Ripe Tomato Research Articles

Changes in flavonoid and carotenoid profiles alter volatile organic compounds in purple and orange cherry tomatoes obtained by allele introgression.

Tomatoes are an important source of human health-promoting compounds, and efforts have been made to enhance their nutritional quality through conventional plant breeding or biotechnology. This study assessed the composition of volatile compounds, phenolics and carotenoids in two allele-introgressed tomato lines, an anthocyanin-rich purple tomato and a β-carotene-rich orange tomato, as well as a red tomato. The purple tomato peel accumulated a high amount of anthocyanins, mainly petunidin 3-(p-coumaroyl)-rutinoside-5-glucoside, responsible for the purple color, and other flavonoids such as rutin and kaempferol. The orange tomato did not undergo changes in the flavonoid profile but accumulated a high amount of β-carotene, with impairment on lycopene. A total of 27 volatile compounds were detected in purple tomato, 38 in orange tomato and 39 in red tomato. They comprise terpenes, carbonyls, alcohols, esters and hydrocarbons. The difference in the volatile compound profiles of ripe fruits can be related to differences in some precursor contents in the introgression lines. Orange tomato accumulates volatiles from β-carotene cleavage, not detected in the red fruits. Otherwise, volatiles from lycopene were absent in orange tomato as a result of the inhibition on lycopene accumulation. Phenolic volatiles were higher in the purple tomato, which has the highest total phenolic content. The introgessed alleles seem to have a positive effect on the enrichment of ripe tomato in bioactive compounds such as anthocyanins and β-carotene, improving nutritional quality. However, the allele introgression resulted in marked changes in volatile compound profiles, whose impact on tomato flavor and consumer acceptability needs to be evaluated. © 2019 Society of Chemical Industry.

Revisiting the Role of Master Regulators in Tomato Ripening.

The study of transcriptional regulation of tomato ripening has been led by spontaneous mutations in transcription factor (TF) genes that completely inhibit normal ripening, suggesting that they are 'master regulators'. Studies using CRISPR/Cas9 mutagenesis to produce knockouts of the underlying genes indicate a different picture, suggesting that the regulation is more robust than previously thought. This requires us to revisit our model of the regulation of ripening and replace it with one involving a network of partially redundant components. At the same time, the fast rise of CRISPR/Cas mutagenesis, resulting in unexpectedly weak phenotypes, compared with knockdown technology, suggests that compensatory mechanisms may obscure protein functions. This emphasises the need for assessment of these mechanisms in plants and for the careful design of mutagenesis experiments.

Molecular characterization and transcription analysis of DNA methyltransferase genes in tomato (Solanum lycopersicum).

DNA methylation plays an important role in plant growth and development, gene expression regulation, and maintenance of genome stability. However, only little information regarding stress-related DNA methyltransferases (MTases) genes is available in tomato. Here, we report the analysis of nine tomato MTases, which were categorized into four known subfamilies. Structural analysis suggested their DNA methylase domains are highly conserved, whereas the N-terminals are divergent. Tissue-specific analysis of these MTase genes revealed that SlCMT2, SlCMT3, and SlDRM5 were expressed higher in young leaves, while SlMET1, SlCMT4, SlDRM7, and SlDRM8 were highly expressed in immature green fruit, and their expression declined continuously with further fruit development. In contrast, SlMETL was highly expressed in ripening fruit and displayed an up-regulated tendency during fruit development. In addition, the expression of SlMET1 in the ripening of mutant rin and Nr tomatoes is significantly higher compared to wild-type tomato, suggesting that SlMET1 was negatively regulated by the ethylene signal and ripening regulator MADS-RIN. Furthermore, expression analysis under abiotic stresses revealed that these MTase genes were stress-responsive and may function diversely in different stress conditions. Overall, our results provide valuable information for exploring the regulation of tomato fruit ripening and response to abiotic stress through DNA methylation.

Photosensitisation combined with ozone gas delays the postharvest ripening of stored tomato

Photosensitisation combined with ozone gas delays the postharvest ripening of stored tomato

Photosensitisation combined with ozone gas delays the postharvest ripening of stored tomato

Tomato faces pathogen attack which is a major cause of postharvest losses. The present study is carried out to minimise its postharvest losses and to extend its shelf life by physical elicitors such as photosensitisation, ozone and UV-C. The quality of the fruit was evaluated by the quantitative analysis of physico-chemical, biochemical and enzymatic assay at a regular interval of 5 d during storage. The results showed significantly higher levels of total phenols, ascorbic acid, carotene, lycopene and the antioxidant activity throughout their storage as compared to control. The fruits of T5 group (photosensitisation and ozone gas treatment) remained marketable up to 40 d, while the non-treated fruits were acceptable up to 22 d. The nutritional quality of stored tomato was also found better in treated fruit than control. These results suggest that the photosensitisation and ozone is found effective in the postharvest extension of tomato and maintaining their nutritional quality.

