 50, and 64% for the 8, 16, and 24 GP treatments, respectively. Chinese chives cultivated under the structures reduced N. bilobata populations by 47%. The results suggest that intercropping garlic or undercropping Chinese chives are suitable tools to be tested in integrated pest management in strawberry crops.

Genome-wide analysis of DNA methylation identifies novel differentially methylated regions associated with lipid accumulation improved by ethanol extracts of Allium tubersosum and Capsella bursa-pastoris in a cell model

Hepatic steatosis is the most common chronic liver disease in Western countries. Both genetic and environmental factors are known as causes of the disease although their underlying mechanisms have not been fully understood. This study investigated the association of DNA methylation with oleic acid-induced hepatic steatosis. It also examined effects of food components on DNA methylation in hepatic steatosis. Genome-wide DNA methylation of oleic acid (OA)-induced lipid accumulation in vitro cell model was investigated using reduced representation bisulfite sequencing. Changes of DNA methylation were also analyzed after treatment with food components decreasing OA-induced lipid accumulation in the model. We identified total 81 regions that were hypermethylated by OA but hypomethylated by food components or vice versa. We determined the expression of seven genes proximally located at the selected differentially methylated regions. Expression levels of WDR27, GNAS, DOK7, MCF2L, PRKG1, and CMYA5 were significantly different between control vs OA and OA vs treatment with food components. We demonstrated that DNA methylation was associated with expression of genes in the model of hepatic steatosis. We also found that food components reversely changed DNA methylation induced by OA and alleviated lipid accumulation. These results suggest that DNA methylation is one of the mechanisms causing the hepatic steatosis and its regulation by food components provides insights that may prevent or alleviate lipid accumulation.

Characterization of Plant Volatiles Reveals Distinct Metabolic Profiles and Pathways among 12 Brassicaceae Vegetables

Plants emit characteristic organic volatile compounds (VOCs) with diverse biological/ecological functions. However, the links between plant species/varieties and their phytochemical emission profiles remain elusive. Here, we developed a direct headspace solid-phase microextraction (HS-SPME) technique and combined with non-targeted gas chromatography‒high-resolution mass spectrometry (GC-HRMS) platform to investigate the VOCs profiles of 12 common Brassicaceae vegetables (watercress, rocket, Brussels sprouts, broccoli, kai lan, choy sum, pak choi, cabbage, Chinese cabbage, cauliflower, radish and cherry radish). The direct HS-SPME sampling approach enabled reproducible capture of the rapid-emitting VOCs upon plant tissue disruption. The results revealed extensive variation in VOCs profiles among the 12 Brassicaceae vegetables. Furthermore, principal component analysis (PCA) showed that the VOC profiles could clearly distinguish the 12 Brassicaceae vegetables, and that these profiles well reflected the classical morphological classification. After multivariate statistical analysis, 44 VOCs with significant differences among the Brassicaceae vegetables were identified. Pathway analysis showed that three secondary metabolism pathways, including the fatty acid pathway, methylerythritol phosphate (MEP) pathway and glucosinolate (GLS) pathway, behave distinctively in these vegetables. These three pathways are responsible for the generation and emission of green leaf volatiles (GLVs), terpenes and isothiocyanates (ITCs), respectively. Correlation analysis further showed that volatile metabolites formed via the common pathway had significantly positive correlations, whereas metabolites from different pathways had either non-significant or significantly negative correlations. Genetic influences on these metabolites across various vegetable types were also evaluated. These findings extend our phytochemical knowledge of the 12 edible Brassicaceae vegetables and provide useful information on their secondary metabolism.

Transcriptome analysis and identification of P450 genes relevant to imidacloprid detoxification in Bradysia odoriphaga

Pesticide tolerance poses many challenges for pest control, particularly for destructive pests such as Bradysia odoriphaga. Imidacloprid has been used to control B. odoriphaga since 2013, however, imidacloprid resistance in B. odoriphaga has developed in recent years. Identifying actual and potential genes involved in detoxification metabolism of imidacloprid could offer solutions for controlling this insect. In this study, RNA-seq was used to explore differentially expressed genes in B. odoriphaga that respond to imidacloprid treatment. Differential expression data between imidacloprid treatment and the control revealed 281 transcripts (176 with annotations) showing upregulation and 394 transcripts (235 with annotations) showing downregulation. Among them, differential expression levels of seven P450 unigenes were associated with imidacloprid detoxification mechanism, with 4 unigenes that were upregulated and 3 unigenes that were downregulated. The qRT-PCR results of the seven differential expression P450 unigenes after imidacloprid treatment were consistent with RNA-Seq data. Furthermore, oral delivery mediated RNA interference of these four upregulated P450 unigenes followed by an insecticide bioassay significantly increased the mortality of imidacloprid-treated B. odoriphaga. This result indicated that the four upregulated P450s are involved in detoxification of imidacloprid. This study provides a genetic basis for further exploring P450 genes for imidacloprid detoxification in B. odoriphaga.

