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Anthocyanins are polyphenolic compounds with antioxidant capacity, free radical scavenging power, and signaling activities in animal pathogenesis-associated pathways, thus playing an important role as nutraceuticals. Tomato fruits do not usually contain anthocyanins because their biosynthesis is switched off in these organs, but anthocyanin-enriched purple tomatoes have been produced in recent years. The varieties obtained by breeding express a functional copy of the R2R3-MYB transcription factor AN2-like, necessary to start the biosynthetic pathway, and do not produce a functional MYB-ATV repressor. The combination of these traits allows the accumulation of anthocyanins in tomatoes, strengthened under specific environmental factors such as high light intensity or low temperatures. Light starts anthocyanin synthesis and gradually extends its distribution on the fruit exocarp. The analyses carried out in the present study indicate that anthocyanin biosynthesis triggered by light is under HY5 control. However, the process is not active in mesocarp for the absence of the bHLH factor AN1, necessary to produce the MBW complex inducing the late enzymes of the biosynthetic pathway, as a consequence of insufficient expression of the R2R3-MYB gene AN2-like. This occurs since light cannot be perceived in the tissues underneath the skin because of the solar shield produced by the anthocyanins accumulated in the exocarp and for the activation of regulatory loops controlling HY5 levels. This is shown by the expression of genes involved in the production of photoreceptors and in the light signaling chain operating upstream of the anthocyanin pathway and responsible for its activation.

The present work carries out a quantitative analysis of the major bioactive compounds found in the native Mexican purple tomatoes. Total phenolic content ranged from 7.54 to 57.79 mg TPC/g DM, total flavonoid content ranged from 1.89 to 16.93 mg TFC/g DM, total anthocyanin content ranged from 0.29 to 2.56 mg TAC/g DM, and total carotenoid content ranged from 0.11 to 0.75 mg TCC/ g DM. In addition, 14 phenolic acids were identified, among which caffeoylquinic acid derivatives were the most abundant compounds with chlorogenic acid concentration up to 9.680 mg/g DM, together with flavonoids, such as rutin and quercetin-hexoxide. The qualitative analysis also showed the presence of 9 acylated anthocyanins and 2 carotenoids with significant functional features. As for anthocyanins, their chemical structures disclosed special structural features: glycosylated anthocyanins exhibited cis-trans hydroxycinnamic moieties and petunidin-3-(trans-p-coumaroyl)-rutinoside-5-glucoside was reported to be the main anthocyanin, whitin the range of concentrations between 0.160 and 1.143 mg/g DM. [ABSTRACT FROM AUTHOR]

Anthocyanins are natural compounds that act as antioxidants and pigments and are produced by plants in response to stress and various environmental conditions. Anthocyanin-rich diets protect against many chronic diseases, a wide range of tumors, and inflammatory diseases. The common tomato (Solanum lycopersicum) can synthetize anthocyanins only in the green parts of the plant, but not in the fruit. Recent studies have shown that through genetic engineering and breeding it is possible to re-establish the synthesis of anthocyanins in the fruit. The first purple genetically modified tomatoes were first approved for sale in the USA in 2022. Tomato breeding has led to the development of non-genetically modified (GMO) purple tomatoes by exploiting wild relatives of S. lycopersicum. They contain anthocyanins in the fruit epicarp and have a higher antioxidant power than red tomatoes. They represent a novel nutraceutical food and can be sold in the EU. Over the past decade, progress has been made in the characterization of anthocyanin synthesis in fruits of plants belonging to the tomato clade. The genomic elements underlying the activation of the process were identified, providing the basis for understanding how the pathway works in these species. In this review we explore the genetic mechanisms that have been characterized to date, and detail the various wild relatives of the tomato, which have been crucial for recovering ancestral traits that were probably lost during evolution from green-purple to yellow and red tomatoes. This knowledge should help developing strategies to further enhance the status of the commercial tomato lines on sale, based on both genome editing and breeding techniques. [ABSTRACT FROM AUTHOR]

