Placenta, Pericarp, and Seeds of Tabasco Chili Pepper Fruits Show a Contrasting Diversity of Bioactive Metabolites

Comparative 1H NMR-Based Metabolomics of Traditional Landrace and Disease-Resistant Chili Peppers (Capsicum annuum L.)

Chili peppers (Capsicum annuum L.) are economically valuable crops belonging to the Solanaceae family and are popular worldwide because of their unique spiciness and flavor. In this study, differences in the metabolomes of landrace (Subicho) and disease-resistant pepper cultivars (Bulkala and Kaltanbaksa) widely grown in Korea are investigated using a 1H NMR-based metabolomics approach. Specific metabolites were abundant in the pericarp (GABA, fructose, and glutamine) and placenta (glucose, asparagine, arginine, and capsaicin), highlighting the distinct physiological and functional roles of these components. Both the pericarp and placenta of disease-resistant pepper cultivars contained higher levels of sucrose and hexoses and lower levels of alanine, proline, and threonine than the traditional landrace cultivar. These metabolic differences are linked to enhanced stress tolerance and the activation of defense pathways, imbuing these cultivars with improved resistance characteristics. The present study provides fundamental insights into the metabolic basis of disease resistance in chili peppers, emphasizing the importance of multi-resistant varieties to ensure sustainable agriculture and food security. These resistant varieties ensure a stable supply of high-quality peppers, contributing to safer and more sustainable food production systems.

Red chili powder dietary supplementation regularized the performance, hematobiochemical indices, oxidative status, and 8-hydroxy-2'-deoxyguanosine of aflatoxin B1 exposed broiler chickens

The effects of red chili powder dietary supplementation on the performance, hematobiochemical indices, oxidative status, and DNA damage in broiler chickens fed aflatoxin B1 (AFB1) contaminated diets were studied. Two hundred and forty Cobb 500 breed day-old broiler chicks were randomly distributed into control group (CONT), 0.5 mg/kg AFB1-exposed group (AFTB), 0.5 g/kg red chili pericarp powder supplementation alongside the 0.5 mg/kg AFB1 exposed group (RCPA), and 0.5 g/kg red chili seed powder supplementation alongside the 0.5 mg/kg AFB1 exposed group (RCSA). The red chili supplementation, in both pericarp powder and seed powder, positively influenced broiler performance by improving (P < 0.05) weight gain, feed intake, and feed conversion ratio, with a reduction in mortality rates compared to the AFTB group. Hematological indices showed that AFB1 exposure decreased (P < 0.05) the red blood cell count, packed cell volume, and hemoglobin (Hb) concentration, but the red chili supplementation mitigated these reductions. Additionally, total white blood cell counts were maintained (P > 0.05) in red chili-supplemented groups compared to CONT. Red chili supplementation increased (P < 0.05) the total protein and globulin concentrations and reduced (P < 0.05) liver enzyme levels compared to the AFTB group. The oxidative enzyme levels in RCPA and RCSA were similar (P > 0.05) to CONT groups. The red chili supplementations counteracted DNA damage, as reflected by similar (P > 0.05) 8-hydroxy-2'-deoxyguanosine levels recorded in RCPA, RCSA, and CONT groups levels. These findings suggest that 0.5 g/kg red chili supplementation has the potential to ameliorate the adverse effects of AFB1 exposure on broiler chickens, improving their performance and health.

Metabolomic characterization of 5 native Peruvian chili peppers (Capsicum spp.) as a tool for species discrimination

Many species of chili peppers have overlapping morphological characters and delimitation by visual descriptors in many cases fails to differentiate one species from another. In Peru, there are 413 accessions of native chili pepper and 296 accessions of rocotos conserved in the Germplasm Collections of the National Institute of Agrarian Innovation (INIA), of which five accessions (three species from three locations) were selected for the present metabolomic study. The Discrimination of the three species of native chili peppers and identification of biomarkers was performed using untargeted metabolomic approach based on profiling by UHPLC-HRMS and multivariate data analysis. The samples of fresh chili peppers (whole fruit) from Chincha area were used to construct an OPLS-DA model. To validate the biomarkers (identified 15 biomarkers, mainly flavonoids), an external validation set of the OPLS-DA model was constructed using Chiclayo and Huaral collection datasets. Consequently, the OPLS-DA based on Chincha samples model has a high predictive capacity demonstrating that the biomarkers have a high probability of continuity in any culture space, being successful in discriminating the species by untargeted metabolomics.

