Structural and functional analyses of the wheat genomes based on expressed sequence tags (ESTs) related to abiotic stresses

Genome ◽  
2006 ◽  
Vol 49 (10) ◽  
pp. 1324-1340 ◽  
Author(s):  
J. Ramalingam ◽  
M.S. Pathan ◽  
O. Feril ◽  
Miftahudin ◽  
K. Ross ◽  
...  
Keyword(s):  
Abiotic Stress ◽  
Oryza Sativa L ◽  
Triticum Aestivum L ◽  
Binding Activity ◽  
Homoeologous Chromosome ◽  
D Genome ◽  
B Genome ◽  
Group 4 ◽  
Group 2 ◽  
And Function

To gain insights into the structure and function of the wheat (Triticum aestivum L.) genomes, we identified 278 ESTs related to abiotic stress (cold, heat, drought, salinity, and aluminum) from 7671 ESTs previously mapped to wheat chromosomes. Of the 278 abiotic stress related ESTs, 259 (811 loci) were assigned to chromosome deletion bins and analyzed for their distribution pattern among the 7 homoeologous chromosome groups. Distribution of abiotic stress related EST loci were not uniform throughout the different regions of the chromosomes of the 3 wheat genomes. Both the short and long arms of group 4 chromosomes showed a higher number of loci in their distal regions compared with proximal regions. Of the 811 loci, the number of mapped loci on the A, B, and D genomes were 258, 281, and 272, respectively. The highest number of abiotic stress related loci were found in homoeologous chromosome group 2 (142 loci) and the lowest number were found in group 6 (94 loci). When considering the genome-specific ESTs, the B genome showed the highest number of unique ESTs (7 loci), while none were found in the D genome. Similarly, considering homoeologous group-specific ESTs, group 2 showed the highest number with 16 unique ESTs (58 loci), followed by group 4 with 9 unique ESTs (33 loci). Many of the classified proteins fell into the biological process categories associated with metabolism, cell growth, and cell maintenance. Most of the mapped ESTs fell into the category of enzyme activity (28%), followed by binding activity (27%). Enzymes related to abiotic stress such as β-galactosidase, peroxidase, glutathione reductase, and trehalose-6-phosphate synthase were identified. The comparison of stress-responsive ESTs with genomic sequences of rice (Oryza sativa L.) chromosomes revealed the complexities of colinearity. This bin map provides insight into the structural and functional details of wheat genomic regions in relation to abiotic stress.

scholarly journals A Microsatellite Map of Wheat

Genetics ◽  
1998 ◽  
Vol 149 (4) ◽  
pp. 2007-2023 ◽  
Author(s):  
Marion S Röder ◽  
Victor Korzun ◽  
Katja Wendehake ◽  
Jens Plaschke ◽  
Marie-Hélène Tixier ◽  
...  
Keyword(s):  
Bread Wheat ◽  
Reference Population ◽  
Triticum Aestivum L ◽  
Wheat Genome ◽  
D Genome ◽  
B Genome ◽  
Microsatellite Map ◽  
A Genome ◽  
Polymorphic Microsatellite ◽  
Primer Sets

Abstract Hexaploid bread wheat (Triticum aestivum L. em. Thell) is one of the world's most important crop plants and displays a very low level of intraspecific polymorphism. We report the development of highly polymorphic microsatellite markers using procedures optimized for the large wheat genome. The isolation of microsatellite-containing clones from hypomethylated regions of the wheat genome increased the proportion of useful markers almost twofold. The majority (80%) of primer sets developed are genome-specific and detect only a single locus in one of the three genomes of bread wheat (A, B, or D). Only 20% of the markers detect more than one locus. A total of 279 loci amplified by 230 primer sets were placed onto a genetic framework map composed of RFLPs previously mapped in the reference population of the International Triticeae Mapping Initiative (ITMI) Opata 85 × W7984. Sixty-five microsatellites were mapped at a LOD >2.5, and 214 microsatellites were assigned to the most likely intervals. Ninety-three loci were mapped to the A genome, 115 to the B genome, and 71 to the D genome. The markers are randomly distributed along the linkage map, with clustering in several centromeric regions.

