Over-seasons analysis of quantitative trait loci affecting phenolic content and antioxidant capacity in raspberry

Quantitative trait loci mapping of polyphenol metabolites from a 'Latham' x 'Glen Moy' red raspberry (Rubus idaeus L) cross

OBJECTIVE

The objective of this study was to investigate the genetic control of polyphenol accumulation in red raspberry (Rubus idaeus L).

METHODS

The levels of total anthocyanins and 37 individual polyphenol metabolites were measured over three years in a raspberry biparental mapping population. Quantitative trait loci (QTLs) for these traits were mapped onto a high-density SNP linkage map.

RESULTS

At least one QTL was detected for each trait, with good consistency among the years. On four linkage groups (LG), there were major QTLs affecting several metabolites. On LG1, a QTL had large effects on anthocyanins and flavonols containing a rutinoside or rhamnose group. On LG4, a QTL had large effects on several flavonols and on LG5 and LG6 QTLs had large effects on ellagic acid derivatives. Smaller QTLs were found on LG2 and LG3.

CONCLUSION

The identification of robust QTLs for key polyphenols in raspberry provides great potential for marker-assisted breeding for improved levels of potentially health beneficial components.

Phenolic profiles and their responses to pre- and post-harvest factors in small fruits: a review

The consumption of small fruits has increased in recent years. Besides their appealing flavor, the commercial success of small fruits has been partially attributed to their high contents of phenolic compounds with multiple health benefits. The phenolic profiles and contents in small fruits vary based on the genetic background, climate, growing conditions, and post-harvest handling techniques. In this review, we critically compare the profiles and contents of phenolics such as anthocyanins, flavonols, flavan-3-ols, and phenolic acids that have been reported in bilberries, blackberries, blueberries, cranberries, black and red currants, raspberries, and strawberries during fruit development and post-harvest storage. This review offers researchers and breeders a general guideline for the improvement of phenolic composition in small fruits while considering the critical factors that affect berry phenolics from cultivation to harvest and to final consumption.

Exploring Genotype-by-Environment Interactions of Chemical Composition of Raspberry by Using a Metabolomics Approach

Promoting the consumption of fruits is a key objective of nutrition policy campaigns due to their associated health benefits. Raspberries are well appreciated for their remarkable flavor and nutritional value attributable to their antioxidant properties. Consequently, one of the objectives of present-day raspberry breeding programs is to improve the fruit’s sensory and nutritive characteristics. However, developing new genotypes with enhanced quality traits is a complex task due to the intricate impacts genetic and environmental factors have on these attributes, and the difficulty to phenotype them. We used a multi-platform metabolomic approach to compare flavor- and nutritional-related metabolite profiles of four raspberry cultivars (‘Glen Ample’, ‘Schönemann’, ‘Tulameen’ and ‘Veten’) grown in different European climates. Although the cultivars appear to be better adapted to high latitudes, for their content in soluble solids and acidity, multivariate statistical analyses allowed us to underscore important genotypic differences based on the profiles of important metabolites. ‘Schönemann’ and ‘Veten’ were characterized by high levels of anthocyanins and ellagitannins, respectively, ‘Tulameen’ by its acidity, and ‘Glen Ample’ for its content of sucrose and β-ionone, two main flavor contributors. Our results confirmed the value of metabolomic-driven approaches, which may foster the development of cultivars with enhanced health properties and flavor.

Genetic and genomic resources for Rubus breeding: a roadmap for the future

Rubus fruits are high-value crops that are sought after by consumers for their flavor, visual appeal, and health benefits. To meet this demand, production of red and black raspberries (R. idaeus L. and R. occidentalis L.), blackberries (R. subgenus Rubus), and hybrids, such as Boysenberry and marionberry, is growing worldwide. Rubus breeding programmes are continually striving to improve flavor, texture, machine harvestability, and yield, provide pest and disease resistance, improve storage and processing properties, and optimize fruits and plants for different production and harvest systems. Breeders face numerous challenges, such as polyploidy, the lack of genetic diversity in many of the elite cultivars, and until recently, the relative shortage of genetic and genomic resources available for Rubus. This review will highlight the development of continually improving genetic maps, the identification of Quantitative Trait Loci (QTL)s controlling key traits, draft genomes for red and black raspberry, and efforts to improve gene models. The development of genetic maps and markers, the molecular characterization of wild species and germplasm, and high-throughput genotyping platforms will expedite breeding of improved cultivars. Fully sequenced genomes and accurate gene models facilitate identification of genes underlying traits of interest and enable gene editing technologies such as CRISPR/Cas9.

