A comparison of two existing catalogues of the alleles of gliadin-coding loci in winter common wheat

Two catalogs of alleles of gliadin-coding loci, controlling synthesis of a storage protein of wheat caryopsis, gliadin, were compared. One catalogue comprises the alleles detected according to the electrophoretic patterns in starch gels; the other, in polyacrylamide gels. Determination of the allelic state of gliadin-coding loci in 31 previously not studied cultivars of winter common wheat allowed us to construct a matching system for the alleles compiled in the two catalogs, which gives the possibility to compare the results of wheat cultivar analyses performed at different scientific institutions.     

Global diversity of durum wheat Triticum durum Desf. for alleles of gliadin-coding loci

Genetic diversity for the alleles of gliadin-coding loci was studied with 465 durum wheat accessions from 42 countries. A total of 108 alleles were identified for four loci; 60 alleles were described for the first time. Broad diversity of rare gliadin-coding alleles was observed. The highest genetic diversity was characteristic of durum wheat accessions from the Middle East, Trans-Caucasia, the Pyrenean Peninsula, and the Balkans. Two genetically isolated ancient branches of durum wheat were isolated. A “southern” branch included mostly accessions from the Mediterranean region, the Middle East, and Trans-Caucasia. A “northern” branch included Russian and Ukrainian durum wheat accessions and varieties obtained on their basis. An additional group included durum wheat accessions that had been obtained in several past decades on the basis of the material of international breeding centers (CIMMYT and ICARDA) and had low genetic diversity.     

Genetic differentiation of common wheat cultivars using multiple alleles of gliadin-coding loci

The alleles of gliadin-coding loci have been identified in 105 spring common wheat cultivars bred in Omsk and Saratov by polyacrylamide gel electrophoresis. It has been shown that 49% of the Omsk cultivars and 40% of the Saratov cultivars are heterogeneous, i.e., composed of several biotypes that differ in alleles of the gliadin-coding loci. A total of 278 genotypes have been determined (170 in the Saratov cultivars and 112 in the Omsk cultivars); in these two groups of cultivars, four genotypes are identical. Due to this heterogeneity, the cultivars bred in Omsk and Saratov can be differentiated in a statistically significant manner despite their close kinship, which allows them to be ascribed an accession to a particular breeding center based on the gliadin pattern and the number or frequency of biotypes, as well as to determine its species affiliation with a 95% probability. Close relations prevent 5% of the Saratov cultivars and 4.4% of the Omsk cultivars from being distinguished within populations, since they have identical alleles of gliadin-coding loci.     

Comparative analysis of the genetic diversity dynamics at gliadin loci in the winter common wheat Triticum aestivum L. cultivars developed in Serbia and Italy over 40 years of scientific breeding

The dynamics of genetic transformations at gliadin-coding loci in the winter common wheat cultivars produced in Serbia and Italy over 40 years of scientific breeding was studied. It was demonstrated that a number of alleles unique for the wheat cultivars of each country were substituted with the alleles of a limited number of donor cultivars, in particular, cultivar Bezostaya 1 and its derivatives. On the background of preserved heterogeneity values during various time periods of breeding in each country, the genetic diversity in the total region decreased, as demonstrated by similarity in the sets of alleles of gliadin loci and their frequencies in the modem cultivars of these two Southern European countries. This decrease in the genetic diversity is an erosion of genetic resources within the region, which results in a loss of unique coadapted gene complexes.     

Comparative analysis of the genetic diversity dynamics at gliadin loci in the winter common wheat Triticum aestivum L. cultivars developed in Serbia and Italy over 40 years of scientific breeding

The dynamics of genetic transformations at gliadin-coding loci in the winter common wheat cultivars produced in Serbia and Italy over 40 years of scientific breeding was studied. It was demonstrated that a number of alleles unique for the wheat cultivars of each country were substituted with the alleles of a limited number of donor cultivars, in particular, cultivar Bezostaya 1 and its derivatives. On the background of preserved heterogeneity values during various time periods of breeding in each country, the genetic diversity in the total region decreased, as demonstrated by similarity in the sets of alleles of gliadin loci and their frequencies in the modern cultivars of these two Southern European countries. This decrease in the genetic diversity is an erosion of genetic resources within the region, which results in a loss of unique coadapted gene complexes.     

Genetic control of gliadin components in wheat <Emphasis Type="Italic">Triticum spelta</Emphasis> L.