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.

Identification of a novel N-caprylhistamine-β-glucoside from tomato fruits and LC-MS/MS-based food screening for imidazole alkaloids

The present study aimed at the identification of novel imidazole alkaloids derived from histamine or histidinol and generally investigating the occurrence of suchlike alkaloids in a variety of foodstuffs. Herein, N-caprylhistamine was synthesized and the glucosidic derivative N-caprylhistamine-β-glucoside was isolated from ripe tomato fruits and structurally characterized. The obtained reference standards were used for the extension of an established LC-MS/MS-based method for the quantitation of several imidazole alkaloids in tomato products. After validation for the two additional analytes and demonstrating the applicability of the method to nine other food matrices, 104 food items were screened for the occurrence of the described imidazole alkaloids. Remarkably, all of the investigated alkaloids were only quantifiable in tomato-based products and the occurrence of N-caprylhistamine and N-caprylhistamine-β-glucoside was reported for the first time. These imidazole alkaloids could thus be applicable as specific intake biomarkers for tomatoes and their biological activities as well as metabolic fate should be investigated in future research.

Enhancement of the antioxidant capacity of ripe tomatoes by the application of a hot water treatment at the mature-green stage

Abstract Plants are constantly exposed to abiotic and biotic stresses, inducing the generation of reactive oxygen species (ROS). In response, the synthesis of antioxidants is upregulated to neutralize the deteriorating effects of ROS. We investigated whether promoting this response could enhance the nutritional and sensory quality of tomatoes. In preliminary experiments, mature green tomatoes were immersed in hot water (HW) at 50 °C for 5 min, 52 °C for 5 min, or 54 °C for 2.5 min (25 °C water for 5 min as control); subsequent experiments utilized 52 °C for 5 min. Following those treatments, we evaluated the changes in color, texture, soluble solids, titratable acidity, and the antioxidant system of the fruit during ripening at 20 °C and 85–90 % relative humidity. The HW treatment of 52 °C for 5 min promoted higher accumulation of carotenoids and lipophilic phenolics, resulting in greater color development and slightly higher antioxidant potential, but did not otherwise affect the composition of ripe fruit; the tomatoes ripened normally after HW immersion, with no firmness differences, but were darker red and less yellow-orange with higher antioxidant potential. Furthermore, we observed that the beneficial effects were more noticeable at early stages of ripening, even in varieties that did not exhibit major differences after reaching full ripeness. In this sense, we found that ‘Florida 47’ and ‘Security 28’ tomatoes have a limited response to HW treatment compared with ‘Soraya’ and especially ‘Tasti Lee’ tomatoes, indicating that there might be genetic constraints on the response in the former varieties. The beneficial effect of immersing the tomatoes in HW was proportional to the heat penetration profile inside the fruit; for example, the 52 °C for 5 min treatment increased the temperature up to 45 °C in the peripheral tissues 4 mm below the fruit surface where the content of carotenoids and lipophilic phenolic compounds was mainly increased; whereas, the tissue temperature was 35 °C at the center of the tomato, where we did not observe any change in composition. In conclusion, the HW immersion used in this research promoted the synthesis of lipophilic antioxidants such as carotenoids in tomato fruit, enhancing red color development and antioxidant potential.

Effect of chemical preservatives on the shelf life of tomato juice

Abstract This research conducted with the fully fresh, ripe and sound tomato (Lycopersicon esculentum Mill.) was collected then washed, peeled, seeds removed and transferred to the juice extractor. Sugar, preservatives were added to the extracted filtrated juice. Then the juice was heated, cooled and bottled for preservation. Tomato juice was prepared with three different treatments. Among the three treatments T1, T2 and T3 sample were prepared with no preservative, Na-benzoate preservative and potassium meta-bisulphite (KMS) preservative respectively. The organoleptic observation of this tomato juice was studied for 60 days storage period. Chemical analysis and sensory tests were carried out during the 30 days at an interval of 15 days to assess the effect of chemical additives on the shelf life of tomato juice. Negligible Change in chemical constituents except vitamin C was observed in the prepared juice throughout the 30 days storage period. Color was gradually faded and slightly off flavor develops at the end of the storage periods. The treatment T2 secured highest score for color, flavor, taste and overall acceptability and ranked as “Like very much” by a taste testing panel. Tomato juice prepared with no preservative (T1) spoiled after 45 days storage and juice prepared with KMS preservative (T3) spoiled after 60 days storage. Total number of viable bacteria was highest in tomato juice treated with no preservative (T1) and KMS preservative (T3). Tomato juice with Na-benzoate preservative (T2) contained least viable bacteria which was better than T1 and T3 sample. Considering all the parameters, Na-benzoate tends to be better additives than potassium meta-bisulphite (KMS) for preservation of tomato juice.

