Gliadin Genes Research Articles

Homology of chromosomes of Triticum macha Dek. et Men. and Triticum aestivum L. as shown with the help of genetic markers

Inheritance of the storage protein (gliadin and glutenin) genes of Triticum macha Dek. et Men. and their allelism to Triticum aestivum L. genes have been studied. A close homology of at least chromosomes 1A and 1B of the two species has been found. Results confirm a very close relationship between T. macha and T. aestivum.Key words: seed storage proteins, genetic analysis, chromosome homology, relationship of Triticum macha Dek. et Men. and Triticum aestivum L.

Gliadin genes contain heat-shock elements: Possible relevance to heat-induced changes in grain quality

Etat de la recherche sur la biosynthese des proteines du choc thermique dans le ble soumis a une temperature elevee lors de la culture. Mise en evidence de sequences homologues dans ces proteines et dans la gliadine, ainsi que des elements du choc thermique dans 2 genes gliadine. Relation avec la teneur en gliadine et en glutenine

Involvement of a Novel Peptide in the Heat Shock Response of Australian Wheats

A low molecular weight peptide, induced by exposure of coleoptiles to heat stress at 41°C, has been detected by reversed-phase high performance liquid chromatography of extracts from coleoptiles of five wheat (Triticum aestivum) cultivars. This component is detected within 1 h of a 41°C heat shock, is not detected 48 h after cessation of the heat shock, and remains present during a continuous 24 h heat treatment. The appearance of this component is also induced by exposure of the coleoptile to 0.1 M sodium arsenite or 10% ethanol. When other species such as barley (Hordeum vulgare), soybean (Glycine max), sorghum (Sorghum bicolor), maize (Zea mays), mungbean (Vigna radiata), or rice (Oryza sativa) were examined for the presence of a component eluting in the same position, it was only detected in maize. The amino acid sequence for the heat-induced peptide from wheat was determined to be: V-L-V-P-V-P-Q-L-Q-P-Q-N-Q-P/Q. The sequence of 12 of these amino acids is the same as the N-terminal sequence of α- and β gliadins (wheat endosperm storage proteins). The production of this heat-induced peptide in aneuploids of Chinese spring wheat indicated that the peptide gene was located on the same chromosome arm as one of the gliadin genes. The presence of this gliadin-like peptide in heat-stressed coleoptiles may be due to the presence of five heat shock elements in the gene sequence of gliadins. The potential heat inducibility of the gliadin gene has important implications for end-use quality of wheat. The results also imply that seed proteins may have a function other than storage of nitrogen.

Chromosomal location by F1 monosomic analysis of endosperm proteins in bread wheat

The gliadin components from four bread wheat cultivars: Chinese Spring, Capelle Desprez, Holdfast and Pane-247 and their monosomic F1s for the chromosomes of homoeologous groups 1 and 6 have been analyzed by two-dimensional (2-pH) polyacrylamide gel electrophoresis. Chromosomal location of gliadin genes and the allelic differences were well established by analyzing the different F1 monosomic hybrids, electrophoretical patterns and differences in relative staining intensity. A new gliadin encoded by a gene located on chromosome 6B in Chinese Spring is described. The two-dimensional patterns of gliadin in the other three varieties and the chromosomal location of their genes are reported for the first time. Relationships between gliadins in the two-dimensional patterns and the traditional system for their nomenclature are discussed.

Linkage mapping of genes controlling endosperm storage proteins in wheat

A translocation mapping procedure was used to map gene-centromere distances for the genes controlling endosperm proteins on the short arm of each of the chromosomes 1A, 1B and 1D in wheat. The genes controlling triplet proteins (tentatively designated Tri-1) were found to be closely linked to the centromere on chromosome arms 1AS and 1DS and loosely linked to the gliadin genes (Gli-1) on the same arms. The Gli-1 genes segregated independently or were very loosely linked to their respective centromeres. The Gli-B1-centromere map distance on 1BS was also estimated using conventional telocentric mapping and the result was similar to that obtained with the translocation mapping. A simple two-step one-dimensional electrophoretic procedure is described which allows the low-molecular-weight (LMW) glutenin subunits to be separated from the gliadin bands, thus facilitating the genetic analysis of these LMW subunits. No recombination was observed between the genes (designated Glu-3) controlling some major LMW glutenin subunits and those controlling gliadins on chromosome arms 1AS and 1DS. However, in a separate experiment, the genes controlling LMW glutenin subunits on 1BS (Glu-B3) showed a low frequency of recombination with the gliadin genes.