The componental composition of electrophoretic spectra of gliadin in Triticum spelta L. was studied. By analogy with common wheat T. aestivum L., it was established that genes controlling gliadin components in spelt are also located in short arms of chromosomes of homeological groups 1 and 6. Analysis of gliadin spectra in F₂ grains from the crosses k-20539 × Ershovskaya 32 and k-20558 × Ershovskaya 32 revealed linkage of some components and their grouping into blocks (alleles) of coinherited gliadin components. Alleles of gliadin-coding loci identical to alleles of common wheat and new alleles earlier unknown for wheat populations have been identified.     

The effect of natural selection on the allelic frequency of gliadin-coding loci and their associations in an artificially created hybrid population of winter wheat

Hybrid population with heterogeneity for five gliadin-coding loci was created by crossing of five winter common wheat cultivars (Belozerskaya 47, Ilyichevka, Kyyanka, Mironovskaya 808, Polesskaya 70) by the complete scheme. Frequencies of alleles at these loci and their associations were analyzed after two, four and ten years of resowing. The ratio of alleles at the studied loci was changed as reproduction occurred. Gli 1A5 allele displayed stable tendency to frequency increasing, Gli 1D1--a little tendency and Gli 6A3--very essential tendency. The share of Gli 6D2 allele increased only after ten years of population reproduction. Combination of alleles at two, three, and five loci was not accidental. The most common regularity was predominance of the frequency of allelic associations characteristic of the parents (except for Ilyichevka) over new combinations. Possible causes of this phenomenon are discussed.     

Genealogical and statistical analyses of the inheritance of gliadin-coding alleles in a model set of common wheat <Emphasis Type="Italic">Triticum aestivum</Emphasis> L. cultivars

Allelic diversity of the gliadin-coding loci Gli-1 and Gli-2 was compared with the genealogical profiles of common wheat cultivars developed in Saratov. Allele tracking through their pedigrees and hierarchic cluster analysis associated 31 Gli alleles with groups of original ancestors. The cultivars Poltavka (12 alleles of six loci) and Selivanovskii Rusak (six alleles of six loci) were identified as sources of the majority of alleles. The results of the cluster analysis fully coincided with the results of allele tracking for alleles occurring at high frequencies. For rare alleles, the resolution of the cluster analysis was somewhat lower and depended on the similarity/distance measure. Thus, it proved possible to indirectly identify the donors of gene alleles by multidimensional statistics even when data on alleles identified in ancestors are unavailable. This approach to the analysis of inheritance has two limitations: detailed pedigree data should be known, and relatively high frequencies (no less than 15–20%) should be observed for the alleles in a sample under study. Cluster analysis was used to study the association of gliadin alleles with commercial quality classes. The most important gliadin-coding alleles, which mark strong cultivars, were identified. In the Saratov cultivars, such alleles include Gli-A1f, GliB1e, Gli-D1a, Gli-A2q, Gli-B2s, and Gli-D2e, which were inherited from the landrace Poltavka, and Gli-A1i, Gli-A2s, and Gli-B2q, which were inherited from the landrace Selivanovskii Rusak.     

Catalogue of alleles of gliadin-coding loci in durum wheat (Triticum durum Desf.)

Gliadins are seed storage proteins which are characterized by high intervarietal polymorphism and can be used as genetic markers. As a result of our work, a considerably extended catalogue of allelic variants of gliadin component blocks was compiled for durum wheat; 74 allelic variants for four gliadin-coding loci were identified for the first time. The extended catalogue includes a total of 131 allelic variants: 16 for locus Gli-A1(d), 19 for locus Gli-B1(d), 41 for locus Gli-A2(d), and 55 for locus Gli-B2(d). The electrophoretic pattern of the standard cultivar and a diagram are provided for every block identified. The number of alleles per family is quite small for loci Gli-A1(d) and Gli-B1(d) of durum wheat, as contrasted to loci Gli-A2(d) and Gli-B2(d) that are characterized by large families including many alleles. The presence of large block families determines a higher diversity of durum wheat for loci Gli-A2(d) and Gli-B2(d) as compared to Gli-A1(d) and Gli-B1(d). The catalogue of allelic variants of gliadin component blocks can be used by seed farmers to identify durum wheat cultivars and evaluate their purity; by breeders, to obtain homogenous cultivars and control the initial stages of selection; by gene bank experts, to preserve native varieties and the original biotypic composition of cultivars.     