Pathways to defense metabolites and evading fruit bitterness in genus Solanum evolved through 2-oxoglutarate-dependent dioxygenases

The genus Solanum comprises three food crops (potato, tomato, and eggplant), which are consumed on daily basis worldwide and also producers of notorious anti-nutritional steroidal glycoalkaloids (SGAs). Hydroxylated SGAs (i.e. leptinines) serve as precursors for leptines that act as defenses against Colorado Potato Beetle (Leptinotarsa decemlineata Say), an important pest of potato worldwide. However, SGA hydroxylating enzymes remain unknown. Here, we discover that 2-OXOGLUTARATE-DEPENDENT-DIOXYGENASE (2-ODD) enzymes catalyze SGA-hydroxylation across various Solanum species. In contrast to cultivated potato, Solanum chacoense, a widespread wild potato species, has evolved a 2-ODD enzyme leading to the formation of leptinines. Furthermore, we find a related 2-ODD in tomato that catalyzes the hydroxylation of the bitter α-tomatine to hydroxytomatine, the first committed step in the chemical shift towards downstream ripening-associated non-bitter SGAs (e.g. esculeoside A). This 2-ODD enzyme prevents bitterness in ripe tomato fruit consumed today which otherwise would remain unpleasant in taste and more toxic.

Transcriptional changes during tomato ripening and influence of brackish water irrigation on fruit transcriptome and sugar content

Efficient management and utilization of brackish water irrigation help to minimize yield losses and promote fruit quality and sugar content in tomato fruit. However, the functional genes involved in sugar metabolic pathways and potential molecular pathways responsive to brackish water irrigation remain unknown. To this end, physiological responses and comparative transcriptional profiling was used to analyze the tomato fruit during the white-ripe period (CK1) and mature period (CK2) in plants grown under four water management strategies (rotating irrigation with brackish and fresh water during fruit development, T1; fresh water irrigation, T2; mixed brackish and fresh water irrigation, T3; mixed water and fresh water irrigation in sequence, T4). Comparative analysis revealed that during fruit development (CK2 cv CK1) differentially expressed genes (DEGs) involved in photosynthetic pathways and sucrose-starch metabolism were downregulated. However, two DEGs encoding putative beta-fructofuranosidases were significantly upregulated at the mature stage, which promoted the accumulation of glucose and fructose in CK2. Comparing four types of management strategies, rotating irrigation with brackish water and fresh water (T1) led to reprograming of global gene expression. Moreover, the upregulated DEGs in T1 were significantly enriched for signaling, hormone metabolism, and stress tolerance, suggesting the coordination of both stresses signaling as well as the plant hormone. These results provide a valuable reference for rational use of brackish water in the production of high-quality tomato in arid and semi-arid regions.

The application of UV-C irradiation followed by storage in continuous low level ethylene atmosphere to delay the ripening of mature green tomatoes

The application of UV-C irradiation followed by storage in continuous low level ethylene atmosphere to delay the ripening of mature green tomatoes

Manipulation of Plastidial Protein Quality Control Components as a New Strategy to Improve Carotenoid Contents in Tomato Fruit.

Carotenoids such as β-carotene (pro-vitamin A) and lycopene accumulate at high levels during tomato (Solanum lycopersicum L.) fruit ripening, contributing to the characteristic color and nutritional quality of ripe tomatoes. Besides their role as pigments in chromoplast-harboring tissues such as ripe fruits, carotenoids are important for photosynthesis and photoprotection in the chloroplasts of photosynthetic tissues. Interestingly, recent work in Arabidopsis thaliana (L.) Heynh. has unveiled a critical role of chloroplast protein quality control components in the regulation of carotenoid biosynthesis. The accumulation (i.e. degradation rate) and activity (i.e. folding status) of phytoene synthase (PSY) and other Arabidopsis biosynthetic enzymes is modulated by chaperones such as Orange (OR) and Hsp70 in coordination with the stromal Clp protease complex. OR and Clp protease were recently shown to also influence PSY stability and carotenoid accumulation in tomato. Here we show how manipulating the levels of plastid-localized Hsp70 in transgenic tomato plants can also impact the accumulation of carotenoids in ripe fruit. The resulting carotenoid profile and chromoplast ultrastructure, however, are different from those obtained in tomatoes from transgenic lines with increased OR activity. These results suggest that different chaperone families target different processes related to carotenoid metabolism and accumulation during tomato ripening. We further discuss other possible targets for future manipulation in tomato based on the knowledge acquired in Arabidopsis.

