Metabolite biodiversity in pepper (Capsicum) fruits of thirty-two diverse accessions: variation in health-related compounds and implications for breeding

Metabolite profiling reveals differential accumulation of secondary metabolites related to flavour and colour across four heirloom chilli landraces

Chillies from Northeast India exhibit wide variability in fruit morphology, pungency, bearing habit and crop duration. An untargeted metabolite profiling using LC-HRMS of four 'heirloom' pungent landraces viz. Naga chilli (AL-1), Dalle khursani (AL-2), Sohmynken khnai (AL-3), and J-41(B) was performed and compared with Kashi anmol (KA). While AL-2, J-41(B) and KA belong to C. annuum species, AL-1 is categorised as C. chinense and AL-3 is C. frutescens. A total of 6990 consistent peaks of monoisotopic masses were detected, out of which 2702 metabolites were identified using accurate mass error < 10 ppm. A higher number of differentially accumulated metabolites were seen in J-41(B) versus AL-3 (1376), followed by J-41(B) versus AL-2 (1365), J-41(B) versus AL-1 (1257), KA versus AL-2 (649), AL-3 versus KA (616), KA versus AL-1 (594) and J-41(B) versus KA (413). Variation among species was higher than variation within species. Pathway analysis identified fatty acid, carotenoid, flavonoid and capsaicinoid as key pathways. We identified eight major categories of metabolites, including fatty acids, sterol lipids, and flavonoids, which together account for over 70% of the significantly expressed metabolites across the genotypes. This study explores untargeted metabolites in various chilli species, offering insights into the biochemical and molecular mechanisms which may play a role in governing important fruit traits. Identification of key metabolites and underlying alleles for twenty-one genes across three pathways (flavonoid, capsaicinoid and carotenoid) suggests that the metabolites and associated alleles identified in this study can be used as biomarkers for further characterization of these heirloom chilli and could provide distinct parameter(s) in distinguishing improved cultivars from landraces. This will contribute towards breeding programs in aiding selection of fruits of the desirable traits.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-025-01576-4.

Transcription factor CaPHR3 enhances phosphate starvation tolerance by up-regulating the expression of the CaPHT1;4 phosphate transporter gene in pepper

Plants frequently encounter phosphate (Pi) starvation due to its scarce availability in soil, necessitating an adaptive phosphate starvation response (PSR). This study explores this adaptation in pepper (Capsicum annuum L.) under low-Pi stress, focusing on the PHOSPHATE STARVATION RESPONSE (PHR) gene family. We observably halted shoot growth but promoted root elongation in pepper seedlings under low-Pi conditions, significantly impacting regulatory networks. Our research identified 13 PHR transcription factors in pepper, particularly noting that CaPHR3 rapidly up-regulates in response to low-Pi stress. Overexpressing CaPHR3 in Arabidopsis thaliana enhanced Pi starvation tolerance by modulating PSR-related genes and mitigated hypersensitivity in the Atphr1phl1 double mutant. Furthermore, CaPHR3 binds to the P1BS motif in the pepper PHOSPHATE TRANSPORTER 1;4 (PHT1;4) promoter to boost its expression under Pi deficiency. This activation increased Pi uptake and starvation tolerance when overexpressed. Overall, we pinpointed key players in the PSR mechanism through the CaPHR3-CaPHT1;4 pathway, contributing significantly to our understanding of Pi homeostasis and adaptive strategies in pepper under Pi-deficient conditions.

Susceptibility of Capsicum varieties to Thaumatotibia leucotreta (Lepidoptera: Tortricidae) infestation for production optimization

Thaumatotibia leucotreta Meyrick (Lepidoptera: Tortricidae) is a major threat to the production and marketing of pepper (Capsicum spp.) in Ghana. To reduce the damage of the pest on pepper farming, it is important to find appropriate control methods, which may include the use of resistant host plants. This study investigated the relative susceptibility of 6 pepper varieties commonly cultivated in Ghana: Legon 18, Bird's eye, Scotch bonnet, Cayenne, KA2, and sweet pepper (Yolo wonder+ variety). Choice and no-choice ovipositional preference tests were conducted and the population growth rate of T. leucotreta was determined by establishing life table parameters including the net reproductive rates (R0), the mean generation time (G), intrinsic rate of natural increase (rm), the population doubling time (T), and the finite rate of increase (λ). In the no-choice test, females exhibited oviposition preference for sweet pepper (12.08 eggs/fruit), while Bird's eye was the least preferred (5.00 eggs/fruit). The same results were observed in the choice test. However, the population growth rate of T. leucotreta was highest on the Scotch bonnet and Cayenne, with rm of 0.124 and 0.127, respectively, while the Bird's eye and sweet pepper recorded the least rm of 0.116. Thus, the tested varieties had varying levels of susceptibility to T. leucotreta infestation. Bird's eye was the least susceptible variety, while Cayenne and Scotch bonnet were the most susceptible varieties. These findings could direct farmers on the choices of pepper varieties for cultivation and proffer potential opportunities to breed new varieties resistant to T. leucotreta infestation.

Integrated metabolome and transcriptome analysis provides clues to fruit color formation of yellow, orange, and red bell pepper

Fruit color is a crucial trait for bell pepper. To investigate the mechanism of color formation, three bell pepper lines with different color (yellow, orange and red) were used as materials to conduct comprehensive targeted metabolomic and transcriptomic analyses. During the process of fruit development, 54 carotenoids metabolites were discovered, exhibiting unique accumulation patterns and notable variety specificity. The types and content of carotenoids in orange fruit (OM) were notably greater compared to the other two varieties. Red pigment (capsanthin and capsorubin) was specifically enriched in red fruit (RM), and yellow pigment (lutein and zeaxanthin) is the highest in yellow fruit (YM) and OM. Five modules positively correlated with carotenoid accumulation and one negative module was determined by weighted gene co-expression network analysis (WGCNA). Additionally, transcription factors (TFs) and hub genes related to carotenoid synthesis were predicted. By elucidating the regulation of 7 key carotenoid metabolites by 14 critical genes and 5 key TFs, we constructed a comprehensive carotenoid biosynthesis metabolic network that comprehensively explains the pigment changes observed in green and mature pepper fruit. Overall, the results not only provide important insights into carotenoid synthesis pathway, but also lay a solid base for revealing the mechanism of bell pepper color transformation.

Multi-omics analysis provides insights into the mechanism underlying fruit color formation in Capsicum

Fruit color is a crucial attribute of fruit quality in peppers (Capsicum spp.). However, few studies have focused on the mechanism of color formation in immature pepper fruits. In this study, the light-yellow color observed in immature CSJ009 fruits compared to CSJ010 could be attributed to decreased chlorophyll and carotenoid pigments. Through integrated analysis of the transcriptome and metabolome of CSJ009 and CSJ010, we identified 23,930 differentially expressed genes (DEGs) and 345 differentially accumulated metabolites (DAMs). Furthermore, integrated analysis revealed a strong correlation between the HCT-like gene and metabolite MWS0178 (chlorogenic acid). Paraffin section assay revealed that the epidermal cells of immature CSJ010 fruits exhibited a more compact arrangement with significantly greater length than those of CSJ009. Quantitative determination of carotenoids showed that lutein emerged as the predominant carotenoid in immature pepper fruits. Additionally, missense mutation of LCYB2 is likely to lead to a decrease in β-carotene content in immature CSJ009 fruits, whereas CCS may directly catalyze the conversion of lycopene to β-carotene in mature fruits. The null mutation in CCS promoted the biosynthesis of β,ϵ-branch carotenoids leading to lutein being the most abundant carotenoid found in orange CSJ010 fruits. These findings provide important insights into the mechanism underlying color formation in pepper fruits and establish a foundation for the further exploration of color-related genes.