Detection of insecticide resistance in Bradysia odoriphaga Yang et Zhang (Diptera: Sciaridae) in China

Bradysia odoriphaga Yang et Zhang is a destructive insect pest of Chinese chives. To understand the current status of insecticide resistance of B. odoriphaga in China, the sensitivity variation of eight field populations to six commonly used insecticides, including chlorpyrifos, phoxim, imidacloprid, thiamethoxam, clothianidin and beta-cypermethrin were evaluated. The results showed that almost all the tested B. odoriphaga populations had developed moderate to high resistance to chlorpyrifos and phoxim. There were different resistance levels found in the eight field populations among the three neonicotinoids, imidacloprid, thiamethoxam and clothianidin. Imidacloprid was very effective against B. odoriphaga in most tested populations except those from Yangzhou (10.35-fold) and Tangshan (14.56-fold). While four populations kept susceptible to thiamethoxam, the other four populations showed decreased susceptibility or low resistance. To clothianidin, five populations displayed moderate resistance, two populations displayed low resistance, and one population exhibited susceptibility, respectively. All the tested populations were resistance to beta-cypermethrin, the highest resistance was found in the Tangshan population with a resistance ratio of 172.56-fold. The results of this study provided valuable information for choosing insecticides for control and integrated resistance management of B. odoriphaga.

Control of Bradysia odoriphaga (Diptera: Sciaridae) With Allyl Isothiocyanate Under Field and Greenhouse Conditions

The botanical compound allyl isothiocyanate (AITC) is toxic to many microorganisms and insects. The aim of this study was to assess the effects of AITC on the Bradysia odoriphaga Yang et Zhang (Diptera: Sciaridae) and the seeds and seedlings of the Chinese chive. Allyl isothiocyanate was toxic to all four developmental stages of B. odoriphaga. The adult was significantly more sensitive to AITC than the other three stages, which exhibited no significant differences to one another in sensitivity to the chemical. The control efficacy of AITC against B. odoriphaga was far superior in the greenhouse than the field. In addition, seedling survival was higher in the greenhouse compared with that in the field. In the absence of B. odoriphaga, seed germination and seedling growth of Chinese chives were inhibited by 16 µl/liter of AITC, and significant inhibition occurred under higher doses of AITC. These results indicate that AITC could be used to control B. odoriphaga during cultivation of Chinese chives.

Evaluation of Housekeeping Genes for Quantitative Real-Time PCR Analysis of Bradysia odoriphaga (Diptera: Sciaridae)

The soil insect Bradysia odoriphaga (Diptera: Sciaridae) causes substantial damage to Chinese chive. Suitable reference genes in B. odoriphaga (Bradysia odoriphaga) have yet to be identified for normalizing target gene expression among samples by quantitative real-time PCR (qRT-PCR). This study was focused on identifying the expression stability of 12 candidate housekeeping genes in B. odoriphaga under various experiment conditions. The final stability ranking of 12 housekeeping genes was obtained with RefFinder, and the most suitable number of reference genes was analyzed by GeNorm. The results revealed that the most appropriate sets of internal controls were RPS15, RPL18, and RPS18 across developmental phases; RPS15, RPL28, and GAPDH across temperatures; RPS15 and RPL18 across pesticide treatments; RSP5, RPS18, and SDHA across photoperiods; ACTb, RPS18, and RPS15 across diets; RPS13 and RPL28 across populations; and RPS15, ACTb, and RPS18 across all samples. The use of the most suitable reference genes versus an arbitrarily selected reference gene resulted in significant differences in the analysis of a target gene expression. HSP23 in B. odoriphaga was found to be up-regulated under low temperatures. These results will contribute to the standardization of qRT-PCR and will also be valuable for further research on gene function in B. odoriphaga.

