Nano-selenium foliar intervention-induced resistance of cucumber to Botrytis cinerea by activating jasmonic acid biosynthesis and regulating phenolic acid and cucurbitacin.

PURPOSE AND METHODS: Botrytis cinerea is the primary disease affecting cucumber production. It can be managed by applying pesticides and cultivating disease-resistant cucumber strains. However, challenges, such as drug resistance in pathogenic bacteria and changes in physiological strains, are obstacles in the effective management of B. cinerea. Nano-selenium (Nano-Se) has potential in enhancing crop resistance to biological stress, but the exact mechanism for boosting disease resistance remains unclear. Here, we used metabolomics and transcriptomics to examine how Nano-Se, as an immune activator, induces plant resistance. RESULT: Compared with the control group, the application of 10.0 mg/L Nano-Se on the cucumber plant's leaf surface resulted in increased levels of chlorophyll, catalase (10.2%), glutathione (326.6%), glutathione peroxidase (52.2%), cucurbitacin (41.40%), and metabolites associated with the phenylpropane synthesis pathway, as well as the total antioxidant capacity (21.3%). Additionally, the expression levels of jasmonic acid (14.8 times) and related synthetic genes, namely LOX (264.1%), LOX4 (224.1%), and AOC2 (309.2%), were up-regulated. A transcription analysis revealed that the CsaV3_4G002860 gene was up-regulated in the KEGG enrichment pathway in response to B. cinerea infection following the 10.0 mg/L Nano-Se treatment. DISCUSSION: In conclusion, the activation of the phenylpropane biosynthesis and branched-chain fatty acid pathways by Nano-Se promotes the accumulation of jasmonic acid and cucurbitacin in cucumber plants. This enhancement enables the plants to exhibit resistance against B. cinerea infections. Additionally, this study identified a potential candidate gene for cucumber resistance to B. cinerea induced by Nano-Se, thereby laying a theoretical foundation for further research in this area. © 2023 Society of Chemical Industry.

Improving red pitaya fruit quality by nano-selenium biofortification to enhance phenylpropanoid and betalain biosynthesis.

Red pitaya, the representative tropical and subtropical fruit, is vulnerable to quality deterioration due to climate or agronomic measures. Nano-selenium (Nano-Se) has shown positive effects on crop biofortification in favour of reversing this situation. In this study, Se could be enriched efficiently in red pitayas via root and foliar application by Nano-Se, which induced higher phenolic acids (16.9-94.2%), total phenols (15.7%), total flavonoids (29.5%) and betacyanins (34.1%) accumulation in flesh. Richer antioxidative features including activities of SOD (25.2%), CAT (33.8%), POD (77.2%), and levels of AsA (25.7%) and DPPH (14.7%) were obtained in Nano-Se-treated pitayas as well as in their 4-8 days shelf-life. The non-targeted metabolomics indicated a boost in amino acids, resulting in the stimulation of phenylpropanoid and betalain biosynthesis. In conclusion, the mechanism of Nano-Se biofortification for red pitaya might be fortifying pigment, as well as the enzymatic and non-enzymatic antioxidant substances formation by regulating primary and secondary metabolism facilitated by Se accumulation.

Exogenous nanoselenium alleviates imidacloprid-induced oxidative stress toxicity by improving phenylpropanoid metabolism and antioxidant defense system in Perilla frutescens (L.) Britt.

Few studies have been conducted to investigate the impact of pesticides on the secondary metabolism of traditional Chinese medicine and strategies to mitigate the toxicity of pesticide-induced oxidative stress. The current study focuses on evaluating the potential impacts of nano selenium (NSe) and imidacloprid (IMI) on the quality, physiological biochemistry, and secondary metabolites in Perilla frutescens (L.) Britt. (P. frutescens). The study utilized metabolome analysis to explore the toxicity mechanism of IMI. The study noted that IMI-induced stress could emerge with detrimental effects by targeting the destruction of the phenylpropanoid biosynthesis pathway. IMI-induced phenylpropanoid metabolism disorder resulted in an 8%, 17%, 25%, 10%, 65%, and 29% reduction in phenylalanine, coniferyl aldehyde, ferulic acid, cafestol, p-coumaraldehyde, and p-coumaric acid levels, respectively. Under the treatment of exogenous NSe, the levels of these metabolites were increased by 16%, 32%, 22%, 22%, 92%, and 29%, respectively. The application of exogenous NSe increased the levels of these metabolites and improved the biochemical disorder and quality of P. frutescens leaves by optimizing the phenylpropanoid metabolic pathway and enhancing the antioxidant system. Overall, the results suggest that foliar application of NSe could alleviate the oxidative stress toxicity induced by IMI and improve the quality of P. frutescens.

