N. P. Goncharov

Molecular characterization of vernalization loci VRN1 in wild and cultivated wheats

BackgroundVariability of the VRN1 promoter region of the unique collection of spring polyploid and wild diploid wheat species together with diploid goatgrasses (donor of B and D genomes of polyploid wheats) were investigated. Accessions of wild diploid (T. boeoticum, T. urartu) and tetraploid (T. araraticum, T. timopheevii) species were studied for the first time.ResultsSequence analysis indicated great variability in the region from -62 to -221 nucleotide positions of the VRN1 promoter region. Different indels were found within this region in spring wheats. It was shown that VRN1 promoter region of B and G genome can also contain damages such as the insertion of the transposable element.Some transcription factor recognition sites including hybrid C/G-box for TaFDL2 protein known as the VRN1 gene upregulator were predicted inside the variable region. It was shown that deletions leading to promoter damage occurred in diploid and polyploid species independently. DNA transposon insertions first occurred in polyploid species. At the same time, the duplication of the promoter region was observed in A genomes of polyploid species.ConclusionsWe can conclude that supposed molecular mechanism of the VRN1 gene activating in cultivated diploid wheat species T. monococcum is common also for wild T. boeoticum and was inherited by T. monococcum. The spring polyploids are not related in their origin to spring diploids. The spring T. urartu and goatgrass accessions have another mechanism of flowering activation that is not connected with indels in VRN1 promoter region. All obtained data may be useful for detailed insight into origin of spring wheat forms in evolution and domestication process.

Phylogeny of the a genomes of wild and cultivated wheat species

Diploid species of the genus Triticum L. are its most ancient representatives and have the A genome, which was more recently inherited by all polyploid species. Studies of the phylogenetic relationships among diploid and polyploid wheat species help to identify the donors of elementary genomes and to examine the species specificity of genomes. In this study, molecular analysis of the variable sequences of three nuclear genes (Acc-1, Pgk-1, and Vrn-1) was performed for wild and cultivated wheat species, including both diploids and polyploids. Based on the sequence variations found in the genes, clear differences were observed among elementary genomes, but almost no polymorphism was detected within each genome in polyploids. At the same time, the regions of the three genes proved to be rather heterogeneous in the diploid species Triticum boeoticum Boiss., T. urartu Thum. ex Gandil., and T. monococcum L., thus representing mixed populations. A genome variant identical to the A genome of polyploid species was observed only in T. urartu. Species-specific molecular markers discriminating the diploid species were not found. Analysis of the inheritance of morphological characters also failed to identify a species-specific character for the three diploid wheat species apart from the hairy leaf blade type, described previously.

Q gene variability in wheat species with different spike morphology

Q gene is the major domestication gene of wheat and many questions concerning Q gene genetics, including Q gene variability and its functional influence on phenotype, remain unanswered for the majority of wheat species. Here we crossed wheat species with dominant (Q) and recessive (q) alleles and confirmed that Q gene controls threshability, rachis fragility and spike shape traits. In the present study 18 new Q gene sequences were obtained and the Q gene sequences from 42 di- and polyploid wheat species with variable spike morphology were analyzed. We identified correlation between Q gene variability (coding mutation 329Val/Ile, promoter variability, microRNA172 binding site substitution) and threshability, rachis fragility and spike shape traits in polyploid wheat species. The analysis of 3D structures of q and Q proteins indicated that 329Val/Ile mutation does not affect overall protein structure and likely protein activity. We conclude that alterations in all three regions are essential for the formation of free-threshing non fragile normal phenotype in polyploid wheat.

The order of the bs, Skdh, and Aadh1 genes in chromosome 5R of rye Secale cereale L.

Segregation analysis was performed in the progenies obtained in analyzing crosses of hybrids of spring and winter accessions of rye Secale cereale L. and wild S. montanum subsp. anatolicum (Grossh.) Tzvel. (syn. S. strictum (J. Presl) J. Presl). The test genes controlled the brittle stem (bs), the allelic variants of aromatic alcohol dehydrogenase (Aadh1) and shikimate dehydrogenase (Skdh), and the growth habit (Vrn1). A linkage was observed in the inheritance of the brittle stem and the aromatic alcohol dehydrogenase and shikimate dehydrogenase alloenzymes. The order of genes was established to be bs-Skdh-Aadh1, and the genetic distances were estimated to be bs-(9.0%)-Skdh, bs-(10.8%)-Aadh1, and Skdh-(5.3%)-Aadh1. The recombination coefficient between the Skdh and Aadh1 genes varied from 2.2 to 18.2%, averaging 5.3%. The growth habit was inherited independently of the bs-Skdh-Aadh1 linkage group.

Inheritance and phenotype expression of functional and null alleles of aromatic alcohol dehydrogenase (CAD) in diploid wheats

Functional F and null 0 alleles of the CAD1 (Aadh1) gene, which controls the biosynthesis of aromatic alcohol dehydrogenase, were studied in hybrids of the diploid wheat T. monococcum L. and Triticum sinskajae A. Filat. et Kurk. The gene CAD1 is located in chromosome 5A and is linked with the awnless gene awnS (La) with a recombination frequency of about 32%. Plants with genotypes FF, F0, and 00 were significantly different in the height and mechanical strength of the stalk (culm). The elastic limit of the culm tissues of plants FF was considerably higher than in 00 plants. F0 heterozygotes had intermediate values. The thickness of the wall of the sclerenchyma was thinner in plants with genotype 00. The chemical structure of lignin of plants with the functional CAD allele contained units of a phloroglucinol series missing in the mutant plants. The CAD genotypes had no effect on the relative content of cellulose and lignin in stalks of diploid wheat and insignificantly influenced the ratio of H: G: S units in the lignin structure, as well as some components of extractives. IR-spectroscopy found differences in the distribution of components of cell walls and extractives on the outer and inner surfaces of the culm. The results are discussed in relation to the applied aspects of the use of herbal products. Samples of diploid wheat with various genotypes of CAD can be used as model objects in breeding and genetic research.

