Pepper Fruit Ripening Research Articles

Fine mapping and gene silencing pinpoint Capana10g002229 as a strong candidate gene regulating the deciduous character of ripe pepper fruit (Capsicum spp.).

The pepper S locus, which controls the deciduous character of ripe fruit, was first fine mapped into an interval with a physical length of ~ 38.03kb on chromosome P10. Capana10g002229, encoding a polygalacturonase, was proposed as a strong candidate gene based on sequence comparison, expression pattern analysis and virus-induced gene silencing (VIGS). The deciduous character of ripe fruit, which is controlled by the dominant S locus, is a domesticated trait with potential value in the pepper processing industry (Capsicum spp.). However, the gene associated with the S locus has not been identified. Here, one major QTL designated S10.1 was detected by using the F2 population (n = 155) derived from BA3 (Capsicum annuum) × YNXML (Capsicum frutescens) and was further verified in an intraspecific backcross population (n = 254) derived from the cross between BB3 (C. annuum) and its wild relative Chiltepin (C. annuum var. glabriusculum) with BB3 as the recurrent parent. Then, a large BC1F2 population derived from the self-pollination of BB3 × (BB3 × Chiltepin) individuals and comprising 4217 individuals was used to screen the recombinants, and the S locus was ultimately delimited into a 38.03-kb region on chromosome P10 harbouring four annotated genes. Capana10g002229, encoding a polygalacturonase (PG), was proposed as the best candidate gene for S based on sequence comparison and expression pattern analyses. Downregulation of Capana10g002229 in fruits through VIGS significantly delayed fruit softening and abscission from the fruit-receptacle junction. Taken together, the results show that Capana10g002229 could be regarded as a strong candidate gene associated with the S locus in pepper. These findings not only lay a foundation for deciphering the molecular mechanisms underlying pepper domestication but also provide a strategy for genetic improvement of the deciduous character of ripe fruit using a marker-assisted selection approach.

Small Heat Shock Protein (sHSP) Gene Family from Sweet Pepper (Capsicum annuum L.) Fruits: Involvement in Ripening and Modulation by Nitric Oxide (NO).

Small heat shock proteins (sHSPs) are usually upregulated in plants under diverse environmental stresses. These proteins have been suggested to function as molecular chaperones to safeguard other proteins from stress-induced damage. The ripening of pepper (Capsicum annuum L.) fruit involves important phenotypic, physiological, and biochemical changes, which have associated endogenous physiological nitro-oxidative stress, but they can also be significantly affected by environmental conditions, such as temperature. Based on the available pepper genome, a total of 41 sHSP genes were identified in this work, and their distributions in the 12 pepper chromosomes were determined. Among these genes, only 19 sHSP genes were found in the transcriptome (RNA-Seq) of sweet pepper fruits reported previously. This study aims to analyze how these 19 sHSP genes present in the transcriptome of sweet pepper fruits are modulated during ripening and after treatment of fruits with nitric oxide (NO) gas. The time-course expression analysis of these genes during fruit ripening showed that 6 genes were upregulated; another 7 genes were downregulated, whereas 6 genes were not significantly affected. Furthermore, NO treatment triggered the upregulation of 7 sHSP genes and the downregulation of 3 sHSP genes, whereas 9 genes were unchanged. These data indicate the diversification of sHSP genes in pepper plants and, considering that sHSPs are important in stress tolerance, the observed changes in sHSP expression support that pepper fruit ripening has an associated process of physiological nitro-oxidative stress, such as it was previously proposed.

Speed Breeding Scheme of Hot Pepper through Light Environment Modification

Crop breeding for high yields and quality is an important measure to ensure food security. In conventional breeding, a long generation time is required. Speed breeding could accelerate the flowering and fruiting of crops by providing suitable environmental conditions in order to reduce the generation times. This study aimed to determine a speed breeding scheme for hot peppers. Two hot pepper varieties, ‘Xiangyan 55’ and ‘Xiangla 712’, were investigated for their growth and development under different light intensities, photoperiods, and red-to-far-red ratios. Hot pepper plants bloomed at 39.88 ± 0.74 days after sowing under photosynthetic photon flux density (PPFD) 420 µmol·m−2·s−1 and a 12-h photoperiod and had seed with acceptable germination rates at 82 days after sowing. Blooming was 2–3 days earlier when the photoperiod was extended to 20 h, but the fruit and seed development were not significantly improved. Supplementation of far-red light (R:FR = 2.1) significantly accelerated the red ripening of pepper fruit and improved seed germination rates. The modification of the light environment accelerated hot pepper growth and development, reduced breeding cycles, and could produce up to four generations per year.

