Fruit Pigmentation Research Articles

Transcriptome Profiling Reveals Transcriptional Regulation by DNA Methyltransferase Inhibitor 5-Aza-2'-Deoxycytidine Enhancing Red Pigmentation in Bagged "Granny Smith" Apples (Malus domestica).

The red color of apples (Malus domestica) is an attractive trait for consumers. The green skinned “Granny Smith” cultivar develops red pigmentation after bagging treatment. DNA methylation plays an important role in various developmental processes in plants. To explore the possible functions of DNA methylation in the pigmentation of bagged “Granny Smith” apples, we first analyzed the anthocyanin content of fruit skin following treatment with the DNA methyltransferase inhibitor 5-aza-2′-deoxycytidine (5-aza-dC). The results revealed an increase in anthocyanin content in bagged fruits following 5-aza-dC treatment, while no anthocyanins were detected in unbagged fruits. In addition, 8482 differentially expressed genes between 5-aza-dC-treated and control groups were identified in bagged fruits by RNA sequencing, including genes encoding transcription factors, enzymes related to anthocyanin accumulation, and methylases. Changes in the expression of these genes may be responsible for 5-aza-dC-induced red pigmentation in bagged fruits of “Granny Smith”. The findings provide novel evidence for the involvement of DNA methylation in the red pigmentation of non-red-skinned apples.

Transcriptome profiles reveal new regulatory factors of anthocyanin accumulation in a novel purple-colored cherry tomato cultivar Jinling Moyu

Anthocyanins are important secondary metabolites with high nutraceutical value. They represent the major red, purple, violet and blue pigments in higher plants but are usually not present in the fruits of domesticated tomatoes. Recently, several genes that regulate anthocyanin accumulation have been identified in wild tomatoes or mutation lines; however, whether there are other new factors involved in the regulation of anthocyanin biosynthesis is still unknown. “Jinling Moyu” (MY) is a novel purple cherry tomato that accumulates considerable anthocyanins in its ripe fruit. A transcriptome comparison analysis of MY fruits with pink and green fruit revealed that several structural genes assigned to the anthocyanin biosynthetic pathway were highly expressed in MY tomato, but all six known regulatory genes of anthocyanin accumulation in tomato fruits were rarely expressed among the samples in this study. However, four other R2R3–MYB and five other bHLH transcription factors were highly correlated with the differentially expressed structural genes in the anthocyanin pathway, indicating that these transcription factors might regulate anthocyanin biosynthesis in MY tomato. Our study will aid in understanding the complex mechanism regulating anthocyanin pigmentation in tomato fruits .

Extension of life-span using a RNAi model and in vivo antioxidant effect of Opuntia fruit extracts and pure betalains in Caenorhabditis elegans

Betalains are nitrogenous plant pigments known for their high antioxidant capacity. For the first time, this antioxidant nature has been studied in an in vivo system using the model organism Caenorhabditis elegans. The oxidative stress caused in the fluorescent strain TJ375 (hsp-16.2::GFP) was reversed by the presence of both natural and semi-synthetic betalains, with an ED50 value around 25 μM for betacyanins and up to 10 μM for betaxanthins, with indicaxanthin, the major pigments in prickly pear fruits, as the most effective betalain. The effect of model betalains on the lifespan of the wild-type N2 strain was carefully studied using the automatic platform “Lifespan Machine”. In a search for different approaches to suppress progeny, pop-1 RNAi was used to avoid FUdR use. The presence of betalains in the medium, both as pure compounds and as enriched Opuntia extracts significantly increased the lifespan of C. elegans.