Innovative strategies and challenges mosquito-borne disease control amidst climate change

The revival of the transmission dynamics of mosquito-borne diseases grants striking challenges to public health intensified by climate change worldwide. This inclusive review article examines multidimensional strategies and challenges linked to climate change and the epidemiology of mosquito-borne diseases such as malaria, dengue, Zika, chikungunya, and yellow fever. It delves into how the biology, pathogenic dynamics, and vector distribution of mosquitoes are influenced by continuously rising temperatures, modified rainfall patterns, and extreme climatic conditions. We also highlighted the high likelihood of malaria in Africa, dengue in Southeast Asia, and blowout of Aedes in North America and Europe. Modern predictive tools and developments in surveillance, including molecular gears, Geographic Information Systems (GIS), and remote sensing have boosted our capacity to predict epidemics. Integrated data management techniques and models based on climatic conditions provide a valuable understanding of public health planning. Based on recent data and expert ideas, the objective of this review is to provide a thoughtful understanding of existing landscape and upcoming directions in the control of mosquito-borne diseases regarding changing climate. This review determines emerging challenges and innovative vector control strategies in the changing climatic conditions to ensure public health.

Mapping and cloning of pepper fruit color-related genes based on BSA-seq technology

Fruit color is an important qualitative trait that greatly influences the marketability of peppers. Fruit color can be divided into two categories. Green fruit color denotes commercial maturity, whereas ripe fruit indicates physiological maturity. Herein, segregation populations were created using the 'D24' with pale green in the green fruit stage, orange in the mature fruit stage, and 'D47' with green in the green fruit stage and red in the mature fruit stage. BSA-seq and genetic linkage map analysis revealed green fruit color was linked to (gyqtl1.1) on Chr1 and (gyqtl10.1) on Chr10, while mature fruit color was linked to Chr6. Using functional annotation, sequence, and expression analysis, we speculate that an SNP mutation in the CapGLK2 gene at the gyqtl10.1 interval could initiate premature termination of translation, thus yielding green to pale green fruits in D47. Conversely, the orange color in mature D24 fruits is due to the Indel-mediated premature termination of translation of the CapCCS gene. Our research offers a theoretical foundation for choosing different varieties of pepper fruit based on their color.

The Influence of Different Factors on the Metabolism of Capsaicinoids in Pepper (Capsicum annuum L.)

Pepper is a globally cultivated vegetable known for its distinct pungent flavor, which is derived from the presence of capsaicinoids, a class of unique secondary metabolites that accumulate specifically in pepper fruits. Since the accumulation of capsaicinoids is influenced by various factors, it is imperative to comprehend the metabolic regulatory mechanisms governing capsaicinoids production. This review offers a thorough examination of the factors that govern the metabolism of capsaicinoids in pepper fruit, with a specific focus on three primary facets: (1) the impact of genotype and developmental stage on capsaicinoids metabolism, (2) the influence of environmental factors on capsaicinoids metabolism, and (3) exogenous substances like methyl jasmonate, chlorophenoxyacetic acid, gibberellic acid, and salicylic acid regulate capsaicinoid metabolism. The findings of this study are expected to enhance comprehension of capsaicinoids metabolism and aid in the improvement of breeding and cultivation practices for high-quality pepper in the future.

The genetic architecture of the pepper metabolome and the biosynthesis of its signature capsianoside metabolites

Capsicum (pepper) is among the most economically important species worldwide, and its fruits accumulate specialized metabolites with essential roles in plant environmental interaction and human health benefits as well as in conferring their unique taste. However, the genetics underlying differences in metabolite presence/absence and/or accumulation remain largely unknown. In this study, we carried out a genome-wide association study as well as generating and characterizing a novel backcross inbred line mapping population to determine the genetic architecture of the pepper metabolome. This genetic analysis provided over 1,000 metabolic quantitative trait loci (mQTL) for over 250 annotated metabolites. We identified 92 candidate genes involved in various mQTLs. Among the identified loci, we described and validated a gene cluster of eleven UDP-glycosyltransferases (UGTs) involved in monomeric capsianoside biosynthesis. We additionally constructed the gene-by-gene-based biosynthetic pathway of pepper capsianoside biosynthesis, including both core and decorative reactions. Given that one of these decorative pathways, namely the glycosylation of acyclic diterpenoid glycosides, contributes to plant resistance, these data provide new insights and breeding resources for pepper. They additionally provide a blueprint for the better understanding of the biosynthesis of species-specific natural compounds in general.

A multifunctional role for riboflavin in the yellow nectar of Capsicum baccatum and Capsicum pubescens

A few Capsicum (pepper) species produce yellow-colored floral nectar, but the chemical identity and biological function of the yellow pigment are unknown. A combination of analytical biochemistry techniques was used to identify the pigment that gives Capsicum baccatum and Capsicum pubescens nectars their yellow color. Microbial growth assays, visual modeling, and honey bee preference tests for artificial nectars containing riboflavin were used to assess potential biological roles for the nectar pigment. High concentrations of riboflavin (vitamin B2) give the nectars their intense yellow color. Nectars containing riboflavin generate reactive oxygen species when exposed to light and reduce microbial growth. Visual modeling also indicates that the yellow color is highly conspicuous to bees within the context of the flower. Lastly, field experiments demonstrate that honey bees prefer artificial nectars containing riboflavin. Some Capsicum nectars contain a yellow-colored vitamin that appears to play roles in (1) limiting microbial growth, (2) the visual attraction of bees, and (3) as a reward to nectar-feeding flower visitors (potential pollinators), which is especially interesting since riboflavin is an essential nutrient for brood rearing in insects. These results cumulatively suggest that the riboflavin found in some Capsicum nectars has several functions.

Comparative chloroplast genome analyses of cultivated and wild Capsicum species shed light on evolution and phylogeny

The chloroplast (cp.) genome, also known as plastome, plays crucial roles in plant survival, adaptation, and evolution. The stable genetic structure of cp. genomes provides an ideal system for investigating species evolution. We sequenced three complete cp. genome sequences of Capsicum species and analyzed them using sequences of various Capsicum species retrieved from the NCBI database. The cp. genome of Capsicum species maintains a well-preserved quadripartite structure consisting of two inverted repeats (IRs) flanked by a large single copy (LSC) region and a small single copy (SSC) region. The sizes of cp. genome sequences ranged from 156,583 bp (C. lycianthoides) to 157,390 bp (C.pubescens). A total of 127-132 unique genes, including 83-87 protein-coding, 36-37 tRNA, and eight rRNA genes, were predicted. Comparison of cp. genomes of 10 Capsicum species revealed high sequence similarity in genome-wide organization and gene arrangements. Fragments of trnT-UGU/trnL-UAA, ccsA, ndhD, rps12, and ycf1 were identified as variable regions, and nucleotide variability of LSC and SSC was higher than that of IR. Phylogenetic speciation analysis showed that the major domesticated C. annuum species were the most extensively divergent species and closely related to C. tovarii and C. frutescens. Analysis of divergent times suggested that a substantial range of speciation events started occurring ~ 25.79 million years ago (Mya). Overall, comparative analysis of cp. genomes of Capsicum species not only offers new insights into their genetic variation and phylogenetic relationships, but also lays a foundation for evolutionary history, genetic diversity, conservation, and biological breeding of Capsicum species.