Genetic diversity of modern Russian durum wheat cultivars at the gliadin-coding loci

The allelic diversity at four gliadin-coding loci was studied in modern cultivars of the spring and winter durum wheat Triticum durum Desf. Comparative analysis of the allelic diversity showed that the gene pools of these two types of durum wheat, having different life styles, were considerably different. For the modern spring durum wheat cultivars, a certain reduction of the genetic diversity was observed compared to the cultivars bred in the 20th century.     

Blocks of gliadin components in winter wheat detected by one-dimensional polyacrylamide gel electrophoresis

Summary Inheritance of gliadin components in winter wheat has been studied by one-dimensional polyacrylamide gel electrophoresis. Single F₂ grains from 36 intervarietal hybrid combinations have been analysed. The genetic analysis has revealed blocks, including 1–6 gliadin components, which are inherited as individual mendelian traits. About 80 variants of blocks have been detected. On the basis of the allelism test they are grouped into 6 series in accordance with the number of known gliadin-coding loci located on chromosomes of the homoeologous groups 1 and 6. Each series includes 8–18 blocks controlled by different alleles of one gliadin-coding locus. Blocks of components have been confirmed to be inherited codominantly in accordance to the gene dose in the triploid endosperm. The highest similarity between members of one series is observed in groups of blocks controlled by chromosomes ID and 6D. On the contrary, many blocks controlled by chromosomes 1A and 1B have no bands in common. The presented catalogue of blocks of components may be used to make up gliadin genetic formulae and to compare electrophoregrams obtained by different authors. Blocks of gliadin components are suitable genetic markers for use in revealing and studying heterogeneity of wheat varieties, in tracing their origin, in identifying recombinations, translocations and substitutions of the genetic material and in solving many other problems of the origin, evolution and selection of hexaploid wheat.     

Identification of alleles at gliadin loci Gli-U1 and Gli-M(b) 1 in Aegilops biuncialis Vis

The diversity of alleles of gliadin loci Gli-U1 and Gli-M(b) 1 was studied in the tetraploid species Aegilops biuncialis (UUM(b)M(b)). The collection of 41 Ae. biuncialis accessions and F2 grain obtained from five crossing combinations provides material used in this study. Gliadins were separated by electrophoresis in polyacrylamide gel conducted in the acidic medium. To determine genomic affiliation (Uor M(b)) of components of Ae. biuncialis gliadin pattern, accessions of Ae. umbellulata and Ae. comosa were analyzed. In Ae. biuncialis accessions, 14 alleles were identified at the locus Gli-U1 and 12 alleles, at the locus Gli-M(b) 1. The results testify to a markedly high degree of allele diversity at major gliadin-coding loci of chromosomes belonging to Ae. biuncialis homeologous group 1.     

Effect of an introgression from Aegilops cylindrica host on manifestation of productivity traits in winter common wheat F2 plants

The effect of introgression of a chromosome 1D segment from Aegilops cylindrica to winter common wheat on productivity traits in F2 plants was studied using storage protein loci as genetic markers. An allele of the gliadin-coding Gli-D1 locus served as a marker of the introgression. Using of two- and three-locus interaction models, it was shown that the introgression tagged with Gli-D1 affected the manifestation of productivity traits (productive tillering, grain weight per plant and grain number per plant) through interaction with other marker storage protein loci: Glu-B1, Glu-D1, and Gli-B2.     

Allelic diversity at gliadin-coding gene loci in cultivars of spring durum wheat (<Emphasis Type="Italic">Triticum durum</Emphasis> Desf.) Bred in Russia and former Soviet republics in the 20th century

Allelic diversity at five gliadin-coding gene loci has been studied in the most important spring durum wheat cultivars released in Russia and former Soviet republics in the 20th century (66 cultivars). Seven, 5, 8, 13, and 2 allelic variants of blocks of gliadin components controlled by the loci Gli-A1 ^d , Gli-B1 ^d , Gli-A2 ^d , Gli-B2 ^d , and Gli-B5 ^d , respectively, have been identified. The allelic diversity did not exhibit a consistent trend during the period studied. Nei’s diversity index (H) was 0.68 in the period from 1929 to 1950, increased to 0.70 in 1951–1980, and decreased to 0.58 after the year 1981. It has been found that the most frequent alleles in this collection are relatively rare in other regions of the world, which suggests unique ways of the formation of the diversity of durum wheat cultivars in the former Soviet Union. The efficiency of electrophoresis of storage proteins as a method for identification of durum wheat cultivars by the gliadin electrophoretic pattern has been estimated.     