Combined Application of Tank-mix Adjuvants, Mist Sprayer and Nano-selenium Promoted Pesticide Reduction and Enhanced Strawberry Quality.

In this paper, several technologies suitable for strawberry crops, such as armyworm boards, tank-mix adjuvants, mist sprayers combined with pesticide reduction, and biostimulant nano-selenium, were comprehensively applied and evaluated. The combined use of 60% etoxazole and bifenazate, bucket mixing additives, nano-selenium, and mist sprayers achieved an 86% prevention effect on red spiders. The prevention effect of pesticides according to the recommended dosage was 91%. Similarly, the disease index of strawberry powdery mildew in the green control group (60% carbendazim, bucket mixing additives, nano-selenium, and mist sprayer) decreased from 33.16 to 11.11, with a decrease of 22.05. The disease index of the control group decreased from 29.69 to 8.06, with a decrease of 21.63. Additionally, the combination of pesticide reduction and nano-selenium significantly improved the antioxidant activity and soluble sugar level of strawberry fruit and reduced water loss during storage. Therefore, the integrated application of green control technologies is beneficial for reducing the amount of chemical pesticides and improving their effectiveness, while enhancing the quality of strawberry fruits in disease and pest control.

Integrated non-targeted and targeted metabolomics analysis reveals the mechanism of inhibiting lignification and optimizing the quality of pea sprouts by combined application of nano-selenium and lentinans.

BACKGROUND: Lignification causes a detrimental impact on the quality of edible sprouts. However, the mechanism of inhibition of lignification of edible sprouts by nano-selenium and lentinans remains unclear. RESULTS: To reveal the mechanism of lignification regulation of sprouts by nano-selenium and lentinans, this study investigated the changes in antioxidant indicators, phytohormones, polyphenols, and metabolites in the lignin biosynthesis in pea sprouts following sprays of nano-selenium or/and lentinans twice. There was an overall increase in the aforementioned indices following treatment. In particular, the combined application of 5 mg L-1 nano-selenium and 20 mg L-1 lentinans was more effective than their individual applications in enhancing peroxidase, catalase, DPPH free-radical scavenging rate, luteolin, and sinapic acid, as well as inhibiting malondialdehyde generation and lignin accumulation. Combined with the results from correlation analysis, nano-selenium and lentinans may inhibit lignification by enhancing antioxidant systems, inducing phytohormone-mediated signaling, and enriching precursor metabolites (caffeyl alcohol, sinapyl alcohol, 4-coumaryl alcohol). In terms of the results of non-targeted metabolomics, the combined application of 5 mg L-1 nano-selenium and 20 mg L-1 lentinans mainly affected biosynthesis of plant secondary metabolites, biosynthesis of phenylpropanoids, phenylpropanoid biosynthesis, arginine and proline metabolism, and linoleic acid metabolism pathways, which supported and complemented results from targeted screenings. CONCLUSION: Overall, the combined sprays of nano-selenium and lentinans showed synergistic effects in delaying lignification and optimizing the quality of pea sprouts. This study provides a novel and practicable technology for delaying lignification in the cultivation of edible sprouts. © 2023 Society of Chemical Industry.

A novel perspective to investigate how nanoselenium and melatonin lengthen the cut carnation vase shelf.

Nano-selenium (nano-Se) and melatonin (MT) applications confirmed to boost plant growth and resistance. The mechanism of various ratios of nano-Se and MT foliar application postpone the senescence of fresh cut carnation flowers and improve vase life remains unclear. In this study, a combined effect with nano-Se (nano-Se5, 5 mg/L) and MT(MT1, 1 mg/L) was preferable to the control, nano-Se, and MT treatment alone when it came to delaying flower senescence. They enhance the antioxidant ability of carnation flowers by lowering MDA and H2O2 levels, raising SOD and POD concentrations, and lowering procyanidins biosynthesis (catechins and epicatechin). Inducing the biosynthesis of hormonal compounds (salicylic acid, jasmonic acid, and abscisic acid), their combination also boosted the growth of carnations. Biofortification with nano-Se and MT substantially increased the amounts of key lignin biosynthesis pathway metabolites (L-phenylalanine, p-hydroxycinnamic acid, p-coumaric acid, perillyl alcohol, p-Coumaryl alcohol, and cinnamic acid), which may increase stem cellular thickness and facilitate water absorption and transmission. The study hypothesizes that nano-Se and MT synergistic applications act as a new efficient non-toxic preservative to extend the vase life and improve the decorative value of carnations.