An Analysis of Capsaicin, Dihydrocapsaicin, Vitamin C and Flavones in Different Tissues during the Development of Ornamental Pepper

As a fruit and vegetable crop, the ornamental pepper is not just highly ornamental but also rich in nutritional value. The quality of ornamental pepper fruits is given in their contents of capsaicin, vitamin C (VC), flavonoids and total phenols. The study concentrated on the accumulation of capsaicin and dihydrocapsaicin in different tissues of 18 peppers during fruit growth and development. The results showed that the pericarp and placenta contained significantly higher levels of capsaicin than dihydrocapsaicin. Additionally, the placenta contained significantly higher levels of both capsaicin and dihydrocapsaicin compared to the pericarp. The content of capsaicin was in the range of 0-6.7915 mg·g-1, the range of dihydrocapsaicin content was 0-5.329 mg·g-1. Interestingly, we found that the pericarp is rich in VC (5.4506 mg·g-1) and the placenta is high in flavonoids (4.8203 mg·g-1) and total phenols (119.63 mg·g-1). The capsaicin is the most important component using the correlation analysis and principal component analysis. The qPCR results substantiated that the expression of genes in the placenta was significantly higher than that in the pericarp and that the expression of genes in green ripening stage was higher than that in red ripening stage. This study could be utilized to select the best ripening stages and tissues to harvest peppers according to the use of the pepper and to the needs of producers. It not only provides a reference for quality improvement and processing for consumers and market but also provides a theoretical basis for high-quality pepper breeding.

Response of Tomato Plants, Ailsa Craig and Carotenoid Mutant tangerine, to Simultaneous Treatment by Low Light and Low Temperature

Tomato (Solanum lycopersicum L.) plants, wild type Ailsa Craig, and carotenoid mutant tangerine that accumulates prolycopene instead of all-trans-lycopene were exposed to a combined treatment by low light and low temperature for 5 days. The ability of plants to recover from the stress after development for 3 days at control conditions was followed as well. The suffered oxidative stress was evaluated by the extent of pigment content, lipid peroxidation, membrane stability, and H2O2 generation. The level of MDA content under combined treatment in tangerine implies that the mutant demonstrates lower sensitivity to stress in comparison with Ailsa Craig. The oxidative protective strategy of plants was estimated by following the antioxidant and antiradical activity of phenolic metabolites, including anthocyanins, as well as the activities of antioxidant enzymes superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT). Presented results revealed that the oxidative stress was much stronger expressed after exposure of both types of plants to low light combined with low temperature compared to that after treatment with only low light. The most significant antioxidant protection was provided by phenolic substances, including anthocyanins. The lower sensitivity of tangerine plants to low light can be attributed to the higher activity of the antioxidant enzyme CAT.

Morzeddhu: A Unique Example of a Traditional and Sustainable Typical Dish from Catanzaro

"Morzeddhu" in the local dialect of Catanzaro ("Morzello" in Italian) is an official typical dish of the capital of the Calabria region. It is a peasant dish, almost unknown at an international level, that labels, in an extraordinary way, the culinary identity of Catanzaro, a city founded around the X century. After America's discovery, its preparation was optimized and definitively fixed. Its recipe is strictly based on a cow's "fifth quarter" combined with spicy and typical Mediterranean vegetables. Remarkably, no pork meat is used, and when all traditional ingredients are included in the complex and quite long preparation of this special dish, it can deserve the title of "Illustrissimo". This review provides a scientific description of Illustrissimo, emphasizing its unique properties and connection to the circular economy, food security, and the Mediterranean diet. We also highlight its unique quality compared to other alternatives through an analysis of their nutritional facts and bioactive compounds. Nutritionally, offal and fifth quarter components are a rich source of high-quality protein, with lower levels of total fat and saturated fatty acids compared to other meat cuts. In essence, this dish offers a great example of a high-quality yet affordable meal, aligning perfectly with a Mediterranean diet.

Cloning and Analysis of Expression of Genes Related to Carotenoid Metabolism in Different Fruit Color Mutants of Pepper (Capsicum annuum L.)

The formation of fruit color in pepper is closely related to the processes of carotenoid metabolism. In this study, red wild-type pepper XHB, SP01, PC01 and their corresponding mutants H0809 (orange), SP02 (yellow), and PC02 (orange) were used as research materials. The Ggps, Psy, Lcyb, Crtz, Zep, and Ccs genes involved in carotenoid biosynthesis were cloned, and bioinformatics and expression analyses were carried out. The results showed that the full lengths of the six genes were 1110 bp, 2844 bp, 1497 bp, 2025 bp, 510 bp, and 1497 bp, and they encoded 369, 419, 498, 315, 169, and 498 amino acids, respectively. Except for the full-length Ccs gene, which could not be amplified in the yellow mutant SP02 and the orange mutant PC02, the complete full-length sequences of the other genes could be amplified in different materials, indicating that the formation of fruit color in the SP02 and PC02 mutants could be closely related to the deletion or mutation of the Ccs gene. The analytical results of real-time quantitative reverse transcription PCR (qRT-PCR) showed that the Ggps, Psy, Lcyb, Crtz, and Zep genes were expressed at different developmental stages of three pairs of mature-fruit-colored materials, but their patterns of expression were not consistent. The orange mutant H0809 could be amplified to the full Ccs gene sequence, but its expression was maintained at a lower level. It showed a significant difference in expression compared with the wild-type XHB, indicating that the formation of orange mutant H0809 fruit color could be closely related to the different regulatory pattern of Ccs expression. The results provide a theoretical basis for in-depth understanding of the molecular regulatory mechanism of the formation of color in pepper fruit.

Plant hormones and secondary metabolites under environmental stresses: Enlightening defense molecules

The climatic changes have great threats to sustainable agriculture and require efforts to ensure global food and nutritional security. In this regard, the plant strategic responses, including the induction of plant hormones/plant growth regulators (PGRs), play a substantial role in boosting plant immunity against environmental stress-induced adversities. In addition, secondary metabolites (SMs) have emerged as potential 'stress alleviators' that help plants to adapt against environmental stressors imposing detrimental impacts on plant health and survival. The introduction of SMs in plant biology has shed light on their beneficial effects in mitigating environmental crises. This review explores SMs-mediated plant defense responses and highlights the crosstalk between PGRs and SMs under diverse environmental stressors. In addition, genetic engineering approaches are discussed as a potential revenue to enhance plant hormone-mediated SM production in response to environmental cues. Thus, the present review aims to emphasize the significance of SMs implications with PGRs association and genetic approachability, which could aid in shaping the future strategies that favor agro-ecosystem compatibility under unpredictable environmental conditions.

Capsaicinoids and Their Effects on Cancer: The "Double-Edged Sword" Postulate from the Molecular Scale

Capsaicinoids are a unique chemical species resulting from a particular biosynthesis pathway of hot chilies (Capsicum spp.) that gives rise to 22 analogous compounds, all of which are TRPV1 agonists and, therefore, responsible for the pungency of Capsicum fruits. In addition to their human consumption, numerous ethnopharmacological uses of chili have emerged throughout history. Today, more than 25 years of basic research accredit a multifaceted bioactivity mainly to capsaicin, highlighting its antitumor properties mediated by cytotoxicity and immunological adjuvancy against at least 74 varieties of cancer, while non-cancer cells tend to have greater tolerance. However, despite the progress regarding the understanding of its mechanisms of action, the benefit and safety of capsaicinoids' pharmacological use remain subjects of discussion, since CAP also promotes epithelial-mesenchymal transition, in an ambivalence that has been referred to as "the double-edge sword". Here, we update the comparative discussion of relevant reports about capsaicinoids' bioactivity in a plethora of experimental models of cancer in terms of selectivity, efficacy, and safety. Through an integration of the underlying mechanisms, as well as inherent aspects of cancer biology, we propose mechanistic models regarding the dichotomy of their effects. Finally, we discuss a selection of in vivo evidence concerning capsaicinoids' immunomodulatory properties against cancer.