Application of gliadin polymorphism for pedigree analysis in common wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) from Northern Kazakhstan

Gliadins, seed storage proteins, are popular markers effectively employed for the analysis of common wheat. Gliadin electrophoretic patterns are genotype-specific, reproducible, not dependent on growing conditions and are suitable for germplasm identification complementary to molecular markers. Gliadins have been identified and used in wheat from various countries, but prior to this study little was known about gliadin polymorphism in wheat from Kazakhstan. In this study, 48 alleles of six gliadin-coding loci were identified in 43 cultivars of spring wheat from Northern Kazakhstan. The alleles Gli-A1 f , Gli-B1 e , Gli-D1 a , Gli-A2 p , Gli-B2 d and Gli-D2 e had maximal frequencies in each of the six loci. Identified Gli alleles in the loci formed ‘Gliadin Genetic Formula’ unique for each studied variety, and these were compared to the published data from previously analyzed wheat varieties. Pedigree analysis of 43 varieties studied for gliadin polymorphisms indicated that some Gli alleles were conserved and inherited from the progenitor cultivar Akmolinka 1. In contrast, other Gli alleles were replaced by those from modern germplasms. It is assumed that a higher frequency of gliadin alleles can be associated with the selection of genotypes with improved traits for yield and seed quality in the studied wheat cultivars from Northern Kazakhstan.     

Analysis of diversity of Russian and Ukrainian bread wheat (Triticum aestivum L.) cultivars for high-molecular-weight glutenin subunits

The allelic diversity of high-moleculat-weght glutenin subunits (H WIGS) in Russian and Ukrainian bread wheat cultivars was analyzed. The diversity of spring wheat cultivars for alleles of the Glu-1 loci is characterized by medium values of the polymorphism index (polymorphism information content, PlC), and in winter wheats it varies from high at the Glu-A1 locus to low at the Glu-D1 locus. The spring and winter cultivars differ significantly in the frequencies of alleles of the glutenin loci. The combination of the Glu-A1b, Glu-B1c, and Glu-D1a alleles prevails among the spring cultivars, and the combination of the Glu-A1a, Glu-B1c, and Glu-D1d alleles prevails among the winter cultivars. The distribution of the Glu-1 alleles significantly depends on the moisture and heat supply in the region of origin of the cultivars. Drought resistance is associated with the Glu-D1a allele in the spring wheat and with the Glu-B1b allele in the winter wheat. The sources of the Glu-1 alleles were identified in the spring and wheat cultivars. The analysis of independence of the distribution of the spring and winter cultivars by the market classes and by the alleles of the HMWGS loci showed a highly significant association of the alleles of three Glu-1 loci with the market classes in foreign cultivars and independence or a weak association in the Russian and Ukrainian cultivars. This seems to be due to the absence of a statistically substantiated system of classification of the domestic cultivars on the basis of their quality.     

新疆冬春麦区小麦地方品种贮藏蛋白遗传多样性研究

采用SDS-聚丙烯酰胺凝胶电泳（SDS-PAGE）对236份新疆小麦地方品种的高分子量麦谷蛋白亚基（HMW-GS）的组成进行了分析。结果表明：Glu-Ⅰ位点共有19种等位基因,其中Glu-Al位点3种,Glu-Bl位点7种,Glu—D1住点9种;亚基null、7＋8、2＋12在各自的位点上出现频率最高,分别达到91．95％、85．17％、80．93％;亚基组成类型共有21种,主要为null／7＋8／2＋12,频率达70．34％;同时筛选出33份含有1、2^＊、13＋16、14＋15、5＋10、1．5＋10、174-18等优质亚基的材料,可作为优质基因源。利用酸性聚丙烯酰胺凝胶电泳（A-PAGE）对其中的65份地方品种进行醇溶蛋白多样性分析。结果表明：电泳出现64条迁移率不同的谱带,构成65种组合,其中ω区出现的谱带最多,达17条;其次是β和γ区各16条,α区出现的谱带数最少,为15条。从每条谱带在65份材料中出现的频率看,总的变异范围为1．54％～93．85％;α、β、γ和ω4个分区多样性指数（H1）分别为0．498、0．386、0．523和0．348,表明新疆麦区小麦地方品种贮藏蛋白位点存在丰富的遗传多样性。     

