The Ha locus of wheat: Identification of a polymorphic region for tracing grain hardness in crosses

Genome ◽  
1999 ◽  
Vol 42 (6) ◽  
pp. 1242-1250 ◽  
Author(s):  
M Turner ◽  
Y Mukai ◽  
P Leroy ◽  
B Charef ◽  
R Appels ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Hexaploid Wheat ◽  
Aegilops Tauschii ◽  
Grain Hardness ◽  
High Sequence Identity ◽  
D Genome ◽  
Sequence Identity ◽  
Group 5 ◽  
Grain Softness ◽  
Puroindoline A

The grain softness proteins or friabilins are known to be composed of three main components: puroindoline a, puroindoline b, and GSP-1. cDNAs for GSP-1 have previously been mapped to group-5 chromosomes and their location on chromosome 5D is closely linked to the grain hardness (Ha) locus of hexaploid wheat. A genomic DNA clone containing the GSP-1 gene (wGSP1-A1) from hexaploid wheat has been identified by fluorescent in situ hybridization as having originated from the distal end of the short arm of chromosome 5A. A genomic clone containing the gene (wGSP1-D1) was also isolated from Aegilops tauschii, the donor of the D genome to bread wheat. There are no introns in the GSP-1 genes, and there is high sequence identity between wGSP1-A1 and wGSP1-D1 up to 1 kb 5' and 300 bp 3' to wGSP1-D1. However, regions further upstream and downstream of wGSP1-D1 share no significant sequence identity to corresponding sequences in wGSP1-A1. These regions therefore identified potentially valuable sequences for tracing the Ha locus through assaying polymorphic DNA sequences. The sequence from 300 to 500 bp 3' to wGSP1-D1 (wGSP1-D13) was mapped to the Ha locus in a mapping population. wGSP1-D13 was also tightly linked to genes for puroindoline a and puroindoline b which have been previously mapped to be at the Ha locus. In addition wGSP1-D13 was used to detect RFLPs between near isogenic soft and hard Falcon lines and in a random selection of soft and hard wheats.Key words: wheat, grain hardness, chromosome 5, puroindoline, GSP-1.

The organization of genes tightly linked to the Ha locus in Aegilops tauschii, the D-genome donor to wheat

Genome ◽  
2003 ◽  
Vol 46 (2) ◽  
pp. 330-338 ◽  
Author(s):  
K -M Turnbull ◽  
M Turner ◽  
Y Mukai ◽  
M Yamamoto ◽  
M K Morell ◽  
...  
Keyword(s):  
Aegilops Tauschii ◽  
Bac Library ◽  
Physical Distance ◽  
Bac Clone ◽  
D Genome ◽  
Hardness Locus ◽  
Genome Donor ◽  
Grain Softness ◽  
Puroindoline A

The grain hardness locus, Ha, is located at the distal end of the short arm of chromosome 5D in wheat. Three polypeptides, puroindoline-a, puroindoline-b, and grain softness protein (GSP-1), have been identified as components of friabilin, a biochemical marker for grain softness, and the genes for these polypeptides are known to be tightly linked to the Ha locus. However, this region of the chromosome 5D has not been well characterized and the physical distance between the markers is not known. Separate lambda clones containing the puroindoline-a gene and the puroindoline-b gene have been isolated from an Aegilops tauschii (the donor of the D genome to wheat) genomic lambda library and investigated. Considerable variation appears to exist in the organization of the region upstream of the gene for puroindoline-b among species closely related to wheat. Using in situ hybridization the genes for puroindoline-a, -b, and GSP-1 were demonstrated to be physically located at the tip of the short arm of chromosome 5 of A. tauschii. Four overlapping clones were isolated from a large-insert BAC library constructed from A. tauschii and of these one contained genes for all of puroindoline-a, puroindoline-b, and GSP-1. The gene for puroindoline-a is located between the other two genes at a distance no greater than approximately 30 kb from either gene. The BAC clone containing all three known genes was used to screen a cDNA library constructed from hexaploid wheat and cDNAs that could encode novel polypeptides were isolated.Key words: puroindolines, GSP-1, chromosome 5D, BAC library, tauschii.