The purple tomato variety 'Indigo Rose' (InR) is favored due to its bright appearance, abundant anthocyanins and outstanding antioxidant capacity. SlHY5 is associated with anthocyanin biosynthesis in 'Indigo Rose' plants. However, residual anthocyanins still present in Slhy5 seedlings and fruit peel indicated there was an anthocyanin induction pathway that is independent of HY5 in plants. The molecular mechanism of anthocyanins formation in 'Indigo Rose' and Slhy5 mutants is unclear. In this study, we performed omics analysis to clarify the regulatory network underlying anthocyanin biosynthesis in seedling and fruit peel of 'Indigo Rose' and Slhy5 mutant. Results showed that the total amount of anthocyanins in both seedling and fruit of InR was significantly higher than those in the Slhy5 mutant, and most genes associated with anthocyanin biosynthesis exhibited higher expression levels in InR, suggesting that SlHY5 play pivotal roles in flavonoid biosynthesis both in tomato seedlings and fruit. Yeast two-hybrid (Y2H) results revealed that SlBBX24 physically interacts with SlAN2-like and SlAN2, while SlWRKY44 could interact with SlAN11 protein. Unexpectedly, both SlPIF1 and SlPIF3 were found to interact with SlBBX24, SlAN1 and SlJAF13 by yeast two-hybrid assay. Suppression of SlBBX24 by virus-induced gene silencing (VIGS) retarded the purple coloration of the fruit peel, indicating an important role of SlBBX24 in the regulation of anthocyanin accumulation. These results deepen the understanding of purple color formation in tomato seedlings and fruits in an HY5-dependent or independent manner via excavating the genes involved in anthocyanin biosynthesis based on omics analysis. [ABSTRACT FROM AUTHOR]

Tomatoes are among the most consumed vegetables worldwide and represent a source of health-beneficial substances. Our study represents the first investigating the peel-associated epiphytic bacteria of red and purple (anthocyanin-rich) tomatoes subjected to organic and conventional farming systems. Proteobacteria was the dominant phylum (relative abundances 79–91%) in all experimental conditions. Enterobacteriaceae represented a large fraction (39.3–47.5%) of the communities, with Buttiauxella and Atlantibacter as the most represented genera. The core microbiota was composed of 59 operational taxonomic units (OTUs), including the majority of the most abundant ones. The occurrence of the most abundant OTUs differed among the experimental conditions. OTU 1 (Buttiauxella), OTU 2 (Enterobacteriales), and OTU 6 (Bacillales) were higher in red and purple tomatoes grown under organic farming. OTU 5 (Acinetobacter) had the highest abundance in red tomatoes subjected to organic farming. OTU 3 (Atlantibacter) was among the major OTUs in red tomatoes under both farming conditions. OTU 7 (Clavibacter) and OTU 8 (Enterobacteriaceae) had abundances ≥1% only in red tomatoes grown under conventional farming. PCA and clustering analysis highlighted a high similarity between the bacterial communities of red and purple tomatoes grown under organic farming. Furthermore, the bacterial communities of purple tomatoes grown under organic farming showed the lowest diversity and evenness. This work paves the way to understand the role of nutritional superior tomato genotypes, combined with organic farming, to modulate the presence of beneficial/harmful bacteria and supply healthier foods within a sustainable agriculture. [ABSTRACT FROM AUTHOR]

Purple tomato is the only cultivated tomato containing anthocyanin inside the fruit, while multi-pistil tomato has a unique shape and the ability to be split into smaller parts without damaging the whole fruit. Purple tomato breeding is a new direction of agriculture research to enrich antioxidant fruit, which nowadays is increasingly in demand. The objective of this research was to obtain multi-pistil tomato fruit containing anthocyanin (purple colored), also to discover the inheritance patterns and heritability of qualitative traits related to fruit color and shape obtained from multi-pistil and purple tomato crossing. This research was conducted using seven populations consisted of 2 parental populations (Multi-pistil Tomato and Purple Tomato), 2 first progeny populations (F1 and F1 Reciprocal), 2 backcross populations (BC1.1 and BC1.2), and second progeny population (F2). The result showed that pistil type, unripe fruit color, ripe fruit color, fruit shape and fruit type were inherited autosomally. The inheritance pattern of the traits followed the epistasis gene interaction with moderate to high heritability value.

Tomatoes are among the most consumed vegetables worldwide and represent a source of health-beneficial substances. Our study represents the first investigating the peel-associated epiphytic bacteria of red and purple (anthocyanin-rich) tomatoes subjected to organic and conventional farming systems. Proteobacteria was the dominant phylum (relative abundances 79–91%) in all experimental conditions. Enterobacteriaceae represented a large fraction (39.3–47.5%) of the communities, with Buttiauxella and Atlantibacter as the most represented genera. The core microbiota was composed of 59 operational taxonomic units (OTUs), including the majority of the most abundant ones. The occurrence of the most abundant OTUs differed among the experimental conditions. OTU 1 (Buttiauxella), OTU 2 (Enterobacteriales), and OTU 6 (Bacillales) were higher in red and purple tomatoes grown under organic farming. OTU 5 (Acinetobacter) had the highest abundance in red tomatoes subjected to organic farming. OTU 3 (Atlantibacter) was among the major OTUs in red tomatoes under both farming conditions. OTU 7 (Clavibacter) and OTU 8 (Enterobacteriaceae) had abundances ≥1% only in red tomatoes grown under conventional farming. PCA and clustering analysis highlighted a high similarity between the bacterial communities of red and purple tomatoes grown under organic farming. Furthermore, the bacterial communities of purple tomatoes grown under organic farming showed the lowest diversity and evenness. This work paves the way to understand the role of nutritional superior tomato genotypes, combined with organic farming, to modulate the presence of beneficial/harmful bacteria and supply healthier foods within a sustainable agriculture.

