Gli-A1 Loci Research Articles

Identification of winter common wheat samples of Kharkiv breeding by protein markers

Aim. Identification of new winter wheat breeding material developed in Kharkiv by electrophoretic patterns of storage proteins to select the most promising lines. Methods. Protein fractionation was performed by APAG- and SDS-electrophoresis. Results. The genotypes of winter wheat samples of the competitive variety trial at seven storage protein loci Gli-A1, Gli-B1, Gli-D1, Gli-A3, Glu-A1, Glu-B1, Glu-D1 were studied. We identified eight alleles at the Gli-A1 locus, seven at Gli-B1, five at Gli-D1, four at Gli-A3, five at Glu-B1, three at Glu-A1, and two at Glu-D1. Most of the identified alleles are typical for Ukrainian winter wheat varieties. Along with them, theree were lines with introgressed alleles marking for the wheat-rye translocations 1AL/1RS and 1BL/1RS. The biotype of the line Erythrospermum 484-19 carries an introgressed allele from Ae. tauschii at the Gli-D1 locus. Conclusions. According to field and laboratory trials of samples, there were neither significant advantages nor disadvantages of lines with wheat-rye translocations compared to lines without translocations (typical for the East Forest-Steppe zone). The promising line of the use of the 1AL/RS or 1BL/RS translocations (carrying disease resistance genes) is their coupling with the allele Glu-B1al associated with high grain quality.
 Keywords: winter wheat, storage proteins, alleles, translocations.

Genetic diversity of ukrainian wheat landraces Triticum aestivum L. at gliadin-coding loci

Aim. The aim of the study was to investigate genetic variability of gliadin-coding loci Gli-A1, Gli-B1, Gli-D1 in Ukrainian winter common wheat landraces and obsolete varieties. Methods. APAG electrophoresis of gliadin was used to identify genotypes at Gli-1 loci. Results. Diversity at the Gli-1 loci of 41 winter common wheat landraces, including local varieties Krymka, Banatka, Girka, Theyka, and 13 obsolete winter common wheat varieties, were studied. A total 31 gliadin alleles (including new 7 alleles) were revealed. There are 11 alleles at the Gli-A1 loci, 14 - at the Gli-B1, 6 -at the Gli-D1. Differences in frequencies of gliadin alleles were established. Conclusions. The high level of allelic variation at the Gli-1 loci was observed in Ukrainian winter common wheat landraces. Predominant alleles were revealed: Gli-A1m (46,8 %), Gli-A1d (21 %), Gli-B1b (47,1 %), Gli-D1g (45,8 %), Gli-D1a (33,3 %), Gli-D1j (13,9 %). In genotype of modern Ukrainian winter common wheat are present only 3 of them - Gli-B1b, Gli-D1g, Gli-D1j, which positively relate to dough quality.
 Keywords: Triticum aestivum L., winter wheat, landraces, gliadin , alleles , polymorphism

Comparison of alleles at the Gli-1 loci of common wheat by means of two-dimensional electrophoresis of gliadin and RFLP analysis

Allelic variants of the Gli-1 locus is known to control groups (blocks) of gliadin polypeptides (gliadins). Some allelic variants of blocks that differ in the electrophoretic (acid gel) mobility (EM) of only one gliadin of the block were compared using two-dimensional electrophoresis (SDS-PAGE) and the RFLP procedure. It was found that, in these pairs of similar alleles (Gli-B1f, Gli-B1s, and Gli-D1a as compared with Gli-B1e, Gli-B1n, and Gli-D1c, respectively), faster γ-gliadin had smaller molecular weight (MW). Alleles at the Gli-A1 locus (Gli-A1j, Gli-A1i, Gli-A1a, Gli-A1k, and Gli-A1f) differ in the EM of the γ-gliadin so that Gli-A1j controls the slowest γ-gliadin and Gli-A1f controls the fastest one. We found that, in this order of alleles, faster γ-gliadin always had smaller MW. It was suggested that similar alleles might arise from one another by spontaneous mutations changing the number of repeating sequences or length of the polyglutamine domain present in the γ-gliadin gene thereby influencing MW and EM of encoding polypeptide. Other mechanisms of the mutational appearance of new alleles were found earlier by comparison of allele pairs: Gli-D1a and Gli-D1k (gene silencing) and Gli-D1b and Gli-D1d (gene amplification). We discovered contrasting families of alleles at the Gli-B1 and at the Gli-D1 loci and also two variants of apparently the same allele Gli-D1a that differed in the number of encoded ω-gliadins. Families of alleles at one locus of T. aestivum might inherit from different genotypes of corresponding diploid donor, as we suggested earlier.

