Ecotoxicological effects of tungsten on celery (Apium graveolens L) and pepper (Capsicum spp.).

Background: Tungsten (W) is an emerging heavy metal pollutant, yet research remains scarce on the biomonitor and sensitive biomarkers for W contamination. Methods: In this study, celery and pepper were chosen as study subjects and subjected to exposure cultivation in solutions with five different levels of W. The physiological and biochemical toxicities of W on these two plants were systematically analyzed. The feasibility of utilizing celery and pepper as biomonitor organisms for W contamination was explored and indicative biomarkers were screened. Results: The results indicated that W could inhibit plants' root length, shoot height, and fresh weight while concurrently promoting membrane lipid peroxidation. Additionally, W enhanced the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and total antioxidant capacity (TAOC) to counteract oxidative damage. From a physiological perspective, pepper exhibited potential as a biomonitor for W contamination. Biochemical indicators suggested that SOD could serve as a sensitive biomarker for W in celery, while TAOC and POD were more suitable for the roots and leaves of pepper. In conclusion, our study investigated the toxic effects of W on celery and pepper, contributing to the understanding of W's environmental toxicity. Furthermore, it provided insights for selecting biomonitor organisms and sensitive biomarkers for W contamination.

Interacting effects of phytohormones and fruit pruning on the morpho-physiological and biochemical attributes of bell pepper.

Several factors, such as pruning and phytohormones, have demonstrated an influence on both the quantity and quality in the bell pepper. A factorial experiment using a completely randomized design was conducted on the Lumos yellow bell in a greenhouse. Treatments were the fruit pruning (0, 10, and 30%) and foliar application of phytohormones auxin (AUX) and gibberellic acid (GA3) at concentrations of 10 µM AUX, 10 µM GA3, 10 µM AUX + 10 µM GA3+, and 20 µM AUX + 10 µM GA3 along with controls. The plants were sprayed with phytohormones in four growth stages (1: flowering stage when 50% of the flowers were on the plant, 2: fruiting stage when 50% of the fruits were the size of peas, 3: fruit growth stage when 50% of the fruits had reached 50% of their growth, and 4: ripening stage when 50% of the fruits were at color break). The results of the present investigation showed that pruning rate of 30% yielded the highest flesh thickness and vitamin C content, decreased seed count and hastened fruit ripening. The use of GA3 along with AUX has been observed to augment diverse fruit quality characteristics. According to the results, the application of 10% pruning in combination with 20 µM AUX and 10 µM GA3 demonstrated the most significant levels of carotenoids, chlorophyll, and fruit length. The experimental group subjected to the combined treatment of 30% pruning and 10 µM AUX + 10 µM GA3 showed the most noteworthy levels of vitamin C, fruit weight, and fruit thickness. The groups that received the 10 µM GA3 and 20 µM AUX + 10 µM GA3 treatments exhibited the most favorable fruit flavor. According to the research results, the implementation of hormonal treatments 10 µM AUX and 10 µM AUX + 10 µM GA3 in combination with a 30% pruning strategy resulted in the most advantageous yield of bell peppers.

Modulation of secondary metabolism and redox regulation by exogenously applied glutathione improves the shelf life of Capsicum annuum L. fruit.

Role of redox homeostasis in fruit ripening of Capsicum annuum L. with oxidative metabolism was studied. The research aims the ability to reduce agents during postharvest storage on fruit for delayed ripening with the regulation of oxidative stress. Thus, we applied 10 mM reduced glutathione (GSH) to fruit as pretreatment followed by 1 mM hydrogen peroxide (H2O2) as ripening-inducing treatment and observed during 7 days of storage at 25 °C. A decrease in total soluble solid and firmness under H2O2, was increased while dehydration in tissue was decreased by GSH pretreatment. Glutathione regulated the turnover of organic acids to reducing sugars with higher activity of NADP malic enzyme that sustained the fruit coat photosynthesis through chlorophyll fluorescence, pigment composition, and photosystem II activity. Malondialdehyde accumulation was inversely correlated with GSH content and antioxidative enzyme activity that reduced loss of cell viability. Conclusively, regulation of oxidative stress with GSH may be effective in the extension of shelf life under postharvest storage.