Using headspace solid-phase microextraction for comparison of volatile sulphur compounds of fresh plants belonging to families Alliaceae and Brassicaceae

In this study, an optimisation of extraction of sulphur volatile compounds (SVCs) has been performed using Central Composite Design. The conditions of the highest amount of eluated peaks and total peaks area have been treated. Factors such as coating of fiber for SPME (Solid Phase Microextraction), extraction temperature and extraction time have been optimised. The SVCs have shown the optimal extraction using a DVB/CAR/PDMS (divinylbenzene/carboxen/polydimethylsiloxane) fiber at 73 °C during 50 min. Furthermore, a pre-incubation step lasting 20 min at the extraction temperature has been used. In total, 12 samples have been investigated at the mentioned optimal conditions, eight from the Alliaceae and four from the Brassicaceae family. The highest number of SVCs (24) has been identified in the sample of chive. The most frequently identified compound found in 11 of 12 samples has been dimethyl trisulphide.

Chemical and biochemical mechanisms underlying the cardioprotective roles of dietary organopolysulfides

Foods that are rich in organosulfides are highly regarded for their broad range of functions in disease prevention and health promotion since ancient time yet modern scientific study, particularly clinical studies could not agree with traditional wisdom. One of the complexities is due to the labile nature of organosulfides, which are often transformed to different structures depending on the processing conditions. The recent evidence on polysulfides as H₂S donors may open up a new avenue for establishing structure and health promotion activity relationship. To put this development into perspective, we carried out a review on the recent progress on the chemistry and biochemistry of organopolysulfides with emphasis on their cardioprotective property. First, we briefly surveyed the foods that are rich in polysulfides and their structural diversity. This is followed by in-depth discussion on the chemical transformations of polysulfides under various processing conditions. We further reviewed the potential action mechanisms of polysulfides in cardioprotection through: (a) hydrogen sulfide releasing activity; (b) radical scavenging activity; and (c) activity in enzyme inhibition and intervention of gene regulation pathways. Based on the literature trend, we can conclude that the emerging concept of organopolysulfides as naturally occurring H₂S donors is intriguing and warrants further research to establish the structure and activity relationship of the organopolysulfides as H₂S donors.

Effects of Temperature on the Age-Stage, Two-Sex Life Table of Bradysia odoriphaga (Diptera: Sciaridae)

The demographics of Bradysia odoriphaga were examined with an age-stage, two-sex life table that was developed at 15, 20, 25, and 30°C under controlled conditions. The intrinsic rate of increase and mean generation time were 0.0574 and 48.08 d at 15°C, 0.1175 and 30.09 d at 20°C, 0.1369 and 26.31 d at 25°C, and 0.1247 and 26.55 d at 30°C, respectively. The gross reproductive rate (GRR), the net reproductive rate (R0), and the pre-adult survivorship (la) were consistent with the relationship R0<la×GRR<GRR. Development was slower at 15°C than at the other temperatures. The mean duration of the total pre-adult stages was 38.01, 27.62, 23.74, and 24.10 d at 15, 20, 25, and 30°C, respectively. The highest values for the intrinsic rate of increase, finite rate of increase, and fecundity (0.1369 d(-1), 1.147 d(-1), and 50.53 eggs, respectively) and the shortest mean generation time were at 25°C. Still, B. odoriphaga was able to develop, survive, and reproduce across the entire temperature range (15-30°C). This study provides insight into the temperature-dependent phenology of B. odoriphaga and will contribute to the modeling of its population dynamics and to its management in the field.

Chemical composition, antibacterial and antioxidant activities of six essentials oils from the Alliaceae family

Six essential oils (EOs) from the Alliaceae family, namely garlic (Allium sativum), onion (Allium cepa), leek (Allium porrum), Chinese chive (Allium tuberosum), shallot (Allium ascalonicum) and chive (Allium schoenoprasum) were characterized by GC and GC-MS and evaluated for their functional food properties. Antibacterial properties were tested on five food-borne pathogens: Two Gram-positive Staphylococcus aureus (ATCC 25923), Listeria monocytogenes (ATCC 19115) and three Gram-negative Salmonella Typhimurium (ATCC 14028), Escherichia coli (ATCC 8739) and Campylobacter jejuni (ATCC 33291) bacteria. Antioxidant and radical-scavenging properties were tested by means of Folin-Ciocalteu and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays. Garlic, Chinese chive and onion EOs had the highest antibacterial activity whereas shallot and leek EOs were the strongest antioxidants. Heating caused a decrease in the antioxidant activity of these Eos, as shown in the Total Polar Materials (TPM) test. Suggestions on relationships between chemical composition and biological activities are presented. Results show that the EOs could be of value in the food industry as alternatives to synthetic antioxidants.