The composition of potentially bioactive triterpenoid glycosides in red raspberry is influenced by tissue, extraction procedure and genotype

The beneficial effects of consumption of berry fruits on a range of chronic diseases has been attributed (at least in part) to the presence of unique phytochemicals. Recently, we identified novel ursolic acid-based triterpenoid glycosides (TTPNs) in raspberry fruit and demonstrated their survival in human ileal fluids after feeding which confirmed their colon-availability in vivo. In this paper, in vitro digestion studies demonstrated that certain TTPNs were stable under gastrointestinal conditions and confirmed that these components may have been responsible for bioactivity noted in previous studies. Sequential extractions of raspberry puree, isolated seeds and unseeded puree showed that certain TTPN components (e.g. peak T1 m/z 679, and T2 m/z 1358) had different extractabilities in water/solvent mixes and were differentially associated with the seeds. Purified seed TTPNs (mainly T1 and T2) were shown to be anti-genotoxic in HT29 and CCD841 cell based in vitro colonocyte models. Further work confirmed that the seeds contained a wider range of TTPN-like components which were also differentially extractable in water/solvent mixes. This differential extractability could influence the TTPN composition and potential bioactivity of the extracts. There was considerable variation in total content of TTPNs (∼3-fold) and TTPN composition across 13 Rubus genotypes. Thus, TTPNs are likely to be present in raspberry juices and common extracts used for bioactivity studies and substantial variation exists in both content and composition due to genetics, tissue source or extraction conditions, which may all affect observed bioactivity.

Measurement of ripening of raspberries (Rubus idaeus L) by near infrared and colorimetric imaging techniques

This work includes the evaluation of 168 samples of raspberries 'Glen Lyon', representing whole maturation period, by colorimetric and near infrared imaging techniques, as well as the quantification of total phenols, total anthocyanins and antioxidant activity by chemical methods. Samples showed significant differences depending on the maturation stage using CIELAB colour parameters and total anthocyanins content. The application of partial least squares regression allowed predicting the chemical features from image analysis data, with coefficients of determination (R²) up to 0.75. The best prediction for total anthocyanins including colorimetric data was observed. The proposed methodology can be used as a reference method for assessing important quality attributes of raspberries. Moreover, it is useful, rapid and accurate automatic inspection method.

Mapping and expression of genes associated with raspberry fruit ripening and softening

QTL mapping identifies a range of underlying and unrelated genes with apparent roles in raspberry fruit ripening and softening that show characteristic developing fruit expression profiles. Fruit softening is an important agronomical trait that involves a complex interaction of plant cell processes. We have used both qualitative and quantitative scoring of fruit firmness, length, mass, and resistance to applied force to identify QTL in a raspberry mapping population. QTLs were located primarily on linkage group (LG) 3 with other significant loci on LG 1 and LG 5 and showed mostly additive effects between the two parents. The expression of key genes that underlie these QTLs with roles in cell-wall solubility, water uptake, polyamine synthesis, transcription, and cell respiration was tested across five stages of fruit development, from immature green to red ripe fruit, using real-time RT-qPCR. Gene expression patterns showed variable expression patterns across fruit development with a highly significant positive and negative correlation between genes, supporting precise regulation of expression of different cell processes throughout raspberry fruit development. Variable timing in expression was also found in some genes at different fruit development stages between soft and firm cultivars. Multiple processes have a role to play in fruit softening and this will require development of multiple marker combinations to genes that characterise raspberry fruit softening.

Rubus crataegifolius Bunge regulates adipogenesis through Akt and inhibits high-fat diet-induced obesity in rats

Background

Obesity is one of the greatest public health problems and major risk factors for serious metabolic diseases and significantly increases the risk of premature death. The aim of this study was to determine the inhibitory effects of Rubus crataegifolius Bunge (RCB) on adipocyte differentiation in 3 T3-L1 cells and its anti-obesity properties in high fat diet (HFD)-induced obese rats.

Methods

3 T3-L1 adipocytes and HFD-induced obese rats were treated with RCB, and its effect on gene expression was analyzed using RT-PCR and Western blotting experiments.