A new biostimulant derived from soybean by-products enhances plant tolerance to abiotic stress triggered by ozone.

BACKGROUND: Tropospheric ozone is an air pollutant that causes negative effects on vegetation, leading to significant losses in crop productivity. It is generated by chemical reactions in the presence of sunlight between primary pollutants resulting from human activity, such as nitrogen oxides and volatile organic compounds. Due to the constantly increasing emission of ozone precursors, together with the influence of a warming climate on ozone levels, crop losses may be aggravated in the future. Therefore, the search for solutions to mitigate these losses becomes a priority. Ozone-induced abiotic stress is mainly due to reactive oxygen species generated by the spontaneous decomposition of ozone once it reaches the apoplast. In this regard, compounds with antioxidant activity offer a viable option to alleviate ozone-induced damage. Using enzymatic technology, we have developed a process that enables the production of an extract with biostimulant properties from okara, an industrial soybean byproduct. The biostimulant, named as OEE (Okara Enzymatic Extract), is water-soluble and is enriched in bioactive compounds present in okara, such as isoflavones. Additionally, it contains a significant fraction of protein hydrolysates contributing to its functional effect. Given its antioxidant capacity, we aimed to investigate whether OEE could alleviate ozone-induced damage in plants. For that, pepper plants (Capsicum annuum) exposed to ozone were treated with a foliar application of OEE. RESULTS: OEE mitigated ozone-induced damage, as evidenced by the net photosynthetic rate, electron transport rate, effective quantum yield of PSII, and delayed fluorescence. This protection was confirmed by the level of expression of genes associated with photosystem II. The beneficial effect was primarily due to its antioxidant activity, as evidenced by the lipid peroxidation rate measured through malondialdehyde content. Additionally, OEE triggered a mild oxidative response, indicated by increased activities of antioxidant enzymes in leaves (catalase, superoxide dismutase, and guaiacol peroxidase) and the oxidative stress index, providing further protection against ozone-induced stress. CONCLUSIONS: The present results support that OEE protects plants from ozone exposure. Taking into consideration that the promotion of plant resistance against abiotic damage is an important goal of biostimulants, we assume that its use as a new biostimulant could be considered.

Biochar and silicon relegate the adversities of beryllium stress in pepper by modulating methylglyoxal detoxification and antioxidant defense mechanism.

Industrial activities have escalated beryllium (Be) release in environment which negatively affect plant growth and human health. This investigation describes Be-induced stress in pepper and its palliation by application of pineapple fruit peel biochar (BC) and potassium silicate (Si). The treatment of Be reduced seedling length, biomass, and physiological attributes and enhanced electrolyte leakage, hydrogen peroxide (H2O2), superoxide (O2•-) level in pepper plants; however, these oxidative stress markers were reduced with combined treatment (Be + BC + Si). Application of BC and Si also lowered Be cumulation in roots and shoots of pepper. Under combined treatment, superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) activities exhibited significant enhancement 19, 7.6, 22.8, and 48%, respectively, in Be-stressed pepper. The Be + BC + Si increased peroxidase (POD), glutathione S-transferase (GPX), and glutathione peroxidase (GST) activities 121, 55, and 53%, respectively, as compared to Be-treated pepper. Methylglyoxal level was reduced in pepper with rise in glyoxalase I and II enzymes. Thus, combined application of SS and BC effectively protects pepper against oxidative stress induced by Be by increasing both antioxidant defense and glyoxalase systems. Hence, pineapple fruit peel biochar along with potassium silicate can be used for enhancing crop productivity under Be-contaminated soil.

Potassium silicate and vinasse enhance biometric characteristics of perennial sweet pepper (Capsicum annuum) under greenhouse conditions.