Spike Morphology Genes in Wheat Species (Triticum L.)

Abstract The review examines the state of knowledge on genes that control the architectonics of wheat plant (spike morphology). It is shown that molecular genetic studies, which have been recently started, allow to find both the orthologous genes from relative species of wheat (barley, rye, etc.) and genes that were not previously used for breeding. Use of these genes for further breeding allows to produce modern wheat commercial cultivars.

DEP1 gene in wheat species with normal, compactoid and compact spikes

BackgroundIn rice, a variant of DEP1 gene results in erect panicle architecture, well-developed vascular bundles, an increase in the number of grains per panicle and a consequent increase in the grain yield. Interestingly, DEP1 homologs are present in the other cereals including species of wheat and barley (Hordeum vulgare), even though they do not produce panicles but spikes. In barley, HvDEP1 alleles do not differ between strains of various ear types and geographic origins, while in at least three OsDEP1 variants have been described.ResultsIn this work, we have studied the DEP1 gene from eight accessions which belong to four wheat species, T. monococcum, T. durum, T. compactum, and T. spelta, with either compact, compactoid or normal spike phenotypes. The nucleotide sequences of the 5th exon of DEP1 were determined for all eight accessions. Obtained sequences were species specific. Despite the interspecies diversity, all wheat sequences encoded polypeptides of the same size, similarly to the 5th exons of the DEP1 homologs in T. aestivum, T. urartu, and H. vulgare. For further study, the full-length sequences of the DEP1 gene for all four species were studied. The full-length DEP1 genomic copies were isolated from the genomic sequences of T. aestivum, T. urartu, and Aegilops tauschii.The genome of tetraploid wheat T. durum contains two variants of the DEP1 originating from A and B genomes. In the hexaploid wheats T. aestivum, T. compactum, and T. spelta, three variants of this gene originating from A, B, and D genomes were detected. DEP1 genes of the diploid wheats T. monococcum and T. urartu differ. It seems that a precursor of the DEP1 gene in T. monococcum originates from the wild progenitor T. boeoticum.ConclusionNo DEP1-related differences of nucleotide sequences between the compact (or compactoid) and normal spike phenotypes in the tested wheat species were detected. Therefore, DEP1 gene does not directly participate in the control of the spike architecture in wheats.

Evolution of Triticum aethiopicum Jakubz. from the Position of Chromosome Analysis

Cytogenetic analysis was conducted on a set of 67 Ethiopian wheat accessions collected by the expedition of N.I. Vavilov in 1927 and 85 years later by the Joint Ethiopian–Russian Biological Expedition (JERBE) in 2012 in the same sites of Ethiopia. The preservation of the polymorphism system of heterochromatic chromosome sites upon the change in the Ethiopian wheat population structure over the past period owing to a frequency shift of some specific chromosome variants and an increase in the proportion of genotypes carrying marker rearrangements was demonstrated. The unevenness of the geographical distribution of the 2A:4B translocation and of the 5A inversion was identified, and it was demonstrated that wheat accessions from Eritrea were cytogenetically the most isolated from the population from the central regions of Ethiopia. A low level of the Ethiopian wheat polymorphism was found along with the prevalence of the same chromosome rearrangement variants, which was indicative of monophyletic origin of the species. It was suggested that Triticum aethiopicum could have diverged from Ethiopian emmer as a result of hybridization with other wheat species, while subsequent evolution of these species occurred independently. Evidence for the participation of Ethiopian wheat in the formation of the gene pool of the unique Moroccan group of T. dicoccum was obtained.

Chromosomal localization of aromatic alcohol dehydrogenase fast-migrating isoenzyme Aadh1F (CAD1-F) gene in Triticum aestivum L. bread wheat

Differences in isoenzyme pattern of aromatic alcohol dehydrogenase, NADP-AADH or CAD, were found in the Triticum aestivum L. winter bread wheat cultivars by the method of electrophoresis in the starch gel. A standard three-component spectrum is present in the cv. Zitnica (former Yugoslavia); additional fact-migrating isoenzymes appear in the cv. Novosibirskaya 9 (Institute of Cytology and Genetics, Siberian Branch, Russian Academy of Sciences, Russia). The presence of fast-migrating CAD isoenzymes is designated as FF phenotype; their absence, as 00 phenotype. Hybridological analysis was carried out; the excess of “null” genotypes was found in F2 progenies. Hybridization with nulli-tetrasomic lines of the chromosomes of the fifth homeologous group was conducted for the gene localization. The segregation analysis demonstrated the most probable localization of the CAD1-F gene in the chromosome 5A. The plants with FF and 00 genotypes differed in a number of chemical and anatomical traits, as well as in grain productivity. The results obtained are discussed in connection with the function of this enzyme in the wheat plant tissues.