Results

RCB treatment significantly inhibited adipocyte differentiation by suppressing the expression of C/EBPβ, C/EBPα, and PPARγ in the 3 T3-L1 adipocytes. Subsequently, the expression of the PPARγ target genes aP2 and fatty acid synthase (FAS) decreased following RCB treatment during adipocyte differentiation. In uncovering the specific mechanism that mediates the effects of RCB, we demonstrated that the insulin-stimulated phosphorylation of Akt strongly decreased and that its downstream substrate phospho-GSK3β was downregulated following RCB treatment in the 3 T3-L1 adipocytes. Moreover, LY294002, an inhibitor of Akt phosphorylation, exerted stronger inhibitory effects on RCB-mediated suppression of adipocyte differentiation, leading to the inhibition of adipocyte differentiation through the downregulation of Akt signaling. An HFD-induced obesity rat model was used to determine the inhibitory effects of RCB on obesity. Body weight gain and fat accumulation in adipose tissue were significantly reduced by the supplementation of RCB. Moreover, RCB treatment caused a significant decrease in adipocyte size, associated with a decrease in epididymal fat weight. The serum total cholesterol (TC) and triglyceride (TG) levels decreased in response to RCB treatment, whereas HDL cholesterol (HDL-C) increased, indicating that RCB attenuated lipid accumulation in adipose tissue in HFD-induced obese rats.

Conclusion

Our results demonstrate an inhibitory effect of RCB on adipogenesis through the reduction of the adipogenic factors PPARγ, C/EBPα, and phospho-Akt. RCB had a potent anti-obesity effect, reducing body weight gain in HFD-induced obese rats.

Electronic supplementary material

The online version of this article (doi:10.1186/s12986-016-0091-0) contains supplementary material, which is available to authorized users.

Bioactive Compounds and Antioxidant Activity in Different Types of Berries

Berries, especially members of several families, such as Rosaceae (strawberry, raspberry, blackberry), and Ericaceae (blueberry, cranberry), belong to the best dietary sources of bioactive compounds (BAC). They have delicious taste and flavor, have economic importance, and because of the antioxidant properties of BAC, they are of great interest also for nutritionists and food technologists due to the opportunity to use BAC as functional foods ingredients. The bioactive compounds in berries contain mainly phenolic compounds (phenolic acids, flavonoids, such as anthocyanins and flavonols, and tannins) and ascorbic acid. These compounds, either individually or combined, are responsible for various health benefits of berries, such as prevention of inflammation disorders, cardiovascular diseases, or protective effects to lower the risk of various cancers. In this review bioactive compounds of commonly consumed berries are described, as well as the factors influencing their antioxidant capacity and their health benefits.

Biochemical Characterization of Dovyalis hebecarpa Fruits: A Source of Anthocyanins with High Antioxidant Capacity

Dovyalis hebecarpa, which is also known as the Ceylon gooseberry, is an attractive exotic purple berry that is produced in the southwest of Brazil with high yields. Current literature lacks information about the nutritional composition and antioxidant capacity of this fruit. As such, this work aimed to evaluate and compare the proximate composition, phytochemical content, and antioxidant capacity of D. hebecarpa over two seasons through the application of a range of different methods, including FRAP, ABTS, and ORAC assays. The proximate composition and biometric parameters were monitored for quality purposes. The results significantly changed between seasons in accordance with variations in rain incidence and average temperatures. The Ceylon gooseberry contained a similar or higher content of anthocyanins (ACY) than other berries commonly consumed in human diet. These ACY were identified at higher levels in the fruit's skin (284 to 351 mg of cyanidin-3-glucoside equivalents/100 g of fresh weight [FW]) than in its pulp (49 to 69 mg/100 g of FW). The use of an ORAC assay identified higher antioxidant activity (145 μmol of Trolox equivalents [TE]/g in the skins and 179 μmol of TE/g in the pulp on a FW basis) than all other methods used to determine antioxidant activity. Thus, D. hebecarpa is a rich source of ACY that demonstrates high antioxidant activity against the peroxyl radicals formed in ORAC assay conditions.

PRACTICAL APPLICATION

Ceylon gooseberry fruit is a source of phytochemicals that could be used in the human diet providing defense against free radicals damage. Moreover, the skins of the fruit, which are not typically consumed, contained higher levels of polyphenols than the pulp. This indicates that the skins of the Ceylon gooseberry may represent a promising source of natural pigments and antioxidants for industrial applications.

