A. V. Doroshkov

Morphological characterization and inheritance 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 line 102/00i of the cultivar Rodina carrying the gene for leaf hairiness introgressed from Aegilops speltoides. Morphological differences in leaf hairiness were detected and described in detail. The genetic control of hairiness 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 line 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 this cultivar were found to form more but shorter trichomes under field conditions.

Extraction of quantitative characteristics describing wheat leaf pubescence with a novel image-processing technique

Leaf pubescence (hairiness) in wheat plays an important biological role in adaptation to the environment. However, this trait has always been methodologically difficult to phenotype. An important step forward has been taken with the use of computer technologies. Computer analysis of a photomicrograph of a transverse fold line of a leaf is proposed for quantitative evaluation of wheat leaf pubescence. The image-processing algorithm is implemented in the LHDetect2 software program accessible as a Web service at http://wheatdb.org/lhdetect2. The results demonstrate that the proposed method is rapid, adequately assesses leaf pubescence density and the length distribution of trichomes and the data obtained using this method are significantly correlated with the density of trichomes on the leaf surface. Thus, the proposed method is efficient for high-throughput analysis of leaf pubescence morphology in cereal genetic collections and mapping populations.

Regions of the bread wheat D genome associated with variation in key photosynthesis traits and shoot biomass under both well watered and water deficient conditions

A quantitative trait locus (QTL) approach was taken to reveal the genetic basis in wheat of traits associated with photosynthesis during a period of exposure to water deficit stress. The performance, with respect to shoot biomass, gas exchange and chlorophyll fluorescence, leaf pigment content and the activity of various ascorbate-glutathione cycle enzymes and catalase, of a set of 80 wheat lines, each containing a single chromosomal segment introgressed from the bread wheat D genome progenitor Aegilops tauschii, was monitored in plants exposed to various water regimes. Four of the seven D genome chromosomes (1D, 2D, 5D, and 7D) carried clusters of both major (LOD >3.0) and minor (LOD between 2.0 and 3.0) QTL. A major QTL underlying the activity of glutathione reductase was located on chromosome 2D, and another, controlling the activity of ascorbate peroxidase, on chromosome 7D. A region of chromosome 2D defined by the microsatellite locus Xgwm539 and a second on chromosome 7D flanked by the marker loci Xgwm1242 and Xgwm44 harbored a number of QTL associated with the water deficit stress response.

Genetic analysis of leaf pubescence in isogenic lines of bread wheat Novosibirskaya 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 Novosibirskaya 67 wheat variety. According to visual analysis, the recipient variety 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 Novosibirskaya 67 variety has a gene that increases the density of pubescence. The obtained data allowed to formulate 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 bread wheat.

WheatPGE: A system for analysis of relationships among the phenotype, genotype, and environment in wheat

In this paper, to solve problems of integration of genotypic and phenotypic data, as well as of environmental parameters and to analyze interrelations between the genotype and phenotype in wheat, the system WheatPGE is presented. The system is used to integrate heterogeneous data about the plant, storage of information about relations describing various characteristics of the plant’s genotype, phenotype, and environmental factors, and access to it. The system has a web-based interface and is available at www.wheatdb.org. Possibilities of using the system in the genetic experiments are exemplified by the analysis of quantitative characteristics of hairiness of a wheat leaf. Using WheatPGE, we carried out a classification of leaf hairiness of 47 varieties of spring wheat by the method of multidimensional scaling. The analysis results revealed differences between leaf hairiness in plants of Russian and German varieties.

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.

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.

Interactions between leaf pubescence genes in bread wheat as assessed by high throughput phenotyping

Leaves of many angiosperm species develop trichomes. These epidermal outgrowths have been exploited to the study the determination of cell fate, plant cell differentiation mechanisms and cell morphogenesis in the model plant species. It was found that even simple shape trichomes (leaf hairs) offer protection against both biotic and abiotic stress factors. Currently, in monocotyledonous plants, the genetic basis of leaf hair formation is poorly understood. This study sought to establish the genetic control of leaf pubescence formation in bread wheat (Triticum aestivum L.) in terms of leaf hair patterning and growth. A set of cultivars and lines carrying allelic combinations of three pubescence controlling genes, Hl1, Hl3 and Hl2aesp was used for quantitative phenotyping. It was demonstrated that these genes differ in their effect on leaf hair formation: Hl1 and Hl3 more affected leaf hair initiation and growth, while Hl2aesp modified leaf hair length. Their action was independent to a large extent. A model of Hl1, Hl3 and Hl2aesp genes action is proposed.

Genetic dissection of earliness by analysis of a recombinant chromosome substitution double haploid mapping population of bread wheat ( Triticum aestivum L.) in different geographic regions

Abstract The synchronization of flowering with the time of most favorable temperatures and light has substantial effects on grain yield and quality. In bread wheat, the major developmental genes determining vernalization requirement (Vrn-1) and photoperiod response are used in breeding cultivars adapted to different latitudes and climates. Fine regulation of flowering date is provided by minor genes whose allelic variation is not well studied. Although spring cultivars Saratovskaya 29 (S29) and Yanetzkis Probat (YP) carry the same two dominant Vrn-1 alleles, YP is several days later in flowering compared to S29. The aim of the current study was to establish the chromosomal and map locations of loci determining this difference. Inter-cultivar single chromosome substitution lines S29(YP) and a set of recombinant chromosome substitution double haploid lines grown at three contrasting climatic and geographic locations in Western Siberia and Europe. The substitution line S29(YP 4D*7A) carrying the entire donor chromosome 4D and an additional fragment of chromosome 7A showed the largest delay in flowering at all sites. A quantitative trait locus (QTL) between microsatellite markers Xgwm0089 and Xgwm4736 on chromosome 4D was detected only in Europe following substantially earlier sowing. It was manifested under increasing day length, and, therefore, was regarded as a photoperiod response locus. Another QTL associated with (TG)8 or 9-(CG)3 polymorphism of the TaFTA gene on chromosome 7A was effective under both long and short days thus representing an intrinsic earliness per se gene. This knowledge could aid the fine regulation of flowering in cultivars tailored for growing in specific agro-climatic conditions.

Diversity of leaf pubescence in bread wheat and relative species

Interspecific hybridization and polyploidization are the characteristic processes of evolution in the world of plants. The allopolyploid genomes undergo numerous structural rearrangements associated with the adaptation of separate genomes to each other. An important issue is to establish which part of the total diversity of genes characteristic of the ancestral forms have been preserved and manifested in the complex genomes. The aim of this work was to compare the diversity of the adaptive morphological trait-leaf pubescence among the relatives and the ancestors of hexaploid wheats to establish the variability of its phenotypic manifestation as a result of evolution and domestication. This was achieved through the study of quantitative characteristics of leaf pubescence among 47 representatives of di-, tetra- and hexaploid species of genera Triticum and Aegilops, the donors of the individual genomes of the allopolyploid Triticum species. Quantification of leaf pubescence was based on automated counting of the trichome number (N) and trichome length (L) estimation on a leaf fold and calculation of the pubescence index H (L/N). The species with different sets of elementary genomes differed for the type of pubescence. The ploidy level affected only the trichome length and the index of pubescence HL/N. The density of the hairs was affected by the individual genomes A and B, whereas genome D significantly influenced all of the studied pubescence parameters. The diploid species showed the largest variability while the cultivated durum wheats lacked pubescence. Bread wheat demonstrated pubescence characterized by a close correlation between N and L.