Authentication of berries and berry-based food products.

Berries represent one of the most important and high-valued group of modern-day health-beneficial "superfoods" whose dietary consumption has been recognized to be beneficial for human health for a long time. In addition to being delicious, berries are rich in nutrients, vitamins, and several bioactive compounds, including carotenoids, flavonoids, phenolic acids, and hydrolysable tannins. However, due to their high value, berries and berry-based products are often subject to fraudulent adulteration, commonly for economical gain, but also unintentionally due to misidentification of species. Deliberate adulteration often comprises the substitution of high-value berries with lower value counterparts and mislabeling of product contents. As adulteration is deceptive toward customers and presents a risk for public health, food authentication through different methods is applied as a countermeasure. Although many authentication methods have been developed in terms of fast, sensitive, reliable, and low-cost analysis and have been applied in the authentication of a myriad of food products and species, their application on berries and berry-based products is still limited. The present review provides an overview of the development and application of analytical chemistry methods, such as isotope ratio analysis, liquid and gas chromatography, spectroscopy, as well as DNA-based methods and electronic sensors, for the authentication of berries and berry-based food products. We provide an overview of the earlier use and recent advances of these methods, as well as discuss the advances and drawbacks related to their application.

Natural variation of DNA methylation and gene expression may determine local adaptations of Scots pine populations.

Long-lived conifers are vulnerable to climate change because classical evolutionary processes are slow in developing adaptive responses. Therefore, the capacity of a genotype to adopt different phenotypes is important. Gene expression is the primary mechanism that converts genome-encoded information into phenotypes, and DNA methylation is employed in the epigenetic regulation of gene expression. We investigated variations in global DNA methylation and gene expression between three Scots pine (Pinus sylvestris L.) populations located in northern and southern Finland using mature seeds. Gene expression levels were studied in six DNA methyltransferase (DNMT) genes, which were characterized in this study, and in 19 circadian clock genes regulating adaptive traits. In embryos, expression diversity was found for three DNMT genes, which maintain DNA methylation. The expression of two DNMT genes was strongly correlated with climate variables, which suggests a role for DNA methylation in local adaptation. For adaptation-related genes, expression levels showed between-population variation in 11 genes in megagametophytes and in eight genes in embryos, and many of these genes were linked to climate factors. Altogether, our results suggest that differential DNA methylation and gene expression contribute to local adaptation in Scots pine populations and may enhance the fitness of trees under rapidly changing climatic conditions.

Targeted bisulfite sequencing of Scots pine adaptation-related genes.

During environmental changes, epigenetic processes can enable adaptive responses faster than natural selection. In plants, very little is known about the role of DNA methylation during long-term adaptation. Scots pine is a widely distributed coniferous species which must adapt to different environmental conditions throughout its long lifespan. Thus, epigenetic modifications may contribute towards this direction. We provide bisulfite next-generation sequencing data from the putative promoters and exons of eight adaptation-related genes (A3IP2, CCA1, COL1, COL2, FTL2, MFT1, PHYO, and ZTL) in three Scots pine populations located in northern and southern parts of Finland. DNA methylation levels were studied in the two seed tissues: the maternal megagametophyte which contributes to embryo viability, and the biparental embryo which represents the next generation. In most genes, differentially methylated cytosines (DMCs) were in line with our previously demonstrated gene expression differences found in the same Scots pine populations. In addition, we found a strong correlation of total methylation levels between the embryo and megagametophyte tissues of a given individual tree, which indicates that DNA methylation can be inherited from the maternal parent. In conclusion, our results imply that DNA methylation differences may contribute to the adaptation of Scots pine populations in different climatic conditions.

Chloroplast genome assemblies and comparative analyses of commercially important Vaccinium berry crops.

