Pectic enzymes as potential enhancers of ascorbic acid production through the D-galacturonate pathway in Solanaceae

The increase of L-Ascorbic Acid (AsA) content in tomato (Solanum lycopersicum) is a common goal in breeding programs due to its beneficial effect on human health. To shed light into the regulation of fruit AsA content, we exploited a Solanum pennellii introgression line (IL12-4-SL) harbouring one quantitative trait locus that increases the content of total AsA in the fruit. Biochemical and transcriptomic analyses were carried out in fruits of IL12-4-SL in comparison with the cultivated line M82 at different stages of ripening. AsA content was studied in relation with pectin methylesterase (PME) activity and the degree of pectin methylesterification (DME). Our results indicated that the increase of AsA content in IL12-4-SL fruits was related with pectin de-methylesterification/degradation. Specific PME, polygalacturonase (PG) and UDP-D-glucuronic-acid-4-epimerase (UGlcAE) isoforms were proposed as components of the D-galacturonate pathway leading to AsA biosynthesis. The relationship between AsA content and PME activity was also exploited in PMEI tobacco plants expressing a specific PME inhibitor (PMEI). Here we report that tobacco PMEI plants, altered in PME activity and degree of pectin methylesterification, showed a reduction in low methylesterified pectic domains and exhibited a reduced AsA content. Overall, our results provide novel biochemical and genetic traits for increasing antioxidant content by marker-assisted selection in the Solanaceae family

Bioaccessibility of Deoxynivalenol and its natural co-occurrence, with Ochratoxin A and Aflatoxin B1 in italian commercial pasta

Cereals products for direct human consumption are rarely contaminated by moulds, unlike raw materials, which are often infected, either in the field or during storage. In this study, 27 samples of dried pasta characterised by size, packaging and marketing intended for young children consumption were collected and analysed by liquid chromatography (LC) and liquid chromatography– tandem mass spectrometry (LC–MS/MS) for Deoxynivalenol (DON), Ochratoxin A (OTA) and Aflatoxin B1 (AFB1) determination. The samples that showed the highest amounts of one of the mycotoxins were cooked for 10 min, digested with an in vitro gastrointestinal protocol and bioaccessibility values were calculated. Seven of the 27 samples exceeded from 120% to 225% the legal limit of 200 lg/kg for DON fixed for processed cereal-based baby foods by an European Regulation; all the collected samples were under the OTA legal limit (0.05 lg/kg) fixed by the European Regulation and no sample was contaminated by AFB1 over the instrumental limit of detection of 0.10 lg/kg. The mean value of gastric bioaccessibility verified for the DON resulted of 23.1%, whereas mean duodenal bioaccessibility was 12.1%

Study of thermal resistance and in vitro bioaccessibility of patulin from artificially contaminated apple products

Apple juices and purees represent categories widely consumed by whole population and above all children. Patulin (PAT) is a mycotoxin known for its acute and chronic effects in animals. Several studies indicate there is a risk associated to the PAT intake, through the consumption of purees and apple juices. In this study, apple juice and puree were prepared and artificially contaminated with PAT at 50 lg/kg and submitted to a thermal treatment simulating pasteurization to evaluate PAT’s reduction. In a second phase of the work, apple products samples (n = 7) included juices, nectars and purees belonging to different commercial brands were collected, artificially contaminated with PAT at 50 lg/L (limit established for PAT in juices) and 25 lg/kg (limit established for PAT in purees), digested with an in vitro gastrointestinal protocol and bioaccessibility values (%) were calculated. After thermal treatment, the PAT’s loss evidenced in purees and juices was of 1.41 ± 0.52% and 62.62 ± 2.53% respectively. Related to the bioaccessibility data, two juices with pulp showed values of 70.89 ± 4.93 and 67.30 ± 10.76%; two purees showed levels of 58.15 ± 5.50 and 55.69 ± 4.73%, whereas nectar and two clarified juice showed percentages of 38.88 ± 2.42, 28.59 ± 0.46 and 25.28 ± 0.61%, respectively

Impact of heat treatments on technological performance of re-milled semolina dough and bread

