Elena I. Gordeeva

The Regulation of Anthocyanin Synthesis in the Wheat Pericarp

Bread wheat producing grain in which the pericarp is purple is considered to be a useful source of dietary anthocyanins. The trait is under the control of the Pp-1 homoealleles (mapping to each of the group 7 chromosomes) and Pp3 (on chromosome 2A). Here, TaMyc1 was identified as a likely candidate for Pp3. The gene encodes a MYC-like transcription factor. In genotypes carrying the dominant Pp3 allele, TaMyc1 was strongly transcribed in the pericarp and, although at a lower level, also in the coleoptile, culm and leaf. The gene was located to chromosome 2A. Three further copies were identified, one mapping to the same chromosome arm as TaMyc1 and the other two mapping to the two other group 2 chromosomes; however none of these extra copies were transcribed in the pericarp. Analysis of the effect of the presence of combinations of Pp3 and Pp-1 genotype on the transcription behavior of TaMyc1 showed that the dominant allele Pp-D1 suppressed the transcription of TaMyc1.

The D genome carries a gene determining purple grain colour in wheat

Previously, it was suggested that purple grain colour was transferred to bread wheat from purple-grained tetraploid T. durum. In the current study, we demonstrated that the D genome of bread wheat ‘Purple’ carries one of two complementary genes determining purple grain colour. This gene was mapped on the short arm of chromosome 7D 2.5 cM distal to the locus Rc-D1 determining red coleoptile colour. This position is highly comparable with that of the Pp1 gene mapped earlier on the short arm of chromosome 7B in tetraploid T. durum.We suggest the Pp genes on T. durum chromosome 7B and T. aestivum chromosome 7D are orthologous. We designated them Pp-B1 and Pp-D1, respectively. Microsatellite-based genotyping of near-isogenic lines ‘i:S29Pp1Pp2PF’ and ‘i:S29Pp1Pp3P’, their recurrent (T. aestivum ‘Saratovskaya 29’) and donor (T. aestivum ‘Purple Feed’ and ‘Purple’, respectively) parents showed the presence of donor introgressions on chromosomes 2A and 7D in both near-isogenic lines. In addition to previously des...

Marker-assisted development of bread wheat near-isogenic lines carrying various combinations of purple pericarp (Pp) alleles

The commercial interest in pigmented wheat grain flows from an understanding that they are nutritionally superior to white kernels. The pigment of purple coloured bread and durum wheat grains results from the accumulation of anthocyanins in the pericarp; its genetic basis is the action of Pp-1 and Pp3 genes. Here, the development of a set of bread wheat near isogenic lines (NILs) carrying various combinations of Pp alleles is described, along with a demonstration of their utility for the genetic dissection of the purple pericarp trait. A marker-assisted backcrossing strategy was based on the use of microsatellite markers linked to Pp3 (chromosome 2A), Pp-A1 (7A) and Pp-D1 (7D). Pp-A1 is a newly uncovered gene of weak effect. A qRT-PCR-based analysis of the anthocyanin synthesis structural genes [Chi (chalcone-flavanone isomerase) and F3h (flavanone 3-hydroxylase)] transcript abundance in the pericarp of the NILs suggested that the Pp genes up-regulate their transcription in contrasting ways. These NILs represent a resource for studying the effect of grain pigmentation on other wheat traits and end products.

Flavonoid Biosynthesis Genes in Wheat

Biosynthesis of flavonoid compounds is one of the most studied plant metabolic pathways. Researchers’ attention to the biochemical, physiological and genetic aspects of the flavonoid biosynthesis is associated primarily with a wide range of their biological properties. In addition, a genetic system for the flavonoid biosynthesis is an excellent genetic model. The recent development of molecular and genomics methods has led to considerable progress in understanding the molecular-genetic basis of the flavonoid biosynthesis in bread wheat (Triticum aestivum L.). This article provides a brief review of the structural and functional organization of genes involved in the flavonoid biosynthesis in wheat and its relatives.

Cold Stress Response of Wheat Genotypes Having Different Rc Alleles

Nine wheat genotypes differing by Rc (red coleoptile) alleles were investigated for the dynamics of seedling growth and relative anthocyanin content in the coleoptiles in response to cold. The stressed genotypes showed either reduced, similar or increased anthocyanin content compared to unstressed plants. This difference can be partially explained by the allelic state of the Rc genes. In ‘Saratovskaya 29’ weak Rc allele causes low anthocyanin content under optimal growth conditions. Upon cold treatment the level of anthocyanins decreased, whereas it increased in two near isogenic lines (NILs) with strong Rc alleles developed on ‘Saratovskaya 29’, and in some other genotypes having high anthocyanin content under optimal growth conditions. The changes in anthocyanin content correlated negatively with the changes of growth parameters in response to cold stress, suggesting the presence of some stress-dependent regulation of anthocyanin biosynthesis in wheat coleoptiles.