The purple and black tomato are sources of different antioxidants such as carotenoids and flavonoids that seem to have dose-dependent antioxidant, anti-inflammatory, anti-proliferative and hypnotic effects. The aim of this review is to discuss their advantageous role in health promotion and prophylaxis against chronic conditions induced by inflammation and oxidative stress. Data research was conducted on five major databases using specific keywords to extract relevant articles. The anti-proliferative effect was seen in a deep purple tomato in two human cancer cell lines: human colorectal adenocarcinoma cell line and HeLa cell line. Potential anticancer properties were attributed to radical scavenging activity, enzyme detoxification, reduced cell proliferation, angiogenesis and invasiveness. Ingestion of purple and black tomato seeds was proven to increase circulating melatonin levels and improve hypnosis. Purple and black tomato anthocyanin treatment was also significantly associated with increased sperm motility and spermatogenic cell density. The high content of bioactives in purple and black tomato may find application in prevention of cancer and cardiovascular diseases as well as management of sleep and fertility disorders. [ABSTRACT FROM AUTHOR]

Dietary anthocyanins are important health-promoting antioxidants that make a major contribution to the quality of fruits. It is intriguing that most tomato cultivars do not produce anthocyanins in fruit. However, the purple tomato variety Indigo Rose, which has the dominant Aft locus combined with the recessive atv locus from wild tomato species, exhibits light-dependent anthocyanin accumulation in the fruit skin. Here, we report that Aft encodes a functional anthocyanin activator named SlAN2-like, while atv encodes a nonfunctional version of the anthocyanin repressor SlMYBATV. The expression of SlAN2-like is responsive to light, and the functional SlAN2-like can activate the expression of both anthocyanin biosynthetic genes and their regulatory genes, suggesting that SlAN2-like acts as a master regulator in the activation of anthocyanin biosynthesis. We further showed that cultivated tomatoes contain nonfunctional alleles of SlAN2-like and therefore fail to produce anthocyanins. Consistently, expression of a functional SlAN2-like gene driven by the fruit-specific promoter in a tomato cultivar led to the activation of the entire anthocyanin biosynthesis pathway and high-level accumulation of anthocyanins in both the peel and flesh. Taken together, our study exemplifies that efficient engineering of complex metabolic pathways could be achieved through tissue-specific expression of master transcriptional regulators. Through characterization of the purple tomato "Indigo Rose," which only shows anthocyanin pigmentation in the skin in a light-dependent manner, this study reveals that the R2R3-MYB protein SlAN2-like orchestrates a hierarchical transcriptional network to promote anthocyanin accumulation. Expression of a functional SlAN2-like gene could bypass light and activate anthocyanin biosynthesis in both the peel and flesh of tomato cultivars. [ABSTRACT FROM AUTHOR]

Fruits of cultivated tomato (Solanum lycopersicum) generally do not present significant amounts of anthocyanins. However, the Aft and atv loci present in some wild tomato wild relatives are responsible for the presence of anthocyanins in these wild species. Suggested candidate genes for Aft and atv are SlANT1 and SlMYBATV, respectively. Herein, we reported variations in SlANT1 and SlMYBATV in two partially purple and three fully purple tomatoes, and the genetic requirements of both variations to induce full anthocyanin pigmentation. Twelve SNPs at SlANT1 leading to eight missense mutations and a 4-bp insertion at SlMYBATV leading to a premature termination codon were found in the purple tomatoes. Anthocyanin levels were 2–7 folds higher in fully purple tomato fruits than in partially purple tomato fruits and anthocyanin levels in the stems and leaves did not significantly differ between the two types. DNA markers of SlANT1 and SlMYBATV were developed and used for the genetic assessment of purple tomatoes. In two different F2 populations, segregating partial and full pigmentation, SlANT1 co-segregated with the presence of anthocyanin accumulation in fruits and the combination of SlANT1 and slmybatv was necessary for full purple pigmentation. These results will be useful for marker-assisted selection of anthocyanin-rich fruits in tomato. [ABSTRACT FROM AUTHOR]

