The relationship between the genetic status of the Vrn-1 locus and the size of the root system in bread wheat (Triticum aestivum L.)

One of the main ways to fine-tune the adaptive potential of wheat cultivars is to regulate the timing of flowering using the genes of the Vrn-1 locus, which determines the type and rate of development. Recently, with the use of introgression and isogenic lines of bread wheat, it was shown that this locus is involved in the genetic control of root length and weight both under irrigation and drought conditions. It turned out that the VrnA1 gene is associated with a significant decrease in the size of the root system in a winter genotype. The Vrn-A1 gene had the strongest effect on the reduction of the root system in comparison with the homoeoallelic genes Vrn-B1 and Vrn-D1. The aim of this work was to determine whether the allelic composition of the genes at the Vrn-1 locus affects the root size in seven spring cultivars and in two lines of bread wheat differing in flowering time under conditions of normal watering and drought. The research was carried out in a hydroponic greenhouse; drought was created at the tillering stage. In this work, we have shown that early flowering wheat cultivars with the dominant Vrn-A1а allele have more lightweight and shorter roots under normal watering conditions compared to the late flowering carriers of the dominant homoeoalleles Vrn-B1 and Vrn-D1. In drought conditions, the root length decreased insignificantly, but the weight of the roots significantly decreased in all genotypes, with the exception of Diamant 2. It has been hypothesized that the level of the transcription factor VRN-1 at the onset of drought may affect the size of the root system. The large variability in root weight may indicate the participation, in addition to the Vrn-1 locus, of other gene networks in the formation of this trait. Breeders working to develop early maturing varieties should consider the possibility of reducing the root size, especially in arid conditions. A significant increase in the root size of line 821 with introgressions into chromosomes 2A, 2B, and 5A from T. timopheevii indicates the possibility of using congeners as a source of increasing the trait in wheat.

Phenotypic diversity of bread wheat lines with introgressions from the diploid cereal Aegilops speltoides for technological properties of grain and f lour

The creation of varieties adapted to changing environmental conditions, resistant to various pathogens, and satisfying various grain purposes is impossible without using the genetic diversity of wheat. One of the ways to expand the genetic diversity of wheat is to introduce new variants of genes from the genetic pool of congeners and wild relatives into the genotypes of existing varieties. In this study, we used 10 lines from the Arsenal collection created on the genetic basis of the spring variety ‘Rodina’ and the diploid species Aegilops speltoides in the Federal Research Center “Nemchinovka” in 1994. The lines were previously characterized for the presence of translocations and chromosomal rearrangements cytologically and using molecular markers. Technological analyses were performed on grain obtained in Western Siberia and Moscow region. The aim of this study was to establish the possibilities of expanding the phenotypic diversity for technological properties of grain and flour as a result of such hybridization of bread wheat and the diploid cereal Aegilops speltoides. The variety ‘Rodina’ forms a vitreous grain with a high gluten content in Siberia, but has low physical properties of flour and dough. Five derived lines were found to have significantly higher protein and gluten content in grain. The highest values under both growing conditions were found in lines 73/00ⁱ, 82/00ⁱ, and 84/00ⁱ. Two lines (69/00ⁱ and 76/00ⁱ) showed a high flour strength and dough elasticity, characterizing the lines as strong and valuable in quality. These lines can be used for baking bread. Line 82/00ⁱ inherited from Ae. speltoides a soft-grain endosperm, which indicates the introgression of the Ha- Sp gene, homoeoallelic to the Ha gene of bread wheat, into ‘Rodina’. Flour of this line is suitable for the manufacture of confectionery without the use of technological additives. The lines generally retained their characteristics in different growing conditions. They can be attracted as donors of new alleles of genes that determine the technological properties of grain and resistance to biotic stresses.