More than one origin of hexaploid wheat is indicated by sequence comparison of low-copy DNA

Genome ◽  
1998 ◽  
Vol 41 (3) ◽  
pp. 402-407 ◽  
Author(s):  
L E Talbert ◽  
L Y Smith ◽  
N K Blake
Keyword(s):  
Dna Sequences ◽  
Hexaploid Wheat ◽  
Restriction Site ◽  
Cereal Crop ◽  
Crop Species ◽  
Wheat Evolution ◽  
D Genome ◽  
Restriction Site Variation ◽  
Site Variation ◽  
Copy Dna

Allohexaploid bread wheat is grown on more acreage than any other cereal crop, yet variation at the DNA level seems to be less than that observed in many diploid crop species. A common explanation for the small amount of DNA-level variation is that a severe bottleneck event resulted from the polyploidization events that gave rise to hexaploid wheat, whereby wheat was genetically separated from its progenitors. In this report, we test the extent of the bottleneck separating wheat from its D-genome progenitor, Triticum tauschii, by comparative DNA sequence analysis. Restriction site variation of low-copy DNA sequences amplified by PCR showed an average of 2.9 and 2.4 alleles per primer set in T. tauschii and wheat, respectively. Two different restriction patterns were present in T. tauschii for DNA amplified with a primer set for the A1 locus. Both alleles were also present in wheat. Alleles at the A1 locus were cloned and 527 bp of sequence obtained from 12 and 13 diverse accessions of wheat and T. tauschii, respectively. Average genetic distance among the wheat alleles was similar to that among the T. tauschii alleles (0.0127 and 0.0133, respectively). Nucleotide differences indicated that two distinct alleles existed in T. tauschii, both of which were present in wheat. These data suggest that hexaploid wheat formed at least twice, and that the bottleneck separating wheat from T. tauschii may be less constrictive than previously supposed.Key words: wheat, evolution, DNA.

scholarly journals Empirical verification of heterogeneous DNA fragments generated from wheat genome-specific SSR primers

2008 ◽  
Vol 88 (6) ◽  
pp. 1065-1071 ◽  
Author(s):  
Qijiao Chen ◽  
Lianquan Zhang ◽  
Zhongwei Yuan ◽  
Zehong Yan ◽  
Youliang Zheng ◽  
...  
Keyword(s):  
Common Wheat ◽  
Hexaploid Wheat ◽  
Chinese Spring ◽  
Triticum Turgidum ◽  
Sequence Data ◽  
Aegilops Tauschii ◽  
Single Locus ◽  
Synthetic Hexaploid Wheat ◽  
D Genome ◽  
Synthetic Hexaploid

Due to the high polymorphisms between synthetic hexaploid wheat (SHW) and common wheat, SHW has been widely used in genetic studies. The transferability of simple sequence repeats (SSR) among common wheat and its donor species, Triticum turgidum and Aegilops tauschii, and their SHW suggested the possibility that some SSRs, specific for a single locus in common wheat, might appear in two or more loci in SHWs. This is an important genetic issue when using synthetic hexaploid wheat population and SSR for mapping. However, it is largely ignored and never empirically well verified. The present study addressed this issue by using the well-studied SSR marker Xgwm261 as an example. The Xgwm261 produced a 192 bp fragment specific to chromosome 2D in common wheat Chinese Spring, but generated a 176 bp fragment in the D genome of Ae. tauschii AS60. Chromosomal location and DNA sequence data revealed that the176 bp fragment also donated by 2B chromosome of durum wheat Langdon. These results indicated that although a single 176 bp fragment was appeared in synthetic hexaploid wheat Syn-SAU-5 between Langdon and AS60, the fragment contained two different loci, one from chromosome 2D of AS60 and the other from 2B of Langdon which were confirmed by the segregating analysis of SSR Xgwm261 in 185 plants from a F2 population between Syn-SAU-5 and Chinese Spring. If Xgwm261 in Syn-SAU-5 was considered as a single locus in genetic analysis, distorted segregation or incorrect conclusions would be yielded. A proposed strategy to avoid this problem is to include SHW’s parental T. turgidum and Ae. tauschii in SSR analysis as control for polymorphism detection. Key words: Synthetic hexaploid wheat, microsatellite, segregation distortion, Xgwm261, transferability

scholarly journals The homoeologous genes for the Rec8-like meiotic cohesin in wheat: structure, function, and evolutionary implication

2018 ◽  
Author(s):  
Guojia Ma ◽  
Wei Zhang ◽  
Liwang Liu ◽  
Wun S. Chao ◽  
Yong Qiang Gu ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Hexaploid Wheat ◽  
Expression Patterns ◽  
Aegilops Tauschii ◽  
Tetraploid Wheat ◽  
Nucleotide Polymorphisms ◽  
Origin And Evolution ◽  
Homoeologous Genes ◽  
The One ◽  
Functional Analyses