Chemical characterization of a red raspberry fruit extract and evaluation of its pharmacological effects in experimental models of acute inflammation and collagen-induced arthritis

Berries are an important dietary source of fibres, vitamins, minerals and some biologically active non-nutrients. A red raspberry fruit extract was characterized in terms of phenolic content and the anti-inflammatory properties and protective effects were evaluated in two experimental models of inflammation. The antioxidant potential of the extract, the cellular antioxidant activity and the effects over neutrophils' oxidative burst were also studied to provide a mechanistic insight for the anti-inflammatory effects observed. The extract was administered in a dose of 15 mg kg(-1), i.p. and significantly inhibited paw oedema formation in the rat. The same dose was administered via i.p. and p.o. routes in the collagen-induced arthritis model in the rat. The extract showed pharmacological activity and was able to significantly reduce the development of clinical signs of arthritis and markedly reduce the degree of bone resorption, soft tissue swelling and osteophyte formation, preventing articular destruction in treated animals.

RNA-seq analysis of Rubus idaeus cv. Nova: transcriptome sequencing and de novo assembly for subsequent functional genomics approaches

Using Illumina sequencing technology, we have generated the large-scale transcriptome sequencing data containing abundant information on genes involved in the metabolic pathways in R. idaeus cv. Nova fruits. Rubus idaeus (Red raspberry) is one of the important economical crops that possess numerous nutrients, micronutrients and phytochemicals with essential health benefits to human. The molecular mechanism underlying the ripening process and phytochemical biosynthesis in red raspberry is attributed to the changes in gene expression, but very limited transcriptomic and genomic information in public databases is available. To address this issue, we generated more than 51 million sequencing reads from R. idaeus cv. Nova fruit using Illumina RNA-Seq technology. After de novo assembly, we obtained 42,604 unigenes with an average length of 812 bp. At the protein level, Nova fruit transcriptome showed 77 and 68 % sequence similarities with Rubus coreanus and Fragaria versa, respectively, indicating the evolutionary relationship between them. In addition, 69 % of assembled unigenes were annotated using public databases including NCBI non-redundant, Cluster of Orthologous Groups and Gene ontology database, suggesting that our transcriptome dataset provides a valuable resource for investigating metabolic processes in red raspberry. To analyze the relationship between several novel transcripts and the amounts of metabolites such as γ-aminobutyric acid and anthocyanins, real-time PCR and target metabolite analysis were performed on two different ripening stages of Nova. This is the first attempt using Illumina sequencing platform for RNA sequencing and de novo assembly of Nova fruit without reference genome. Our data provide the most comprehensive transcriptome resource available for Rubus fruits, and will be useful for understanding the ripening process and for breeding R. idaeus cultivars with improved fruit quality.

Identification of antioxidant capacity -related QTLs in Brassica oleracea

Brassica vegetables possess high levels of antioxidant metabolites associated with beneficial health effects including vitamins, carotenoids, anthocyanins, soluble sugars and phenolics. Until now, no reports have been documented on the genetic basis of the antioxidant activity (AA) in Brassicas and the content of metabolites with AA like phenolics, anthocyanins and carotenoids. For this reason, this study aimed to: (1) study the relationship among different electron transfer (ET) methods for measuring AA, (2) study the relationship between these methods and phenolic, carotenoid and anthocyanin content, and (3) find QTLs of AA measured with ET assays and for phenolic, carotenoid and anthocyanin contents in leaves and flower buds in a DH population of B. oleracea as an early step in order to identify genes related to these traits. Low correlation coefficients among different methods for measuring AA suggest that it is necessary to employ more than one method at the same time. A total of 19 QTLs were detected for all traits. For AA methods, seven QTLs were found in leaves and six QTLs were found in flower buds. Meanwhile, for the content of metabolites with AA, two QTLs were found in leaves and four QTLs were found in flower buds. AA of the mapping population is related to phenolic compounds but also to carotenoid content. Three genomic regions determined variation for more than one ET method measuring AA. After the syntenic analysis with A. thaliana, several candidate genes related to phenylpropanoid biosynthesis are proposed for the QTLs found.

Polyphenol variability in the fruits and juices of a cider apple progeny

BACKGROUND

Polyphenols have a favourable antioxidant potential on human health, suggesting that their high content in apple is responsible for the beneficial effects of apple consumption. They are also linked to the quality of apple juices and ciders since they are predominantly responsible for astringency, bitterness and colour. Major phenolic compounds were quantified by liquid chromatography in fruits and juices from a cider apple progeny harvested for 3 years. The total content of procyanidins and their average degree of polymerisation (DPn) were also determined in fruits by phloroglucinolysis. Variability and extraction yield of these compounds were determined.

RESULTS

The variability observed in the progeny was representative of the variability observed in many cider apple varieties. Hydroxycinnamic acids were the most extractable group, with an average extraction yield of 67%, whereas flavonols and anthocyanins were the least.

