Relationship between the anthocyanin content values in the leaf sheath base of barley cultivars and in the grain of the hybrids derived from them

Background. The development of barley cultivars accumulating anthocyanins in grain is an important task for breeding, which is based on the Ant1 and Ant2 genes that control synthesis of these compounds. To optimize the breeding strategy and selection of the initial material, quantitative assay of anthocyanin content in the leaf sheath base of barley cultivars was carried out and the relationship between this parameter for some of the barley cultivars and anthocyanin content in grain of the hybrids derived from them was evaluated.Materials and methods. The anthocyanin content in the leaf sheath base was studied in 32 barley cultivars in the tillering stage and in mature grains of 11 purple-grain hybrids selected from the hybrid populations using DNA-markers.Results and discussion. It was shown that there were quantitative differences in the anthocyanin content in the leaf sheath base among barley cultivars, which varied from 1 to 191 mg/kg. A cluster analysis helped to identify three groups of cultivars: with low, medium and high anthocyanin content. The hybrids from crossing cultivars differing in their anthocyanin content in the leaf sheath base with line P18, the donor of the dominant allele of the Ant2 gene, showed variation of the anthocyanin content in grain from 22 to 71 mg/kg. The observed differences among the hybrids were determined by the genotypes of individual plants and the allelic state of Ant2. A weak correlation (rs = 0.37, p = 0.0362) was shown between the anthocyanin contents in the leaf sheath base and in the grain of the obtained hybrids.Conclusion. The results of the study would help to optimize the breeding strategy for the development of new barley cultivars with high anthocyanin content in the grain and substantiate the need to test the anthocyanin content in the grain of individual lines

Differently expressed ‘Early’ flavonoid synthesis genes in wheat seedlings become to be co-regulated under salinity stress

Synthesis of flavonoid compounds in plants is associated with their response to environmental stress; however, the way in which the transcription of the relevant structural genes is regulated in stressed plants is still obscure. Transcription of the ‘early’ flavonoid synthesis genes Chi-1 and F3h-1 in the wheat coleoptile was investigated by quantitative real-time PCR in seedlings exposed to 100 mM or 200 mM NaCl. Under mild stress, transcript abundance of both Chi-1 and F3h-1 was increased significantly after six days of exposure. Under severe stress, the level of transcription was the same or even lower than that seen in nonstressed seedlings. In non-stressed conditions, the transcription patterns of Chi-1 and F3h-1 were quite distinct from one another, whereas under stress they became similar. An observed alteration in structural genes regulation mode under stress conditions may optimize flavonoid biosynthesis pathway to produce protective compounds with maximum efficiency

Effects of the Blp1 locus, which controls melanin accumulation in the barley ear, on the size and weight of seeds

Background. In cereals, photosynthetically active parts of the ear significantly contribute to seed size and weight at the grain-filling stage. In barley, ear tissues may accumulate melanin pigments synthesized in chloroplast-derived melanoplasts. Effects of such pigments on yield parameters of seeds have not been evaluated to date.Materials and methods. Seed weight and size assessed by image analysis were compared between two near-isogenic barley lines differing in alleles of the Blp1 gene, which determines melanin accumulation in ear tissues. Data on grainrelated parameters were collected during 6 years and include data on seeds grown either in the field or under greenhouse conditions.Results and discussion. A negative effect of the Blp1 locus on the weight of 1000 seeds harvested in the field but not in the greenhouse was revealed. To determine whether this effect is related to grain size, a comparison of two-dimensional linear parameters of seeds between the lines was performed. It was shown that unlike the length and the area of seeds, the width of seeds was also negatively affected by the Blp1 locus. Although the same factors affected the weight of 1000 seeds and the width of seeds, a correlation between them was not found, implying a dependence of seed weight on other factors such as thickness and its related parameter, seed volume.Conclusion. Effects of barely ear pigmentation and of the gene controlling it on yield-related parameters of seeds were studied here for the first time. The observed negative impact of the Blp1 locus on seed weight and size may be mediated by an interfering chloroplast activity and/or accumulation of assimilates via melanogenesis. Additional studies are necessary to test this supposition and to investigate the interaction of melanin synthesis and photosynthetic activity of the tissues accumulating this pigment

Structural and functional divergence of homoeologous genes in allopolyploid plant genomes

Allopolyploid organisms can be formed by hybridization between closely related plant species with similar genomes. It is believed that many plant species have passed through allopolyploidization, which played a significant role in the formation of a huge diversity of plants, as well as their high adaptive capacity. Thanks to the whole genome sequencing of a wide range of angiosperm species and comparative analysis of genome structure, the sequence of events that formed the genomes of modern plant taxa was restored. These studies have shown that many diploid species have passed through more than one cycle of polyploidization-diploidization. The purpose of this review is to summarize the estimates of what proportion of genes is undergoing changes due to allopoly-ploidization and to illustrate the variety of mechanisms underlying the functional divergence of homoeologous copies (orthologous genes in allopolyploid subgenomes). Changes of individual copies can be associated with epigenetic features of the gene organization (the methylation status of the promoter region or the presence of copy-specific small interfering RNA) or can affect structure of the coding or regulatory regions of the gene. Studies on artificial allopolyploid plants showed widespread transcriptional dominance and change of the transcription level as compared with the genes of diploid parental forms. The study of the transcription of certain homoeologous gene copies allowed estimating the extent of the complete suppression of certain homoeologous genes in newly synthesized (0.4–5.0 %) and natural (30 %) allopolyploids. One the whole, full or partial suppression affects up to 49% of the wheat genes