Identification and in silico characterization of cis-acting elements of genes involved in carotenoid biosynthesis in tomato.

Carotenoids, the widespread and structurally diverse class of pigments, accumulate in the fruits of tomato plants in a tissue specific manner. The carotenoid biosynthetic pathway genes have been cloned and characterized in tomato and other plants, however, its regulation is still obscure. We collected and analyzed forty different accessions of tomato for the present study. HPLC analysis revealed differential accumulation of major carotenoids (lycopene and ß-carotene) in the ripe fruit tissue. In order to understand the underlying regulatory mechanisms in carotenoid biosynthesis and accumulation, we sequenced the cis-acting elements i.e. promoter, 5' and 3' untranslated regions of the carotenoid pathway genes, in all accessions, followed by their in silico validation. Major differences observed in the CAAT Box, Opaque-2 Box and L-box in the promoters of carotenoid isomerase and lycopene-beta cyclase genes, respectively, along with the variations in musashi binding element of 5' untranslated regions of the carotenoid isomerase gene, suggest their differential role in regulating the carotenogenesis process in tomato. The binding sites for various transcription factors namely RIN, AGAMOUS, CRY, RAP2.2 and PIF1 on the promoters of important carotenoid pathway genes were predicted in silico. We propose that expression of carotenoid genes and also the formation of protein product in ripe tomato fruits, is regulated efficiently by the binding of these transcription factors at selected sites in the promoter region. Finally, the differential expression of the above-mentioned genes in different developmental tissues supports the possible involvement of promoters and untranslated regions in carotenoid biosynthesis and accumulation process. The present study has generated significant information concerning regulatory players involved in the carotenoid biosynthesis in tomato.

Genetic and metabolic effects of ripening mutations and vine detachment on tomato fruit quality.

SummaryTomato (Solanum lycopersicum) fruit ripening is regulated co‐operatively by the action of ethylene and a hierarchy of transcription factors, including RIPENING INHIBITOR (RIN) and NON‐RIPENING (NOR). Mutations in these two genes have been adopted commercially to delay ripening, and accompanying textural deterioration, as a means to prolong shelf life. However, these mutations also affect desirable traits associated with colour and nutritional value, although the extent of this trade‐off has not been assessed in detail. Here, we evaluated changes in tomato fruit pericarp primary metabolite and carotenoid pigment profiles, as well as the dynamics of specific associated transcripts, in the rin and nor mutants during late development and postharvest storage, as well of those of the partially ripening delayed fruit ripening (dfd) tomato genotype. These profiles were compared with those of the wild‐type tomato cultivars Ailsa Craig (AC) and M82. We also evaluated the metabolic composition of M82 fruit ripened on or off the vine over a similar period. In general, the dfd mutation resulted in prolonged firmness and maintenance of quality traits without compromising key metabolites (sucrose, glucose/fructose and glucose) and sectors of intermediary metabolism, including tricarboxylic acid cycle intermediates. Our analysis also provided insights into the regulation of carotenoid formation and highlighted the importance of the polyamine, putrescine, in extending fruit shelf life. Finally, the metabolic composition analysis of M82 fruit ripened on or off the vine provided insights into the import into fruit of compounds, such as sucrose, during ripening.

Determination of developmental and ripening stages of whole tomato fruit using portable infrared spectroscopy and Chemometrics

BackgroundDevelopment and ripening of tomato (Solanum lycopersicum) fruit are important processes for the study of crop biology related to industrial horticulture. Versatile uses of tomato fruit lead to its harvest at various points of development from early maturity through to red ripe, traditionally indicated by parameters such as size, weight, colour, and internal composition, according to defined visual ‘grading’ schemes. Visual grading schemes however are subjective and thus objective classification of tomato fruit development and ripening are needed for ‘high-tech’ horticulture. To characterize the development and ripening processes in whole tomato fruit (cv. Moneymaker), a biospectroscopy approach is employed using compact portable ATR-FTIR spectroscopy coupled with chemometrics.ResultsThe developmental and ripening processes showed unique spectral profiles, which were acquired from the cuticle-cell wall complex of tomato fruit epidermis in vivo. Various components of the cuticle including Cutin, waxes, and phenolic compounds, among others, as well as from the underlying cell wall such as celluloses, pectin and lignin like compounds among others. Epidermal surface structures including cuticle and cell wall were significantly altered during the developmental process from immature green to mature green, as well as during the ripening process. Changes in the spectral fingerprint region (1800–900 cm− 1) were sufficient to identify nine developmental and six ripening stages with high accuracy using support vector machine (SVM) chemometrics.ConclusionsThe non-destructive spectroscopic approach may therefore be especially useful for investigating in vivo biochemical changes occurring in fruit epidermis related to grades of tomato during development and ripening, for autonomous food production/supply chain applications.