An effective strategy for enhancing fruit production continuity during extended sweet pepper season involves adopting innovative biostimulants such as potassium silicate (PS) and vinasse. Adjusting PS and vinasse concentrations are crucial for maintaining the balance between vegetative and fruit growth, particularly in sweet pepper with a shallow root system, to sustain fruiting over prolonged season. However, the interaction between PS and vinasse and the underlying physiological mechanisms that extend the sweet pepper season under greenhouse conditions remain unclear. This study aimed to investigate the impact of PS and vinasse treatments on the yield and biochemical constituents of perennial pepper plants cultivated under greenhouse conditions. For two consecutive seasons [2018/2019 and 2019/2020], pepper plants were sprayed with PS (0, 0.5, and 1 g/l) and drenched with vinasse (0, 1, 2, and 3 l/m3). To estimate the impact of PS and vinasse on the growth, yield, and biochemical constituents of pepper plants, fresh and dry biomass, potential fruit yield, and some biochemical constituents were evaluated. Results revealed that PS (0.5 g/l) coupled with vinasse (3 l/m3) generated the most remarkable enhancement, in terms of plant biomass, total leaf area, total yield, and fruit weight during both growing seasons. The implementation of vinasse at 3 l/m3 with PS at 0.5 and 1 g/l demonstrated the most pronounced augmentation in leaf contents (chlorophyll index, nitrogen and potassium), alongside improved fruit quality, including total soluble solid and ascorbic acid contents, of extended sweet pepper season. By implementing the optimal combination of PS and vinasse, growers can significantly enhance the biomass production while maintaining a balance in fruiting, thereby maximizing the prolonged fruit production of superior sweet pepper under greenhouse conditions.

CaWRKY30 Positively Regulates Pepper Immunity by Targeting CaWRKY40 against Ralstonia solanacearum Inoculation through Modulating Defense-Related Genes.

The WRKY transcription factors (TFs) network is composed of WRKY TFs' subset, which performs a critical role in immunity regulation of plants. However, functions of WRKY TFs' network remain unclear, particularly in non-model plants such as pepper (Capsicum annuum L.). This study functionally characterized CaWRKY30-a member of group III Pepper WRKY protein-for immunity of pepper against Ralstonia solanacearum infection. The CaWRKY30 was detected in nucleus, and its transcriptional expression levels were significantly upregulated by R. solanacearum inoculation (RSI), and foliar application ethylene (ET), abscisic acid (ABA), and salicylic acid (SA). Virus induced gene silencing (VIGS) of CaWRKY30 amplified pepper's vulnerability to RSI. Additionally, the silencing of CaWRKY30 by VIGS compromised HR-like cell death triggered by RSI and downregulated defense-associated marker genes, like CaPR1, CaNPR1, CaDEF1, CaABR1, CaHIR1, and CaWRKY40. Conversely, transient over-expression of CaWRKY30 in pepper leaves instigated HR-like cell death and upregulated defense-related maker genes. Furthermore, transient over-expression of CaWRKY30 upregulated transcriptional levels of CaWRKY6, CaWRKY22, CaWRKY27, and CaWRKY40. On the other hand, transient over-expression of CaWRKY6, CaWRKY22, CaWRKY27, and CaWRKY40 upregulated transcriptional expression levels of CaWRKY30. The results recommend that newly characterized CaWRKY30 positively regulates pepper's immunity against Ralstonia attack, which is governed by synergistically mediated signaling by phytohormones like ET, ABA, and SA, and transcriptionally assimilating into WRKY TFs networks, consisting of CaWRKY6, CaWRKY22, CaWRKY27, and CaWRKY40. Collectively, our data will facilitate to explicate the underlying mechanism of crosstalk between pepper's immunity and response to RSI.

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.

Genome-Wide Identification and Transcriptional Expression Analysis of Annexin Genes in Capsicum annuum and Characterization of CaAnn9 in Salt Tolerance.

Annexin (Ann) is a polygenic, evolutionarily conserved, calcium-dependent and phospholipid-binding protein family, which plays key roles in plant growth, development, and stress response. However, a comprehensive understanding of CaAnn genes of pepper (Capsicum annuum) at the genome-wide level is limited. Based on the available pepper genomic information, we identified 15 members of the CaAnn gene family. Phylogenetic analysis showed that CaAnn proteins could be categorized into four different orthologous groups. Real time quantitative RT-PCR analysis showed that the CaAnn genes were tissue-specific and were widely expressed in pepper leaves after treatments with cold, salt, and drought, as well as exogenously applied MeJA and ABA. In addition, the function of CaAnn9 was further explored using the virus-induced gene silencing (VIGS) technique. CaAnn9-silenced pepper seedlings were more sensitive to salt stress, reflected by the degradation of chlorophyll, the accumulation of reactive oxygen species (ROS), and the decrease of antioxidant defense capacity. This study provides important information for further study of the role of pepper CaAnn genes and their coding proteins in growth, development, and environmental responses.