Addendum: López-Vidal et al. Is Autophagy Involved in Pepper Fruit Ripening? Cells 2020, 9, 106

The authors would like to make an addendum to their published paper [...]

Identification of miRNAs and Their Targets Involved in Flower and Fruit Development across Domesticated and Wild Capsicum Species.

MicroRNAs (miRNAs) are regulators of the post-transcription stage of gene activity documented to play central roles in flower and fruit development in model plant species. However, little is known about their roles and differences in domesticated and wild Capsicum species. In this study, we used high-throughput sequencing to analyze the miRNA content at three developmental stages (flower, small fruit, and middle fruit) from two cultivated (C. baccatum and C. annuum) and two wild (C. chacoense and C. eximium) pepper species. This analysis revealed 22 known and 27 novel miRNAs differentially expressed across species and tissues. A number of stage- and species-specific miRNAs were identified, and Gene Ontology terms were assigned to 138 genes targeted by the miRNAs. Most Gene Ontology terms were for the categories “genetic information processing”, “signaling and cellular processes”, “amino acid metabolism”, and “carbohydrate metabolism”. Enriched KEGG analysis revealed the pathways amino acids, sugar and nucleotide metabolism, starch and sucrose metabolism, and fructose-mannose metabolism among the principal ones regulated by miRNAs during pepper fruit ripening. We predicted miRNA–target gene interactions regulating flowering time and fruit development, including miR156/157 with SPL genes, miR159 with GaMYB proteins, miR160 with ARF genes, miR172 with AP2-like transcription factors, and miR408 with CLAVATA1 gene across the different Capsicum species. In addition, novel miRNAs play an important role in regulating interactions potentially controlling plant pathogen defense and fruit quality via fructokinase, alpha-L-arabinofuranosidase, and aromatic and neutral amino acid transporter. Overall, the small RNA-sequencing results from this study represent valuable information that provides a solid foundation for uncovering the miRNA-mediated mechanisms of flower and fruit development between domesticated and wild Capsicum species.

Pre- and postharvest factors affecting quality and safety of Pepper ( Piper nigrum L.)

Abstract The quality and safety of pepper ( Piper nigrum L.) are a function of crop management practices, harvest maturity, harvesting methods and subsequent handling after harvest, including storage conditions and processing methods. The review shows that volatile oil decreases with shade intensity (15–30%). Essential oil, oleoresin, piperine and monoterpenes (thujene, α-pinene, sabinene, limonene, α-phellandrene and linalool) increase with altitude, while β-caryophyllene and total phenol decrease with increase in altitude. Fermentation of ripe pepper fruits forms odorants (butanoic acid, 3-methylindole, and 4-methylphenol) attributing intense faecal/shed-like off-flavour white pepper powder. Low-drying temperature (≤56°C) and duration (≤3 hrs) lead to low bulk density (0.17 g/ml) and low moisture loss (31%). Excessive soaking of black peppercorns prior to mechanical decortication reduces volatile oil and increases moisture content and broken berries. Availability of heavy metals in grinding machines increases the level of heavy metals; Fe (69.8–1147 mg/kg), Pb (21.3–947 μg/kg) and V (64.1–1072 μg/kg) in pepper powder. Storing peppercorns along with other materials enhances cross-contamination of heavy metals; Pb, Cd and Cr. High moisture content (>13%) and farmers’ unawareness resulted in high (2200 to >30000 cfu/g) mycotoxins contamination. Environmental and industrial pollutants such as plasticizers, bisphenol A, polycyclic aromatic hydrocarbons and pesticides are also pepper contaminants of high merit. Radiofrequency pasteurization, vacuum-assisted steaming, ethylene oxide fumigation, atmospheric pressure plasma, dry heat sterilization, gamma-irradiation and ultraviolet-C light treatments are among strategies to enhance the quality and safety of pepper. More precautions also have to be taken to regulate the shade, drying temperature and duration, soaking duration, hygienic processing and storage in order to retain quality, minimize the risk of microbial or chemical contaminations and comply with standards.