Metabolomic Analysis Identifies Differences Between Wild and Domesticated Chili Pepper Fruits During Development (Capsicum annuum L.)

Capsicum spp. members are a rich source of specialized compounds due to their secondary metabolism. Some metabolic pathways have suffered modifications during the domestication process and improvement of agricultural traits. Here, we compared non-targeted LC-MS profiles from several areas: wild accessions (C. annuum L. var. glabriusculum), domesticated cultivars (C. annuum L.), and the F1 progeny of a domesticated, and a wild accession cross (in both directions) throughout seven stages of fruit development of chili pepper fruits. The main detected differences were in glycerophospholipid metabolism, flavone and flavonol biosynthesis, sphingolipid metabolism, and cutin biosynthesis. The domesticated group exhibited a higher abundance in 12'-apo-β-carotenal, among others capsorubin, and β-tocopherol. Palmitic acid and derivates, terpenoids, and quercitrin were prevalent in the wild accessions. F1 progeny showed a higher abundance of capsaicin, glycol stearate, and soyacerebroside I. This work supports evidence of the side-affectation of trait selection over the metabolism of chili pepper fruit development. Furthermore, it was also observed that there was a possible heterosis effect over the secondary metabolism in the F1 progeny.

Dynamics of Bioactive Compounds during Spontaneous Fermentation of Paste Obtained from Capsicum ssp.-Stage towards a Product with Technological Application

Six cultivars of chili (Cherry, Bulgarian Chilli, Cayenne, Fatalii, Habanero, and Carolina Reaper) from two species (Capsicum annuum and Capsicum chinense) have been studied. Anaerobic, spontaneous fermentation of pure chili paste was conducted for 21 days at 20 °C. The unfermented (UCP) and fermented chili pastes (FCP) were both subjected to physicochemical and microbiological characterization consisting of capsaicinoid, ascorbic acid, short-chain organic acids, phenolic compounds, and simple sugars analysis. Cell viability for Lactic Acid Bacteria (LAB) and Leuconostoc was determined before and after fermentation. Results indicate that capsaicinoids are very stable compounds, as notable differences between unfermented and fermented samples could not be seen. Carolina Reaper and Fatalii cultivars were amongst the most pungent, whereas Cherry, Cayenne, and Bulgarian types were low to moderate in pungency. Average loss of total ascorbic acid was 19.01%. Total phenolic compounds ranged between 36.89−195.43 mg/100 g for the fresh fruits and 35.60−180.40 mg/100 g for the fermented product. Losses through fermentation were not significant (p < 0.05). Plate counts indicated low initial numbers for LAB in the fresh samples, values ranging between 50−3700 CFU/g (colony-forming units). After fermentation, day 21, concentration of LAB (3.8 × 106−6.2 × 108 CFU/g) was high in all samples. Fermented chilies paste with enhanced biochemical and bacterial properties might further be used in the technology of vegetable (brining) or meat (curing) products, processes that generally involve the fermenting activity of different microorganisms, especially (LAB). Thus, the purpose of this research was the investigation of biochemical and microbial transformations that naturally occur in fermented chilies with a future perspective towards technological applications in cured meat products.

Transcriptional Regulation of Ripening in Chili Pepper Fruits (Capsicum spp.)

Chili peppers represent a very important horticultural crop that is cultivated and commercialized worldwide. The ripening process makes the fruit palatable, desirable, and attractive, thus increasing its quality and nutritional value. This process includes visual changes, such as fruit coloration, flavor, aroma, and texture. Fruit ripening involves a sequence of physiological, biochemical, and molecular changes that must be finely regulated at the transcriptional level. In this review, we integrate current knowledge about the transcription factors involved in the regulation of different stages of the chili pepper ripening process.