Phenolic Compounds and Capsaicinoids in Three Capsicum annuum Varieties: From Analytical Characterization to In Silico Hypotheses on Biological Activity

The affinity of specific phenolic compounds (PCs) and capsaicinoids (CAPs) present in three Capsicum annuum varieties (Friariello, Cayenne and Dzuljunska Sipka) to the transient receptor potential vanilloid member 1 (TRPV1) was investigated by integrating an analytic approach for the simultaneous extraction and analysis through high-performance liquid chromatography coupled with ion trap mass spectrometry (HPLC/ITMS) and UV detection (HPLC-UV) of PCs and CAPs and structural bioinformatics based on the protein modelling and molecular simulations of protein-ligand docking. Overall, a total of 35 compounds were identified in the different samples and CAPs were quantified. The highest content of total polyphenols was recorded in the pungent Dzuljunska Sipka variety (8.91 ± 0.05 gGAE/Kg DW) while the lowest was found in the non-pungent variety Friariello (3.58 ± 0.02 gGAE/Kg DW). Protein modelling generated for the first time a complete model of the homotetrameric human TRPV1, and it was used for docking simulations with the compounds detected via the analytic approach, as well as with other compounds, as an inhibitor reference. The simulations indicate that different capsaicinoids can interact with the receptor, providing details on the molecular interaction, with similar predicted binding energy values. These results offer new insights into the interaction of capsaicinoids with TRPV1 and their possible actions.

Effect of Low Light on Photosynthetic Performance of Tomato Plants-Ailsa Craig and Carotenoid Mutant Tangerine

The effects of a five-day treatment with low light intensity on tomato plants-Ailsa Craig and tangerine mutant-at normal and low temperatures and after recovery for three days under control conditions were investigated. The tangerine tomato, which has orange fruits, yellowish young leaves, and pale blossoms, accumulates prolycopene rather than all-trans lycopene. We investigated the impact of low light at normal and low temperatures on the functioning and effectiveness of photosynthetic apparatuses of both plants. The photochemical activities of Photosystem I (PSI) and Photosystem II (PSII) were assessed, and the alterations in PSII antenna size were characterized by evaluating the abundance of PSII-associated proteins Lhcb1, Lhcb2, CP43, and CP47. Alterations in energy distribution and interaction of both photosystems were analyzed using 77K fluorescence. In Aisla Craig plants, an increase in thylakoid membrane fluidity was detected during treatment with low light at a low temperature, while for the tangerine mutant, no significant change was observed. The PSII activity of thylakoids from mutant tangerine was more strongly inhibited by treatment with low light at a low temperature while low light barely affected PSII in Aisla Craig. The obtained data indicated that the observed differences in the responses of photosynthetic apparatuses of Ailsa Craig and tangerine when exposed to low light intensity and suboptimal temperature were mainly related to the differences in sensitivity and antenna complexes of PSII.

Capsicum chinense var. BRS Moema: chemical characterization by HPLC-ESI-MS/MS and antiproliferative screening

Capsiate and phenolics present in the free, esterified, glycosylated, and insoluble-bound forms of BRS Moema peppers were characterized and quantified using UHPLC-ESI-MS/MS. Additionally, the in vitro antiproliferative activity of BRS Moema extract was evaluated. The peppers showed considerable quantities of capsiate and phenolic compounds. Esterified phenolics were the main fraction, followed by the insoluble-bound fraction, indicating that relying solely on the extraction of soluble phenolics may underestimate the total phenolic content. Among the fourteen phenolics identified in extract fractions, gallic acid was the major constituent. Phenolic fractions displayed high antioxidant capacity by TEAC and ORAC assays. Nevertheless, the correlation between phenolic compounds and antioxidant activity suggested that other bioactive or phenolic compounds may contribute to the overall phenolic compounds and antioxidant capacity of the obtained fractions. Concerning the antiproliferative activity, the extract did not exhibit any effect on cell proliferation within the evaluated concentration range. These findings indicated that BRS Moema peppers can serve as a rich source of phenolic compounds. Therefore, fully utilizing them could bring advantages to the food and pharmaceutical industries, as well as to consumers and producers.

Antioxidant potential and factors influencing the content of antioxidant compounds of pepper: A review with current knowledge

The use of natural food items as antioxidants has gained increasing popularity and attention in recent times supported by scientific studies validating the antioxidant properties of natural food items. Peppers (Capsicum spp.) are also important sources of antioxidants and several studies published during the last few decades identified and quantified various groups of phytochemicals with antioxidant capacities as well as indicated the influence of several pre- and postharvest factors on the antioxidant capacity of pepper. Therefore, this review summarizes the research findings on the antioxidant activity of pepper published to date and discusses their potential health benefits as well as the factors influencing the antioxidant activity in pepper. The major antioxidant compounds in pepper include capsaicinoids, capsinoids, vitamins, carotenoids, phenols, and flavonoids, and these antioxidants potentially modulate oxidative stress related to aging and diseases by targeting reactive oxygen and nitrogen species, lipid peroxidation products, as well as genes for transcription factors that regulate antioxidant response elements genes. The review also provides a systematic understanding of the factors that maintain or improve the antioxidant capacity of peppers and the application of these strategies offers options to pepper growers and spices industries for maximizing the antioxidant activity of peppers and their health benefits to consumers. In addition, the efficacy of pepper antioxidants, safety aspects, and formulations of novel products with pepper antioxidants have also been covered with future perspectives on potential innovative uses of pepper antioxidants in the future.

Antifungal activity of chili pepper extract with potential for the control of some major pathogens in grapevine

BACKGROUND

In recent years, biofungicides have drawn increasing interest in vineyards for a more sustainable integrated and copper-limited pest management. Among alternatives, botanicals could represent valuable tools, being rich sources of biologically active compounds. Conversely to the well-known antioxidant and biological properties in relation to health benefits, investigation on bioactivity of hot pungent Capsicum sp. products against fungal phytopathogens in vineyards is still scarce. Therefore, the present study aimed at exploring the biologically active compounds profile of a chili pepper (Capsicum chinense Jacq.) pod extract and its antimicrobial properties against some of the major fungal and Oomycetes pathogens of grapevine, including Botrytis cinerea Pers., Guignardia bidwellii (Ellis) Viala & Ravaz and Plasmopara viticola (Berk. & M.A. Curtis) Berl. & De Toni.

RESULTS

The ethyl acetate-extracted oleoresin from the most pungent varieties was rich in capsaicinoids and polyphenols (371.09 and 268.5 μg mg-1 dry weight, respectively). Capsaicin and dihydrocapsaicin, hydroxycinnamic and hydroxybenzoic acids and quercetin derivatives were the most abundant, while carotenoids represented only a minor fraction. The oleoresin was efficient to inhibit all three pathogenic fungi and ED50 values were determined, evidencing that G. bidwellii was the more sensitive (0.233 ± 0.034 mg mL-1 ).

CONCLUSION

The results suggested a potentiality of chili pepper extract for the control of some important grapevine pathogens, their possible application being helpful for the recommended limitation in extensive use of copper in vineyard. The complex mixture of high amounts of capsaicinoids, associated to specific phenolic acids and other minor bioactive components might contribute to the observed antimicrobial action of chili pepper extract. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The Genus Capsicum: A Review of Bioactive Properties of Its Polyphenolic and Capsaicinoid Composition

Chili is one of the world's most widely used horticultural products. Many dishes around the world are prepared using this fruit. The chili belongs to the genus Capsicum and is part of the Solanaceae family. This fruit has essential biomolecules such as carbohydrates, dietary fiber, proteins, and lipids. In addition, chili has other compounds that may exert some biological activity (bioactivities). Recently, many studies have demonstrated the biological activity of phenolic compounds, carotenoids, and capsaicinoids in different varieties of chili. Among all these bioactive compounds, polyphenols are one of the most studied. The main bioactivities attributed to polyphenols are antioxidant, antimicrobial, antihyperglycemic, anti-inflammatory, and antihypertensive. This review describes the data from in vivo and in vitro bioactivities attributed to polyphenols and capsaicinoids of the different chili products. Such data help formulate functional foods or food ingredients.