Effect of 2-(4-chlorophenylthio) ethylamine hydrochloride on lycopene biosynthesis in pepper fruits

Lycopene is an intermediate metabolic product of the capsanthin biosynthesis pathway in pepper fruits and is one of the strongest antioxidants found in plants. During the ripening of pepper fruits, lycopene is almost completely transformed into the downstream metabolic product capsanthin as well as other substances. As a result, lycopene cannot be enriched in ripe pepper fruits; however, the lycopene content can be increased by 2-(4-chlorophenylthio) ethylamine hydrochloride (CPTA) treatment, using the optimal concentration at the optimal development stage of pepper fruits. The current study tested different CPTA concentrations and fruit developmental stages to increase the lycopene content in pepper fruits. The results showed that the lycopene content was significantly enriched in pepper fruits treated with 0.1% CPTA applied at the turning stage. Real-time quantitative polymerase chain reaction analysis showed that CPTA treatment significantly promoted the expression of the upstream genes (Psy and PDS) involved in the anabolic metabolism of lycopene; however, CPTA treatment had a significant inhibitory effect on the downstream gene (Lcyb) of lycopene synthesis. Therefore, in pepper fruits, CPTA inhibits the normal expression of the Lcyb gene downstream of lycopene, thus achieving notable lycopene enrichment.

Superoxide Radical Metabolism in Sweet Pepper (Capsicum annuum L.) Fruits Is Regulated by Ripening and by a NO-Enriched Environment.

Superoxide radical (O2•–) is involved in numerous physiological and stress processes in higher plants. Fruit ripening encompasses degradative and biosynthetic pathways including reactive oxygen and nitrogen species. With the use of sweet pepper (Capsicum annuum L.) fruits at different ripening stages and under a nitric oxide (NO)-enriched environment, the metabolism of O2•– was evaluated at biochemical and molecular levels considering the O2•– generation by a NADPH oxidase system and its dismutation by superoxide dismutase (SOD). At the biochemical level, seven O2•–-generating NADPH-dependent oxidase isozymes [also called respiratory burst oxidase homologs (RBOHs) I–VII], with different electrophoretic mobility and abundance, were detected considering all ripening stages from green to red fruits and NO environment. Globally, this system was gradually increased from green to red stage with a maximum of approximately 2.4-fold increase in red fruit compared with green fruit. Significantly, breaking-point (BP) fruits with and without NO treatment both showed intermediate values between those observed in green and red peppers, although the value in NO-treated fruits was lower than in BP untreated fruits. The O2•–-generating NADPH oxidase isozymes I and VI were the most affected. On the other hand, four SOD isozymes were identified by non-denaturing electrophoresis: one Mn-SOD, one Fe-SOD, and two CuZn-SODs. However, none of these SOD isozymes showed any significant change during the ripening from green to red fruits or under NO treatment. In contrast, at the molecular level, both RNA-sequencing and real-time quantitative PCR analyses revealed different patterns with downregulation of four genes RBOH A, C, D, and E during pepper fruit ripening. On the contrary, it was found out the upregulation of a Mn-SOD gene in the ripening transition from immature green to red ripe stages, whereas a Fe-SOD gene was downregulated. In summary, the data reveal a contradictory behavior between activity and gene expression of the enzymes involved in the metabolism of O2•– during the ripening of pepper fruit. However, it could be concluded that the prevalence and regulation of the O2•– generation system (NADPH oxidase-like) seem to be essential for an appropriate control of the pepper fruit ripening, which, additionally, is modulated in the presence of a NO-enriched environment.

Is Autophagy Involved in Pepper Fruit Ripening?

Autophagy is a universal self-degradation process involved in the removal and recycling of cellular constituents and organelles; however, little is known about its possible role in fruit ripening, in which the oxidation of lipids and proteins and changes in the metabolism of different cellular organelles occur. In this work, we analyzed several markers of autophagy in two critical maturation stages of pepper (Capsicum annuum L.) fruits where variations due to ripening become clearly visible. Using two commercial varieties that ripen to yellow and red fruits respectively, we studied changes in the gene expression and protein content of several autophagy (ATG) components, ATG4 activity, as well as the autophagy receptor NBR1 and the proteases LON1 and LON2. Additionally, the presence of intravacuolar vesicles was analyzed by electron microscopy. Altogether, our data reveal that autophagy plays a role in the metabolic changes which occur during ripening in the two studied varieties, suggesting that this process may be critical to acquiring final optimal quality of pepper fruits.