ABSTRACTThe Rec8-like cohesin is a cohesion protein essential for orderly chromosome segregation in meiosis. Here, we cloned two Rec8-like homoeologous genes (homoeoalleles) from tetraploid wheat (TtRec8-A1 and TtRec8-B1) and one from hexaploid wheat (TaRec8-D1), and performed expression and functional analyses of the homoeoalleles. Also, we identified other two Rec8 homoeoalleles in hexaploid wheat (TaRec8-A1 and TaRec8-B1) and the one in Aegilops tauschii (AetRec8-D1) by comparative analysis. The coding DNA sequences (CDS) of these six Rec8 homoeoalleles are all 1,827 bp in length, encoding 608 amino acids. They differed from each other primarily in introns although single nucleotide polymorphisms were detected in CDS. Substantial difference was observed between the homoeoalleles from the subgenome B (TtRec8-B1 and TaRec8-B1) and those from the subgenomes A and D (TtRec8-A1, TaRec8-A1, and TaRec8-D1). TtRec8-A1 expressed dominantly over TtRec8-B1, but comparably to TaRec8-D1. Therefore, the Rec8 homoeoalleles from the subgenomes A and D may be functionally more active than the one from the subgenome B in wheat. The structural variation and differential expression of the Rec8 homoeoalleles indicate a unique cross-genome coordination of the homoeologous genes in the polyploid, and imply the distinction of the wheat subgenome B from other subgenomes in the origin and evolution.HIGHLIGHTThis work revealed the structural and expression patterns of the Rec8-like homoeologous genes in polyploid wheat, implying a unique origin and evolutionary route of the wheat B subgenome.

scholarly journals Allopolyploidization Enhances Genetic Recombination of the Ancestral Diploid Genome in the Evolution of Wheat

2020 ◽  
Author(s):  
Hongshen Wan ◽  
Jun Li ◽  
Shengwei Ma ◽  
Fan Yang ◽  
Liang Chai ◽  
...  
Keyword(s):  
Hexaploid Wheat ◽  
Genetic Recombination ◽  
Recombination Frequency ◽  
Aegilops Tauschii ◽  
Synthetic Hexaploid Wheat ◽  
Evolutionary Potential ◽  
D Genome ◽  
Diploid Genome ◽  
Synthetic Hexaploid ◽  
The Impact

Abstract Background: Genetic recombination produces different allelic combinations potentially, providing new variations to the selection pools for domestication. Allopolyploidization increases evolutionary potential of the hexaploid common wheat by taking its advantages of heterosis and gene redundancy. May there be any relationship between allopolyploidization and genetic recombination? To study the impact of allopolyploidization on genetic recombination in different ancestral genomes of wheat, we generated synthetic hexaploid wheat by crossed tetraploid Triticum turgidum with diploid Aegilops tauschii to simulate its evolutionary hexaploidization process. Results: Using Wheat Breeder’s Genotyping Array, the genotypes of F2 individuals were investigated in both tetraploid (A1A1B1B1 x A2A2B2B2) and their synthetic hexaploid wheat derived populations (A1A1B1B1DD x A2A2B2B2DD). And the genotypes of the diploid population (D1D1 x D2D2) and their synthetic hexaploid wheat derived population (AABBD1D1 x AABBD2D2) were obtained with DArT-Seq™ technology. Based on genotypes of F2 populations, the genetic recombination frequency of homologous chromosome were consequently calculated in ancestral tetraploid AABB (4x), diploid DD (2x) and their synthetic hexaploid AABBDD (6x) plants, respectively. The recombination frequency of the ancestral diploid genome DD from Aegilops tauschii was found enhanced significantly more than 2 folds after their hexaploidization, while no significant changes was found in their ancestral tetraploid genome AABB via hexaploidization.Conclusions: Allopolyploidization enhancing genetic recombination of the ancestral diploid genome is found to increase the evolutionary potential of wheat, which is beneficial for wheat to conquer their narrow origination of D genome, quickly spread and make it a major crop of the world.

scholarly journals Polyploidization enhancing genetic recombination of the ancestral diploid genome in the evolution of hexaploid wheat

2020 ◽  
Author(s):  
Hongshen Wan ◽  
Jun Li ◽  
Shengwei Ma ◽  
Qin Wang ◽  
Xinguo Zhu ◽  
...  
Keyword(s):  
Hexaploid Wheat ◽  
Genetic Recombination ◽  
Aegilops Tauschii ◽  
Tetraploid Wheat ◽  
Synthetic Hexaploid Wheat ◽  
Evolutionary Potential ◽  
D Genome ◽  
Diploid Genome ◽  
Synthetic Hexaploid ◽  
The Impact