A conventional breeding approach was framed to combine lycopene enhancing mutant gene, dg or hp-2 dg and anthocyanin synthesizing gene, Aft in one genotype in maximizing the accumulation of both lycopene and anthocyanin pigment in tomato fruit. This breeding scheme involves one crossing, Alisa Craig AftAft  × BCT-115 dgdg followed by two selfings for selection of the desirable double homozygous genotype, AftAft dgdg , the “Purple tomato” based on morphological marker characters conditioned by two genes, dark green fruit of dgdg due to very high total chlorophyll content (18.19 mg/100 g fresh weight) and purple colour for anthocyanin pigment of Aft - gene. Lycopene content in ripe fruits of BCT-115 dgdg (6.22 mg/100 g fresh weight) was 62.41% higher compared to Alisa Craig Aft / Aft while that of Alisa Craig AftAft had high anthocyanin content (14.51 mg/ 100 g fresh weight) contrary to nil in BCT 115 dgdg . Segregation pattern confirmed the expected 3:1 ratio for single dominant Aft gene and 1:3 ratio for single recessive dg gene. The F 2 segregates could be grouped into 5 phenotypic classes in the ratio of 6:3:3:3:1 instead of usual 9:3:3:1 in digenic segregation due to variable expression of anthocyanin in the homozygous ( Aft Aft ) and heterozygous ( Aft aft ) genotype. Of the selfed progeny of the 34 desirable F 2 segregates (dark green fruit with intense anthocyanin pigmentation) clustered in the Group-1 family (F 3 population), 9 segregates bred true confirming the presence of two targeted genes in homozygous condition, AftAft dgdg , the “Purple tomato line”. This breeding approach proved to be a viable option to develop a new variety “Purple tomato” with unique combination of high lycopene (6.13 mg/100 g fresh weight), anthocyanin (20.73 mg/100 g fresh weight) and ascorbic acid (31.56 mg/100 g fresh weight) contents. [ABSTRACT FROM AUTHOR]

Anthocyanins are natural pigments distributed widely among higher plants. Anthocyanins in plant-derived food are also important nutrient constituents, due to their dietary health benefits. Tomato (Solanum lycopersicum L.) is an important vegetable crop grown worldwide, many with anthocyanins in their fruit tissues, but the pigmentation varies specially in the popular purple tomato. To develop tomatoes with a high anthocyanin content, we conducted cultivation experiments under natural temperature and sunlight conditions using two purple cherry tomato cultivars 'Toscana Violet' and 'Blue Bingo' and an ordinary cherry tomato cultivar 'Amakko' as a control to clarify problems which we may encounter during year-round cultivation of purple tomatoes. The content of anthocyanins was high in the tomatoes cultivated in the winter but extremely low in those cultivated in the summer. These findings suggested that the high temperature in summer may cause poor anthocyanin production resulting in less pigmented fruits, although the yield of fruits itself is not be affected greatly. Furthermore, treatment of 'Blue Bingo' fruits at late growth and maturation stage by a night (8 h)-andday (16 h) temperature regime of 15-22 °C resulted in marked accumulation of anthocyanins in skin and outer pericarp of the fruits, but those of 20-27 °C and 25-32 °C had no or little accumulation. [ABSTRACT FROM AUTHOR]

Highlights: [•] The in vitro antioxidant and in vivo anti-inflammatory activities of a unique purple tomato V118. [•] The bioaccessibility of the phytochemicals in V118 before and after gastrointestinal digestion. [•] Correlation between the phytochemicals and cellular antioxidant activity. [•] Changes of biomarkers and enzyme activities in the carrageenan-induced paw oedema rat. [Copyright &y& Elsevier]

A great emphasis of plant research is being placed on developing crops with increased nutritional value. Generating plant materials suitable for controlled studies as potential tools for pre-breeding is still the main hurdle. Improvements are needed in generating different allele combinations to stack various nutrients into a single genotype, without losses in fruit yield or quality, and in testing the specific effects of nutrients in their original matrix, avoiding the noise caused by the characteristic mix of compounds. An elegant approach in both pre-breeding and diet supplementation tests is the use of near-isogenic lines (NILs). Here, we tap on the large pool of monogenic mutants and natural genetic variation available in tomato to create a series of NILs in the genetic background of the cultivar Micro-Tom (MT). We describe the introgression of the mutations Anthocyanin fruit (Aft), atroviolacium (atv), Aubergine (Abg), Beta-carotene (B), old-gold crimson (og) and high pigment 1 and 2 (hp1, hp2) and characterize their fruit metabolic profiles in single, double and triple mutant combinations. We show that Brix can be raised without yield penalty, along with increases in lycopene, β-carotene and ascorbic acid, and a concomitant enhancement of anti-oxidant capacity. As proof-of-concept of the suitability of stacking alleles for breeding nutrient-rich tomatoes, we introduce three mutations leading to uniformly purple fruits and enhanced nutrient contents from MT into a commercial cherry tomato cultivar. [ABSTRACT FROM AUTHOR]