Light-Controlled Fruit Pigmentation and Flavor Volatiles in Tomato and Bell Pepper.

Light is a major environmental factor affecting the regulation of secondary metabolites, such as pigments and flavor. The Solanaceae plant family has diverse patterns of fruit metabolisms that serve as suitable models to understand the molecular basis of its regulation across species. To investigate light-dependent regulation for fruit pigmentation and volatile flavors, major fruit pigments, their biosynthetic gene expression, and volatiles were analyzed in covered fruits of tomato and bell pepper. Immature covered fruits were found to be ivory in color and no chlorophyll was detected in both plants. The total carotenoid content was found to be reduced in ripe tomato and bell pepper under cover. Naringenin chalcone decreased more than 7-fold in ripe tomato and total flavonoids decreased about 10-fold in immature and ripe pepper fruit under light deficiency. Light positively impacts fruit pigmentation in tomato and bell pepper by regulating gene expression in carotenoid and flavonoid biosynthesis, especially phytoene synthase and chalcone synthase, respectively. Nineteen volatile flavors were detected, and seven of these exhibited light-dependent regulations for both ripe tomato and pepper. This study will help in improving fruit quality and aid future research works to understand the molecular mechanisms regulating the influence of light-dependency on pigments and flavor volatiles.

Sweet Pepper (Capsicum annuum L.) Fruits Contain an Atypical Peroxisomal Catalase That is Modulated by Reactive Oxygen and Nitrogen Species.

During the ripening of sweet pepper (Capsicum annuum L.) fruits, in a genetically controlled scenario, enormous metabolic changes occur that affect the physiology of most cell compartments. Peroxisomal catalase gene expression decreases after pepper fruit ripening, while the enzyme is also susceptible to undergo post-translational modifications (nitration, S-nitrosation, and oxidation) promoted by reactive oxygen and nitrogen species (ROS/RNS). Unlike most plant catalases, the pepper fruit enzyme acts as a homodimer, with an atypical native molecular mass of 125 to 135 kDa and an isoelectric point of 7.4, which is higher than that of most plant catalases. These data suggest that ROS/RNS could be essential to modulate the role of catalase in maintaining basic cellular peroxisomal functions during pepper fruit ripening when nitro-oxidative stress occurs. Using catalase from bovine liver as a model and biotin-switch labeling, in-gel trypsin digestion, and nanoliquid chromatography coupled with mass spectrometry, it was found that Cys377 from the bovine enzyme could potentially undergo S-nitrosation. To our knowledge, this is the first report of a cysteine residue from catalase that can be post-translationally modified by S-nitrosation, which makes it especially important to find the target points where the enzyme can be modulated under either physiological or adverse conditions.

Phytochemical Composition and Nutritive Value of Unripe and Ripe Dennettia tripetala (DT) Fruits

Aims: To determine phytochemical and nutritive value of unripe and ripe pepper fruit.
 Place and Duration of Study: Biochemistry Department, University of Port Harcourt, Rivers State, between the period of April and July, 2018.
 Methodology: Phytochemical, proximate, minerals and vitamin composition were carried out using standard methods.
 Results: The unripe fruit of DT had significant (P<0.05) higher concentrations of terpenes, phytosterol, steroid, oxalate, saponin, alkaloid and phytate when compared to the ripe fruit; while tannins, phenol, flavonoid, coumarin, cardiac and cyanogenic glycosides were higher in the ripe fruit compared to the unripe fruit. The ash and lipid content of DT fruits were significantly (p< 0.05) higher in the ripe DT fruit than unripe DT fruit; while the carbohydrate and the crude fibre content were significantly (p<0.05) higher in the unripe than the ripe DT fruit. The energy value (kcal/100 g sample) calculated from Atwater factors of 4, 9, 4 for carbohydrates, lipids and proteins was 347.2 for unripe and 331.4 for ripe DT fruits. Potassium composition of DT fruits were significantly (p<0.05) higher in the ripe fruit than the unripe fruit, while zinc was higher in the unripe fruit than the ripe fruit. The concentration of Na, Se, Pb, Ca, Fe and Cu did not differ significantly (p<0.05) between the two fruits. DT fruits possessed a significantly (p<0.05) higher concentrations of vitamin A, B1, B2, B3, B5, B7, B9, B12 and C than the ripe fruit; while the unripe fruits showed a significantly higher concentrations of Vitamin B6 and K than the ripe fruit.
 Conclusion: Therefore, unripe and ripe DT fruits may be consumed as potential sources of nutrients and phytochemicals which may be significant as dietary supplements.