Effects of Allelic Variation in Glutenin Subunits and Gliadins on Baking-Quality in Near-isogenic Lines of Common Wheat cv. Longmai 19

Two lines, L-19-613 and L-19-626, were produced from the common wheat cultivar Longmai 19 (L-19) by six consecutive backcrosses using biochemical marker-assisted selection. L-19 (Glu-D1a, Glu-A3c/Gli-A1?; Gli-A1? is a gene coding for unnamed gliadin) and L-19-613 (Glu-D1d, Glu-A3c/Gli-A1?) formed a set of near-isogenic lines (NILs) for HMW-GS, while L-19-613 and L-19-626 (Glu-D1d, Glu-A3e/Gli-A1m) constituted another set of NILs for the LMW-GS/gliadins. The three L-19 NILs were grown in the wheat breeding nursery in 2007 and 2008. The field experiments were designed using the three-column contrast arrangement method with four replicates. The three lines were ranked as follows for measurements of gluten strength, which was determined by the gluten index, Zeleny sedimentation, the stability and breakdown time of the farinogram, the maximum resistance and area of the extensogram, and the P andWvalues of the alveogram: L-19-613 > L-19-626 > L-19. The parameters listed above were significantly different between lines at the 0.05 or 0.01 level. The Glu-D1 and Glu-A3/Gli-A1 loci had additive effects on the gluten index, Zeleny sedimentation, stability, breakdown time, maximum resistance, area, P and W values. Although genetic variation at the Glu-A3/Gli-A1 locus had a great influence on wheat quality, the genetic difference between Glu-D1d and Glu-D1a at the Glu-D1 locus was much larger than that of Glu-A3c/Gli-A1? and Glu-A3e/Gli-A1m at the Glu-A3/Gli-A1 locus. Glu-D1d had negative effects on the extensibility and the L value compared with Glu-D1a. In contrast, Glu-A3c/Gli-A1? had a positive effect on these traits compared with Glu-A3e/Gli-A1m.

Variation at storage protein loci in winter common wheat cultivars of the central forest-steppe of Ukraine

Genotypes at the gliadin loci Gli-A1, Gli-B1, Gli-D1 and the high-molecular-weight glutenin subunit loci Glu-A1, Glu-B1, Glu-D1 were identified in 77 winter common wheat cultivars developed in the Central Forest Steppe of Ukraine in different periods of time. The highest level of variation was observed at the Gli-A1 locus. Predominant alleles (one or two per locus) were revealed. The comparison of allele frequencies in groups of cultivars developed in different periods of time (before 1996 and in 1996-2007) has demonstrated appearance of new alleles and change of frequencies of existing alleles at the storage protein loci. The high frequency of cultivars with the wheat-rye 1BL/1RS translocation was detected (about 40%). The wheat rye 1AL/1RS translocation was identified in six cultivars developed in the last decade. Four gliadin alleles, Gli-A1w (a marker for the 1AL/1RS translocation), Gli-A1x, Gli-A1y and Gli-B1x, were proposed for cataloging.

Polymorphism, variation and genetic identity of Spanish common wheat germplasm based on gliadin alleles

Gliadin analysis has shown that Spanish common wheat germplasm is highly polymorphic and rather unique. In total, 81 different alleles, 70 of them catalogued, were identified in the 52 Spanish landraces studied, and 25 new gliadin alleles, not present in germplasm from other countries, were found. Eleven alleles were identified at the Gli-A1 locus, 14 at the Gli-B1, 9 at the Gli-D1, 17 at the Gli-A2, 14 at the Gli-B2 and 16 at the Gli-D2. Comparison of gliadin alleles among varieties released before and after 1966 revealed significant differences for 46 gliadin alleles. Forty-six alleles (36 of them catalogued) present in the material developed before 1966 were lost. In contrast, 25 alleles (23 of them catalogued) appear for the first time in the genepool bred after 1966. On the other hand, most of the Gli alleles frequent in recent Spanish cultivars were already present in Spanish landraces. In general, the results showed that Spanish varieties have suffered qualitative alterations of genetic variation during the last 35 years mainly due to changes in breeding goals and crosses with foreign germplasm. Seventy-five percent of the landraces analysed were shown to have maintained their genetic identity in the genebank although they have been regenerated several times during the last century. However, mistakes in three accessions modified 10 alleles (allele losses or presence of new alleles), and error in one suggests alteration of five alleles. These results demonstrate that great care during maintenance and handling of samples is an important requirement in conserving germplasm collections. Gliadin alleles allowed us to identify 48 different genotypes, some accession duplicates and one intermixing. Also, several mistakes could be resolved using gliadins as genetic markers.