Tomato (Solanum lycopersicum) SlIPT4, encoding an isopentenyltransferase, is involved in leaf senescence and lycopene biosynthesis during fruit ripening

BackgroundLycopene is an important carotenoid pigment in red fruits and vegetables, especially in tomato. Although lycopene biosynthesis and catabolism have been found to be regulated by multiple factors including phytohormones, little is known about their regulatory mechanism. Cytokinins are crucial to various aspects of plant growth. Isopentenyltransferases (IPTs) catalyze the initial rate-limiting step of cytokinins biosynthesis, however, their roles in fruit ripening remain unclear.ResultsHere, the functions of SlIPT4, encoding an isopentenyltransferase, were characterized via RNAi-mediated gene silencing in tomato. As we expected, silencing of SlIPT4 expression resulted in accelerated leaf senescence. However, down-expression of SlIPT4 generated never-red orange fruits, corresponding with a dramatic reduction of lycopene. Among lycopene biosynthesis-related genes, the fact of remarkable decrease of ZISO transcript and upregulation of other genes, revealed that SlIPT4 regulates positively lycopene biosynthesis via directly affecting ZISO expression, and also supported the existence of regulatory loops in lycopene biosynthesis pathway. Meanwhile, the accumulation of abscisic acid (ABA) was reduced and the transcripts PSY1 were increased in SlIPT4-RNAi fruits, supporting the feedback regulation between ABA and lycopene biosynthesis.ConclusionThe study revealed the crucial roles of SlIPT4 in leaf senescence and the regulatory network of lycopene biosynthesis in tomato, providing a new light on the lycopene biosynthesis and fruit ripening.

Reduced Anthocyanins in Petioles codes for a GST anthocyanin transporter that is essential for the foliage and fruit coloration in strawberry.

The red color of the foliage and fruit in strawberry comes from anthocyanins stored in the vacuole; however, how this anthocyanin accumulation is regulated remains unclear. A reduced anthocyanin in petioles (rap) mutant was identified in an N-ethyl-N-nitrosourea (ENU) mutagenized population of YW5AF7, a white-fruited variety of the wild strawberry Fragaria vesca. The causative mutation was identified to be a premature stop codon in a glutathione S-transferase (GST) gene. In addition to the foliage coloration, RAP also mediates fruit pigmentation and acts downstream of the fruit-specific transcription factor FvMYB10. Among all eight GST genes in the same subfamily, RAP is most abundantly expressed in the ripening fruit. Expression analysis and transient expression assays demonstrated that RAP is the principal transporter of anthocyanins among the paralogs. Moreover, domain-swap experiments showed that both the N- and C-terminals of RAP are essential for the binding capability of anthocyanins. In addition, transient knock-down of RAP resulted in reduced fruit coloration in cultivated strawberry. Collectively, our results demonstrate that RAP encodes the principal GST transporter of anthocyanins in the strawberry foliage and fruit, and it could be modified to alter the fruit color in strawberry.

Fine Mapping Identifies SmFAS Encoding an Anthocyanidin Synthase as a Putative Candidate Gene for Flower Purple Color in Solanum melongena L.

Anthocyanins are the main pigments in flowers and fruits. These pigments are responsible for the red, red-purple, violet, and purple color in plants, and act as insect and animal attractants. In this study, phenotypic analysis of the purple flower color in eggplant indicated that the flower color is controlled by a single dominant gene, FAS. Using an F2 mapping population derived from a cross between purple-flowered ‘Blacknite’ and white-flowered ‘Small Round’, Flower Anthocyanidin Synthase (FAS) was fine mapped to an approximately 165.6-kb region between InDel marker Indel8-11 and Cleaved Amplified Polymorphic Sequences (CAPS) marker Efc8-32 on Chromosome 8. On the basis of bioinformatic analysis, 29 genes were subsequently located in the FAS target region, among which were two potential Anthocyanidin Synthase (ANS) gene candidates. Allelic sequence comparison results showed that one ANS gene (Sme2.5_01638.1_g00003.1) was conserved in promoter and coding sequences without any nucleotide change between parents, whereas four single-nucleotide polymorphisms were detected in another ANS gene (Sme2.5_01638.1_g00005.1). Crucially, a single base pair deletion at site 438 resulted in premature termination of FAS, leading to the loss of anthocyanin accumulation. In addition, FAS displayed strong expression in purple flowers compared with white flowers and other tissues. Collectively, our results indicate that Sme2.5_01638.1_g00005.1 is a good candidate gene for FAS, which controls anthocyanidin synthase in eggplant flowers. The present study provides information for further potential facilitate genetic engineering for improvement of anthocyanin levels in plants.

Delphinidin induces apoptosis and inhibits epithelial-to-mesenchymal transition via the ERK/p38 MAPK-signaling pathway in human osteosarcoma cell lines.