Metabolomic analysis on the mechanism of nanoselenium alleviating cadmium stress and improving the pepper nutritional value.

Selenium (Se) maintains soil-plant homeostasis in the rhizosphere and regulates signaling molecules to mitigate cadmium (Cd) toxicity. However, there has been no systematic investigation of the effects of nano-selenium (nano-Se) on the regulation of non-target metabolites and nutritional components in pepper plants under Cd stress. This study investigated the effects of Cd-contaminated soil stress and nano-Se (1, 5, and 20 mg/L) on the metabolic mechanism, fruit nutritional quality, and volatile organic compounds (VOCs) composition of pepper plants. The screening of differential metabolites in roots and fruit showed that most were involved in amino acid metabolism and capsaicin production. Amino acids in roots (Pro, Trp, Arg, and Gln) and fruits (Phe, Glu, Pro, Arg, Trp, and Gln) were dramatically elevated by nano-Se biofortification. The expression of genes of the phenylpropane-branched fatty acid pathway (BCAT, Fat, AT3, HCT, and Kas) was induced by nano-Se (5 mg/L), increasing the levels of capsaicin (29.6%), nordihydrocapsaicin (44.2%), and dihydrocapsaicin (45.3%). VOCs (amyl alcohol, linalool oxide, E-2-heptaldehyde, 2-hexenal, ethyl crotonate, and 2-butanone) related to crop resistance and quality were markedly increased in correspondence with the nano-Se concentration. Therefore, nano-Se can improve the health of pepper plants by regulating the capsaicin metabolic pathway and modulating both amino acid and VOC contents.

Application of insecticides on peppermint (Mentha × piperita L.) induces lignin accumulation in leaves by consuming phenolic acids and thus potentially deteriorates quality.

Irrational use of pesticides may lead to physiological and metabolic disorders in different crops. However, there are limited investigations on impacts of insecticides on physiology and biochemistry, secondary metabolic pathways, and associated quality of medicinal plants such as peppermint (Mentha × piperita L.). In this study, target metabolites in peppermint were monitored following foliar spraying of five insecticides: imidacloprid, pyriproxyfen, acetamiprid, chlorantraniliprole, and chlorfenapyr. Compared with the control, all insecticide treatments caused a significant loss of soluble protein (decreased by 22.3-38.7%) in peppermint leaves. Insecticides induced an increase in the levels of phytohormones jasmonic acid and abscisic acid in response to these chemical stresses. Among them, imidacloprid increased jasmonic acid by 388.3%, and pyriproxyfen increased abscisic acid by 98.8%. The contents of phenylpropanoid metabolites, including rutin, quercetin, apigenin, caffeic acid, 4-hydroxybenzoic acid, ferulic acid, syringic acid, and sinapic acid showed a decreasing trend, with pyriproxyfen decreasing the levels of quercetin and 4-hydroxybenzoic acid by 78.8% and 72.6%, respectively. Combined with correlation analysis, the content of lignin in leaves shows different degrees of negative correlations with several phenolic acids. It could be inferred that insecticides may trigger plant defense mechanisms that accumulate lignin (increased by 24.6-49.1%) in leaves by consuming phenolic acids to barricade absorption of insecticides. Through constructing networks between phytohormones and secondary metabolites, peppermint may regulate the contents of caffeic acid, 4-hydroxybenzoic acid, and sinapic acid by the antagonistic effect between salicylic acid and abscisic acid in response to insecticidal stresses. Principal component analysis and systemic cluster analysis revealed that the most pronounced changes in physiological indexes and metabolites were caused by the pyriproxyfen treatment. In conclusion, this study improves our understanding of the mechanism by which insecticides affect plant physiological and metabolic processes, thus potentially altering the quality and therapeutic value of peppermint as an example.

Feeding foliar nano-selenium biofortified panax notoginseng could reduce the occurrence of glycolipid metabolism disorder in mice caused by high-fat diets.