Nucleotide sequence of a γ gliadin gene: Comparisons with other γ gliadin sequences show the structure of γ gliadin genes and the general primary structure of γ gliadins

A low stringency screening of a wheat ( Triticum aestivum L.) genomic library produced three types of γ gliadin clones. The sequence of one clone, λ10–20, encoded a γ gliadin of 34.3 kDa. Comparisons of this protein with the proteins encoded by other γ gliadin DNA sequences revealed a general γ gliadin structure: a 19-residue signal peptide; 12-residue mature amino terminus; 12–16 copies of a proline- and glutamine-rich heptapeptide repeat; a 76-residue region high in glutamine containing most of the cyysteines and charged residues: a 6–16-residue polyglutamine region; and the 41-residue carboxyl terminus. Comparisons of the 5′ and 3′ flanking regions of several γ gliadins reveals the high homology and general structure of γ gliadin genes. A further comparison of the 5′ flanking regions with the 5′ flanking regions of other prolamin genes showed that γ gliadin genes contain three copies of a conserved sequence seen within approx. 600 b.p. upstream of the translation start sites of prolamin genes.

A Possible Association Between Heading Time and the GM‐A2 Locus in Bread Wheat

AbstractA line without expression (null form) o: the α‐gliadins controlled by the 6A chromosome was found when screening electrosboretically single seeds of the bread wheat ‘Raeder’. Differences in heading time were also observed between this null line and the normal one. A linkage between 6A gliadin genes and heading time gene(s) is hypothesized.

Analyses of α/β-type gliadin genes from diploid and hexaploid wheats

The αβ-gliadin genes isolated from both hexaploid wheat (cv. Yamhill) and the diploid A genome progenitor Triticum urartu had remarkably similar sequences and differ by only a few point mutations. Primer extension analysis indicated that the transcriptional start points for individual genes in the family cluster within a few nucleotides. Comparison of the promoter region of several α/β-gliadin and B-hordein genes reveals two conserved regions at about −130 and −250 bp. DNA from the hexaploid cultivars, Cheyenne and Chinese Spring, and the diploid progenitors T. urartu and Aegilops squarrosa was analysed by Southern blotting. Restriction fragment lengths of the α/β-gliadin genes varied only slightly between the various wheats, although the overall copy number varied significantly. A region between approx. −1700 and −700 bp upstream from the TATA box was highly repeated in all three wheat genomes. For the hexaploid-derived gene, over 1700 bp of sequence upstream from the TATA box was determined, revealing an additional open reading frame between approx. −1550 and −1250 bp relative to the gliadin TATA box. Northern blot analysis indicated that RNA homologous to this repeated sequence family was present only in developing seed and accumulated to a maximum at late stages of maturation.

Chromosomal location of seed storage protein genes in the genome of Elytrigia elongata

Additions of complete and telocentric chromosomes of Elytrigia elongata (Host) Nevski in Triticum aestivum L. 'Chinese Spring' were employed to assign the genes coding for seed storage proteins to chromosome arms in the E. elongata genome. Genes coding for prolamins equivalent to wheat gliadins were found on chromosome arms 1ES and 6Ep. Genes on chromosome arm 1ES, which is presumably the p arm, coded for several components with electrophoretic mobilities (lactate–PAGE) corresponding to those of β-, γ-, and ω- gliadins and those on chromosome arm 6Ep coded for two components with mobilities corresponding to those of β-gliadins. Amino acid sequencing of mixtures of prolamins from E. elongata and from E. pontica (Podp.) Holub, a species closely related to E. elongata, indicated that prolamins of these species correspond to α-type (which includes β-gliadins), γ-type, and ω-type gliadins. Restriction fragments of genomic DNAs from substitution lines of chromosome 6E of E. elongata in 'Chinese Spring' were separated electrophoretically in agarose gels and probed with a cloned α-type gliadin gene from 'Yamhill'. This Southern blot showed that chromosome 6E yields DNA fragments identical in size to those characteristic of the α-gliadin gene cluster that is on chromosome 6A of 'Chinese Spring', 'Cheyenne', and 'Yamhill'. These results indicate that structural genes for prolamins of Elytrigia are similar to those of wheat gliadins and are located on the same chromosome arms as those in Triticum species. A high molecular weight (HMW) protein likely to be a HMW glutenin subunit was located on the long arm of chromosome 1E, which presumably is the q arm; this also is in accordance with the location of HMW glutenin subunit genes in Triticum. It is concluded that the appearance of α-type gliadin genes on chromosomes of homoeologous group 6 in T. aestivum occurred prior to divergence of Triticum and Elytrigia but after the divergence of Secale, Hordeum, and the Triticum–Elytrigia lineages, since neither Secale or Hordeum appear to have α-type genes. It is, however, possible that α-type gliadin genes were deleted from the ancestors of Secale and Hordeum after divergence from the Triticum–Elytrigia lineage.Key words: Elytrigia elongata, gene location, prolamins, gliadins, wheat.