Multispectral Assessment of Sweet Pepper (Capsicum annuum L.) Fruit Quality Affected by Calcite Nanoparticles.

Sweet pepper (Capsicum annuum L.) is one of the most important vegetable crops in the world because of the nutritional value of its fruits and its economic importance. Calcium (Ca) improves the quality of sweet pepper fruits, and the application of calcite nanoparticles in agricultural practice has a positive effect on the morphological, physiological, and physicochemical properties of the whole plant. The objectives of this study were to investigate the effect of commercial calcite nanoparticles on yield, chemical, physical, morphological, and multispectral properties of sweet pepper fruits using a combination of conventional and novel image-based nondestructive methods of fruit quality analysis. In the field trial, two sweet pepper cultivars, i.e., Soroksari and Kurtovska kapija, were treated with commercial calcite nanoparticles (at a concentration of 3% and 5%, calcite-based foliar fertilizer (positive control), and water (negative control) three times during vegetation). Sweet pepper fruits were harvested at the time of technological and physiological maturity. Significant differences were observed between pepper cultivars as well as between harvests times. In general, application of calcite nanoparticles reduced yield and increased fruit firmness. However, different effects of calcite nanoparticles were observed on almost all properties depending on the cultivar. In Soroksari, calcite nanoparticles and calcite-based foliar fertilizers significantly increased N, P, K, Mg, Fe, Zn, Mn, and Cu at technological maturity, as well as P, Ca, Mg, Fe, Zn, Mn, Cu, and N at physiological maturity. However, in Kurtovska kapija, the treatments increased only Ca at technological maturity and only P at physiological maturity. The effect of treatments on fruit morphological properties was observed only at the second harvest. In Soroksari, calcite nanoparticles (3% and 5%) increased the fruit length, minimal circle area, and minimal circle radius, and it decreased the fruit width and convex hull compared to the positive and negative controls, respectively. In Kurtovska kapija, calcite nanoparticles increased the fruit width and convex hull compared to the controls. At physiological maturity, lower anthocyanin and chlorophyll indices were found in Kurtovska kapija in both treatments with calcite nanoparticles, while in Soroksari, the opposite effects were observed.

Peppers: A "Hot" Natural Source for Antitumor Compounds.

Piper, Capsicum, and Pimenta are the main genera of peppers consumed worldwide. The traditional use of peppers by either ancient civilizations or modern societies has raised interest in their biological applications, including cytotoxic and antiproliferative effects. Cellular responses upon treatment with isolated pepper-derived compounds involve mechanisms of cell death, especially through proapoptotic stimuli in tumorigenic cells. In this review, we highlight naturally occurring secondary metabolites of peppers with cytotoxic effects on cancer cell lines. Available mechanisms of cell death, as well as the development of analogues, are also discussed.

Identification of Compounds with Potential Therapeutic Uses from Sweet Pepper (Capsicum annuum L.) Fruits and Their Modulation by Nitric Oxide (NO).