Characterization of the Key Compounds of Bell Pepper by Spectrophotometry and Gas Chromatography on the Effects of Induced Stress on the Concentration of Secondary Metabolite

Sweet peppers are consumed worldwide, and traditional uses have sparked interest in their applications as dietary antioxidants, which can be enhanced in plants using elicitors. These are endowed with phytochemicals with potential health benefits such as antioxidants, bioavailability, and bioaccessibility. The trend in metabolomics shows us chemical fingerprints linking metabolomics, innovative analytical form, and bioinformatics tools. The objective was to evaluate the impact of multiple stress interactions, elicitor concentrations, and electrical conductivity on the concentration of secondary metabolites to relate their response to metabolic pathways through the foliar application of a cocktail of said elicitors in pepper crops under greenhouse conditions. The extracts were analyzed by spectrophotometry and gas chromatography, and it was shown that the PCA analysis identified phenolic compounds and low molecular weight metabolites, confirming this as a metabolomic fingerprint in the hierarchical analysis. These compounds were also integrated by simultaneous gene and metabolite simulants to obtain effect information on different metabolic pathways. Showing changes in metabolite levels at T6 (36 mM H₂O₂ and 3.6 dS/m) and T7 (0.1 mM SA and 3.6 dS/m) but showing statistically significant changes at T5 (3.6 dS/m) and T8 (0.1 mM SA, 36 mM H₂O₂, and 3.6 dS/m) compared to T1 (32 dS/m) or control. Six pathways changed significantly (p < 0.05) in stress-induced treatments: aminoacyl t-RNA and valine-leucine-isoleucine biosynthesis, and alanine-aspartate-glutamate metabolism, glycoxylate-dicarboxylate cycle, arginine-proline, and citrate. This research provided a complete profile for the characterization of metabolomic fingerprint of bell pepper under multiple stress conditions.

Genetics and breeding of phenolic content in tomato, eggplant and pepper fruits

Phenolic acids and flavonoids are large groups of secondary metabolites ubiquitous in the plant kingdom. They are currently in the spotlight due to the numerous health benefits associated with their consumption, as well as for their vital roles in plant biological processes and in plant-environment interaction. Tomato, eggplant and pepper are in the top ten most consumed vegetables in the world, and their fruit accumulation profiles have been extensively characterized, showing substantial differences. A broad array of genetic and genomic tools has helped to identify QTLs and candidate genes associated with the fruit biosynthesis of phenolic acids and flavonoids. The aim of this review was to synthesize the available information making it easily available for researchers and breeders. The phenylpropanoid pathway is tightly regulated by structural genes, which are conserved across species, along with a complex network of regulatory elements like transcription factors, especially of MYB family, and cellular transporters. Moreover, phenolic compounds accumulate in tissue-specific and developmental-dependent ways, as different paths of the metabolic pathway are activated/deactivated along with fruit development. We retrieved 104 annotated putative orthologues encoding for key enzymes of the phenylpropanoid pathway in tomato (37), eggplant (29) and pepper (38) and compiled 267 QTLs (217 for tomato, 16 for eggplant and 34 for pepper) linked to fruit phenolic acids, flavonoids and total phenolics content. Combining molecular tools and genetic variability, through both conventional and genetic engineering strategies, is a feasible approach to improve phenolics content in tomato, eggplant and pepper. Finally, although the phenylpropanoid biosynthetic pathway has been well-studied in the Solanaceae, more research is needed on the identification of the candidate genes behind many QTLs, as well as their interactions with other QTLs and genes.

CaMYB12-like underlies a major QTL for flavonoid content in pepper (Capsicum annuum) fruit

The regulation of flavonoid biosynthesis is only partially explored in pepper (Capsicum annuum L.). The genetic basis underlying flavonoid variation in pepper fruit was studied. Variation of flavonoids in fruit of a segregating F2 population was studied using LC-MS followed by quantitative trait locus (QTL) analysis. Near-isogenic lines (NILs), BC₁ S₁ populations, virus-induced gene silenced (VIGS) and transgenic overexpression were used to confirm the QTL and the underlying candidate gene. A major QTL for flavonoid content was found in chromosome 5, and a CaMYB12-like transcription factor gene was identified as candidate gene. Near-isogenic lines (NILs) contrasting for CaMYB12-like confirmed its association with the flavonoid content variation. Virus-induced gene silencing (VIGS) of CaMYB12-like led to a significant decrease in the expression of several flavonoid pathway genes and a drastic decrease in flavonoid levels in silenced fruits. Expression of CaMYB12-like in the tomato slmyb12 mutant led to enhanced levels of several flavonoids in the fruit skin. Introgression of the CaMYB12-like allele into two cultivated varieties also increased flavonoid content in their fruits. A combination of metabolomic, genetic and gene functional analyses led to discovery of CaMYB12-like as a major regulator of flavonoid variation in pepper fruit and demonstrated its potential to breed for high-flavonoid content in cultivated pepper.

Comprehensive fruit quality assessment and identification of aroma-active compounds in green pepper (Capsicum annuum L.)

The wrinkled pepper (Capsicum annuum L.) is a type of chili pepper domesticated in northwestern China, with a characteristic flavor. Fifteen wrinkled and four smooth-skinned pepper varieties were evaluated for morphology, texture, color, nutrients, capsaicinoids, and volatile compounds at the mature fruit stage. The sensory evaluation showed wrinkled pepper was superior to smooth pepper in texture, and it has a highly significant correlation (p < 0.01) with cuticle thickness, maximum penetrating force, lignin content, and moisture content. Citric acid was the major organic acid in peppers, accounting for 39.10-63.55% of the total organic acids, followed by quininic acid. The average oxalic acid content of smooth peppers was 26.19% higher than that of wrinkled peppers. The pungency of wrinkled pepper fruits ranged from 1748.9 to 25529.4 SHU, which can be considered slightly to very spicy, while the four smooth varieties ranged between 866.63 and 8533.70 SHU, at slightly to moderately spicy. A total of 199 volatile compounds were detected in the 19 pepper varieties. The average volatile content of wrinkled pepper was 39.79% higher than that of smooth pepper. Twenty-nine volatile compounds, including 14 aldehydes, four alcohols, three esters, three ketones, two furans, one pyrazine, one acid, and one phenol, contributed to the fragrance of peppers and could be regarded as aroma-active compounds, with 2-isobutyl-3-methoxypyrazine being the major contributor among the 19 pepper varieties. Wrinkled pepper can be confidently distinguished from smooth pepper and is of superior quality. The current findings outlined the major texture-related characteristics of pepper as well as the main aroma-active compounds, providing valuable information for pepper quality breeding and consumer guidelines.