Re-milled semolina used for bread making is appreciated from consumers for its typical sensory features and nutritional attributes. Fluid bed drying treatment can be applied to semolina to change its bacteriological properties, to prolong shelf life by decreasing the risk of mould development, and to degrade some mycotoxins. The main goal of the present work was to evaluate the impact of heat treatment on structural development of semolina dough during mixing and leavening and on bread characteristics. Semolina was treated with fluidized bed drying at 90°C, 120°C, or 150°C for 5, 15 or 30 min. The heat treatment affected colour, moisture content, and farinograph indices of semolina. Results showed that the use of heat treated re-milled semolina significantly (P <0.05) affected the dough leavening kinetics and bread parameters such as crumb structure and mechanical parameters, in particular for treatment at 150°C for 30 min. On the contrary, after treatment of semolina at 120°C for 30 min, an improvement in the leavening phase of dough and no significant effects on bread quality were observed. Therefore, moderate heat treatment can be applied to semolina without having any negative impact

Enhancing the Health-Promoting Effects of Tomato Fruit for Biofortified Food

Consumption of tomato fruits, like those of many other plant species that are part of the human diet, is considered to be associated with several positive effects on health. Indeed, tomato fruits are an important source of bioactive compounds with known beneficial effects including vitamins, antioxidants, and anticancer substances. In particular, antioxidant metabolites are a group of vitamins, carotenoids, phenolic compounds, and phenolic acid that can provide effective protection by neutralizing free radicals, which are unstable molecules linked to the development of a number of degenerative diseases and conditions. In this review, we will summarize the recent progress on tomatoes nutritional importance and mechanisms of action of different phytochemicals against inflammation processes and prevention of chronic noncommunicable diseases (e.g., obesity, diabetes, coronary heart disease, and hypertension). In addition, we will summarize the significant progress recently made to improve the nutritional quality of tomato fruits through metabolic engineering and/or breeding

New insights in the control of antioxidants accumulation in tomato by transcriptomic analyses of genotypes exhibiting contrasting levels of fruit metabolites

Abstract Background Tomato is an economically important crop with fruits that are a significant source of bioactive compounds such as ascorbic acid and phenolics. Nowadays, the majority of the enzymes of the biosynthetic pathways and of the structural genes controlling the production and the accumulation of antioxidants in plants are known; however, the mechanisms that regulate the expression of these genes are yet to be investigated. Here, we analyzed the transcriptomic changes occurring during ripening in the fruits of two tomato cultivars (E1 and E115), characterized by a different accumulation of antioxidants, in order to identify candidate genes potentially involved in the biosynthesis of ascorbic acid and phenylpropanoids. Results RNA sequencing analyses allowed identifying several structural and regulator genes putatively involved in ascorbate and phenylpropanoids biosynthesis in tomato fruits. Furthermore, transcription factors that may control antioxidants biosynthesis were identified through a weighted gene co-expression network analysis (WGCNA). Results obtained by RNA-seq and WGCNA analyses were further confirmed by RT-qPCR carried out at different ripening stages on ten cultivated tomato genotypes that accumulate different amount of bioactive compounds in the fruit. These analyses allowed us to identify one pectin methylesterase, which may affect the release of pectin-derived D-Galacturonic acid as metabolic precursor of ascorbate biosynthesis. Results reported in the present work allowed also identifying one L-ascorbate oxidase, which may favor the accumulation of reduced ascorbate in tomato fruits. Finally, the pivotal role of the enzymes chalcone synthases (CHS) in controlling the accumulation of phenolic compounds in cultivated tomato genotypes and the transcriptional control of the CHS genes exerted by Myb12 were confirmed. Conclusions By using transcriptomic analyses, candidate genes encoding transcription factors and structural genes were identified that may be involved in the accumulation of ascorbic acid and phenylpropanoids in tomato fruits of cultivated genotypes. These analyses provided novel insights into the molecular mechanisms controlling antioxidants accumulation in ripening tomato fruits. The structural genes and regulators here identified could also be used as efficient genetic markers for selecting high antioxidants tomato cultivars

A basic Helix-Loop-Helix (SlARANCIO), identified from a Solanum pennellii introgression line, affects carotenoid accumulation in tomato fruits