Influence of Different Concentrations of 1-Methylcyclopropene (1-MCP) and Storage Conditions on the Physico-chemical Properties and Shelf-life of Tomatoes (Solanum lycopersicum L.)

‘Power’ tomato cultivar was harvested at the mature green stage and studied to determine how different 1-Methylcyclopropene (1-MCP) concentrations and storage conditions may influence its quality and shelf-life. A 3 x 2 factorial arrangement in Completely Randomized Design (CRD) was used and it was replicated three times. The factors were the tomato cultivar: ‘Power’, three 1-MCP concentration levels: 1 ppm, 2 ppm, untreated was 0 ppm and two storage conditions: Ambient and refrigerator conditions. The research was conducted between January and May 2017 at the Department of Horticulture, KNUST in Kumasi, Ghana. The 1-MCP concentration required were obtained by adding 100 ml of heated distilled water at 50°C to appropriate amounts of 1-MCP (MaxFresh, 3.3%) powder to obtain the 1 ppm and 2 ppm concentrations. After the 1-MCP powder has completely dissolved, it was then placed in a sealed bottle with a mini fan attached and then placed in the treatment chamber and released in a form of vapour on fruits and sealed immediately to avoid gas loss for a period of 24 hours. They were then stored in the refrigerator and ambient conditions at a temperature of 13°C-15°C and 29.5°C with Relative Humidity of 60-75% and 80-85% respectively. There was a significantly (P<0.01) delayed in ripening as characterized by changes in pH, firmness and total titratable acidity. Tomatoes treated with 1 ppm and 2 ppm of 1-MCP concentrations had delayed ripening when stored in the refrigerator and as a result had a longer shelf-life of 74 and 90 days respectively compared to fruits that were not treated and kept at ambient condition which took 60 days. There is confirmation from these results that the use of 1-MCP have saleable outlook for those who grow and trade in a way of delaying the ripening of green tomatoes.

Omics analysis of the ethylene signal transduction in tomato as a function of storage temperature

This study has focussed on the effect of low temperature storage on the postharvest ripening of green tomatoes; more specifically, on the ethylene signal transduction in relation to the ethylene biosynthesis pathway. To this end, the first elements of the ethylene signal transduction, ethylene receptors, CTR and EIN2 have been analysed in tomatoes stored at three different temperatures in terms of both their gene and protein expression levels. These results have been related to quality changes and enzymes and intermediates of the ethylene biosynthesis pathway to better understand the ethylene control of ripening under low temperatures. The first changes observed during low temperature storage took place at the ethylene biosynthesis level, which might enhance changes in the ethylene signal transduction. Although expression of most ethylene signalling genes decreased with chilling, none of the protein levels showed a significant decrease, pointing at a differential regulation at the gene and protein level.

Chemical and Microbiological Evaluation of Dried Tomato slices for Nigerian System

Effect of two simple drying methods (sun drying and oven drying at 40 °C, 50 °C and 60 °C) on the quality of tomato slices were evaluated. Fresh tomato sample served as the control. Firm and fresh ripe tomatoes were washed and sliced to a uniform thickness of 7mm.

Gibberellins Play a Role in Regulating Tomato Fruit Ripening.

Although exogenous applications of gibberellins (GAs) delay tomato ripening, the regulatory mechanisms of GAs in the process have never been well recognized. Here, we report that the concentration of endogenous GAs is declined before the increase of ethylene production in mature-green to breaker stage fruits. We further demonstrate that reductions in GA levels via overexpression of a GA catabolism gene SlGA2ox1 specifically in fruit tissues lead to early ripening. Consistently, we have also observed that application of a GA biosynthetic inhibitor, prohexadione-calcium, at the mature-green stage accelerates fruit ripening, while exogenous GA3 application delays the process. Furthermore, we demonstrate that ethylene biosynthetic gene expressions and ethylene production are activated prematurely in GA-deficient fruits but delayed/reduced in exogenous GA3-treated WT fruits. We also show that the GA deficiency-mediated activation of ethylene biosynthesis is due to the activation of the ripening regulator genes RIN, NOR and CNR. In conclusion, our results demonstrate that GAs play a negative role in tomato fruit ripening.