AbstractAllopolyploidy increases its evolutionary potential by fixing heterosis and the advantage of gene redundancy. Allelic combinations generated from genetic recombination potentially provide many variations to the selection pools for evolution. May there be any relationship between allopolyploidization and genetic recombination? To study the impact of polyploidy on genetic recombination, we selected wheat as a model and simulated its evolution pathway of allopolyploidy by developing synthetic hexaploid wheat. The change of homologous chromosome recombination were investigated on their diploid DD and tetraploid AABB genomes after their allohexaploidization, respectively. The genetic recombination of the ancestral diploid genome of Aegilops tauschii was enhanced significantly more than 2 folds after their hexaploidization. Hexaploidization enhancing genetic recombination of the ancestral diploid D genome was firstly reported to be a new way to increase evolutionary potential of wheat, which is beneficial for wheat to conquer their narrow origination of D genome, quickly spread and make it a major crop of the world. Finally, re-synthetizing hexaploid wheat using diverse Ae. tauschii species with tetraploid wheat can be considered as a pleiotropic strategy to speed adaptive evolution of bread wheat in breeding processes by increasing both gene allele types and genetic recombination variations.

Variation in puroindoline polypeptides in Australian wheat cultivars in relation to grain hardness

2000 ◽  
Vol 27 (2) ◽  
pp. 153 ◽  
Author(s):  
Kym-Marie Turnbull ◽  
Therese Gaborit ◽  
Didier Marion ◽  
Sadequr Rahman
Keyword(s):  
Protein Sequence ◽  
Sequence Variation ◽  
Wheat Cultivars ◽  
Grain Hardness ◽  
Australian Wheat ◽  
Grain Softness ◽  
Puroindoline A ◽  
Selection Of ◽  
Do So

The sequence of the puroindoline-b gene from 15 Australian wheat cultivars was determined. Sequence variation was observed in the WPTKWWKGGCE motif of the deduced puroindoline-b protein sequence. Previously, it has been suggested that this sequence is crucial in determining grain hardness. In this study, no correlation was found between the variation in this sequence and the hardness or softness of the cultivar. The amounts of puroindo-line- a and puroindoline-b protein in a selection of hard and soft Australian wheat cultivars were also determined using ELISA techniques. Both soft and hard cultivars had variable amounts of puroindoline-a and puroindoline-b. In particular, it is notable that the hard cultivars Cook and Diaz contained high amounts of puroindoline-a and puroin-doline- b and also contained the puroindoline-b sequence previously reported to be associated with grain softness. These results suggest that if the puroindoline proteins are involved in determining grain softness or hardness they do so as part of a multi-component mechanism.

Phylogenetic relationships of Triticum tauschii, the D-genome donor to hexaploid wheat. 4. Variation and chromosomal location of 5S DNA

Genome ◽  
1989 ◽  
Vol 32 (6) ◽  
pp. 1017-1025 ◽  
Author(s):  
E. S. Lagudah ◽  
B. C. Clarke ◽  
R. Appels
Keyword(s):  
Dna Sequences ◽  
Hexaploid Wheat ◽  
Chromosomal Location ◽  
Thermal Dissociation ◽  
D Genome ◽  
Triticum Tauschii ◽  
Main Cluster ◽  
Chinese Spring Wheat ◽  
Close Phylogenetic Relationship ◽  
5S Dna

The 5S DNA sequences in Triticum tauschii are organised in large clusters containing units that are primarily either 420 ("short") or 490 base pairs (bp) in length ("long"). The main cluster of short units was shown to be located on chromosome 1D in hexaploid wheat and is designated 5SDna-Dl, while the cluster of long units was shown to be on chromosome 5D and is designated 5SDna-D2. The chromosomal locations in hexaploid wheat most likely correspond to those in T. tauschii and this could be shown directly for the 5SDna-D2 locus by using a T. tauschii 5D substitution in 'Chinese Spring' wheat. The sequence alignment of units derived from 5SDna-D1 and 5SDna-D2 revealed three apparent deletions in the noncoding spacer region, which were fixed in units from 5SDna-D1, and one deletion, which was fixed in units from 5SDna-D2. A minor size class, 400 bp long and closely related to the units from 5SDna-D1, was found in 2 of 415 accessions surveyed. A continuous range of quantitative changes in the number of 5S DNA units at the two loci was evident with up to a 10-fold relative abundance level of units being found in some accessions. Triticum tauschii var. typica was particularly noteworthy in that many accessions showed more units at 5SDna-D2 relative to 5SDna-D1. Partial thermal dissociation experiments with radioactive probes, synthesized from either the short or long 5S DNA units, hybridized to genomic DNA showed that the population of units at the respective loci were relatively homogeneous and clearly distinct from each other. In addition, these experiments further established the close phylogenetic relationship between T. tauschii and the D genome of wheat.Key words: Triticum tauschii, 5S DNA, sequence variation, chromosomal location.

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