Delphinidin is major anthocyanidin that is extracted from many pigmented fruits and vegetables. This substance has anti‐oxidant, anti‐inflammatory, anti‐angiogenic, and anti‐cancer properties. In addition, delphinidin strongly suppresses the migration and invasion of various cancer cells during tumorigenesis. Although delphinidin has anti‐cancer effects, little is known about its functional roles in osteosarcoma (OS). For these reasons, we have demonstrated the effects of delphinidin on OS cell lines. The effects of delphinidin on cell viability and growth of OS cells were assessed using the MTT assay and colony formation assays. Hoechst staining indicated that the delphinidin‐treated OS cells were undergoing apoptosis. Flow cytometry, confocal microscopy, and a western blot analysis also indicated evidence of apoptosis. Inhibition of cell migration and invasion was found to be associated with epithelial‐to‐mesenchymal transition (EMT), observed by using a wound healing assay, an invasion assay, and a western blot analysis. Furthermore, delphinidin treatment resulted in a profound reduction of phosphorylated forms of ERK and p38. These findings demonstrate that delphinidin treatment suppressed EMT through the mitogen‐activated protein kinase (MAPK) signaling pathway in OS cell lines. Taken together, our results suggest that delphinidin strongly inhibits cell proliferation and induces apoptosis. Delphinidin treatment also suppresses cell migration and prevents EMT via the MAPK‐signaling pathway in OS cell lines. For these reasons, delphinidin has anti‐cancer effects and can suppress metastasis in OS cell lines, and it might be worth using as an OS therapeutic agent.

ANTHOCYANIN, THE NATURAL COLORANT AND ITS IMPLICATIONS IN HEALTH AND FOOD INDUSTRY: A SEARCH

Anthocyanins are unique plant pigments since they are critical for most of the red, purple and blue pigmentation of flowers, fruits and vegetables. Meanwhile, they are reactive in nature, anthocyanins degrade easily, or react with other compounds such as reactive metals such as iron, aluminum, and tin in the media, toform colorless or brown colored by products. Anthocyanins are glycosides of anthocyanidins (aglycones) and sugars. Anthocyanidins are almost always glycosylated in the 3-position, though glycosylation in other positions and in more than one position at a time is also encountered. Furthermore, the sugar moiety may be acylated with aliphatic or aromatic acids. Anthocyanidins are less in number but anthocyanins show much diversity offered by glycosylation and acylation. 635 anthocyanins were identified in nature, featuring six common aglycones and various types of glycosylations and acylations. Reports suggest that dietary consumption of anthocyanins is good for health. Based upon many cell-line studies, animal models, and human clinical trials, it has been suggested that anthocyanins possess anti-inflammatory and anticarcinogenic activity, cardiovascular disease prevention, obesity control, and diabetes alleviation properties,all of which are more or less associated with their potent antioxidant property. Evidence suggests that absorption of anthocyanins occurs in the stomach and small intestine. Epithelial tissue uptake seems to be highly efficient, yet transportation into circulation, tissue distribution, and urine excretion are very limited.The bioactivity of bioavailable anthocyanins should be a focus of future research regarding their putative health-promoting effects.

Differential Sensitivity of Fruit Pigmentation to Ultraviolet Light between Two Peach Cultivars.

Anthocyanins provide nutritional benefits and are responsible for red coloration in many fruits. Light affects anthocyanin biosynthesis in peach (Prunus persica). However, some cultivars show differential sensitivity to light. In the present study, ‘Hujingmilu (HJ),’ a naturally deeply colored cultivar, and ‘Yulu (YL),’ showing low pigmentation, were used to study the mechanism underlying UV-light-induced anthocyanin biosynthesis. Both UVA and UVB induced fruit pigmentation of ‘HJ,’ but ‘YL’ was only sensitive to UVB. Transcriptomic analyses showed over 5000 genes were differentially expressed by pairwise comparisons of RNA libraries isolated from tissue of each cultivar treated with darkness, UVA and UVB. Twenty-three genes related to anthocyanin biosynthesis were identified from the transcriptome data, which were coordinately up-regulated during accumulation of anthocyanins, and down-regulated in the dark. Altered expression of several light receptors, as well as CONSTITUTIVE PHOTOMORPHOGENIC10 (COP10) and ELONGATED HYPOCOTYL 5 homolog (HYH), and a specific anthocyanin transporter glutathione S-transferase (GST), in ‘YL’ fruit appears to be responsible for the insensitivity to UVA of this cultivar. Expression profiles of several transcription factors of the families MYB, bHLH, bZIP and NAC were highly correlated with those of the anthocyanin biosynthesis genes. The study provides a valuable overview of the underlying molecular mechanisms of UV-light induced anthocyanin response using peach cultivars with differing light sensitivities.