Vaccinium is a large genus of shrubs that includes a handful of economically important berry crops. Given the numerous hybridizations and polyploidization events, the taxonomy of this genus has remained the subject of long debate. In addition, berries and berry-based products are liable to adulteration, either fraudulent or unintentional due to misidentification of species. The availability of more genomic information could help achieve higher phylogenetic resolution for the genus, provide molecular markers for berry crops identification, and a framework for efficient genetic engineering of chloroplasts. Therefore, in this study we assembled five Vaccinium chloroplast sequences representing the economically relevant berry types: northern highbush blueberry (V. corymbosum), southern highbush blueberry (V. corymbosum hybrids), rabbiteye blueberry (V. virgatum), lowbush blueberry (V. angustifolium), and bilberry (V. myrtillus). Comparative analyses showed that the Vaccinium chloroplast genomes exhibited an overall highly conserved synteny and sequence identity among them. Polymorphic regions included the expansion/contraction of inverted repeats, gene copy number variation, simple sequence repeats, indels, and single nucleotide polymorphisms. Based on their in silico discrimination power, we suggested variants that could be developed into molecular markers for berry crops identification. Phylogenetic analysis revealed multiple origins of highbush blueberry plastomes, likely due to the hybridization events that occurred during northern and southern highbush blueberry domestication.

Trace Element Concentration and Stable Isotope Ratio Analysis in Blueberries and Bilberries: A Tool for Quality and Authenticity Control.

Vaccinium genus berries-wild bilberries (Vaccinium myrtillus L.) and cultivated highbush blueberries (Vaccinium corymbosum L.)-are consumed worldwide, and their consumption has a trend of stable increase. Thus, considering their wide use in ethnomedicine, for juice and jam production, as functional food, as well as their use in preparations of extracts which have application potential in pharmaceutical and cosmetics industries, studies regarding the composition of these berries are of special importance. The aim of this study is to characterise the elemental and isotopic composition, as well as variation in element concentration in bilberries gathered from different sites in Northern Europe and in commercially available blueberry samples from across the World. Furthermore, our aim was to develop tools for authenticity and quality control of these berries. The elemental composition of berries was analysed using inductively coupled plasma with optical emission detection (ICP-OED), while isotope ratio mass spectrometry (IRMS) was used for the determination of isotope ratio values. The results demonstrated detectable differences between macro- and microelement values in bilberries. IRMS analysis of blueberries revealed significant differences in isotope ratios based on the place of origin, indicating the possibility to use this analytical method for authenticity testing. In none of the samples, pollution was detected, even though there were indications of different growth conditions and geochemical differences affecting bilberry composition.

Moderate stress responses and specific changes in polyamine metabolism characterize Scots pine somatic embryogenesis.

Somatic embryogenesis (SE) is one of the methods with the highest potential for the vegetative propagation of commercially important coniferous species. However, many conifers, including Scots pine (Pinus sylvestris L.), are recalcitrant to SE and a better understanding of the mechanisms behind the SE process is needed. In Scots pine SE cultures, embryo production is commonly induced by the removal of auxin, addition of abscisic acid (ABA) and the desiccation of cell masses by polyethylene glycol (PEG). In the present study, we focus on the possible link between the induction of somatic embryo formation and cellular stress responses such as hydrogen peroxide protection, DNA repair, changes in polyamine (PA) metabolism and autophagy. Cellular PA contents and the expression of the PA metabolism genes arginine decarboxylase (ADC), spermidine synthase (SPDS), thermospermine synthase (ACL5) and diamine oxidase (DAO) were analyzed, as well as the expression of catalase (CAT), DNA repair genes (RAD51, KU80) and autophagy-related genes (ATG5, ATG8) throughout the induction of somatic embryo formation in Scots pine SE cultures. Among the embryo-producing SE lines, the expression of ADC, SPDS, ACL5, DAO, CAT, RAD51, KU80 and ATG8 showed consistent profiles. Furthermore, the overall low expression of the stress-related genes suggests that cells in those SE lines were not stressed but recognized the ABA+PEG treatment as a signal to trigger the embryogenic pathway. In those SE lines that were unable to produce embryos, cells seemed to experience the ABA+PEG treatment mostly as osmotic stress and activated a wide range of stress defense mechanisms. Altogether, our results suggest that the direction to the embryogenic pathway is connected with cellular stress responses in Scots pine SE cultures. Thus, the manipulation of stress response pathways may provide a way to enhance somatic embryo production in recalcitrant Scots pine SE lines.