Nano-selenium (nano-Se) has been extensively explored as a biostimulant for improving the quality of grain crops. However, there are few reports about the effect on the medicinal components of Chinese herbal medicine cultured with nano-Se. Here, we sprayed nano-Se during the cultivation of Panax notoginseng (SePN), and measured the changes of medicinal components compared with conventional Panax notoginseng (PN). Furthermore, we identified a more pronounced effect of SePN on reducing obesity in animals compared with PN. By measuring antioxidant capacity, histopathology, gene expression related to glycolipid metabolism, and gut microbiota composition, we propose a potential mechanism for SePN to improve animal health. Compared with the control groups, foliar spraying of nano-Se increased saponins contents (Rb2, Rb3, Rc, F2, Rb2, and Rf) in the roots of Panax notoginseng, the content of Rb2 increased by 3.9 times particularly. Interestingly, animal studies indicated that taking selenium-rich Panax notoginseng (SePN) can further ameliorate liver antioxidation (SOD, MDA, and GSH) and enzyme activities involved in glycolipid metabolism (ATGL and PFK). It also relieved inflammation and regulated the expression of genes (MCAD, PPAR-α, and PCSK9) related to fatty acid oxidation. The abundance ratio of Firmicutes/Bacteroides and beneficial bacteria abundance (Bifidobacterium, Butyricimonas, and Parasutterella) in gut microbiota were improved relative to the control. In summary, the application of nano-Se on PN may effectively raise the content of Panax notoginseng saponins (PNS) and immensely lower the risk of metabolic disorders of glycolipids.

Nano-selenium enhances the antioxidant capacity, organic acids and cucurbitacin B in melon (Cucumis melo L.) plants.

Pesticides are widely used in melon production causing safety issues around the consumption of melon and increasing pathogen and insect tolerance to pesticides. This study investigated whether a nano-selenium (Nano-Se) spray treatment can improve resistance to biological stress in melon plants, reducing the need for pesticides, and how this mechanism is activated. To achieve this, we examine the ultrastructure and physio-biochemical responses of two melon cultivars after foliar spraying with Nano-Se. Nano-Se treatment reduced plastoglobulins in leaf mesophyll cells, thylakoid films were left intact, and compound starch granules increased. Nano-Se treatment also increased root mitochondria and left nucleoli intact. Nano-Se treatment enhanced ascorbate peroxidase, peroxidase, phenylalanine ammonia lyase, ß-1,3-glucanase, chitinase activities and their mRNA levels in treated melon plants compared to control plants (without Nano-Se treatments). Exogenous application of Nano-Se improved fructose, glucose, galactitol, stachyose, lactic acid, tartaric acid, fumaric acid, malic acid and succinic acid in treated plants compared to control plants. In addition, Nano-Se treatment enhanced cucurbitacin B and up-regulated eight cucurbitacin B synthesis-related genes. We conclude that Nano-Se treatment of melon plants triggered antioxidant capacity, photosynthesis, organic acids, and up-regulated cucurbitacin B synthesis-related genes, which plays a comprehensive role in stress resistance in melon plants.

Dissipative behavior, residual pattern, and risk assessment of four pesticides and their metabolites during tea cultivation, processing and infusion.

BACKGROUND: In recent years, metabolic products of pesticides have gained much attention due to their substantial characteristics as organic pollutants. So far, the behavior and metabolite levels of pesticide metabolites in crops have not been characterized well. In the present study, four registered pesticides (imidacloprid, diafenthiuron, malathion and chlorothalonil) were applied on tea plants in Fujian and Sichuan to characterize their metabolites residue pattern and dietary risk. RESULTS: Four pesticides dissipated first-order kinetics in the fresh tea leaves with the half-lives of 1.4-3.8 days. Nine metabolites were detected in the fresh tea leaves and green tea after processing. The metabolites residues showed an increasing trend first and then declined after treatment, and reached the maximum near the half-lives of pesticide. Compared with the parent pesticide, the total residue and acute risk (included the metabolites) increased by 1.7-105.2 times. Some metabolites, especially those whose parent pesticides have high water solubility and low Log Kow, will be more easily transferred to tea infusion. CONCLUSION: Pesticides were metabolized rapidly on tea plants after application, but the production of metabolites increased the health risk of tea consumption. These results could provide insights to use the pesticides in tea gardens and risk monitoring after application. © 2022 Society of Chemical Industry.

Multi-residue analytical method development and risk assessment of 56 pesticides and their metabolites in tea by chromatography tandem mass spectroscopy.