Identification and Functional Characterization of Tomato CircRNAs Derived from Genes Involved in Fruit Pigment Accumulation

CircRNAs, a class of widespread circular RNAs produced from precursor mRNA back-splicing, have been implicated in regulation of gene expression in eukaryotes, but their biological functions in plants have not yet been elucidated. By deep sequencing of rRNA-removed and RNase R-digested RNA samples we have identified several thousands of putative back-splicing sites in tomato fruit (Solanum lycopersicum) and show that the abundance of some of these circRNAs derived from fruit pigment biosynthesis genes are regulated by fruit ripening. Herein, we overexpressed a circRNA derived from Phytoene Synthase 1 (PSY1) in tomato ‘Ailsa Craig’ and microTom. The PSY1 mRNA abundance, the lycopene and β-carotene accumulation were decreased significantly in the transgenic tomato fruits, likely due to the continuous highly expressed circRNAs and/or the low abundant linear RNAs generated from the overexpression vector. Besides, overexpression of a circRNA derived from Phytoene Desaturase (PDS) showed similar results. Our results provide biological insights into plant circRNAs.

Overexpression of SlPRE2, an atypical bHLH transcription factor, affects plant morphology and fruit pigment accumulation in tomato

The basic helix-loop-helix (bHLH) proteins are a large family of transcription factors that control various developmental processes in eukaryotes, but the biological roles of most bHLH proteins are not very clear, especially in tomato. In this study, a PRE-like atypical bHLH gene was isolated and designated as SlPRE2 in tomato. SlPRE2 was highly expressed in immature-green fruits, moderately in young leaves, flowers, and mature-green fruits. To further research the function of SlPRE2, a 35 S:PRE2 binary vector was constructed and transformed into wild type tomato. The transgenic plants showed increased leaf angle and stem internode length, rolling leaves with decreased chlorophyll content. The water loss rate of detached leaves was increased in young transgenic lines but depressed in mature leaves. Besides, overexpression of SlPRE2 promoted morphogenesis in seedling development, producing light-green unripening fruits and yellowing ripen fruits with reduced chlorophyll and carotenoid accumulation in pericarps, respectively. Quantitative RT-PCR analysis showed that expression of the chlorophyll related genes, such as GOLDEN 2-LIKE and RbcS, were decreased in unripening 35 S:PRE2 fruit, and carotenoid biosynthesis-related genes PHYTOENE SYNTHASE1A and ζ-CAROTENE DESATURASE in ripening fruit were also down-regulated. These results suggest that SlPRE2 affects plant morphology and is a negative regulator of fruit pigment accumulation.

Examination of molecular mechanism for the color mutation in Chinese wild grapevine (Vitis davidii)

The Chinese wild grapevine, Vitis davidii, is disease resistant, matures late, and is the only Vitis species with white-fruit type native to China, and is ideal for grape breeding programs. To uncover the molecular mechanisms responsible for the V. davidii white-fruit phenotype and the relationship between accessions with white and pigmented fruits, the SSR markers, DNA sequencing and qRT-PCR were used. We found a high coefficient of genetic similarity between the two phenotypes; 12 markers, in particular, revealed that the white-skinned V. davidii “Baiciputao” evolved from the pigmented “Hunanci”. The MybA1 gene sequence analysis results revealed that “Baiciputao” harbored only MybA1a at the MybA1 locus, and in “Hunanci”, both MybA1a and MybA1c alleles were detected. This was also linked to grape skin color of the control cultivars, which were Pinot blanc and Pinot noir, Muscat blanc and Muscat rouge. To verify our conclusions, the elementary composition of the anthocyanin profiles of V. davidii and V. vinifera were analyzed using high-performance liquid chromatography and electrospray ionization mass spectrometry (HPLC–ESI–MS/MS), revealing divergent chemical profiles. The main cyanidin derivative in V. davidii was 3-O-glucoside-5-O-glucoside, whereas it was 3-O-glucoside in V. vinifera. The qRT-PCR results indicated that the total anthocyanin content in V. davidii grape skins was not solely determined by UFGT or MYB-related expression levels. These data support the conclusion that the molecular mechanism leading to the white-skinned V. davidii phenotype is the MybA1 gene mutation.