Plant species are precursors of a wide variety of secondary metabolites that, besides being useful for themselves, can also be used by humans for their consumption and economic benefit. Pepper (Capsicum annuum L.) fruit is not only a common food and spice source, it also stands out for containing high amounts of antioxidants (such as vitamins C and A), polyphenols and capsaicinoids. Particular attention has been paid to capsaicin, whose anti-inflammatory, antiproliferative and analgesic activities have been reported in the literature. Due to the potential interest in pepper metabolites for human use, in this project, we carried out an investigation to identify new bioactive compounds of this crop. To achieve this, we applied a metabolomic approach, using an HPLC (high-performance liquid chromatography) separative technique coupled to metabolite identification by high resolution mass spectrometry (HRMS). After chromatographic analysis and data processing against metabolic databases, 12 differential bioactive compounds were identified in sweet pepper fruits, including quercetin and its derivatives, L-tryptophan, phytosphingosin, FAD, gingerglycolipid A, tetrahydropentoxylin, blumenol C glucoside, colnelenic acid and capsoside A. The abundance of these metabolites varied depending on the ripening stage of the fruits, either immature green or ripe red. We also studied the variation of these 12 metabolites upon treatment with exogenous nitric oxide (NO), a free radical gas involved in a good number of physiological processes in higher plants such as germination, growth, flowering, senescence, and fruit ripening, among others. Overall, it was found that the content of the analyzed metabolites depended on the ripening stage and on the presence of NO. The metabolic pattern followed by quercetin and its derivatives, as a consequence of the ripening stage and NO treatment, was also corroborated by transcriptomic analysis of genes involved in the synthesis of these compounds. This opens new research perspectives on the pepper fruit's bioactive compounds with nutraceutical potentiality, where biotechnological strategies can be applied for optimizing the level of these beneficial compounds.

Exogenous glutathione alleviates chilling injury in postharvest bell pepper by modulating the ascorbate-glutathione (AsA-GSH) cycle.

We investigated the effect of exogenous glutathione (GSH) on chilling injury (CI) in postharvest bell pepper fruits stored at low temperature and explored the mechanism of this treatment from the perspective of the ascorbate-glutathione (AsA-GSH) cycle. Compared with the control, fruits treated with exogenous GSH before refrigeration displayed only slight CI symptoms and mitigated CI-induced cell damage after 10 d. Moreover, the treated peppers had lower lipid peroxidation product, H2O2, and O2- content than those did the control. Glutathione treatment enhanced the ascorbate-glutathione cycle by upregulating CaAPX1, CaGR2, CaMDHAR1, and CaDHAR1 and the antioxidant enzymes APX, GR, and MDHAR associated with the ascorbate-glutathione cycle. Glutathione treatment also increased ascorbate and glutathione concentrations. Taken together, our results showed that exogenous GSH treatment could alleviate CI in pepper fruits during cold storage by triggering the AsA-GSH cycle and improving antioxidant capacity.

Antifungal activity of liquiritin in Phytophthora capsici comprises not only membrane-damage-mediated autophagy, apoptosis, and Ca2+ reduction but also an induced defense responses in pepper.

Phytophthora capsici causes a severe soil-borne disease in a wide variety of vegetables; to date, no effective strategies to control P. capsici have been developed. Liquiritin (LQ) is a natural flavonoid found in licorice (Glycyrrhiza spp.) root, and it is used in pharmaceuticals. However, the antifungal activity of LQ against P. capsici remains unknown. In the present study, we demonstrated that LQ inhibits P. capsici mycelial growth and sporangial development. In addition, the EC50 of LQ was 658.4 mg/L and LQ caused P. capsici sporangia to shrink and collapse. Next, LQ severely damaged the cell membrane integrity, leading to a 2.0-2.5-fold increase in relative electrical conductivity and malondialdehyde concentration, and a 65-70% decrease in sugar content. Additionally, the H2O2 content was increased about 2.0-2.5 fold, but the total antioxidant activity, catalase activity and laccase activity were attenuated by 40-45%, 30-35% and 70-75%. LQ also induced autophagy, apoptosis, and reduction of intracellular Ca2+ content. Furthermore, LQ inhibited P. capsici pathogenicity by reducing the expression of virulence genes PcCRN4 and Pc76RTF, and stimulating the plant defense (including the activated transcriptional expression of defense-related genes CaPR1, CaDEF1, and CaSAR82, and the increased antioxidant enzyme activity). Our results not only elucidate the antifungal mechanism of LQ but also suggest a promising alternative to commercial fungicides or a key compound in the development of new fungicides for the control of the Phytophthora disease.

Salicylic acid-induced hydrogen sulphide improves lead stress tolerance in pepper plants by upraising the ascorbate-glutathione cycle.