Biology and host selection stage of Symmetrischema dulce Povolny (Lepidoptera: Gelechiidae) in chili pepper.

The pepper-fruit-borer Symmetrischema dulce Povolny (Lepidoptera: Gelechiidae) is an important chili pepper pest causing significant yield losses. However, chili pepper has insufficient crop protection support and primary information about S. dulce is scarce. In the present study, we aimed to study the biology and ecology of S. dulce in pepper plants (Capsicum frutescens L.) focusing to support integrated pest management programs. In the field, we sampled ripe and unripe chili pepper fruits in three different plant strata. In the laboratory, we established colonies of the S. dulce and we recorded the duration, viability, morphology of each life stage, and number of larval instars. We conducted experiments to evaluate insect reproduction, whereby we registered the pre-oviposition and oviposition period, daily oviposition rate, and sex ratio. From these results, we estimated the reproductive success of S. dulce through the intrinsic population growth rate. The higher occurrence of S. dulce was in unripe fruits with no difference between plant strata. Egg stage lasted 4days with 94% viability, and larval phase lasted on average 10.72days and presented four instars with viability of 66.6%. Pupal stage lasted 9.61days with viability of 94.73%. The adult stage lasted 24.14days with a pre-oviposition period of 3days and oviposition period of 13.85days. The intrinsic growth rate (rm) recorded was 0.0035. Our results suggest that the biology of S. dulce has similarities with other Lepidoptera, but its peculiarities in reproductive parameters are essential for future programs of pest management.

Nitric oxide-dependent regulation of sweet pepper fruit ripening.

Ripening is a complex physiological process that involves changes in reactive nitrogen and oxygen species that govern the shelf-life and quality of fruits. Nitric oxide (NO)-dependent changes in the sweet pepper fruit transcriptome were determined by treating fruits at the initial breaking point stage with NO gas. Fruits were also harvested at the immature (green) and ripe (red) stages. Fruit ripening in the absence of NO resulted in changes in the abundance of 8805 transcripts whose function could be identified. Among these, functional clusters associated with reactive oxygen/nitrogen species and lipid metabolism were significantly modified. NO treatment resulted in the differential expression of 498 genes framed within these functional categories. Biochemical analysis revealed that NO treatment resulted in changes in fatty acid profiling, glutathione and proline contents, and the extent of lipid peroxidation, as well as increases in the activity of ascorbate peroxidase and lipoxygenase. These data provide supporting evidence for the crucial role of NO in the ripening of pepper fruit.

Progression of the Total and Individual Capsaicinoids Content in the Fruits of Three Different Cultivars of Capsicum chinense Jacq.

The evolution of individual and total capsaicinoids content in three pepper varieties of Capsicum chinense Jacq. (‘Bode’ (B), ‘Habanero’ (H), and ‘Habanero Roxo’ (Hr)) during fruit ripening was studied. The five major capsaicinoids (nordihydrocapsaicin, capsaicin, dihydrocapsaicin, homocapsaicin, and homodihydrocapsaicin) were extracted using ultrasound-assisted extraction and the extracts were analysed by ultra-performance liquid chromatography with fluorescence detection (UHPLC-Fl). The plants were grown in a glasshouse and sampled every 7 days until over-ripening. As expected, the results indicated that the total capsaicinoids content increases during the ripening of pepper fruits. The maximum contents of capsaicinoids were reached at different fruit development stages depending on the cultivar. The ‘Habanero Roxo’ pepper presented the greatest total capsaicinoids content (3.86 mg g−1 fresh weigh, F.W.), followed by the ‘Habanero’ pepper (1.33 mg g−1 F.W.) and ‘Bode’ pepper (1.00 mg g−1 F.W.). In all the samples, capsaicin represented more than 80% of the total capsaicinoids content. Due to the high variability observed in the evolution of capsaicinoids content over the ripening process, this work intends to contribute to the existing knowledge on this aspect in relation to the quality of peppers.

NADPH Oxidase (Rboh) Activity is Up Regulated during Sweet Pepper (Capsicum annuum L.) Fruit Ripening.