A modified QuEChERS method coupled to chromatography tandem mass spectroscopy was established and used to identify 56 pesticides and 21 metabolites residues in tea samples. The average recoveries for the target compounds ranged from 71% to 109% with RSDs of 1-17%. Pesticides and metabolites residues in 248 tea samples from China were investigated by the developed method, and the dietary intake risk for consumers was estimated. The results showed that 36 pesticides and 14 metabolites were detected with concentrations of 0.0050-7.7 mg/kg. There are unlikely to present a public health concern for Chinese consumers. The acute risk of pesticides would be exaggerated when calculated by the residue level in tea instead of tea infusion. The unauthorized and banned pesticide contributed to the chronic and acute hazard index by 68% and 36%, respectively. The cumulative risk of residual pesticides and their metabolites on human health deserve further attention.

Nanoselenium transformation and inhibition of cadmium accumulation by regulating the lignin biosynthetic pathway and plant hormone signal transduction in pepper plants.

Selenium (Se) can promote the growth and resistance of agricultural crops as fertilizers, while the role of nano-selenium (nano-Se) against Cd remains unclear in pepper plants (Capsicum annuum L.). Biofortification with nano-Se observably restored Cd stress by decreasing the level of Cd in plant tissues and boosting the accumulation in biomass. The Se compounds transformed by nano-Se were primarily in the form of SeMet and MeSeCys in pepper tissues. Differential metabolites and the genes of plant signal transduction and lignin biosynthesis were measured by employing transcriptomics and determining target metabolites. The number of lignin-related genes (PAL, CAD, 4CL, and COMT) and contents of metabolites (sinapyl alcohol, phenylalanine, p-coumaryl alcohol, caffeyl alcohol, and coniferaldehyde) were remarkably enhanced by treatment with Cd1Se0.2, thus, maintaining the integrity of cell walls in the roots. It also enhanced signal transduction by plant hormones and responsive resistance by inducing the biosynthesis of genes (BZR1, LOX3, and NCDE1) and metabolites (brassinolide, abscisic acid, and jasmonic acid) in the roots and leaves. In general, this study can enable a better understanding of the protective mechanism of nano-Se in improving the capacity of plants to resist environmental stress.

Nanoselenium foliar application enhances biosynthesis of tea leaves in metabolic cycles and associated responsive pathways.

An emerging stress of pesticides in plant and soil is closely watched as it affects crop antioxidant systems, nutritional quality, and flavor. Although selenium (Se) can enhance the resistance of plants, the protective mechanism of nanoselenium is still not known under the long-term pesticide stress in tea trees. In this study, we investigated the potential effects of foliar application of nanoselenium for a two-year field experiment on tea plants under pesticide-induced oxidative stress. Compared to control, nano-Se (10 mg/L) markedly enhanced the protein, soluble sugar, carotenoid, tea polyphenols, and catechins contents. High levels of theanine, glutamic acid, proline, and arginine were found to be induced most likely by adjusting the GS-GOGAT cycle. Se-supplementation may promote tea leaves' secondary metabolism, thus increasing the accumulation of total phenols and flavonoids (apigenin, kaempferol, quercetin, myricetin, and rutin). It also minimized the accumulation of malondialdehyde, hydrogen peroxide, and superoxide anion by activating the antioxidants enzymes including in the AsA-GSH cycle. Selenium-rich tea also showed better fragrance and flavor. In summary, nano-Se can ameliorate the nutrients quality and abiotic stresses resistance of crops.

Nanoselenium Foliar Applications Enhance the Nutrient Quality of Pepper by Activating the Capsaicinoid Synthetic Pathway.

Increasing the crop quality through enhancement of plant health is a challenging task. In this study, nanoselenium (nano-Se) was sprayed on pepper leaves, and the pepper components were compared to those of selenite. It was found that nano-Se (20 mg/L) resulted in a greater performance of plant health. It increased the chlorophyll and soluble sugar levels, which could activate phenylpropane and branched-chain fatty acid pathways, as well as AT3-related enzymes and gene expressions. These led to an enhancement for the synthesis of capsaicinoids, flavonoids, and total phenols. The nano-Se treatment also significantly promoted the expression of phyto-hormones synthesis genes, and consequently increased jasmonic, abscisic, and salicylic acid levels. Proline pathway-related compounds were increased, which could decrease the malondialdehyde and hydroxyl radical levels in crops. This study shows that nano-Se activated capsaicinoid pathways by enhancing photosynthesis and raising soluble sugar levels. The capsaicinoid contents in peppers were then increased, which consequently promoted the accumulation of secondary metabolites and antioxidants.