The genomic inheritance of aluminum tolerance in 'Atlas 66' wheat

Genome ◽  
1992 ◽  
Vol 35 (4) ◽  
pp. 689-693 ◽  
Author(s):  
William A. Berzonsky
Keyword(s):  
Root Growth ◽  
Aluminum Tolerance ◽  
Triticum Aestivum L ◽  
Nuclear Genes ◽  
D Genome ◽  
Hard Red Spring Wheat ◽  
Al Stress ◽  
Soft Red Winter Wheat ◽  
B Genome ◽  
Segregation Ratios

Toxicity to aluminum (Al) limits wheat (Triticum aestivum L. em. Thell.) yields. 'Atlas 66', a soft red winter wheat classified as tolerant (root growth ≥ 0.5 cm after Al stress) to 0.44 mM Al, was hybridized with tetraploid (4x) and hexaploid (6x) 'Canthatch', a hard red spring wheat classified as sensitive (root growth < 0.5 cm after Al stress) to 0.44 mM Al. Progenies produced from these hybridizations were tested for tolerance to 0.44 mM Al in solution to ascertain the number of genes and the genomes of 'Atlas 66', which determine tolerance to aluminum. Tests of 'Atlas 66', 6x-'Canthatch', and the F1's resulting from hybridizations between the parents indicated that dominant, nuclear genes carried by 'Atlas 66' determine tolerance to 0.44 mM Al. Segregation ratios for the F2 significantly differed from ratios expected for a dominant, duplicate genetic mechanism. F1 backcross segregation ratios did not significantly differ from ratios expected for dominant, duplicate nuclear genes for tolerance to aluminum. The expression of genes for tolerance to 0.44 mM Al for 'Atlas 66' appears to be more complex than is predicted by the existence of two dominant genes. A crossing scheme, which involved hybridizing 4x-'Canthatch' with 'Atlas 66', was executed to produce 42-chromosome plants having recombinant A- and B-genome chromosomes and D-genome chromosomes derived exclusively from 'Atlas 66'. Eleven F6 and F7 lines, developed from these plants, were selfed and plants in the F6 generation were backcrossed to 'Atlas 66' and 6x-'Canthatch'. The F6 and F7 lines were subjected to 0.44 mM Al in solution as were the backcrosses. While none of the lines had more than 50% of their seedlings classified as sensitive to Al in the F6 generation, four lines exhibited such a response in the F7 generation. In general, backcrossing the F6 lines to 6x-'Canthatch' increased sensitivity to Al, while backcrossing to 'Atlas 66' increased tolerance. Results suggest that genes for tolerance to Al in 'Atlas 66' wheat are not all located on D-genome chromosomes.Key words: aluminum tolerance, genomic inheritance, Triticum.

Tapetal development and abiotic stress: a centre of vulnerability

2012 ◽  
Vol 39 (7) ◽  
pp. 553 ◽  
Author(s):  
Roger W. Parish ◽  
Huy A. Phan ◽  
Sylvana Iacuone ◽  
Song F. Li
Keyword(s):  
Cell Wall ◽  
Abiotic Stress ◽  
Oryza Sativa L ◽  
Triticum Aestivum L ◽  
Pollen Abortion ◽  
Cell Wall Invertase ◽  
Developmental Program ◽  
Specific Effects ◽  
Hexose Sugars ◽  
Microspore Stage

Many self-fertilising crops are particularly sensitive to abiotic stress at the reproductive stage. In rice (Oryza sativa L.) and wheat (Triticum aestivum L.), for example, abiotic stress during meiosis and the young microspore stage indicates the tapetum is highly vulnerable and that the developmental program appears to be compromised. Tapetal hypertrophy can occur as a consequence of cold and drought stress, and programmed cell death (PCD) is delayed or inhibited. Since the correct timing of tapetal PCD is essential for pollen reproduction, substantial losses in grain yield occur. In wheat and rice, a decrease in tapetal cell wall invertase levels is correlated with pollen abortion and results in the amount of hexose sugars reaching the tapetum, and subsequently the developing microspores, being severely reduced (‘starvation hypothesis’). ABA and gibberellin levels may be modified by cold and drought, influencing levels of cell wall invertase(s) and the tapetal developmental program, respectively. Many genes regulating tapetal and microspore development have been identified in Arabidopsis thaliana (L.) Heynh. and rice and the specific effects of abiotic stresses on the program and pathways can now begin to be assessed.