Physiological responses to water deficiency in bread wheat (Triticum aestivum L.) lines with genetically different leaf pubescence

Studying the relationship between leaf pubescence and drought resistance is important for assessing Triticum aestivum L. genetic resources. The aim of the work was to assess resistance of common wheat genotypes with different composition and allelic state of genes that determine the leaf pubescence phenotype. We compared the drought resistance wheat variety Saratovskaya 29 (S29) with densely pubescent leaves, carrying the dominant alleles of the Hl1 and Hl3 genes, and two near isogenic lines, i: S29 hl1, hl3 and i: S29 Hl2aesp, with the introgression of the additional pubescence gene from diploid species Aegilops speltoides. Under controlled conditions of the climatic chamber, the photosynthetic pigments content, the activity of ascorbate-glutathione cycle enzymes and also the parameters of chlorophyll fluorescence used to assess the physiological state of the plants photosynthetic apparatus were studied in the leaves of S29 and the lines. Tolerance was evaluated using the comprehensive index D, calculated on the basis of the studied physiological characteristics. The recessive state of pubescence genes, as well as the introduction of the additional Hl2aesp gene, led to a 6-fold decrease in D. Under the water deficit influence, the fluorescence parameters profile changed in the lines, and the viability index decreased compared with S29. Under drought, the activity of ascorbate peroxidase, glutathione reductase and dehydroascorbate reductase in the line i: S29 hl1, hl3 decreased 1.9, 3.3 and 2.3 times, in the line i: S29 Hl2aesp it decreased 1.8, 3.6 and 1.8 times respectively, compared with S29. In a hydroponic greenhouse, line productivity was studied. Compared with S29, the thousand grains mass in the line i: S29 hl1, hl3 under water deficit was reduced. The productivity of the line i: S29 Hl2aesp was significantly reduced regardless of water supply conditions in comparison with S29. Presumably, the revealed effects are associated with violations of cross-regulatory interactions between the proteins of the trichome formation network and transcription factors that regulate plant growth and stress response.

[Methods of high-throughput plant phenotyping for large-scale breeding and genetic experiments]

Phenomics is a field of science at the junction of biology and informatics which solves the problems of rapid, accurate estimation of the plant phenotype; it was rapidly developed because of the need to analyze phenotypic characteristics in large scale genetic and breeding experiments in plants. It is based on using the methods of computer image analysis and integration of biological data. Owing to automation, new approaches make it possible to considerably accelerate the process of estimating the characteristics of a phenotype, to increase its accuracy, and to remove a subjectivism (inherent to humans). The main technologies of high-throughput plant phenotyping in both controlled and field conditions, their advantages and disadvantages, and also the prospects of their use for the efficient solution of problems of plant genetics and breeding are presented in the review.

[Genetic analysis of leaf pubescence in isogenic lines of conmmon wheat Novosibirsk 67]

In this study, genetic and monosomic analyses of the leaf pubescence of ANK 7A, ANK 7B, and ANK 7C wheat isogenic lines were carried out based on the Novosibirsk 67 wheat variety. According to visual analysis, the variety-recipient has a soft, uniform pubescence, and lines have trichomes on the surfaces of their leaves inherited from the two. Chinese varieties and one Soviet variety. Using the high throughput phenotyping method LHDetect2, which allows one to allocate the phenotypic classes of offspring in crosses based on the quantitative characteristics of leaf pubescence, it was found that chromosome 7B of the isogenic lines has a gene that determines the presence of long trichomes, and chromosome 7D of the Novosibirsk 67 variety has a gene that increases the density of pubescence. The obtained data allowed for the formulation of a hypothesis for the existence of a homoallelic series of genes that control leaf pubescence in the chromosomes of the seventh homeologous group of common wheat.

[Chromosomal localization of the speltoidy gene, introgressed into bread wheat from Aegilops speltoides Tausch., and its interaction with the Q gene of Triticum spelta L]

The differences between bread wheat (Triticum aestivum L.) and spelt (Triticum spelta L.) in the shape of the spike and threshing character are determined by the allelic status of one major Q gene, mapped to the long arm of chromosome 5A. This gene is a member of the APETALA2 family of transcription factors and plays an important role in domestication of wheat. In the present study, using monosomic analysis, we determined the chromosomal localization of the Q(S)gene, introgressed into bread wheat from Aegilops speltoides Tausch. and homoallelic to the Q gene. It was demonstrated that the Q(S) gene was located in chromosome 5A of the bread wheat line from the Arsenal collection. This gene conferred spike speltoidy in the line itself, as well as in its hybrids with bread wheat cultivars. The Q(S) gene dominated over the bread wheat Q gene and was equally effective in the homo-, hemi-, and heterozygous states. In hybrids between the introgression line and a number of spring spelt accessions, interaction between the Q and Q(S) genes was observed, manifested as the formation of superspeltoid spike.