Selection of functional lactic acid bacteria as starter cultures for the fermentation of Korean leek (Allium tuberosum Rottler ex Sprengel.)

The purpose of this research was to find safe and suitable starter cultures for the fermentation of Korean leek (Allium tuberosum Rottler), also known as garlic chives or Oriental garlic. This traditional herb has several functional properties and a strong flavour; its leaves are used as food material. Eighteen strains of lactic acid bacteria (LAB) were isolated from well-fermented leek kimchi. Controlled fermentation of the leek leaves was conducted with 2 strains (Weissella confusa LK4 and Lactobacillus plantarum LK8), selected as potential starter cultures on the basis of their safety properties, and on the pH, total titratable acidity (TTA), and viable cell numbers [colony forming units (CFUml(-1))] achieved during the fermentation. Microbial dynamics was also followed during fermentation by using PCR-DGGE (Denaturing Gradient Gel Electrophoresis) on DNA level. To analyse bioactive compounds such as thiols and allicin (diallyl thiosulfinates), the total flavonoid and polyphenolic contents were determined by colorimetric methods. Functional properties were assessed on the basis of anti-oxidative capacities by determining the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging effect, and ferric reducing antioxidant power (FRAP). W. confusa LK4 rapidly increased during the first stage of leek fermentation, and was mainly responsible for accelerated fermentation during the early period in contrast to L. plantarum LK8, a stronger acid producer during the later stages of fermentation. After 48 h fermentation, leeks fermented with W. confusa LK4 showed the highest radical scavenging effects and reducing ability. The detectable amount of allicin of fermented leeks decreased relative to the change in pH, whereas the concentration of thiols significantly increased. Total flavonoid and poly-phenolic contents changed during fermentation and showed correlation with anti-oxidant effects. We therefore suggest the suitability of W. confusa LK4 as a potential starter culture for fermentation of leeks.

Effect of processing conditions on the organosulfides of shallot (Allium cepa L. Aggregatum group)

There is a growing account of the health benefits of H2S as an endogenous cell-signaling molecule. H2S from organic polysulfides, in particular, is increasingly gaining attention for their beneficial effects to cardiovascular health. Here, we studied shallot as a potential dietary source of organic polysulfides and examined the effects of processing conditions on its polysulfide profiles. Boiling, autoclaving, and freeze-drying were tested on whole and crushed shallot bulbs, analyzing their effect on the yield of organosulfides. Seventeen organosulfides, including disulfides, trisulfides, and cyclic polysulfides, were identified. Significant differences in the quantitative and qualitative profiles of organosulfides in the hydrodistilled and solvent extracted oils were observed. Freeze-drying retained the majority of the organosulfides, but the whole-autoclaved and whole-boiled shallots lost more than 95% of their organic polysulfides. Crushed-boiled and crushed-autoclaved shallot lost 76-80% of their organosulfides, likely due to the thermal sensitivity of these compounds. The organosulfide profiles are sensitive to the pH values of the processing media. In general, disulfides increased at basic pH (pH 9.0) while trisulfides and cyclic organosulfides are much higher at the acidic to neutral pH values (pH 3.0-5.0). Our results provide important information on the effects of processing conditions that are relevant for optimizing extraction of organosulfides from shallot for further studies evaluating their H2S-releasing activity.

Sulfur compounds identification and quantification from Allium spp. fresh leaves

Pyruvic acid concentration is a Allium spp. pungency. This study was initiated to accurately measure the background pyruvic acid levels in Romanian Allium spp. From the pungency point of view, all analyzed plant varieties in this study are considered low pungent cultivars based on the enzymatically produced pyruvate level (between 42 μmol/g and 222 μmol/g fresh wt). Chromatographic analysis was carried out for the different varieties of the most popular fresh leaves (Allium cepa var. “Diamant”, Allium cepa var. “Rubiniu”, and Allium ursinum L.) in order to identify the sulfur compounds. The thin layer chromatography analysis led to the identification of allicin, with R_f = 0.377–0.47, as an important sulfur compound. The gas chromatography-mass spectrometry analysis of the leaves’ extracts detected disulfides as the major sulfur compounds. Principal component analysis was performed to establish the differences in plant composition. These studies suggest the potential good uses of the fresh leaves of Romanian Allium spp. as condiment, ingredient, or preservative in the food industry.