Gene-dosage compensation of endosperm proteins in hexaploid wheat Triticum aestivum

Several aneuploid lines and one intervarietal substitution line of the hexaploid wheat Triticum aestivum (2n = 6x = 42; genomes AABBDD) cv. Chinese Spring were used to study the effects of different doses of chromosomes 1B, 1D, or 1A on the amount of the high molecular weight ("HMW") glutenins and gliadins of endosperm. These homeologous chromosomes carry HMW glutenin and gliadin gene clusters on their long and short arms, respectively. Increasing the dosage of chromosome 1B of Chinese Spring in plants having in their 3n endosperm zero or the normal three doses of the homeologue 1D, as well as in plants carrying in their endosperm one dose of 1B of the cultivar Timstein, had a dual effect: on one hand, a nonlinear increase in the amount of each subunit encoded by the chromosome whose dosage was elevated and, on the other hand, a compensating nonspecific decrease in the amount of other HMW glutenin and gliadin subunits encoded either by the homeoalleles on 1D or by the homoalleles on 1B of Timstein, respectively. Deletion of chromosome arm 1BL, which carries only a few HMW glutenin genes, had no significant effect on the amount of HMW glutenins encoded by 1DL and HMW gliadins encoded by 1DS and 1BS. However, deletion of 1BS or 1DS, each carrying many gliadin genes, caused a significant but nonspecific increase in the HMW glutenins and gliadins encoded by the remaining arms of 1B and 1D. The possible mechanism and evolutionary implications of gene-dosage compensation in polyploid wheat are discussed.

Nucleic acid (cDNA) and amino acid sequences of alpha-type gliadins from wheat (Triticum aestivum).

The complete amino acid sequence for an alpha-type gliadin protein of wheat (Triticum aestivum Linnaeus) endosperm has been derived from a cloned cDNA sequence. An additional cDNA clone that corresponds to about 75% of a similar alpha-type gliadin has been sequenced and shows some important differences. About 97% of the composite sequence of A-gliadin (an alpha-type gliadin fraction) has also been obtained by direct amino acid sequencing. This sequence shows a high degree of similarity with amino acid sequences derived from both cDNA clones and is virtually identical to one of them. On the basis of sequence information, after loss of the signal sequence, the mature alpha-type gliadins may be divided into five different domains, two of which may have evolved from an ancestral gliadin gene, whereas the remaining three contain repeating sequences that may have developed independently.

Developmentally regulated plant genes: the nucleotide sequence of a wheat gliadin genomic clone.

Gliadins, the major wheat seed storage proteins, are encoded by a multigene family. Northern blot analysis shows that gliadin genes are transcribed in endosperm tissue into two classes of poly(A)+ mRNA, 1400 bases (class I) and 1600 bases (class II) in length. Using poly(A)+ RNA from developing wheat endosperm we constructed a cDNA library from which a number of clones coding for alpha/beta and gamma gliadins were identified by hybrid-selected mRNA translation and DNA sequencing. These cDNA clones were used as probes for the isolation of genomic gliadin clones from a wheat genomic library. One such genomic clone was characterized in detail and its DNA sequence determined. It contains a gene for a 33-kd alpha/beta gliadin protein (a 20 amino acid signal peptide and a 266 amino acid mature protein) which is very rich in glutamine (33.8%) and proline (15.4%). The gene sequence does not contain introns. A typical eukaryotic promoter sequence is present at -104 (relative to the translation initiation codon) and there are two normal polyadenylation signals 77 and 134 bases downstream from the translation termination codon. The coding sequence contains some internal sequence repetition, and is highly homologous to several alpha/beta gliadin cDNA clones. Homology to a gamma-gliadin cDNA clone is low, and there is no homology with known glutenin or zein cDNA sequences.