Genome-Wide Analysis of the MYB-Related Transcription Factor Family in Pepper and Functional Studies of CaMYB37 Involvement in Capsaicin Biosynthesis

Chili pepper is an important economic vegetable worldwide. MYB family gene members play an important role in the metabolic processes in plant growth and development. In this study, 103 pepper MYB-related members were identified and grouped into nine subfamilies according to phylogenetic relationships. Additionally, a total of 80, 20, and 37 collinear gene pairs were identified between pepper and tomato, pepper and Arabidopsis, and tomato and Arabidopsis, respectively. We performed promoter cis-element analysis and showed that CaMYB-related members may be involved in multiple biological processes such as growth and development, secondary metabolism, and circadian rhythm regulation. Expression pattern analysis indicated that CaMYB37 is significantly more enriched in fruit placenta, suggesting that this gene may be involved in capsaicin biosynthesis. Through VIGS, we confirmed that CaMYB37 is critical for the biosynthesis of capsaicin in placenta. Our subcellular localization studies revealed that CaMYB37 localized in the nucleus. On the basis of yeast one-hybrid and dual-luciferase reporter assays, we found that CaMYB37 directly binds to the promoter of capsaicin biosynthesis gene AT3 and activates its transcription, thereby regulating capsaicin biosynthesis. In summary, we systematically identified members of the CaMYB-related family, predicted their possible biological functions, and revealed that CaMYB37 is critical for the transcriptional regulation of capsaicin biosynthesis. This work provides a foundation for further studies of the CaMYB-related family in pepper growth and development.

Biomedical and Antioxidant Potentialities in Chilli: Perspectives and Way Forward

Worldwide, since ages and nowadays, traditional medicine is well known, owing to its biodiversity, which immensely contributed to the advancement and development of complementary and alternative medicines. There is a wide range of spices, herbs, and trees known for their medicinal uses. Chilli peppers, a vegetable cum spice crop, are bestowed with natural bioactive compounds, flavonoids, capsaicinoids, phytochemicals, phytonutrients, and pharmacologically active compounds with potential health benefits. Such compounds manifest their functionality over solo-treatment by operating in synergy and consortium. Co-action of these compounds and nutrients make them potentially effective against coagulation, obesity, diabetes, inflammation, dreadful diseases, such as cancer, and microbial diseases, alongside having good anti-oxidants with scavenging ability to free radicals and oxygen. In recent times, capsaicinoids especially capsaicin can ameliorate important viral diseases, such as SARS-CoV-2. In addition, capsaicin provides an ability to chilli peppers to ramify as topical agents in pain-relief and also benefitting man as a potential effective anesthetic agent. Such phytochemicals involved not only make them useful and a much economical substitute to wonder/artificial drugs but can be exploited as obscene drugs for the production of novel stuffs. The responsibility of the TRPV1 receptor in association with capsaicin in mitigating chronic diseases has also been justified in this study. Nonetheless, medicinal studies pertaining to consumption of chilli peppers are limited and demand confirmation of the findings from animal studies. In this artifact, an effort has been made to address in an accessible format the nutritional and biomedical perspectives of chilli pepper, which could precisely upgrade and enrich our pharmaceutical industries towards human well-being.

Investigation of genetic factors regulating chlorophyll and carotenoid biosynthesis in red pepper fruit

Chlorophylls and carotenoids are synthesized in the chloroplast and chromoplast, respectively. Even though the two pigments are generated from the same precursor, the genetic correlation between chlorophyll and carotenoid biosynthesis has not yet been fully understood. We investigated the genetic correlation of chlorophyll and carotenoid biosynthesis during fruit ripening. Two recombinant inbred lines populations, "Long Sweet" × "AC2212" ("LA") RILs derived from a cross between Capsicum annuum "Long Sweet" with light-green and light-red fruit and C. annuum "AC2212" with dark-green and brown-fruit and "3501 (F)" × "3509 (C)" ("FC") RILs from C. annuum "3501" with dark-green and dark-red fruit and C. annuum "3509" with intermediate green and light-red fruit, were used. As the fruit ripened, three accessions produced high levels of xanthophyll. The dark-green immature fruit accumulated more total carotenoids than the light-green fruit. This trend corresponded to the expression pattern of 1-deoxy-d-xylulose 5-phosphate synthase (DXS) and CaGLK2 genes during fruit development. The expression levels of DXS and CaGLK2 in the dark-green accession "3501" were significantly higher than those of "3509" and "Long Sweet" during the early stages of fruit development. Furthermore, the genotype analysis of the transcription factor controlling chloroplast development (CaGLK2) in LA RILs revealed that CaGLK2 expression affected both carotenoid and chlorophyll contents. The single nucleotide polymorphism (SNP) linkage maps were constructed using genotyping-by-sequencing (GBS) for the two populations, and QTL analysis was performed for green fruit color intensity and carotenoid content. The QTL (LA_BG-CST10) for capsanthin content in LA RILs located at 24.4 to 100.4 Mbp on chromosome 10 was overlapped with the QTL (FC15-Cap10) for capsanthin content in FC RILs. Three QTLs for capsanthin content, American spice trade association (ASTA) value, and immature green fruit color intensity were also overlapped from 178.2 to 204 Mbp on chromosome 10. At the location, 151.6 to 165 Mbp on chromosome 8, QTLs (FC15-tcar8, FC17-ASTA8.1, and FC17-ASTA8.2) for total carotenoid content and ASTA value were discovered, and this region contained 2-C-methyl-d-erythritol 4-phosphate cytidylyltransferase (MCT), which is involved in the MEP pathway. This result is the first report to show the correlation between carotenoid and chlorophyll biosynthesis in pepper. This research will expand our understanding of the mechanism of the chloroplast-to-chromoplast transition and the development of high pigment pepper varieties.

Genetic divergence in transcriptional regulators of defense metabolism: insight into plant domestication and improvement

A number of mutational changes in transcriptional regulators of defense metabolism have occurred during plant domestication and improvement. Plant domestication and improvement entail genetic changes that underlie divergence in development and metabolism, providing a tremendous model of biological evolution. Plant metabolism produces numerous specialized alkaloids, terpenoids, phenolics, and cyanogenic glucosides with indispensable roles in defense against herbivory and microbial infection. Many compounds toxic or deterrent to predators have been eliminated through domestication and breeding. Series of genes involved in defense metabolism are coordinately regulated by transcription factors that specifically recognize cis-regulatory elements in promoter regions of downstream target genes. Recent developments in DNA sequencing technologies and genomic approaches have facilitated studies of the metabolic and genetic changes in chemical defense that have occurred via human-mediated selection, many of which result from mutations in transcriptional regulators of defense metabolism. In this article, we review such examples in almond (Prunus dulcis), cucumber (Cucumis sativus), pepper (Capsicum spp.), potato (Solanum tuberosum), quinoa (Chenopodium quinoa), sorghum (Sorghum bicolor), and related species and discuss insights into the evolution and regulation of metabolic pathways for specialized defense compounds.

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.

The Capsicum MYB31 regulates capsaicinoid biosynthesis in the pepper pericarp

Pepper (Capsicum) are consumed worldwide as vegetables and food additives due to their pungent taste. Capsaicinoids are the bioactive compounds that confer the desired pungency to pepper fruits. Capsaicinoid biosynthesis was thought to occur exclusively in fruit placenta. Recently, biosynthesis in the pericarp of extremely pungent varieties was discovered, however, the mechanism of capsaicinoid biosynthesis regulation in the pericarp remains largely unknown. Here, the capsaicinoid contents of placenta and pericarp were analyzed. The results indicated that the Capsicum chinense pericarp accumulated a vast amount of capsaicinoids. Expression of the master regulator MYB31 and capsaicinoid biosynthesis genes (CBGs) were significantly upregulated in the pericarp in C. chinense accessions compared to accessions in other tested species. Moreover, in fruit of extremely-pungent 'Trinidad Moruga Scorpion' (C. chinense) and low-pungent '59' inbred line (C. annuum), the capsaicinoid accumulation patterns in the pericarp were consistent with expression levels of CBGs and MYB31. Silencing MYB31 in 'Trinidad Moruga Scorpion' pericarp leads to a significantly decreased CBGs transcription level and capsaicinoids content. Taken together, our results provide insights into the molecular mechanism arising from the expression of MYB31 in the pericarp that results in exceedingly hot peppers.