[Lipoxygenase from the leaves of wheat grown under different water supply conditions]

Lipoxygenase (LOG) in protein fractions isolated from the leaves of substituted wheat lines was investigated. Three molecular forms of the enzyme were detected. A water deficiency caused the induction of a membrane-bound form (mLOG) and resulted in a decrease in the activity of "soluble" enzymes (s1LOG) and (s2LOG) in most genotypes. A correlation analysis demonstrated the dependence between the level of enzymatic activity and indices of resistance to drought. A genetic control of the s 1 LOG and s2LOG activity at an optimal water supply level was associated with chromosomes 1A, 1D, 3A, 5A, 5B, and 5D, while under the conditions of the modeled soil drought, it was associated with chromosomes 1B and 1D.

[Morphological and genetic characteristics of leaf hairiness in wheat (Triticum aestivum L.) as analyzed by computer-aided phenotyping]

Computer-aided image processing was used to study the morphology of leaf hairiness in the wheat cultivars Saratovskaya 29 and Golubka, as well as the introgressed strain 102/00i of the cultivar Rodina carrying the hairiness control gene introgressed from Aegilops speltoides. Morphological differences in leaf hairiness were detected and described in detail. The genetic control ofhairiness was studied in two cultivars (Golubka and Saratovskaya 29) with similar hairiness patterns. Crossing these cultivars with the cultivar Rodina showed a monogenic inheritance in the cultivar Golubka and a digenic inheritance in the cultivar Saratovskaya 29, which has a denser hairiness. In the strain 102/00i and the cultivar Golubka, the number of trichomes was positively correlated with their mean length. The cultivar Golubka was used as an example to study the effect of environmental conditions on the formation of hairiness. Plants of these cultivars were found to form more but shorter trichomes.

[Role of lipoxygenase in the determination of wheat grain quality]

Analysis of the correlation between endogenous lipoxygenase activity and 15 wheat grain quality parameters in three bread wheat populations has shown that enzyme activity influences the weight of 1000 grains, dough deformation energy, dough tenacity, and mixing properties. The correlations between the enzyme activity and the basic quality parameters are negative at high activity levels. The optimum values of specific lipoxygenase activity at which all quality parameters studied have the maximum values range from 108.5 +/- 1.2 to 126.4 +/- 1.9. It has been found that the ability of lipoxygenase to strengthen gluten is related to the lowering of dough extensibility.

[Genetic analysis of the traits introgressed from Aegilops speltoides Tausch. to common wheat and determined by chromosome 5A genes]

A winter common wheat accession from the Arsenal collection was genetically examined to study the results of introgression, which substantially changed the physiological and morphological traits of the original spring cultivar Rodina. Apart from its winter habit, the accession was characterized by awned speltoid spikes, suggesting introgression into chromosome 5A, which carried marker genes in the order Vrn-Al-Q-Bl. Genetic analysis showed that the chromosome fragment introgressed from Aegilops speltoides recombined well with the homeologous region of common wheat chromosome 5A in the region between the Vrn-Al and Q genes. Recombination between the Vrn-Al and Bl genes was not detected, and it was assumed that the order of the marker genes of chromosome 5A was inverted to produce Q-Vrn-Al-Bl. When the winter introgression line was crossed with Triticum spelta, an interaction of two dominant genes determining the spike character was for the first time detected in F1, increasing the spike length and the number of spikelets, and was transmitted to F2. It was assumed that Ae. speltoides had a homeoallelic speltoid gene, which was designated as Q(S).

[Mapping of the quantitative trait loci (QTL) associated with grain quality characteristics of the common wheat grown under different environmental conditions]

The quantitative trait loci (QTL) associated with individual characteristics of grain and flour quality in wheat lines grown under contrasting environmental conditions were mapped. Overall, 22 QTL that manifested under contrasting environmental conditions with various significances were detected on 10 chromosomes. Grain hardness and vitreousness were associated with three loci on chromosomes 5D, 6A, and 3A, while the gluten content, with two loci on chromosomes 5B and 7A. Dough extensibility was associated with only one QTL localized in the region of Glu-A1 locus. One of the loci determining flour and dough strengths is located in the region of Gli-B1 and Glu-B3 loci and the rest, in various regions of chromosomes 1B, 5D, and 4B, where no particular genes associated with grain quality have been yet found. The detected QTL can be used in further experiments on genetic control of gluten formation and quality in wheat.