Mapping of glutenin and gliadin genes located on chromosome 1B of common wheat

The inheritance of the high molecular weight (HMW) glutenins and of several gliadins controlled, respectively, by the long and short arms of chromosome 1B of common wheat was studied. Analysis was carried out on the progeny of two inter-varietal crosses in which the parental lines possessed differentially migrating subunits as revealed by sodium dodecyl sulphate polyacrylamide gel electrophoresis. No recombination event was detected either within the fraction of the HMW glutenins or among most of the gliadin subunits studied indicating that they are controlled by tightly linked gene clusters. One gliadin subunit (B30) showed 25.5% recombination frequency with the rest of the gliadin subunits and 23.5% recombination frequency with the fraction of the HMW glutenin subunits. It has been concluded that this subunit is controlled by a separate locus (Gld-B6), proximal to the major gliadin gene cluster on the short arm of chromosome 1B. Consequently, the recombination percentage between the glutenin loci and most of the gliadin loci was calculated as 49.0 and the distance in centi-Morgans (cM) as 53.6. The estimated distance in cM is very close to the observed recombination percentage. A genetic map of these storage protein genes is presented.

DISTRIBUTION OF NONSTRUCTURAL VARIATION BETWEEN WHEAT CULTIVARS ALONG CHROMOSOME ARM 6Bp: EVIDENCE FROM THE LINKAGE MAP AND PHYSICAL MAP OF THE ARM

Metaphase I (MI) pairing of homologous chromosomes in wheat intercultivar hybrids (heterohomologous chromosomes) is usually reduced relative to that within the inbred parental cultivars (euhomologous chromosomes). It was proposed elsewhere that this phenomenon is caused by polymorphism in nucleotide sequences (nonstructural chromosome variation) among wheat cultivars. The distribution of this polymorphism along chromosome arm 6Bp (=6BS) of cultivars Chinese Spring and Cheyenne was investigated. A population of potentially recombinant chromosomes derived from crossing over between telosome 6Bp of Chinese Spring and Cheyenne chromosome 6B was developed in the isogenic background of Chinese Spring. The approximate length of the Chinese Spring segment present in each of these chromosomes was assessed by determining for each chromosome the interval in which crossing over occurred (utilizing the rRNA gene region, a distal C-band and the gliadin gene region as markers). The MI pairing frequencies of these chromosomes (only the complete chromosomes were used) with the normal Chinese Spring telosome 6Bp were determined. These were directly proportional to the length of the euhomologous segment. The longer the incorporated euhomologous segment the better was the MI pairing. This provided evidence that the heterohomologous chromosomes are differentiated from each other in numerous sites distributed throughout the arm.-The comparison of the physical map of arm 6Bp with the linkage map showed a remarkable distortion of the linkage map; no crossing over was detected in the proximal 68% of the arm. A population of 49 recombinant chromosomes was assayed for recombination within the rRNA gene region, but none was detected. No new length variants of the nontranscribed spacer separating the 18S and 26S rRNA genes were detected either.

Structural and genetical studies on the high-molecular-weight subunits of wheat glutenin

The genes controlling the synthesis of the high-molecular-weight subunits of glutenin on the long arms of chromosomes 1A and IB were mapped to the ω-gliadin genes on the short arms by analysing the progeny of three test crosses by sodium dodecyl sulphate, polyacrylamide-gel electrophoresis. Only very weak linkages were detected: the percentage recombination ranged from 39% to 47% and as the values did not significantly differ from each other, the data was pooled. A mean recombination of 43% was obtained and the map distance between glutenin and gliadin genes was calculated to be 66 cM. The analysis of three crosses involving telocentric lines revealed that the glutenin subunit genes on chromosomes 1A, IB and ID are tightly linked to the centromere, the mean map distance being 9.0 cM.