Comparative analysis of pigments in red and yellow banana fruit

Color is an important characteristic determining the fruit value. Although ripe bananas usually have yellow peels, several banana cultivars have red peels. As details of the pigments in banana fruits are unknown, we investigated these pigments contents and compositions in the peel and pulp of red cultivar ‘Hongjiaowang’ and yellow cultivar ‘Baxijiao’ by UPLC-PDA-QTOF-MS and HPLC-PDA techniques. The ‘Hongjiaowang’ peel color was mainly determined by the presence of anthocyanin-containing epidermal cells. Rutinoside derivatives of cyanidin, peonidin, petunidin, and malvidin were unique to the red peel, and possibly responsible for the red color. ‘Hongjiaowang’ contained higher total content of carotenoids than ‘Baxijiao’ in both pulp and peel. Lutein, α-carotene, and β-carotene were main carotenoids, which might play a more important role than flavonoids in producing the yellow banana color owing to the properties and distribution in the fruit. The information will help us understand a complete profile of pigments in banana.

Expression Profiling of Strawberry Allergen Fra a during Fruit Ripening Controlled by Exogenous Auxin.

Strawberry fruit contain the allergenic Fra a proteins, members of the pathogenesis-related 10 protein family that causes oral allergic syndrome symptoms. Fra a proteins are involved in the flavonoid biosynthesis pathway, which might be important for color development in fruits. Auxin is an important plant hormone in strawberry fruit that controls fruit fleshiness and ripening. In this study, we treated strawberry fruits with exogenous auxin or auxin inhibitors at pre- and post-harvest stages, and analyzed Fra a transcriptional and translational expression levels during fruit development by real-time PCR and immunoblotting. Pre-harvest treatment with 1-naphthaleneacetic acid (NAA) alone did not affect Fra a expression, but applied in conjunction with achene removal NAA promoted fruit pigmentation and Fra a protein accumulation. The response was developmental stage-specific: Fra a 1 was highly expressed in immature fruit, whereas Fra a 2 was expressed in young to ripe fruit. In post-harvest treatments, auxin did not contribute to Fra a induction. Auxin inhibitors delayed fruit ripening; as a result, they seemed to influence Fra a 1 expression. Thus, Fra a expression was not directly regulated by auxin, but might be associated with the ripening process and/or external factors in a paralog-specific manner.

Inferring the Genetic Determinants of Fruit Colors in Tomato by Carotenoid Profiling.

Carotenoids are essential for plant and animal nutrition, and are important factors in the variation of pigmentation in fruits, leaves, and flowers. Tomato is a model crop for studying the biology and biotechnology of fleshy fruits, particularly for understanding carotenoid biosynthesis. In commercial tomato cultivars and germplasms, visual phenotyping of the colors of ripe fruits can be done easily. However, subsequent analysis of metabolic profiling is necessary for hypothesizing genetic factors prior to performing time-consuming genetic analysis. We used high performance liquid chromatography (HPLC), employing a C30 reverse-phase column, to efficiently resolve nine carotenoids and isomers of several carotenoids in yellow, orange, and red colored ripe tomatoes. High content of lycopene was detected in red tomatoes. The orange tomatoes contained three dominant carotenoids, namely δ-carotene, β-carotene, and prolycopene. The yellow tomatoes showed low levels of carotenoids compared to red or orange tomatoes. Based on the HPLC profiles, genes responsible for overproducing δ-carotene and prolycopene were described as lycopene ε-cyclase and carotenoid isomerase, respectively. Subsequent genetic analysis using DNA markers for segregating population and germplasms were conducted to confirm the hypothesis. This study establishes the usefulness of metabolic profiling for inferring the genetic determinants of fruit color.