The contribution of hydrogen sulphide (H2 S) to salicylic acid (SA) induced lead (Pb) stress tolerance modulated by the ascorbate-glutathione (AsA-GSH) cycle was examined in pepper (Capsicum annuum L.) plants. One week after germination, pepper seedlings were sprayed with 0.5 mM SA once a day for a week. Thereafter, seedlings were grown under control (no Pb) or Pb stress (Pb-S treatment consisting of 0.1 mM PbCl2 ) for a further 2 weeks. Lead stress reduced plant growth and leaf water status as well as the activities of dehydroascorbate reductase and monodehydroascorbate reductase. However, lead stress elevated leaf Pb, the proline contents, oxidative stress, activities of glutathione reductase and ascorbate peroxidase, as well as the endogenous H2 S content. Supplements of SA resulted in improvements in growth parameters, biomass, leaf water status and AsA-GSH cycle-related enzyme activities, as well as increasing the H2 S content. The positive effect of SA was further enhanced when sodium hydrosulphide was added. However, 0.1 mM hypotaurine (HT) treatment reversed the beneficial effect of SA by reducing the plant H2 S content. Application of NaHS in combination with SA + HT suppressed the adverse effect of HT mainly by restoring the plant H2 S content, suggesting that higher H2 S content, induced by exogenous SA supply, resulted in elevated regulation of the AsA-GSH cycle.

Germination response of diverse wild and landrace chile peppers (Capsicum spp.) under drought stress simulated with polyethylene glycol.

Responses to drought within a single species may vary based on plant developmental stage, drought severity, and the avoidance or tolerance mechanisms employed. Early drought stress can restrict emergence and seedling growth. Thus, in areas where water availability is limited, rapid germination leading to early plant establishment may be beneficial. Alternatively, germination without sufficient water to support the seedling may lead to early senescence, so reduced germination under low moisture conditions may be adaptive at the level of the population. We studied the germination response to osmotic stress of diverse chile pepper germplasm collected in southern Mexico from varied ecozones, cultivation systems, and of named landraces. Drought stress was simulated using polyethylene glycol solutions. Overall, survival time analysis revealed delayed germination at the 20% concentration of PEG across all ecozones. The effect was most pronounced in the genotypes from hotter, drier ecozones. Additionally, accessions from wetter and cooler ecozones had the fastest rate of germination. Moreover, accessions of the landraces Costeño Rojo and Tusta germinated more slowly and incompletely if sourced from a drier ecozone than a wetter one, indicating that slower, reduced germination under drought stress may be an adaptive avoidance mechanism. Significant differences were also observed between named landraces, with more domesticated types from intensive cultivation systems nearly always germinating faster than small-fruited backyard- or wild-types, perhaps due to the fact that the smaller-fruited accessions may have undergone less selection. Thus, we conclude that there is evidence of local adaptation to both ecozone of origin and source cultivation system in germination characteristics of diverse chile peppers.

Optimized carboxymethyl cellulose and guanidinylated chitosan enriched with titanium oxide nanoparticles of improved UV-barrier properties for the active packaging of green bell pepper.

Edible films based on chitosan biguanidine hydrochloride and CMC were optimized for the minimum water vapor permeability (WVP) using the 3-level factorial design. Titanium oxide nanoparticles (nTiO2) were incorporated in different contents into the optimized film (Owvp). FTIR and 1H NMR confirmed the successful preparation of films. FE-SEM showed that nTiO2 was homogeneously distributed, with a size of about 25.78 nm for the film containing 5 wt% of nTiO2. XRD was used to study the film's crystallinity, and calculate the crystallite size of nTiO2 using Debye-Scherrer Equation. Thermal stability, by TGA, was improved while the water vapor permeability was reduced upon increasing the nTiO2 content. Color measurements showed that the nTiO2 incorporation didn't significantly affect the transparency. Elongation at break was decreased upon nTiO2 incorporation while tensile strength and Young's modulus were increased with increasing nTiO2 up to 3 wt% then begin to decrease. The nanocomposites exhibited significant UV-barrier properties and enhanced antimicrobial activity especially at high contents of nTiO2. Shelf-life studies on green bell pepper coated with the nanocomposite films showed excellent resistance to mass loss and spoilage during storage. The obtained data confirm the efficiency of the prepared nTiO2 nanocomposite films to extend the shelf-life of food.