Complexity of the Gli-A3 locus in bread wheat

Two bread wheat cultivars, 'Ariana 8' and 'Cajeme 71', and 129 F 2 grains from the cross between them were analysed for gliadin composition. Two monodimensional (A-PAGE and SDS-PAGE) and two different two-dimensional (SDS-PAGE x SDS-PAGE and A-PAGE x SDS-PAGE) electrophoretic methods were used. Parents differed at the Gli-A1 locus, detected by A-PAGE. The SDS-PAGE of the aqueous ethanol extractable protein under nonreduced conditions showed two bands of 'Ariana 8' and one of 'Cajeme 71', encoded by genes located 22 cM from the Gli-A1 locus, and therefore, located at the Gli-A3 locus. This locus has been considered to contain genes coding for ω-gliadins alone. The two-dimensional maps of the parents showed that one band from 'Ariana 8' was an ω-gliadin, but the other two bands, one from each parent, were y-gliadins. Results obtained indicated that Gli-A3, like Gli-A1, is a complex locus coding for both ω-and γ-gliadins.

Genetic characterization of storage proteins in a set of F1-derived haploid lines in bread wheat

Wheat storage proteins were evaluated by SDS-PAGE in a population of 206 doubled haploid (DH) lines, produced from a cross between bread wheat cvs Chinese Spring (CS) and Courtot (CT). The analysis of gliadins and high- and low-molecular-weight glutenins gave rise to 11 protein markers between parental varieties. Among these, one each was encoded at the Glu-A1, Gli-A1, Gli-A2, Gli-A5, Glu-B3, Gli-B1 and Gli-D1 loci and four were encoded at the Glu-D3 locus. Only the Gli-A2 marker showed a distorted segregation. A distance of 1.94 cM was evaluated between the Gli-A1 locus and the recently found Gli-A5 locus. Among the DH lines, only nine exhibited an unexpected pattern. The chromosome allocation was determined for almost all the LMW-GS and gliadin bands of CS using nullitetrasomic and ditelosomic lines. Two C LMW-GS were found to be coded by 6DS. Similarly, substitution lines into CT allowed the allelic determination of numerous LMW-GS and gliadin bands. A correspondence between gliadin markers separated in SDS-PAGE and in A-PAGE revealed that the common allele Gli-Aa between CS and CT determined in A-PAGE was able to be separated into two alleles when SDS-PAGE was used.

Inheritance of B subunits of glutenin and ω-and γ-gliadins in tetraploid wheats

A double-1RS wheat-rye translocation line lacking all B subunits of glutenin was produced in durum wheat cv 'Langdon' for use in backcrosses and testcrosses in the study of the inheritance of low-molecular-weight (LMW) glutenin subunits in tetraploid wheats. The B subunits of glutenin and γ-and ω-gliadin bands present in parents derived from Triticum durum and T. dicoccoides, encoded by Glu-3 and Gli-1 loci, respectively, were found to be inherited mainly as units (blocks), as reported previously. Two rare recombination events between the Glu-A3 and Gli-A1 loci were detected in testcross progeny from 'Edmore' x T. dicoccoides landrace 19-27. Several rare recombinants were also detected within the 1BS-controlled B subunits of glutenin blocks, suggesting that there are two separate tightly linked loci (3.07±1.35 cM) within the Glu-B3 'locus'. Evidence was also obtained for the presence of an additional locus coding for a B subunit of glutenin in 'Edmore' that is loosely linked (20.9±3.18%) with the main Glu-B3 'locus'.