In plants, NADPH oxidase (NOX) is also known as a respiratory burst oxidase homolog (Rboh). This highly important enzyme, one of the main enzymatic sources of superoxide radicals (O2•−), is involved in the metabolism of reactive oxygen and nitrogen species (ROS and RNS), which is active in the non-climacteric pepper (Capsicum annuum L.) fruit. We used sweet pepper fruits at two ripening stages (green and red) to biochemically analyze the O2•−-generating Rboh activity and the number of isozymes during this physiological process. Malondialdehyde (MDA) content, an oxidative stress marker, was also assayed as an index of lipid peroxidation. In red fruits, MDA was observed to increase 2-fold accompanied by a 5.3-fold increase in total Rboh activity. Using in-gel assays of Rboh activity, we identified a total of seven CaRboh isozymes (I–VII) which were differentially modulated during ripening. CaRboh-III and CaRboh-I were the most prominent isozymes in green and red fruits, respectively. An in vitro assay showed that CaRboh activity is inhibited in the presence of nitric oxide (NO) donors, peroxynitrite (ONOO−) and glutathione (GSH), suggesting that CaRboh can undergo S-nitrosation, Tyr-nitration, and glutathionylation, respectively. In summary, this study provides a basic biochemical characterization of CaRboh activity in pepper fruits and indicates that this O2•−-generating Rboh is involved in nitro-oxidative stress associated with sweet pepper fruit ripening.

Endogenous hydrogen sulfide (H2S) is up-regulated during sweet pepper (Capsicum annuum L.) fruit ripening. In vitro analysis shows that NADP-dependent isocitrate dehydrogenase (ICDH) activity is inhibited by H2S and NO

Like nitric oxide (NO), hydrogen sulfide (H2S) has been recognized as a new gasotransmitter which plays an important role as a signaling molecule in many physiological processes in higher plants. Although fruit ripening is a complex process associated with the metabolism of reactive oxygen species (ROS) and nitrogen oxygen species (RNS), little is known about the potential involvement of endogenous H2S. Using sweet pepper (Capsicum annuum L.) as a model non-climacteric fruit during the green and red ripening stages, we studied endogenous H2S content and cytosolic l-cysteine desulfhydrase (L-DES) activity which increased by 14% and 28%, respectively, in red pepper fruits. NADPH is a redox compound and key cofactor required for cell growth, proliferation and detoxification. We studied the NADPH-regenerating enzyme, NADP-isocitrate dehydrogenase (NADP-ICDH), whose activity decreased by 34% during ripening. To gain a better understanding of its potential regulation by H2S, we obtained a 50–75% ammonium sulfate-enriched protein fraction containing the NADP-ICDH protein; with the aid of in vitro assays in the presence of H2S, we observed that 2 and 10 mM NaHS used as H2S donors resulted in a decrease of up to 36% and 45%, respectively, in NADP-ICDH activity, which was unaffected by reduced glutathione (GSH). On the other hand, peroxynitrite (ONOO−), S-nitrosocyteine (CysNO) and DETA-NONOate, with the last two acting as NO donors, also inhibited NADP-ICDH activity. In silico analysis of the tertiary structure of sweet pepper NADP-ICDH activity (UniProtKB ID A0A2G2Y555) suggests that residues Cys133 and Tyr450 are the most likely potential targets for S-nitrosation and nitration, respectively. Taken together, the data reveal that the increase in the H2S production capacity of red fruits is due to higher L-DES activity during non-climacteric pepper fruit ripening. In vitro assays appear to show that H2S inhibits NADP-ICDH activity, thus suggesting that this enzyme may be regulated by persulfidation, as well as by S-nitrosation and nitration. NO and H2S may therefore regulate NADPH production and consequently cellular redox status during pepper fruit ripening.