A focus on high-lycopene tomato cultivars: horticultural performance and functional quality

Both transgenic and conventional breeding methods have been used to increase levels and diversify the profile of antioxidants in ripe tomato fruit. The high-pigment (hp) tomato mutants exemplify this approach, representing useful genetic resources to be introgressed into elite cultivars (high-lycopene cultivars) to simultaneously enhance the levels of different classes of antioxidants. Although several studies have been recently published on high-lycopene cultivars, information on their horticultural performance, processing attributes and functional quality is still scarce. In spite of the high content of lycopene, flavonoids and ascorbic acid, high-lycopene tomato cultivars are claimed to have poor horticultural performance, which limits their commercial acceptance. Therefore, the aim of this study was to review their agronomic and horticultural performance briefly as well as to review the functional quality of some recently developed high-lycopene tomato cultivars. Experiments conducted in the Mediterranean region showed that all the assayed high-lycopene tomato cultivars ('HLY02', 'HLY13', 'HLY18', 'Kalvert' and 'Lyco 2', including the latest developed lines 'HLT-F61' and 'HLT-F62') were vigorous, with an excellent dark-green foliage cover and characterized by dark-green immature fruits without morphological aberrations. Tomato yield ranged from 110 to 152 t ha-1, exceeding in some trials the yield of the elite industrial tomato cultivars ('Perfectpeel', 'Rio Grande' and 'Donald'). The average fruit weight ranged from 70 to 93 g, and soluble solids content was higher than 6 °Brix in some cases, associated with desirable titratable acidity values (0.381 for 'HLY18'). Regarding the phytochemical profiles, experiments under different geographical and environmental conditions confirmed that all tested high-lycopene cultivars were characterized by enhanced synthesis and accumulation of carotenoids, mainly lycopene and β-carotene (more than 280 and 20 mg kg-1 fw, respectively), as well as of other valuable health-promoting molecules such as phenolics, flavonoids and vitamins. Thus, the central role of high-lycopene tomato cultivars in enhancing fruit pigmentation and functional quality, summarized in this report, justifies extended efforts and breeding programs to decrease some initial adverse pleiotropic effects on their horticultural performance.

Serum carotenoid interactions in premenopausal women reveal α-carotene is negatively impacted by body fat.

Increasing body mass indices (BMIs) across the globe reflect pandemic shifts towards habitual positive energy imbalances. Excess body fat in individuals is often associated with high-energy and high-fat diets scanty in fresh produce. Carotenoids are fat-soluble pigments plentiful in many fruits and vegetables. They are well-known for provitamin A and antioxidant functions, but little research has been done related to carotenoid-body mass interactions. Serum carotenoids were analyzed relative to body fat to determine correlations between major serum carotenoids, retinol, BMI, fat mass, and lean mass. Healthy women ( n = 76), 19-50 years old, were categorized into two comparison groups determined by percent body fat measured by air displacement plethysomography (BOD POD®), i.e. <31% and ≥31% fat mass. Anthropometric and three-day diet records were completed for BMI and nutrient intake calculations, respectively. Serum α-carotene concentrations were strongly inversely associated with all measures of body composition ( P < 0.001 α-carotene) controlling for dietary intake and age, while β-carotene, lutein, and lycopene were not ( P > 0.05). Dietary intake between groups did not differ, including carrot consumption (a high dietary source of α-carotene). These results confirm previous carotenoid-health research and propose the need for further investigation of potential protective roles that α-carotene may perform for optimal health. Serum α-carotene may provide a deeper and clinically relevant purpose, beyond previous suggestions for its use as a biomarker for fruit and vegetable consumption, in that α-carotene may be a biomarker for chronic disease risk frequently linked with obesity. Impact statement Carotenoids are important pigments in fruit and vegetables and found in human serum. This study isolated a negative relationship between serum α-carotene and body fatness. As humans begin to live over a century, determining biomarkers of ultimate health is important. α-Carotene does not have the same distribution in the food supply as β-carotene and therefore is often overlooked in surveys. In part, this is due to the fact that β-carotene provides two molecules of vitamin A, while α-carotene provides one upon central cleavage. This study shows a very clear association between α-carotene and body fatness, which appears to go beyond its fat-soluble nature. Dietary intake data were not able to explain the association. Further work is needed to determine what dietary components infer health benefits.