CONCLUSION

This study is the first to introduce variability and extraction yields of the main phenolic compounds in both fruits and juices of a cider apple progeny. This dataset will be used for an upcoming QTL mapping study, an original approach that has never been undertaken for cider apple.

Evolution of ellagitannin content and profile during fruit ripening in Fragaria spp

Ellagitannins and ellagic acid conjugates are polyphenols present in the human diet, in particular strawberries (Fragaria spp.). The first aim of this study was isolation and structural characterization of casuarictin and 3-O-methyl ellagic acid 3'-O-α-rhamnopyranoside, which were found to be abundant in Fragaria spp., along with agrimoniin. The second aim was accurate profiling and quantification of 26 ellagitannins and ellagic acid conjugates in six Fragaria x ananassa cultivars and two Fragaria vesca species. The third aim was to describe the ellagitannins behavior during fruit ripening from the green stage to over-ripeness. It was shown that there are major qualitative and quantitative differences in the amount and profile of ellagitannins and ellagic acid conjugates between Fragaria spp. Genotype is a major factor in defining ellagitannin concentration and patterns between strawberries, and variable behavior of the genotypes was observed, in the context of a significant drop in ellagitannins during ripening.

Identification of phenolic constituents in red chicory salads (Cichorium intybus) by high-performance liquid chromatography with diode array detection and electrospray ionisation tandem mass spectrometry

Phenolic acids and flavonoids extracted from several types of Cichorium intybus var. silvestre salads ("Chioggia", "Treviso", "Treviso tardivo", and "Verona") were characterised by high-performance liquid chromatography-electrospray ionisation/mass spectrometry. Among the 64 compounds detected, several hydroxycinnamic acid derivatives including 8 mono- and dicaffeoylquinic acids, 3 tartaric acid derivatives, 31 flavonol and 2 flavone glycosides, as well as 10 anthocyanins were characterised based on UV spectra and MS(n) fragmentation patterns. Furthermore, several isomers of caffeic acid derivatives were distinguished for the first time by their specific mass spectral data. This is the first study reporting the glycosylation type and position of mono- and diglycosylated flavonoids in red salads.

QTL involved in the modification of cyanidin compounds in black and red raspberry fruit

Fruit from Rubus species are highly valued for their flavor and nutritive qualities. Anthocyanin content contributes to these qualities, and although many studies have been conducted to identify and quantify the major anthocyanin compounds from various Rubus species, the genetic control of the accumulation of these complex traits in Rubus is not yet well understood. The identification of the regions of the genome involved in the production of anthocyanins is an important first step in identifying the genes underlying their expression. In this study, ultra and high-performance liquid chromatography (UHPLC and HPLC) and two newly developed Rubus linkage maps were used to conduct QTL analyses to explore the presence of associations between concentrations of five anthocyanins in fruit and genotype. In total, 27 QTL were identified on the Rubus linkage maps, four of which are associated with molecular markers designed from transcription factors and three of which are associated with molecular markers designed from anthocyanin biosynthetic pathway candidate genes. The results of this study suggest that, while QTL for anthocyanin accumulation have been identified on six of seven Rubus linkage groups (RLG), the QTL on RLG2 and RLG7 may be very important for genetic control of cyanidin modification in Rubus.

Secondary metabolite components of kiwifruit

Both green and gold kiwifruit contain high concentrations of vitamin C, and much of the "health story" of kiwifruit involves this vitamin. Kiwifruit also contain other compounds that are bioactive and beneficial to health. In this chapter, the secondary metabolite composition of kiwifruit is presented. Although there are limited compositional data for kiwifruit published in the scientific literature, the concentrations of 42 compounds have been documented. Included are compounds that are often associated with "healthfulness," such as the vitamins (A, C, E, and K), carotenoids (lutein and β-carotene), folate, and antioxidant phenolic compounds. Metabolite discovery is advancing rapidly with the introduction of "metabolomic" studies where the goal is to identify and measure the complete metabolite composition of a sample. In a metabolomic experiment using liquid chromatography and high-resolution mass spectrometry, it was possible to measure more than 500 metabolites in kiwifruit extracts. The large number of detectable metabolites present suggests that there is an abundance of kiwifruit metabolites still to be discovered. Such studies will provide a more complete understanding of the metabolite composition of kiwifruit that will lead to new and improved hypotheses as to the function and effects of kiwifruit metabolites, including their relevance to human health.