Modulated Light Dependence of Growth, Flowering, and the Accumulation of Secondary Metabolites in Chilli

Chili is widely used as a food additive and a flavouring and colouring agent and also has great importance in health preservation and therapy due to the abundant presence of many bioactive compounds, such as polyphenols, flavonoids, carotenoids, and capsaicinoids. Most of these secondary metabolites are strong antioxidants. In the present study, the effect of light intensity and spectral composition was studied on the growth, flowering, and yield of chilli together with the accumulation of secondary metabolites in the fruit. Two light intensities (300 and 500 μmol m-2 s-1) were applied in different spectral compositions. A broad white LED spectrum with and without FR application and with blue LED supplement was compared to blue and red LED lightings in different (80/20 and 95/5%) blue/red ratios. High light intensity increased the harvest index (fruit yield vs. biomass production) and reduced the flowering time of the plants. The amount of secondary metabolites in the fruit varied both by light intensity and spectral compositions; phenolic content and the radical scavenging activity were stimulated, whereas capsaicin accumulation was suppressed by blue light. The red colour of the fruit (provided by carotenoids) was inversely correlated with the absolute amount of blue, green, and far-red light. Based on the results, a schematic model was created, representing light-dependent metabolic changes in chilli. The results indicated that the accumulation of secondary metabolites could be modified by the adjustment of light intensity and spectral composition; however, different types of metabolites required different light environments.

Mapping of CaPP2C35 involved in the formation of light-green immature pepper (Capsicum annuum L.) fruits via GWAS and BSA

Genome-wide association study, bulked segregant analysis, and genetic analysis delimited the LG locus controlling light-green immature pepper fruits into a 35.07 kbp region on chromosome 10. A strong candidate gene, CaPP2C35, was identified in this region. In pepper (Capsicum annuum L.), the common colors of immature fruits are yellowish white, milky yellow, green, purple, and purplish black. Genes related to dark green, white, and purple immature fruits have been cloned; however, only a few studies have investigated light-green immature fruits. Here, we performed a genetic study using light-green (17C827) and green (17C658) immature fruits. The light-green color of immature fruits was controlled by a single locus-dominant genetic trait compared with the green color of immature fruits. We also performed a genome-wide association study and bulked segregant analysis of immature-fruit color and mapped the LG locus to a 35.07 kbp region on chromosome 10. Only one gene, Capana10g001710, was found in this region. A G-A substitution occurred at the 313th base of the Capana10g001710 coding sequence in 17C827, resulting in the conversion of the α-helix of its encoded PP2C35 protein into a β-fold. The expression of Capana10g001710 (termed CaPP2C35) in 17C827 was significantly higher than in 17C658. Silencing CaPP2C35 in 17C827 resulted in an increase in chlorophyll content in the exocarp and the appearance of green stripes on the surface of the fruit. These results indicate that CaPP2C35 may be involved in the formation of light-green immature fruits by regulating the accumulation of chlorophyll content in the exocarp. Thus, these findings lay the foundation for further studies and genetic improvement of immature-fruit color in pepper.

Widely targeted metabolome profiling of different colored sesame (Sesamum indicum L.) seeds provides new insight into their antioxidant activities

Sesame seeds are considered worldwide as a functional food due to their nutritional and therapeutical values. Several physiological functions are being associated with sesame seeds and their derived products. However, the phytochemicals responsible for these various proprieties are not well understood. Thus, to acknowledge the diversity and variability of metabolites in sesame seeds of different colors and reveal key metabolites and pathways contributing to differences in antioxidant activities, black, brown, yellow, and white sesame seeds from 12 varieties were subjected to LC-MS/MS-based widely targeted metabolomics analysis. Totally, 671 metabolites were identified and chemically classified. The metabolic compounds varied significantly with the seed coat color and genotype. Many flavonoids, amino acids, and terpenoids were up-regulated in dark seeds. Sixty key differential metabolites were filtered out. Phenylpropanoid biosynthesis, amino acids biosynthesis, and tyrosine metabolism were the main differently regulated pathways. The DPPH, ABTS, and FRAP assays showed that the antioxidant activities of the seeds increased with the seed coat darkness. Therefore, the pharmacological proprieties of black seeds might be related to their high content of flavonoids and essential amino acids mostly. These findings expand phytochemicals composition information of different colored sesame seeds and provide resources for their comprehensive use and quality improvement.

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.

Effect of the Soil and Ripening Stage in Capsicum chinense var. Jaguar on the Content of Carotenoids and Vitamins

The purpose of this work was to investigate the effect of the ripening stage and type of soil on the concentration of carotenoids and vitamins in Habanero pepper (Capsicum chinense Jacq.). Pepper plants were grown in two soils named according to the Mayan classification as: K’ankab lu’um (red soil) and Box lu’um (black soil). The results of two harvests at 320 and 334 PTD (post-transplant day) showed that the ripening stage exhibited a significant effect (p < 0.05) on the concentration of carotenoids and vitamins, while the effect of the soil type was negligible. The concentration of carotenoids decreases as the ripening process of the fruit takes place, with the highest concentration of lutein (49.47 ± 0.34 mg/100 g of dry mass), β-carotene (99.92 ± 0.69 mg/100 g of dry mass) and β-cryptoxanthin (20.93 ± 0.04 mg/100 g of dry mass) in the unripe peppers. The concentration of vitamins increases as the ripening process develops, with the highest concentration of Vitamin E (9.69 ± 0.02 mg/100 g of dry mass) and Vitamin C (119.44 ± 4.72 mg/100 g of dry mass) in the ripe peppers. This knowledge could be used to select the best ripening stage to harvest Habanero peppers according to the use of the pepper and to the needs of producers/company.

Inhibitory effects of luteolin and its derivatives on osteoclast differentiation and differences in luteolin production by Capsicum annuum varieties

Luteolin, an abundant flavonoid in the leaves of Capsicum annuum, has antioxidant activity and is, thus, a key chemical for promoting plant residue utilization, especially for the development of healthcare products. We assessed the inhibitory effect of luteolin and its glycosides on osteoclastic differentiation in human cells and found that the differentiation was effectively inhibited at noncytotoxic concentrations. We also screened 47 varieties of C. annuum for the accumulation of luteolin and apigenin to determine the prevalence of luteolin in diverse cultivars and identify varieties with high and/or selective luteolin production. The glycosides of luteolin and apigenin were found in all the tested varieties, with luteolin predominant over apigenin in most varieties. The identification and characterization of highly productive varieties of C. annuum is expected to be beneficial for the effective development of useful luteolin-based products from plant residues.

Capsaicinoid biosynthesis in the pericarp of chili pepper fruits is associated with a placental septum-like transcriptome profile and tissue structure

CAP biosynthesis in the pericarp of chili pepper fruits occurs with an ambiguous boundary in the placental septum and pericarp. Capsaicinoid (CAP) is a pungent ingredient of chili pepper fruits. Generally, CAP biosynthesis is limited to the placental septum of fruits, but it has been reported that its biosynthesis occurs even in the pericarp of some extremely pungent varieties, resulting in a substantial increase in total content. To examine the mechanism of CAP biosynthesis in the pericarp, comparative transcriptome analysis of a variety that produces CAP in the pericarp (MY) and a variety that does not (HB) was carried out. RNA-seq revealed that 2264 genes were differentially expressed in the MY pericarp compared with the HB pericarp. PCA analysis and GO enrichment analysis indicated that the MY pericarp has a gene expression profile more like placental septum than the HB pericarp. The gene expression of CAP biosynthesis-related genes in the MY pericarp changed coordinately with the placental septum during fruit development. In most Capsicum accessions including HB, the distribution of slender epidermal cells producing CAP was limited to the placental septum, and the morphological boundary between the placental septum and pericarp was clear. In some extremely pungent varieties such as MY, slender epidermal cells ranged from the placental septum to the pericarp region, and the pericarp was morphologically similar to the placental septum, such as the absence of large sub-epidermal cells and abundant spaces in the parenchymal tissue. Our data suggest that CAP biosynthesis in the pericarp occurred with an ambiguous boundary in the placental septum and pericarp. These findings contribute to further enhancement of CAP production in chili pepper fruits.