Evaluation of processing effects on anthocyanin content and colour modifications of blueberry (Vaccinium spp.) extracts: Comparison between HPLC-DAD and CIELAB analyses

Colour is the first organoleptic property that consumers appreciate of a foodstuff. In blueberry (Vaccinium spp.) fruits, the anthocyanins are the principal pigments determining the colour as well as many of the beneficial effects attributed to this functional food. Commercial blueberry-derived products represent important sources of these healthy molecules all year round.In this study, blueberries were produced into purees comparing two homogenization methods and further heated following different thermal treatments. All the supernatants of the homogenates were monitored for pH. Then, the hydroalcoholic extracts of the same samples were characterized by CIELAB and HPLC-DAD analyses. These analytical techniques provide complementary information on fruit pigments content as a whole and on quali-quantitative profile of the single bioactive colorants. These data could be very interesting to know the best manufacturing procedure to prepare blueberry-derived products, well accepted by the consumers, while maintaining their healthy properties unaltered.

Post-transcriptional regulation of fruit ripening and disease resistance in tomato by the vacuolar protease SlVPE3

BackgroundProteases represent one of the most abundant classes of enzymes in eukaryotes and are known to play key roles in many biological processes in plants. However, little is known about their functions in fruit ripening and disease resistance, which are unique to flowering plants and required for seed maturation and dispersal. Elucidating the genetic mechanisms of fruit ripening and disease resistance is an important goal given the biological and dietary significance of fruit.ResultsThrough expression profile analyses of genes encoding tomato (Solanum lycopersicum) cysteine proteases, we identify a number of genes whose expression increases during fruit ripening. RNA interference (RNAi)-mediated repression of SlVPE3, a vacuolar protease gene, results in alterations in fruit pigmentation, lycopene biosynthesis, and ethylene production, suggesting that SlVPE3 is necessary for normal fruit ripening. Surprisingly, the SlVPE3 RNAi fruit are more susceptible to the necrotrophic pathogen Botrytis cinerea. Quantitative proteomic analysis identified 314 proteins that differentially accumulate upon SlVPE3 silencing, including proteins associated with fruit ripening and disease resistance. To identify the direct SlVPE3 targets and mechanisms contributing to fungal pathogen resistance, we perform a screening of SlVPE3-interacting proteins using co-immunoprecipitation coupled with mass spectrometry. We show that SlVPE3 is required for the cleavage of the serine protease inhibitor KTI4, which contributes to resistance against the fungal pathogen B. cinerea.ConclusionsOur findings contribute to elucidating gene regulatory networks and mechanisms that control fruit ripening and disease resistance responses.

MYBs affect the variation in the ratio of anthocyanin and flavanol in fruit peel and flesh in response to shade

Fruit pigment accumulation, which represents an important indicator of nutrient quality and appearance value, is often affected by low light under rain, cloud, fog and haze conditions during the veraison period. It is not known whether continuous low light interferes with the production and accumulation of secondary metabolites in veraison fruit. In this paper, we measured pigments and the transcriptional level of genes related to secondary metabolites, i.e., flavonoid biosynthesis in the peel and flesh of Malus crabapple ‘Radiant’ fruit in response to normal light and shade from 10th July to 30th August. The results showed crosstalk between the flavonoid biosynthetic genes and the involvement of key transcription factors such as McMYB4, McMYB7, McMYB10, and McMYB16 in the regulation of the ratio of anthocyanins and flavanols, which accounted for the different colouration of the fruit peel and flesh under shade conditions. A model is proposed for the regulation of the flavonoid pathway in the peel and flesh of ‘Radiant’ fruit based on our study results. Moreover, the molecular mechanism for ‘Radiant’ fruit colouration provides reference information for understanding the light regulatory mechanism involved in the biosynthesis of flavonoids and for designing the next generation of apple breeding.