CYTOLOGY AND FERTILITY OF PENTAPLOID WHEAT HYBRIDS WITH INDUCED PAIRING BETWEEN HOMOEOLOGOUS CHROMOSOMES

1982 ◽  
Vol 24 (4) ◽  
pp. 397-408 ◽  
Author(s):  
U. Kushnir ◽  
G. M. Halloran
Keyword(s):  
Chromosome Pairing ◽  
Hexaploid Wheat ◽  
Triticum Turgidum ◽  
Triticum Aestivum L ◽  
The Other ◽  
Homoeologous Chromosome ◽  
D Genome ◽  
Homoeologous Chromosome Pairing ◽  
Wheat Hybrids ◽  
Homoeologous Chromosomes

Two mutants, each promoting homoeologous chromosome pairing in hexaploid wheat (Triticum × aestivum L. emend gr. aestivum), in the cultivar Chinese Spring, ph1b at the Ph locus on chromosome 5BL and the other, ph2, on chromosome 3DS, were compared for their influence on chromosome pairing and fertility in pentaploid hybrids with Triticum turgidum L. emend var. dicoccoides (Korn. in litt. in Schweinf.). The mutants induced increased multivalent frequency over the normal pentaploid. Lower univalent frequencies in the ph2-pentaploid, compared with the normal pentaploid, indicated that D-genome chromosomes of the former were substantially involved in homoeologous pairing. Certain differences in other meiotic processes and fertility among the pentaploids may reflect differences in the activity of the pairing genes. There appeared to be a higher level of univalent elimination in pollen and egg cells in the ph2-, compared with the ph1b-pentaploid. Tetrad formation was close to normal in the ph2- pentaploid but exhibited high levels of abnormality (monads, dyads, triads and apolar tetrads) in the ph1b-pentaploid. Fertility levels in crosses of the pentaploids with hexaploid wheat, while low, were much lower for the ph1b-, compared with the ph2-pentaploid.

Complex genome rearrangements reveal evolutionary dynamics of pericentromeric regions in the Triticeae

Genome ◽  
2006 ◽  
Vol 49 (12) ◽  
pp. 1628-1639 ◽  
Author(s):  
Lili Qi ◽  
Bend Friebe ◽  
Bikram S. Gill
Keyword(s):  
Triticum Aestivum ◽  
Hexaploid Wheat ◽  
Evolutionary Dynamics ◽  
Triticum Aestivum L ◽  
Genome Rearrangements ◽  
Aegilops Speltoides ◽  
Agropyron Elongatum ◽  
B Genome ◽  
Group 4 ◽  
Pericentric Inversions

Most pericentromeric regions of eukaryotic chromosomes are heterochromatic and are the most rapidly evolving regions of complex genomes. The closely related genomes within hexaploid wheat ( Triticum aestivum L., 2n = 6x = 42, AABBDD), as well as in the related Triticeae taxa, share large conserved chromosome segments and provide a good model for the study of the evolution of pericentromeric regions. Here we report on the comparative analysis of pericentric inversions in the Triticeae, including Triticum aestivum, Aegilops speltoides , Ae. longissima, Ae. searsii, Hordeum vulgare , Secale cereale , and Agropyron elongatum . Previously, 4 pericentric inversions were identified in the hexaploid wheat cultivar ‘Chinese Spring’ (‘CS’) involving chromosomes 2B, 4A, 4B, and 5A. In the present study, 2 additional pericentric inversions were detected in chromosomes 3B and 6B of ‘CS’ wheat. Only the 3B inversion pre-existed in chromosome 3S, 3Sl, and 3Ss of Aegilops species of the Sitopsis section, the remaining inversions occurring after wheat polyploidization. The translocation T2BS/6BS previously reported in ‘CS’ was detected in the hexaploid variety ‘Wichita’ but not in other species of the Triticeae. It appears that the B genome is more prone to genome rearrangements than are the A and D genomes. Five different pericentric inversions were detected in rye chromosomes 3R and 4R, 4Sl of Ae. longissima, 4H of barley, and 6E of Ag. elongatum. This indicates that pericentric regions in the Triticeae, especially those of group 4 chromosomes, are undergoing rapid and recurrent rearrangements.

scholarly journals Novel fluorescent sequence-related amplified polymorphism(FSRAP) markers for the construction of a genetic linkage map of wheat(Triticum aestivum L.)