Identification of α-Glucosidase Inhibitors from Leaf Extract of Pepper (Capsicum spp.) through Metabolomic Analysis

Metabolomics and in vitro α-glucosidase inhibitory (AGI) activities of pepper leaves were used to identify bioactive compounds and select genotypes for the management of type 2 diabetes mellitus (T2DM). Targeted metabolite analysis using UPLC-DAD-QToF-MS was employed and identified compounds that belong to flavone and hydroxycinnamic acid derivatives from extracts of pepper leaves. A total of 21 metabolites were detected from 155 samples and identified based on MS fragmentations, retention time, UV absorbance, and previous reports. Apigenin-O-(malonyl) hexoside, luteolin-O-(malonyl) hexoside, and chrysoeriol-O-(malonyl) hexoside were identified for the first time from pepper leaves. Pepper genotypes showed a huge variation in their inhibitory activity against α-glucosidase enzyme(AGE) ranging from 17% to 79%. Genotype GP38 with inhibitory activity of 79% was found to be more potent than the positive control acarbose (70.8%.). Orthogonal partial least square (OPLS) analyses were conducted for the prediction of the AGI activities of pepper leaves based on their metabolite composition. Compounds that contributed the most to the bioactivity prediction model (VIP >1.5), showed a strong inhibitory potency. Caffeoyl-putrescine was found to show a stronger inhibitory potency (IC₅₀ = 145 µM) compared to acarbose (IC₅₀ = 197 µM). The chemometric procedure combined with high-throughput AGI screening was effective in selecting polyphenols of pepper leaf for T2DM management.

Post-Harvest Quality and Sensory Evaluation of Mini Sweet Peppers

Sweet pepper (Capsicum annuum L.) is one of the most consumed vegetables in the world, being recognized as a food with high nutritional value. Recently, the market for sweet and colorful mini peppers has increased, especially among the most demanding consumers in the novelties in vegetables and functional foods. In this sense, we evaluated mini sweet peppers genotypes (Akamu, Kaiki, Kalani, Kaolin e Moke from Isla® seeds) regarding the physical-chemical, nutritional and sensory analysis aspects. A wide variability was observed among genotypes, highlighting the Kalani genotype for total carotenoids, and the genotypes Akamu, Kaiki and Kaolin for phenolic totals content and antioxidant activity. Moke and Kaolin showed higher vitamin C content and fruit firmness. Based on sensory analysis, Kalani, Kaiki, Kaolin and Akamu obtained greater global acceptance. The genotypes can be considered an important marketing strategy of mini sweet peppers trade, associating different shapes, colors and nutritional quality.

Linking genetic determinants with salinity tolerance and ion relationships in eggplant, tomato and pepper

The Solanaceae family includes commercially important vegetable crops characterized by their relative sensitivity to salinity. Evaluation of 8 eggplant (Solanum melongena), 7 tomato (Solanum lycopersicum), and 8 pepper (Capsicum spp.) heirloom cultivars from different geographic regions revealed significant variation in salt tolerance. Relative fruit yield under salt treatment varied from 52 to 114% for eggplant, 56 to 84% for tomato, and 52 to 99% for pepper. Cultivars from all three crops, except Habanero peppers, restricted Na transport from roots to shoots under salinity. The high salt tolerance level showed a strong association with low leaf Na concentration. Additionally, the leaf K-salinity/K-control ratio was critical in determining the salinity tolerance of a genotype. Differences in relative yield under salinity were regulated by several component traits, which was consistent with the gene expression of relevant genes. Gene expression analyses using 12 genes associated with salt tolerance showed that, for eggplant and pepper, Na⁺ exclusion was a vital component trait, while sequestration of Na⁺ into vacuoles was critical for tomato plants. The high variability for salt tolerance found in heirloom cultivars helped characterize genotypes based on component traits of salt tolerance and will enable breeders to increase the salt tolerance of Solanaceae cultivars.

Impact of Moderate Cold and Salt Stress on the Accumulation of Antioxidant Flavonoids in the Leaves of Two Capsicum Cultivars

The horticultural production of bell peppers generates large quantities of residual biomass. Abiotic stress stimulates the production of protective flavonoids, so the deliberate application of stress to the plants after fruit harvest could provide a strategy to valorize horticultural residuals by increasing flavonoid concentrations, facilitating their industrial extraction. Here we exposed two Capsicum cultivars, a chilli and a bell pepper, to cold and salt stress and combinations thereof to determine their valorization potential. Noninvasive image-based phenotyping and multiparametric fluorescence measurements indicated that all stress treatments inhibited plant growth and reduced the leaf chlorophyll fluorescence index, with the chilli cultivar showing greater sensitivity. The fluorescence-based FLAV index allowed the noninvasive assessment of foliar luteolin glycosides. High-performance liquid chromatography-mass spectrometry (HPLC-MS) analysis showed that moderate cold increased the levels of two foliar antioxidant luteolin glycosides in both cultivars, with bell pepper containing the highest amounts (induced to maximum 5.5 mg g^-1 DW cynaroside and 37.0 mg g^-1 DW graveobioside A) after combined stress treatment. These data confirm the potential of abiotic stress for the valorization of residual leaf biomass to enhance the industrial extraction of antioxidant and bioactive flavonoids.

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).

Chili Pepper Carotenoids: Nutraceutical Properties and Mechanisms of Action

Chili pepper is a prominent cultivated horticultural crop that is traditionally used for food seasoning and is applied for the treatment and prevention of multiple diseases. Its beneficial health properties are due to its abundance and variety of bioactive components, such as carotenoids, capsaicinoids, and vitamins. In particular, carotenoids have important nutraceutical properties, and several studies have focused on their potential in the prevention and treatment of human diseases. In this article, we reviewed the state of knowledge of general aspects of chili pepper carotenoids (biosynthesis pathway, types and content in Capsicum spp., and the effects of processing on carotenoid content) and recent findings on the effects of carotenoid nutraceuticals, such as antioxidant, cancer preventive, anti-inflammatory, cardiovascular disorder preventive, and anti-obesity effects.

Relations between fruit chemical components of biquinho pepper cultivars in different crop seasons

The species Capsicum chinense, variety biquinho, has been gaining space in cooking, but little is known about its cultivars, mainly related to the chemical composition of fruits. The objective of this study was to characterize the nutritional composition of two biquinho pepper cultivars in different growing seasons and to define the relationships between the variables and their direct and indirect effects. An experiment was conducted in a randomized block design with two cultivars of biquinho pepper, two growing seasons. The variables were plastochron (PLAS), fruit mass (MASS), pH, total soluble solids (Brix), acidity, total phenolic compounds (PHE), carotenoids (CAR), antioxidant potential (ANT), capsaicin (CAP), and dihydrocapsaicin (DIH). The cultivar BRS Moema showed higher levels for chemical compounds, while the cultivar Airetama was the most productive. Principal component analysis (PCA) was performed to determine relationships among variables, and path analysis was used to determine direct and indirect effects between variables. The chemical composition of biquinho pepper is modified according to cultivar and growing season. Important relationships between pH and CAR, ANT, PHE, CAP, and pH. CAR and PHE have an indirect effect and the MASS and PLAS have a direct effect on the ANT.