Differential expression of MEKK subfamily genes in Capsicum annuum L. in response to abscisic acid and drought stress.

Mitogen-activated protein kinase kinase kinases (MAPKKKs or MEKKs) are crucial components of the MAPK signaling cascades, which play central roles in the signaling transduction pathways for plant growth, development, and response to abiotic stresses such as drought. The MAPKKK gene families in pepper have not been functionally characterized yet. Here, from the pepper genome, we predicted 27 putative MAPKKK genes belonging to the MEKK subfamily (named CaMEKK1-27), based on in silico analysis. Phylogenetic analysis revealed that 14 CaMEKK genes were clustered into A5 of the five groups (A1-A5), of which 9 genes are primarily on chromosomes 2 and 7, and are located close to each other. These nine genes showed transcriptional regulation by treatment with abscisic acid (ABA) and drought stress in quantitative reverse-transcription PCR analysis. Among the ABA- and/or drought-induced CaMEKK genes, in a previous study, we isolated CaAIMK1 (Capsicum annuum ABA Induced MAP Kinase 1), which plays a positive role in drought resistance via an ABA-dependent pathway. Our expression analysis and functional characterization of the MEKK subfamily genes will provide a better understanding of the functional roles of pepper MAPK cascades in ABA-mediated drought responses.

Chitosan nanoparticles as edible surface coating agent to preserve the fresh-cut bell pepper (Capsicum annuum L. var. grossum (L.) Sendt).

This work synthesized chitosan nanoparticles (CSNPs) by ionic gelation method using sodium tripolyphosphate pentabasic (STPP) and applied as nano-coating agent to extend the shelf life of fresh cut bell pepper (FCP) by preventing the microbial contaminations. The CSNPs were spherical shaped and 22.55 ± 1.69 d.nm sized with ζ-potential of 45.10 ± 1.42 mV confirmed by UHR-SEM, FE-TEM, and ζ-potential size analyses. The crystallinity and functional group changes were determined by XRD and FT-IR analyses respectivelly. The antioxidant activity of CSNPs was determined in terms of DPPH and ABTS scavenging activities. The 1% and 3% of CSNPs were found to be minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) respectively against all tested bacteria. The MBC of CSNPs was exhibited the promising anti-biofilm activity. Therefore, the 3% of CSNPs was used to prepare the chitosan nano-coating (CSNC), and applied on surface of FCP to prevent the microbial contaminations such as fungi, bacteria including Listeria monocytogenes and Salmonella enterica. The experimental results showed that the application of CSNC was maintained the FCP for 12 days at 5 °C without loss of weight, and sensory quality.

Identification of QTLs Controlling α-Glucosidase Inhibitory Activity in Pepper (Capsicum annuum L.) Leaf and Fruit Using Genotyping-by-Sequencing Analysis.

Diabetes mellitus, a group of metabolic disorders characterized by hyperglycemia, is one of the most serious and common diseases around the world and is associated with major complications such as diabetic neuropathy, retinopathy, and cardiovascular diseases. A widely used treatment for non-insulin-dependent diabetes is α-glucosidase inhibitors (AGIs) such as acarbose, which hinders hydrolytic cleavage of disaccharides and retard glucose absorption. The ability to inhibit α-glucosidase activity has been reported in leaf and fruit of pepper (Capsicum annuum L.). In this study, we aimed to identify quantitative trait loci (QTLs) controlling α-glucosidase inhibitory activity (AGI activity) in pepper leaf and fruit using enzyme assay and genotyping-by-sequencing (GBS) analysis. The AGI activity at three stages of leaf and one stage of fruit development was analyzed by 96 F2 individuals. GBS analysis identified 17,427 SNPs that were subjected to pepper genetic linkage map construction. The map, consisting of 763 SNPs, contained 12 linkage groups with a total genetic distance of 2379 cM. QTL analysis revealed seven QTLs (qAGI1.1, qAGI11.1, qAGI5.1, qAGI9.1, qAGI12.1, qAGI5.2, and qAGI12.2) controlling AGI activity in pepper leaf and fruit. The QTLs for AGI activity varied by plant age and organ. This QTL information is expected to provide a significant contribution to developing pepper varieties with high AGI activity.