Contrast optimization of mass spectrometry imaging (MSI) data visualization by threshold intensity quantization (TrIQ)

Mass spectrometry imaging (MSI) enables the unbiased characterization of surfaces with respect to their chemical composition. In biological MSI, zones with differential mass profiles hint towards localized physiological processes, such as the tissue-specific accumulation of secondary metabolites, or diseases, such as cancer. Thus, the efficient discovery of 'regions of interest' (ROI) is of utmost importance in MSI. However, often the discovery of ROIs is hampered by high background noise and artifact signals. Especially in ambient ionization MSI, unmasking biologically relevant information from crude data sets is challenging. Therefore, we implemented a Threshold Intensity Quantization (TrIQ) algorithm for augmenting the contrast in MSI data visualizations. The simple algorithm reduces the impact of extreme values ('outliers') and rescales the dynamic range of mass signals. We provide an R script for post-processing MSI data in the imzML community format (https://bitbucket.org/lababi/msi.r) and implemented the TrIQ in our open-source imaging software RmsiGUI (https://bitbucket.org/lababi/rmsigui/). Applying these programs to different biological MSI data sets demonstrated the universal applicability of TrIQ for improving the contrast in the MSI data visualization. We show that TrIQ improves a subsequent detection of ROIs by sectioning. In addition, the adjustment of the dynamic signal intensity range makes MSI data sets comparable.

Transcriptome Analyses Throughout Chili Pepper Fruit Development Reveal Novel Insights into the Domestication Process

Chili pepper (Capsicum spp.) is an important crop, as well as a model for fruit development studies and domestication. Here, we performed a time-course experiment to estimate standardized gene expression profiles with respect to fruit development for six domesticated and four wild chili pepper ancestors. We sampled the transcriptomes every 10 days from flowering to fruit maturity, and found that the mean standardized expression profiles for domesticated and wild accessions significantly differed. The mean standardized expression was higher and peaked earlier for domesticated vs. wild genotypes, particularly for genes involved in the cell cycle that ultimately control fruit size. We postulate that these gene expression changes are driven by selection pressures during domestication and show a robust network of cell cycle genes with a time shift in expression, which explains some of the differences between domesticated and wild phenotypes.

Influence of intra and inter species variation in chilies (Capsicum spp.) on metabolite composition of three fruit segments

Twenty-one different cultivars from four different species were examined. The highest dry weight was present in seeds (between 35 and 50%) and the average water content was 60%. Placenta and pericarp contained on average 86% water. Total sugars variation between species was 60%. The most concentrated in the various cultivar pericarps were ascorbic acid ranging from 368.1 to 2105.6 mg/100 g DW and citric acid ranging from 1464.3 to 9479.9 mg/100 g DW. Total phenolic content ranged from 2599.1 mg/100 DW in 'Chilli AS- Rot' to 7766.7 mg/100 g DW in 'Carolina Reaper'. The placenta had 23.5 times higher phenolic content than seeds. C. chinense and C. chinense × C. frutescens had 3.5 to 5 times higher capsaicinoid content compared to C. annuum and C. baccatum, with 'Carolina Reaper' having the highest content at 7334.3 mg/100 g DW and 'Chilli AS- Rot' the lowest (318.7 mg/100 g DW).

Special Issue on "Fruit Metabolism and Metabolomics"

Over the past 10 years, knowledge about several aspects of fruit metabolism has been greatly improved. Notably, high-throughput metabolomic technologies have allowed quantifying metabolite levels across various biological processes, and identifying the genes that underly fruit development and ripening. This Special Issue is designed to exemplify the current use of metabolomics studies of temperate and tropical fruit for basic research as well as practical applications. It includes articles about different aspects of fruit biochemical phenotyping, fruit metabolism before and after harvest, including primary and specialized metabolisms, and bioactive compounds involved in growth and environmental responses. The effect of genotype, stages of development or fruit tissue on metabolomic profiles and corresponding metabolism regulations are addressed, as well as the combination of other omics with metabolomics for fruit metabolism studies.