GENES DETERMINING THE SYNTHESIS OF LAVONOID AND MELANIN PIGMENTS IN BARLEY

In addition to the green color caused by chlorophyll, grain and vegetative organs of barley can be colored by compounds of phenolic nature, such as melanins and lavonoids, which include anthocyanins, proanthocyanidins. Due to the wide biological activity of these pigmented compounds and their uncolored precursors in respect to plants and humans, there has recently been an increased interest in studying genes that determine pigmentation in plants. The gene network determining the synthesis of lavonoid pigments is the most studied one. Since the 1970s, structural genes that encode the enzymes of lavonoid metabolism, as well as regulatory genes that determine the tissue-speciic accumulation of these pigments in grain tissues, as well as in vegetative organs have been identiied and localized in the barley genome. The Ant1 and Ant2 genes, determining the accumulation of anthocyanins in grain pericarp, the Ant28 gene controlling the biosynthesis of proanthocyanidins (condensed tannins) in seed coat, as well as the HvMpc2, HvMyc2 and HvWD40 genes responsible for the accumulation of anthocyanins in the aleurone layer of barley grain have been determined. Melanins are less studied pigments of plants. Due to the complex structure and resistance to various solvents, the chemical nature of these pigments has not been established. However, due to the comparative analysis of transcriptomes in the colored and uncolored lemma and grain pericarp of barley near-isogenic lines, it was possible to identify the metabolic pathways underlying the formation of the melanin pigmentation. The proposed article reviews the results of the studies on the genetic control of barley coloration

Anthocyanin content in grains of barley and oat accessions from the VIR collection

Background. Barley (Hordeum vulgare L.) and oat (Avena sativa L.) are grain crops belonging to one of the main sources of food and forage in the Russian Federation. They contain proteins, various groups of vitamins, fats, carbohydrates, β-glucans, minerals and different bioloactive compounds, including anthocyanins. Recently, much attention has been given to anthocyanins due to their various valuable properties. Therefore, the grain of barley and oat is a potentially promising economic product and a component of functional nutrition. The aim of this work was to estimate the content of anthocyanins in barley and oat accessions with different pigmentation of kernels and lemma. Materials and methods. 32 barley and 11 oat accessions were studied by spectrophotometry. Anthocyanins were extracted from barley and oat kernels with a 1% HCl solution in methanol. Results and discussion. As a result of the study, accessions and varieties with the highest content of anthocyanins were identified: for barley these are k-15904 (China), k-19906 (Mongolia), k-18709 (Japan), k-18723, k-18729 (Canada), k-17725 (Turkey) belonging to var. violaceum; k-29568 (Japan) – var. densoviolaceum; k-8690 (Ethiopia) – var. griseinigrum; k-28205 (Germany) – var. nudidubium; and for oat these are k-15527 (A. ayssinica Hochst. var. braunii Koern., Ethiopia) and k-15245 (A. strigosa Schreb. subsp. brevis var. tephera Mordv. ex Sold. et Rod., Poland). Conclusion. The obtained results demonstrated that the VIR collection includes accessions with potential value for the development of varieties with an increased anthocyanin content, which can be used as functional food products

Molecular-genetic mechanisms underlying fruit and seed coloration in plants

Diverse patterns of plant fruit and seed coloration are determined by the presence of two main types of pigment, carotenoids (red, orange and yellow color) and anthocyanins (purple, blue, red). Thеy belong to two groups of secondary metabolites, isoprenoids and flavonoids. Interest towards the genetic mechanisms that control coloration in plants has recently increased due to the antioxidant and antimicrobial properties of some pigments and their colorless precursors consumed with plant-derived food. The genes encoding enzymes involved in step-bystep conversion of initial organic molecules to final pigmented compounds are referred to as structural genes, while regulatory genes are responsible for activation of the expression of structural genes and control the synthesis of pigments at certain times and in proper tissue. The data in plant genetics accumulated to date show that the inter- and intraspecies phenotypic diversity in coloration is mainly related with regulatory genes. Previously developed rich gene collections and precise genetic models for coloration traits in dicots and monocots as well as the rapid development of molecular genetic methods for studying plants allowed for studying genetic regulation of pigment synthesis at a molecular level. The peculiarities of the regulation of carotenoid biosynthesis are exemplified with Solanaceae fruits. The genetic mechanisms underlying the synthesis of various flavonoid pigments are exemplified with a study of seed color in Poaceae plants. In summary, prospects for the practical use of regulatory genes that control pigment synthesis are discussed and examples of their practical use in vegetable and cereal crop breeding are given