[The effect of intercultivar substitution of wheat Triticum aestivum L. chromosomes on lipoxygenase activity and its correlation with the technological properties of flour]

The effects of intercultivar substitution of individual chromosome pairs (except for 1B, 6D, and 7A) in the wheat cultivars Saratovskaya 29 and Janetzkis Probat, differing in quality, on specific lipoxygenase activity, the grain yield per spike, and the main technological properties of flour and dough were studied. It was demonstrated that the substitution of individual chromosomes of the recipient cultivar Saratovskaya 29 with the homologous chromosomes of the donor cultivar Janetzkis Probat caused significant changes in lipoxygenase activity and several other quality characteristics. The correlations between the lipoxygenase activity and the parameters of physical dough properties were determined. Three molecular forms of lipoxygenase (Lpx-1, Lpx-2, and Lpx-3), differing in the value of surface charge and enzymatic activity, were detected by native PAGE.

Comparative mapping of genes for glume colouration and pubescence in hexaploid wheat (Triticum aestivum L.)

Microsatellite markers were used to map the major genes Bg (determining black glume colour), Rg1 and Rg3 (red glume), and a locus determining smokey-grey coloured glume to the distal ends of the short arms of the homoeologous group 1 chromosomes, proximally (or closely linked) to Xgwm1223 and distal to Xgwm0033. On this basis, we propose that these genes represent a set of homoeoloci, designated Rg-A1, Rg-B1, and Rg-D1. Rg3 and Bg appear to be variant alleles of Rg-A1. Both Rg3 and Bg are closely linked with the major glume pubescence gene Hg. Similarly, the hexaploid wheat smokey-grey glume gene and Rg2 represent alleles at Rg-D1. The microsatellite markers linked to the Rg genes were used to analyse a phenotypically and genotypically characterized set of Siberian spring wheats. A coincidence between the presence of the 264-bp allele of Xgwm0136 and Rg-A1b (Rg3) was observed; so Xgwm0136 can probably be used as a diagnostic marker for this gene.

[Hybrid and monosomic analyses of smoky coloration of the ear in common wheat]

The results of the hybrid and monosomic analyses of smoky ear coloration in the common wheat variety columbina are reported. The character has been found to be monogenic, and its gene has been located to chromosome IDS. The smoky ear coloration is determined by an allele of gene Rg2 introgressed to wheat from Aegilops tauschii.

[Analysis of inheritance of morphological and biochemical characters introgressed into common wheat from Aegilops speltoides Tausch]

Genetic control of some morphological traits and the gliadin composition were examined in plants of two lines of common wheat carrying genes introgressed from the wild diploid cereal Aegilops speltoides. Leaf hairiness was shown to be controlled by a single introgressed dominant gene that was not allelic to the known common wheat gene Hl1. Waxlessness of the whole plant is controlled by the introgressed from Ae. speltoides inhibitor gene allelic to gene W1 located on chromosome 2B. This gene was epistatic to the introgressed gene controlling spike waxlessness. The introgressed gene of spike color was shown to be allelic to Rg1 located on chromosome 1B of common wheat. However, the former gene proved to be linked to an allele of the Gli-B1 locus other than in wheat.

[Analysis of isogenic lines of the soft wheat carrying dominant alleles of Bg, Hg, and Rg1 genes using microsatellite and protein markers]

To determine tight linkage between morphological and molecular markers of the first homologous group of chromosomes of common wheat, microsatellite analysis of six near-isogenic lines with marker dominant alleles controlling back color (Bg; 1AS) and hairy glume (Hg; 1AS) and two lines bearing the dominant alleles of the gene for red glume color (Rgl; 1BS) was conducted. The component composition of gliadins in these lines was studied. Tight linkage of Bg, Hg, and Gli-A1 genes with a microsatellite marker Xgwm136 (1AS) and of Rg1 and Gli-B1 genes with markers Xgwm33 and Xgwm550 (1BS) was shown. Based on the results obtained and literature data, the most probable order of morphological and molecular markers on chromosomes of common wheat was determined. On chromosome 1AS, from the centromere to the telomere, the markers are located as follows: Xgwm136-Gli-A1-BgHg; on chromosome 1BS, in the same direction: Xgwm33-Gli-B1-Rg1-Xgwm550.