Genetika ◽  
2017 ◽  
Vol 49 (3) ◽  
pp. 1081-1093 ◽  
Author(s):  
Lingbo Zhao ◽  
Zhang Li ◽  
Jipeng Qu ◽  
Yan Yu ◽  
Lu Lu ◽  
...  
Keyword(s):  
Genetic Linkage Map ◽  
Average Distance ◽  
Triticum Aestivum L ◽  
Genetic Maps ◽  
The Novel ◽  
Linkage Groups ◽  
D Genome ◽  
Wheat Varieties ◽  
B Genome ◽  
A Genome

Novel fluorescent sequence-related amplified polymorphism (FSRAP) markers were developed based on the SRAP molecular marker. Then, the FSRAP markers were used to construct the genetic map of a wheat (Triticum aestivumL.) recombinant inbred line population derived from a Chuanmai 42?Chuannong 16 cross. Reproducibility and polymorphism tests indicated that the FSRAP markers have repeatability and better reflect the polymorphism of wheat varieties compared with SRAP markers. A total of 430 polymorphic loci between Chuanmai 42 and Chuannong 16 were detected with 189 FSRAP primer combinations. A total of 281 FSARP markers and 39 SSR markers re classified into 20 linkage groups. The maps spanned a total length of 2499.3cM with an average distance of 7.81cM between markers. A total of 201 markers were mapped on the B genome and covered a distance of 1013cM. On the A genome, 84 markers were mapped and covered a distance of 849.6cM. On the D genome, however, only 35 markers were mapped and covered a distance of 636.7cM. No FSRAP markers were distributed on the 7D chromosome. The results of the present study revealed that the novel FSRAP markers can be used to generate dense, uniform genetic maps of wheat.

Hypervariation associated with a 12-nucleotide direct repeat and inferences on intergenomic homogenization of ribosomal RNA gene spacers based on the DNA sequence of a clone from the wheat Nor-D3 locus

Genome ◽  
1987 ◽  
Vol 29 (5) ◽  
pp. 770-781 ◽  
Author(s):  
Michael Lassner ◽  
Olin Anderson ◽  
Jan Dvořák
Keyword(s):  
Dna Sequence ◽  
Ribosomal Rna ◽  
Consensus Sequence ◽  
Direct Repeat ◽  
Triticum Aestivum L ◽  
Sequence Information ◽  
D Genome ◽  
Ribosomal Rna Gene ◽  
Nontranscribed Spacer ◽  
B Genome

A ribosomal RNA gene (rDNA) unit from the Nor-D3 locus (D genome) of Triticum aestivum L. was cloned and the "nontranscribed spacer" (NTS) was sequenced. The DNA sequence was compared with previously reported Nor-B2 locus (B genome) NTS sequences to study the molecular basis of evolution of these repeated genes and to look for evidence of homogenization between B- and D-genome rDNA. The NTS has seven subrepeats with a modal repeat length of 120 nucleotides; the subrepeats are shorter than Nor-B2 subrepeats owing to loss of one element of a 12-bp duplication present in Nor-B2 subrepeats. This 12 nucleotide sequence or its permutation, whose consensus sequence is CACGTACACGGA, is found at all sites where the B- and D-genome rDNA spacers differ by insertions or deletions longer than two nucleotides. The DNA sequence information was used to identify restriction sites unique to each locus that could be used in search of conversions between the B- and D-genome rDNA loci. Despite the coexistence of rDNA of the B- and D-genomes in the same nucleus for a minimum of 8000 years, no evidence for frequent interchromosomal conversion events between chromosomes 1B or 6B and 5D was found. Key words: Triticum, rDNA, concerted evolution, spacer.

Molecular mapping of wheat. Homoeologous group 2

Genome ◽  
1995 ◽  
Vol 38 (3) ◽  
pp. 516-524 ◽  
Author(s):  
James C. Nelson ◽  
Allen E. Van Deynze ◽  
Mark E. Sorrells ◽  
Enrique Autrique ◽  
Yun Hai Lu ◽  
...  
Keyword(s):  
Bread Wheat ◽  
Molecular Mapping ◽  
Triticum Aestivum L ◽  
Homoeologous Group ◽  
Hordeum Vulgare L ◽  
Crop Species ◽  
D Genome ◽  
Wheat Group ◽  
Group 2 ◽  
Stem Rust Resistance Genes

A molecular-marker map of bread wheat having many markers in common with other grasses in the Gramineae family is a prerequisite for molecular level genetic studies and breeding in this crop species. We have constructed restriction fragment length polymorphism maps of the A-, B-, and D-genome chromosomes of homoeologous group 2 of hexaploid wheat (Triticum aestivum L. em. Thell) using 114 F7 lines from a synthetic × bread wheat cross and clones from 11 libraries. Chromosomes 2A, 2B, and 2D comprise 57, 60, and 56 markers and each spans about 200 cM. Comparisons between chromosomes are facilitated by 26 sets of homoeoloci. Genes mapped include a heterologous abscisic acid responsive locus cloned as pBS128, the epidermal waxiness inhibitor W21, and two presumed leaf rust and stem rust resistance genes. Anomalies suggesting ancestral rearrangements in chromosome 2B are pointed out and features of wheat group 2 chromosomes that are common to barley (Hordeum vulgare L.), rice (Oryza spp.), and T. tauschii are discussed.Key words: RFLP, wheat, waxy, rust.