Identification of nuclear genes controlling chlorophyll synthesis in barley by RNA-seq

BackgroundAlbinism in plants is characterized by lack of chlorophyll and results in photosynthesis impairment, abnormal plant development and premature death. These abnormalities are frequently encountered in interspecific crosses and tissue culture experiments. Analysis of albino mutant phenotypes with full or partial chlorophyll deficiency can shed light on genetic determinants and molecular mechanisms of albinism. Here we report analysis of RNA-seq transcription profiling of barley (Hordeum vulgare L.) near-isogenic lines, one of which is a carrier of mutant allele of the Alm gene for albino lemma and pericarp phenotype (line i:BwAlm).Results1221 genome fragments have statistically significant changes in expression levels between lines i:BwAlm and Bowman, with 148 fragments having increased expression levels in line i:BwAlm, and 1073 genome fragments, including 42 plastid operons, having decreased levels of expression in line i:BwAlm. We detected functional dissimilarity between genes with higher and lower levels of expression in i:BwAlm line. Genes with lower level of expression in the i:BwAlm line are mostly associated with photosynthesis and chlorophyll synthesis, while genes with higher expression level are functionally associated with vesicle transport. Differentially expressed genes are shown to be involved in several metabolic pathways; the largest fraction of such genes was observed for the Calvin-Benson-Bassham cycle. Finally, de novo assembly of transcriptome contains several transcripts, not annotated in current H. vulgare genome version.ConclusionsOur results provide the new information about genes which could be involved in formation of albino lemma and pericarp phenotype. They demonstrate the interplay between nuclear and chloroplast genomes in this physiological process.

Anthocyanins participate in protection of wheat seedlings from osmotic stress

Plant secondary metabolites anthocyanins are considered to play a protective role. In bread wheat (Triticum aestivum L.), anthocyanins can be observed in both adult plants and seedlings. The aim of the current study was to investigate the putative role of anthocyanins present in grains and shoots with respect to the protection of seedlings against drought. For this purpose a set of near isogenic lines (NILs) differing in pericarp and coleoptile colour was used. Water stress was created by artificial shortage of moisture under laboratory conditions. Differences among the lines were observed in a way that the lines with dark-purple grains and coleoptiles (genotype Pp-D1Pp-D1Pp3Pp3Rc-A1Rc-A1Rc-D1Rc-D1) demonstrated a higher seedling drought tolerance than plants with uncoloured pericarp and lightpurple coleoptiles (pp-D1pp-D1pp3pp3Rc-A1Rc-A1rc-D1rc-D1). Furthermore, protection of the root system and the shoot was related with the presence of anthocyanins in grains and coleoptiles, respectively.

Effect of seed pre-sowing gamma-irradiation treatment in bread wheat lines differing by anthocyanin pigmentation

Anthocyanins are natural antioxidants able to scavenge free radicals, which appear in plant cells under various environmental stresses. In wheat, anthocyanin pigments can be synthesized in vegetative and reproductive organs. The objective of the current study was to estimate the significance of these substances for wheat seedlings protection under irradiation stress (after treatment of dry seeds with moderate doses of gamma-irradiation, 50, 100 and 200 Gy). For this goal a set of near-isogenic lines (8 NILs) carrying different combinations of the Pp (purple pericarp) and Rc (red coleoptile) alleles were used. The effect of gammairradiation on the growth parameters and anthocyanin content in coleoptiles was studied at the 4th day after germination. The germination rate was not affected, while roots’ and shoots’ lengths and fresh weights as well as root number decreased significantly under irradiation treatment. The effect was deeper under higher doses. Irradiation treatment also induced change of root morphology (‘hairy roots’). The effect of treatment on coleoptile anthocyanin content depended on allelic combination at the Rc loci. At the presence of ‘weak’ Rc-A1 allele anthocyanin content decreased, while it did not change in lines with Rc-A1 + Rc-D1 combination (NILs with intensively colored coleoptiles). Factors ‘pericarp color’ and ‘coleoptile color’ influenced vigor of the seedlings under 50 Gy, whereas under higher doses (100 and 200 Gy) these factors did not contribute to growth parameters changes. Statistically significant positive effect of anthocyanins synthesized in coleoptile (in the presence of Rc-A1 + Rc-D1 dominant alleles) on root growth of seedling germinated from 50 Gy-treated seeds was observed.

Raising highly frost-resistant Agropyron-Triticum hybrids

A protocol for raising highly frost-resistant winter wheat Triticum aestivum varieties has been developed. It is based on the transfer of the frost resistance trait from a wild wheat relative, intermediate wheatgrass (Agropyron glaucum). The protocol includes raising wheatgrass double haploid via anther culture, the selection of wheat genotypes that are able to produce green haploids in vitro, a proximate analysis of frost resistance, remote crosses of frost-resistant wheatgrass genotypes to wheat, and a new leaf-nurse method for transferring frost resistance from wheatgrass to wheat. A large collection of A. glaucum genotypes has been derived from the original material collected in Eastern Kazakhstan, at an elevated site with little snow. The climate of the site implies that the accessions are highly frost-resistant. Winter wheat lines with high frost resistance and performance have been obtained by the leaf-nurse method.