Studying grain color diversity in the barley collection of VIR

Background. Dark color of barley grain (Hordeum vulgare L.) can be caused by the synthesis and accumulation of two types of polyphenolic pigments – anthocyanins and melanins, which perform important functions in plant life, participating in the regulation of growth and development, and protecting plants from adverse environmental conditions. The aim of this study was to investigate the diversity of barley in the VIR collection in the context of grain color.Materials and methods. To analyze the pigment composition of the grain, 150 barley accessions with colored grains were selected from the VIR collection. Anthocyanins and melanins in grain husk were identified using qualitative reactions.Results and discussion. It was shown that in 60% of the accessions the dark color of their grain was induced by independent accumulation of melanin, while the accessions characterized by accumulation of only anthocyanins, and those with combined accumulation of anthocyanins and melanins, were 14.6% and 14%, respectively. For 11.3% of the accessions the presence of anthocyanins and melanins in grain husk was not found; their pigmentation could presumably be associated with an increased content of other polyphenolic pigments – proanthocyanidins. Accessions with melanin in grain predominated in all identified geographic groups, while other types of pigmentation were most evenly represented in the regions with the widest genetic diversity of barleys – Africa, East Asia, and the Middle East.Conclusion. Dark pigmentation of barley grain was shown to be mainly associated with the accumulation of melanin, and this type of pigmentation prevails in all geographical regions identified. The results obtained made it possible to describe the barley collection more fully and expand the possibilities of its utilization

Testing of the STS-marker for the <i>Nud1</i> gene for the selection of naked barley hybrids

Background. Naked barley is a promising food crop. To enhance its production, active breeding is required to create productive varieties. The purpose of this study was to test the STS-marker for the Nud1 gene controlling the hulled phenotype, and use it for the production of naked barley hybrids. Materials and methods. Genotyping of 112 F2 hybrids obtained by crossing the naked black variety ‘Jet’ and the hulled white variety ‘Elf’ was carried out using wF2 and kR1, or tR2 primers in the regular PCR mode to amplify the recessive or dominant alleles of the Nud1 gene, respectively, and also in the multiplex PCR mode, which allows simultaneous amplification of both dominant and recessive alleles of the Nud1 gene. The genotyping data were compared with those on phenotypes of hybrids. Results and discussion. The possibility of using multiplex PCR with a set of primers wF2, kR1, and tR2 for identifying dominant and recessive alleles of the Nud1 gene in hybrid material has been demonstrated. However, while the observed number of hybrids homozygous for the recessive allele nud1 almost completely corresponded to their expected number, the clear predominance of homozygotes for the dominant allele Nud1 and the lack of heterozygotes compared to the expected number of hybrids of these groups indicates erroneous identification of some heterozygotes as dominant homozygotes, which must be taken into account during selection of hulled barleys by genotyping. Conclusions. The STS-marker amplified by primers wF2, kR1, and tR2, can be used to select recessive homozygotes nud1nud1 from hybrid populations, however, additional analysis is required for a more reliable identification of heterozygotes and homozygotes for the dominant allele of the Nud1 gene

Anthocyanins as functional food components

Among the natural pigments, anthocyanins are assumed to represent one of the most studied groups. Starting with the first studies on the physicochemical properties of anthocyanins carried out in the 17th century by British naturalist Robert Boyle, the science about these unique compounds has progressed substantially. To date, the structure and functions of anthocyanins in plant cells have been well studied, and the pathway of their biosynthesis is one of the most fully characterized pathways of secondary metabolite biosynthesis at both the biochemical and genetic levels. Along with these fundamental achievements, we are beginning to realize the potential of anthocyanins as compounds of industrial importance, as pigments themselves, as well as components of functional food that contribute to the prevention and reduction of risk of chronic diseases. For a long time, the biological activity of anthocyanins has been underestimated, in particular, due to the data on their low bioavailability. However, studies showed that in humans and animals, these compounds are actively metabolized and the bioavailability, estimated taking into account their metabolites, exceeded 12 %. It has been experimentally shown that anthocyanins have antioxidant, anti-inflammatory, hypoglycemic, antimutagenic, antidiabetic, anti-cancer, neuroprotective properties, and they are beneficial for eye health. However, the studies conducted cannot always explain the molecular mechanism of action of anthocyanins in the human body. According to some reports, the observed effects are not due to the action of anthocyanins themselves, but to their metabolites, which can be more biologically active because of their increased bioavailability. Other data ascribe the positive effect on human health not to individual anthocyanins, but to the whole complex of polyphenolic compounds consumed. The review summarizes the results of the studies of anthocyanins as components of functional food. Special attention is paid to genetic control of the pigment synthesis. These data are of particular importance in respect to the initiated breeding programs aimed at increasing the content of anthocyanins in cultural plants