Abstract Carotenoid accumulation in tomato (Solanum lycopersicum) fruits is influenced by environmental stimuli and hormonal signals. However, information on the relative regulatory mechanisms are scanty since many molecular players of the carotenoid biosynthetic pathway are still unknown. Here, we reported a basic Helix-Loop-Helix transcription factor, named SlARANCIO (SlAR), whose silencing influences carotenoid accumulation in tomato fruits. The SlAR gene was found in the S. pennellii introgression line (IL) 12-4SL that holds the carotenoid QTL lyc12.1. We observed that the presence of the wild region in a cultivated genetic background led to a decrease in total carotenoid content of IL12-4SL fruits. To get insights into the function of SlAR, a quick reverse genetic approach was carried out. Virus-induced gene silencing of SlAR in S. lycopersicum M82 and MicroTom fruits reproduced the same phenotype observed in IL12-4SL, i.e. decreased content of lycopene and total carotenoids. Vice versa, the overexpression of SlAR in Nicotiana benthamiana leaves increased the content of total carotenoids and chlorophylls. Our results, combined with public transcriptomic data, highly suggest that SlAR acts indirectly on the carotenoid pathway and advances current knowledge on the molecular regulators controlling lyc12.1 and, potentially, precursors of carotenoid biosynthesis

Impact of Wild Loci on the Allergenic Potential of Cultivated Tomato Fruits

Tomato (Solanum lycopersicum) is one of the most extensively consumed vegetables but, unfortunately, it is also able to induce allergic reactions. In the past, it has been shown that the choice of tomato cultivar significantly influenced the allergic reaction of tomato allergic subjects. In this study we investigated the allergenic potential of the cultivated tomato line M82 and of two selected lines carrying small chromosome regions from the wild species Solanum pennellii (i.e. IL7-3 and IL12-4). We evaluated the positive interactions of IgEs of allergic subjects in order to investigate the different allergenic potential of the lines under investigation. We used proteomic analyses in order to identify putative tomato allergens. In addition, bioinformatic and transcriptomic approaches were applied in order to analyse the structure and the expression profiles of the identified allergen-encoding genes. These analyses demonstrated that fruits harvested from the two selected introgression lines harbour a different allergenic potential as those from the cultivated genotype M82. The different allergenicity found within the three lines was mostly due to differences in the IgE recognition of a polygalacturonase enzyme (46 kDa), one of the major tomato allergens, and of a pectin methylesterase (34 kDa); both the proteins were more immunoreactive in IL7-3 compared to IL12-4 and M82. The observed differences in the allergenic potential were mostly due to line-dependent translational control or post-translational modifications of the allergens. We demonstrated, for the first time, that the introgression from a wild species (S. pennellii) in the genomic background of a cultivated tomato line influences the allergenic properties of the fruits. Our findings could support the isolation of favorable wild loci promoting low allergenic potential in tomato

An ascorbic acid-enriched tomato genotype to fight UVA-induced oxidative stress in normal human keratinocytes

UVA radiations contribute up to 95% of the total UV exposure and are known to induce cell damage, leading to apoptosis. Since the benefic effects of ascorbic acid on human health are well known, a new tomato genotype (namedDHO4), highly rich in ascorbic acid, has been recently obtained. Here,we compared the effects of ascorbic acid and hydrophilic DHO4 extracts in protecting human keratinocytes exposed to UVA stress. Keratinocytes were pre-incubated with ascorbic acid or with extracts from the ascorbic acid enriched tomato genotype and irradiated with UVA light. Then, ROS production, intracellular GSH and lipid peroxidation levels were quantified. Western blots were carried out to evaluate mitogen-activated protein kinases cascade, activation of caspase-3 and inflammation levels. We demonstrated that ROS, GSH and lipid peroxidation levels were not altered in cell exposed to UVA stress when cellswere pre-treatedwith ascorbic acid or with tomato extracts. In addition, no evidence of apoptosis and inflammationwere observed in irradiated pre-treated cells. Altogether,we demonstrated the ability of an ascorbic acid enriched tomato genotype to counteract UVA-oxidative stress on human keratinocytes. This protective effect is due to the high concentration of vitamin C that acts as free radical scavenger. This novel tomato genotype may be used as genetic material in breeding schemes to produce improved varieties with higher antioxidant levels