Inhibitory effect of methyl methanethiosulfinate on β-glucuronidase activity

Minced or cut-up leaves of Chinese chive (Allium tuberosum Rottler) contain thiosulfinates and their disproportionate reaction products. Among these organosulfur compounds, methyl methanethiosulfinate was found to be an uncompetitive inhibitor of β-glucuronidase. Approximately 80% of the enzyme activity was inhibited by methyl methanethiosulfinate at 50 µM, the IC50 value being comparable to 3.6 µM.

Control of Panama disease of banana by rotating and intercropping with Chinese chive (Allium tuberosum Rottler): role of plant volatiles

Intercropping and rotating banana (Musa spp.) with Chinese chive (Allium tuberosum Rottler) has been used as an effective method to control Panama disease (Fusarium wilt) of banana in South China. However, the underlying mechanism is unknown. In this study, we used aqueous leachates and volatiles from Chinese chive to evaluate their antimicrobial activity on Fusarium oxysporum f. sp. cubense race 4 (FOC), the causal agent of Panama disease in banana, and identified the antifungal compounds. Both leaf and root leachates of Chinese chive displayed strong inhibition against FOC, but the concentrated leachates showed lower inhibition than the original leachates. In a sealed system volatiles emitted from the leaves and roots of Chinese chive inhibited mycelial growth of FOC. Volatile compounds emitted from the intact growing roots mimicking natural environment inhibited spore germination of FOC. We identified five volatiles including 2-methyl-2-pentenal and four organosulfur compounds (dimethyl trisulfide, dimethyl disulfide, dipropyl disulfide, and dipropyl trisulfide) from the leaves and roots of Chinese chive. All these compounds exhibited inhibitory effects on FOC, but 2-methyl-2-pentenal and dimethyl trisulfide showed stronger inhibition than the other three compounds. 2-Methyl-2-pentenal at 50-100 μl/l completely inhibited the mycelial growth of FOC. Our results demonstrate that antifungal volatiles released from Chinese chive help control Panama disease in banana. We conclude that intercropping and rotating banana with Chinese chive can control Panama disease and increase cropland biodiversity.

Graphene-supported zinc oxide solid-phase microextraction coating with enhanced selectivity and sensitivity for the determination of sulfur volatiles in Allium species

A graphene-supported zinc oxide (ZnO) solid-phase microextraction (SPME) fiber was prepared via a sol-gel approach. Graphite oxide (GO), with rich oxygen-containing groups, was selected as the starting material to anchor ZnO on its nucleation center. After being deoxidized by hydrazine, the Zn(OH)2/GO coating was dehydrated at high temperature to give the ZnO/graphene coating. Sol-gel technology could efficiently incorporate ZnO/graphene composites into the sol-gel network and provided strong chemical bonding between sol-gel polymeric SPME coating and silica fiber surface, which enhanced the durability of the fiber and allowed more than 200 replicate extractions. Results indicated that pure ZnO coated fiber did not show adsorption selectivity toward sulfur compounds, which might because the ZnO nanoparticles were enwrapped in the sol-gel network, and the strong coordination action between Zn ion and S ion was therefore blocked. The incorporation of graphene into ZnO based sol-gel network greatly enlarged the BET surface area from 1.2 m2/g to 169.4 m2/g and further increased the adsorption sites. Combining the superior properties of extraordinary surface area of graphene and the strong coordination action of ZnO to sulfur compounds, the ZnO/graphene SPME fiber showed much higher adsorption affinity to 1-octanethiol (enrichment factor, EF, 1087) than other aliphatic compounds without sulfur-containing groups (EFs<200). Also, it showed higher extraction selectivity and sensitivity toward sulfur compounds than commercial polydimethylsiloxane (PDMS) and polydimethylsiloxane/divinylbenzene (PDMS/DVB) SPME fibers. Several most abundant sulfur volatiles in Chinese chive and garlic sprout were analyzed using the ZnO/graphene SPME fiber in combination with gas chromatography-mass spectrometry (GC-MS). Their limits of detection were 0.1-0.7 μg/L. The relative standard deviation (RSD) using one fiber ranged from 3.6% to 9.1%. The fiber-to-fiber reproducibility for three parallel prepared fibers was 4.8-10.8%. The contents were in the range of 1.0-46.4 μg/g with recoveries of 80.1-91.6% for four main sulfides in Chinese chive and 17.1-122.6 μg/g with recoveries of 73.2-80.6% for three main sulfides in garlic sprout.