Revealing hereditary variation of winter hardiness in cereals

A set of cereal crops and differentiating cultivars was shown to be of utility for identifying the major abiotic factors that limit the survival of winter crops in the cold season of a particular year. With this approach, the season was identified (1997-1998, Belgorod) when the survival of cereals depended on the tolerance to anaerobiosis rather than on the frost resistance. Differentiation of common wheat cultivars with respect to this property was attributed to a locus designated Win1 (Winter hardiness 1) and localized 3.2-5.8% recombination away from the B1 (awnlessness) gene. Winter barley (cultivar Odesskii 165) displayed the highest tolerance to anaerobiosis in the cold season; low and intermediate tolerance was established for winter durum wheat (cultivar Alyi Parus) and winter common wheat, respectively. Frost resistance and winter hardiness type 1 proved to be determined by different genetic systems, which showed no statistical association. Correlation analysis revealed significant positive associations of frost resistance in the field (1996-1997, Belgorod) with productivity, sedimentation index, plant height, and vegetation period in wheat. Statistical analysis associated frost resistance with gliadin-coding alleles of homeologous chromosomes 1 and 6 of the A, B, and D wheat genomes.     

Allelic variations in <Emphasis Type="Italic">Glu-1</Emphasis> and <Emphasis Type="Italic">Glu-3</Emphasis> loci of historical and modern Iranian bread wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) cultivars

Proline and glutamine-rich wheat seed endosperm proteins are collectively referred to as prolamins. They are comprised of HMW-GSs, LMW-GSs and gliadins. HMW-GSs are major determinants of gluten elasticity and LMW-GSs considerably affect dough extensibility and maximum dough resistance. The inheritance of glutenin subunits follows Mendelian genetics with multiple alleles in each locus. Identification of the banding patterns of glutenin subunits could be used as an estimate for screening high quality wheat germplasm. Here, by means of a two-step 1D-SDS-PAGE procedure, we identified the allelic variations in high and low-molecular-weight glutenin subunits in 65 hexaploid wheat (Triticum aestivum L.) cultivars representing a historical trend in the cultivars introduced or released in Iran from the years 1940 to 1990. Distinct alleles 17 and 19 were detected for Glu-1 and Glu-3 loci, respectively. The allelic frequencies at the Glu-1 loci demonstrated unimodal distributions. At Glu-A1, Glu-B1 and Glu-D1, we found that the most frequent alleles were the null, 7 + 8, 2 + 12 alleles, respectively, in Iranian wheat cultivars. In contrast, Glu-3 loci showed bimodal or trimodal distributions. At Glu-A3, themost frequent alleles were c and e. At Glu-B3 the most frequent alleles were a, b and c. At Glu-D3 locus, the alleles b and a, were the most and the second most frequent alleles in Iranian wheat cultivars. This led to a significantly higher Nei coefficient of genetic variations in Glu-3 loci (0.756) as compared to Glu-1 loci (0.547). At Glu-3 loci, we observed relatively high quality alleles in Glu-A3 and Glu-D3 loci and low quality alleles at Glu-B3 locus.     

药用植物天麻（Gastrodia elata Bl.）的等位酶遗传变异及其变型间的遗传关系

采用超薄平板聚丙烯酰胺等电聚焦电泳,对湖北西部药用植物天麻（Gastrodia elata Bl.）的4种变型进行了等位酶遗传变异的初步分析。在6个酶系统共检测到17个清晰位点和37个等位基因,其中多态位点11个,位点最大等位基因数为4,位点Acp-4和Prx-2的等位基因表现出变型特异性。遗传多样性分析结果表明：天麻在物种水平维持着较高遗传多样性,平均多态位点比率P=56.3%,每位点平均等位基因数A=2.1,平均预期杂合度He=0.222;但其变型水平遗传多样性较低（P=42.2%,A=1.7,He=0.146）,其中乌天麻遗传多样性最高,药天麻最低。天麻变型间遗传分化系数（GST）达0.3595,平均基因流（Nm）仅为0.4450,说明天麻变型间遗传分化较大,缺乏基因交流。聚类分析结果表明,天麻居群以变型为单元优先聚类而非地域优先聚类,揭示各天麻变型在遗传上是相对独立的进化显著单元,支持天麻种内变型的划分。红天麻与乌天麻两变型最为近缘,火天麻与药天麻两类群有着较近的遗传关系。