Polymorphism of omega-gliadins in durum wheat as revealed by the two-step APAGE/SDS-PAGE technique

Polymorphism of omega-gliadins was studied in 243 durum wheats from 27 countries using the two-step one-dimensional APAGE/SDS-PAGE technique. A total of 12 bands of different mobility were observed, and four of them were found to be different from those previously detected by Khelifi et al. (1992) in bread wheat. Fifteen alleles, six coded by the Gli-A1 locus and nine coded by the Gli-B1 locus, were identified, accounting for 19 different electrophoretic patterns. Seven new alleles were detected: two at the Gli-A1 locus and five at the Gli-B1 locus. The polymorphism found at the Gli-A1 and Gli-B1 loci was slightly greater than that found in bread wheat. Allelic differences between both species were higher at the Gli-B1 locus. A comparison of the frequencies of alleles in both species was carried out. The null allele, Gli-A1e, was more common in durum wheat than in bread wheat. The Gli-B1b allele, present in 60% of the bread wheats, was found in only 2% of the durum wheats and Gli-B1e, very common in durum wheat (45%), was rare in bread wheat (4%). The Gli-B1IV allele, common in durum wheat (28%), was not detected in bread wheat.

Genetics of gliadins coded by the group 1 chromosomes in the high-quality bread wheat cultivar Neepawa

The inheritance and biochemical properties of gliadins controlled by the group 1 chromosomes of the high-quality bread wheat cultivar Neepawa were studied in the progeny of the cross Neepawa x Costantino by six different electrophoretic procedures. Chromosome 1B of Neepawa contains two gliadin loci, one (Gli-B1) coding for at least six ω- or γ-gliadins, the other (Gli-B3) controlling the synthesis of gliadin N6 only. The map distance between these loci was calculated as 22.1 cM. Amongst the chromosome 1A gliadins, three proteins are encoded at the Gli-A1 locus whereas polypeptides N14-N15-N16 are controlled by a remote locus which recombines with Gli-A1. Six other gliadins are controlled by a gene cluster at Gli-D1 on chromosome 1D. Canadian wheat cultivars sharing the Gli-B1 allele of Neepawa were found to differ in the presence or absence of gliadin N6. The electrophoretic mobilities of proteins N6 and N14-N15-N16 were unaffected by the addition of a reducing agent during two-dimensional sodium dodecyl sulphate polyacrylamid-gel electrophoresis, suggesting the absence of intra-chain disulphide bonds in their structure.

Polymorphism and inheritance of gliadin polypeptides in T. monococcum L.

More than 80 different gliadin electrophoretic patterns (spectra) have been found in 109 accessions of the diploid wheat Triticum monococcum. Each pattern consists of 15-20 gliadin bands. Some patterns are clearly related and might arise from one another through single mutations in the gliadin-coding loci. From the analysis of 15 grains of each, only 61 accessions were found to be uniform; others consisted of two or more grain variants differing in their gliadin spectrum. An analysis of F2 grains from three crosses between different accessions showed that groups (blocks) of components are jointly and codominantly inherited. Two independent major Gli loci were established. The close resemblance of the composition of some blocks of T. monococcum to some of those in polyploid wheats indicates that one locus in each T. monococcum genotype is located on chromosome 1A (Gli-A1) and the other on 6A (Gli-A2). However, the blocks of T. monococcum include more bands than corresponding (equivalent) blocks of polyploid wheats. Two out of 275 F2 grains of the cross k-14244 x k-20409 were found to have gliadin spectra which can be explained as a result of intralocus recombination. Also, a second gliadin-coding locus on chromosome 1A was found in the cross k-46140 x k-46753. This locus recombines with the main Gli-A1 locus with a frequency of about 22% and was clearly analogous to the additional Gli locus found earlier on chromosome 1A of certain polyploid wheats.

The cumulative effect of allelic variation in LMW and HMW glutenin subunits on dough properties in the progeny of two bread wheats

The effects of allelic variation at Gli-A1, GluA3 and Glu-A1 loci coding for gliadins, LMW glutenin subunits and HMW glutenin subunits on dough resistance and extensibility was analysed in 56 F2-derived F6 families from a cross between bread wheats MKR(111/8) and 'Kite'. Extensograph data from two sites giving widely different flour protein levels (approximately 7% and 14%) revealed that the Glu-A3m and Glu-A1b alleles were associated with larger effects on dough resistance and extensibility than the null alleles Glu-A3k and GluA1c, respectively, and moreover, their effects were additive at both protein levels. The effect of the LMW glutenin allele Glu-A3m on both dough resistance and dough extensibility was relatively larger than that of the HMW glutenin allele Glu-A1b at both sites. Variation at the Gli-A1 locus did not appear to contribute towards dough strength. The results also showed the large effect of flour protein content on dough properties.