SOME CHARACTERISTICS OF HEXAPLOID TRITICALE SUBSTITUTION LINES INVOLVING THE A-, B-, AND D-GENOME CHROMOSOMES OF WHEAT

1981 ◽  
Vol 23 (4) ◽  
pp. 679-689 ◽  
Author(s):  
E. N. Larter ◽  
K. Noda
Keyword(s):  
Polyacrylamide Gel Electrophoresis ◽  
Triticum Aestivum L ◽  
Low Fertility ◽  
Specific Chromosome ◽  
Substitution Lines ◽  
D Genome ◽  
Seed Supply ◽  
B Genome ◽  
A Genome ◽  
Definitive Method

Three hexaploid (2n = 6x = 42) triticale lines (× Triticosecale Wittmack) were synthesized in which a specific chromosome of either the A or B genomes was replaced by a homoelogous chromosome of the D genome of wheat (Triticum aestivum L. em Thell.). Two of the substitutions involved the B genome [substitution lines 1D(1B)R-4 and 6D (6B)R-5] and the third involved the A genome [4D(4A)R-1]. Polyacrylamide gel electrophoresis of gliadin proteins produced distinct differences in banding patterns between the three substitutions and provided a definitive method for the identification of specific chromosome substitutions in triticale. Plant and spike characteristics of the substitution triticales were similar to those of the control (unsubstituted) triticale. Substitution 6D(6B)R-5 exhibited extremely low fertility and was difficult to maintain. The substitution 4D(4A), on the other hand, appeared to have no effect on fertility, while substitution 1D(1B) reduced fertility by almost one-half of that of the control triticale. Chromosome pairing in substitution 4D(4A)R-1 was regular whereas 1D(1B)R-4 exhibited an average of five univalents/cell at MI. Limited seed supply prevented a meiotic study of 6D(6B)R-5. Flour proteins of the three substitution triticales ranged from 15.8% for 4D(4A)R-1 to 18.0% for 6D(6B)R-5. A comparison of the three substitutions for amino acid composition indicated that line 6D(6B)R-5 was 25% higher in methionine than the control, while in substitution 4D(4A)R-1 methionine content was reduced by 53%.

Genomic Instability in Wheat Induced by Chromosome 6b(s) of Triticum Speltoides.

Genetics ◽  
1988 ◽  
Vol 120 (4) ◽  
pp. 1085-1094
Author(s):  
R S Kota ◽  
J Dvorak
Keyword(s):  
Chinese Spring ◽  
Wheat Chromosome ◽  
Triticum Aestivum L ◽  
Chromosome Rearrangements ◽  
D Genome ◽  
Dicentric Chromosomes ◽  
B Genome ◽  
Ring Chromosomes ◽  
Chinese Spring Wheat ◽  
A Genome

Abstract A massive restructuring of chromosomes was observed during the production of a substitution of chromosome 6B(s) from Triticum speltoides (Tausch) Gren. ex Richter for chromosome 6B of Chinese Spring wheat (Triticum aestivum L.). Deletions, translocations, ring chromosomes, dicentric chromosomes and a paracentric inversion were observed. Chromosome rearrangements occurred in both euchromatic and heterochromatic regions. Chromosome rearrangements were not observed either in the amphiploid between Chinese Spring and T. speltoides or in Chinese Spring. No chromosome rearrangements were observed in the backcross derivatives; however, after self-pollination of a monosomic substitution (2n = 41) of chromosome 6B(s) for wheat chromosome 6B, 49 of the 138 plants carried chromosome aberrations. Chromosome rearrangements were observed in both wheat and T. speltoides chromosomes. The frequency of chromosome rearrangements was high among the B-genome chromosomes, moderate among the A-genome chromosomes, and low among the D-genome chromosomes. In the B genome, the rearrangements were nonrandom, occurring most frequently in chromosomes 1B and 5B. Chromosome rearrangements were also frequent for the 6B(s) chromosome of T. speltoides. An intriguing aspect of these observations is that they indicate that wheat genomes can be subject to uneven rates of structural chromosome differentiation in spite of being in the same nucleus.

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