Neuroprotective potential of phenolic extracts of <i>Capsicum frutescens</i> as an inhibitor of monoamine oxidase and cholinesterase activities

In this study, we investigated the in vitro antioxidant activity of the extracts from ripe and unripe fruits of Capsicum frutescens . The effects of the extracts on three enzymes which are associated with Parkinson's disease (PD) were also investigated together with quantitation of total phenol, flavonoid and non-flavonoid contents of the extracts. Activities of mitochondrial monoamine oxidase (MAO), acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) from rat brain were determined in the presence of the extracts. 1, 1-diphenyl-2- picrylhydrazyl (DPPH) and OH radicals scavenging abilities, as well as membrane stabilizing effect of the extract via inhibition of Fe 2+ -induced lipid peroxidation in rat brain tissue homogenate were assessed. The results revealed that the extracts exhibited mitochondrial MAO, AChE and BChE inhibitory effects in concentrationdependent manner, with the unripe fruit extract showing significantly higher (P<0.05) inhibitory effects than the ripe fruit extract. However, the ripe fruit extract had significantly higher total phenol and flavonoid contents, as well as exhibited significantly higher (P<0.05) DPPH free radical scavenging and membrane stabilizing effects. The observed antioxidant and enzyme inhibitory properties of ripe and unripe pepper ( C. frutescens ) fruits extracts could be an interplay among their constituent polyphenols. This could be a justification for their use as nutraceutical/dietary intervention in the management of neurodegenerative diseases, especially PD. Collectively, these findings suggest that C. frutescens could serve as a functional food/nutraceutical in the management of PD and our further studies will be directed towards characterization of the biomolecules involved and their mechanism(s) of action in appropriate models. Keywords: Monoamine oxidase, Cholinesterases, Capsicum spp , Neurodegenerative diseases, Functional foods

Characterization of the hot pepper (Capsicum frutescens) fruit ripening regulated by ethylene and ABA

BackgroundRipening of fleshy fruits has been classically defined as climacteric or non-climacteric. Both types of ripening are controlled by plant hormones, notably by ethylene in climacteric ripening and by abscisic acid (ABA) in non-climacteric ripening. In pepper (Capsicum), fruit ripening has been widely classified as non-climacteric, but the ripening of the hot pepper fruit appears to be climacteric. To date, how to regulate the hot pepper fruit ripening through ethylene and ABA remains unclear.ResultsHere, we examined ripening of the hot pepper (Capsicum frutescens) fruit during large green (LG), initial colouring (IC), brown (Br), and full red (FR) stages. We found a peak of ethylene emission at the IC stage, followed by a peak respiratory quotient at the Br stage. By contrast, ABA levels increased slowly before the Br stage, then increased sharply and reached a maximum level at the FR stage. Exogenous ethylene promoted colouration, but exogenous ABA did not. Unexpectedly, fluridone, an inhibitor of ABA biosynthesis, promoted colouration. RNA-sequencing data obtained from the four stages around ripening showed that ACO3 and NCED1/3 gene expression determined ethylene and ABA levels, respectively. Downregulation of ACO3 and NCED1/3 expression by virus-induced gene silencing (VIGS) inhibited and promoted colouration, respectively, as evidenced by changes in carotenoid, ABA, and ethylene levels, as well as carotenoid biosynthesis-related gene expression. Importantly, the retarded colouration in ACO3-VIGS fruits was rescued by exogenous ethylene.ConclusionsEthylene positively regulates the hot pepper fruit colouration, while inhibition of ABA biosynthesis promotes colouration, suggesting a role of ABA in de-greening. Our findings provide new insights into processes of fleshy fruit ripening regulated by ABA and ethylene, focusing on ethylene in carotenoid biosynthesis and ABA in chlorophyll degradation.

P-205 - Expression profiling of redox-metabolism-related genes and proteins during sweet pepper (Capsicum annuum L.) fruit ripening

Pepper (Capsicum annuum, L.) fruit ripening is characterized by important phenotypic and metabolic changes, with emission of volatile compounds, cell wall softening, chlorophyll degradation, and new pigments and proteins’ synthesis. Recent data have shown that reactive oxygen and nitrogen species (ROS/RNS) are involved in fruit ripening by regulating both gene expression and protein functions through post-translational modifications. In this work, using immature (green) and ripe (red) pepper fruits, RNA-sequencing was performed through an Illumina platform. Raw reads were pre-processed and assembled resulting in a representative transcriptome of 63,353 tentative transcripts (TTs), of which 29,716 had a unique orthologue. Differential expression analysis between green and red pepper fruits showed that 4,325 and 3,269 transcripts were down-and up-regulated respectively at ripening. Moreover, isobaric tags for relative and absolute quantification (iTRAQ®) was used as a proteomic approach, identifying 2,574 proteins, of which 1,189 showed differential expression. In this study, we have combined transcriptomic and proteomic data focusing on oxidative metabolism and antioxidative systems to gain insight into their role on fruit ripening.