THE RELATIONSHIP BETWEEN THE GENOME OF TRITICUM URARTU AND THE A AND B GENOMES OF TRITICUM AESTIVUM

1976 ◽  
Vol 18 (2) ◽  
pp. 371-377 ◽  
Author(s):  
Jan Dvořák
Keyword(s):  
Triticum Aestivum ◽  
Chromosome Pairing ◽  
Chinese Spring ◽  
Triticum Urartu ◽  
B Genome ◽  
A Genome ◽  
The Relationship

Triticum urartu (2n = 14) was crossed with T. aestivum lines ditelosomic for chromosomes of the A and B genomes. Except for telosome 4Aα, the rest of the telosomes of the A genome paired in these hybrids while telosomes of the B genome did not pair. This indicates that T. urartu cannot be the donor of the B genome of 4x and 6x wheat, but carries an A genome. Compared to the rest of the hybrids, pairing of T. urartu chromosomes was significantly reduced in hybrids deficient for chromosome arms 5AS or 5BS. It is suggested that this reduction in chromosome pairing resulted from the absence of genes which promote homoelogous pairing and which are normally present on chromosome arms 5AS and 5BS in Chinese Spring.

GENETIC REGULATION OF HETEROGENETIC CHROMOSOME PAIRING IN POLYPLOID SPECIES OF THE GENUS TRITICUM sensu lato

1982 ◽  
Vol 24 (1) ◽  
pp. 57-82 ◽  
Author(s):  
Patrick E. McGuire ◽  
Jan Dvořák
Keyword(s):  
Triticum Aestivum ◽  
Chromosome Pairing ◽  
Chinese Spring ◽  
Genetic Regulation ◽  
Triticum Aestivum L ◽  
Polyploid Species ◽  
D Genome ◽  
Chromosome 5B ◽  
A Genome

Polyploid species of Triticum sensu lato were crossed with Triticum aestivum L. em. Thell. cv. Chinese Spring monotelodisomics or ditelosomics that were monosomic for chromosome 5B. Progeny from these crosses were either euploid, nullisomic for 5B, monotelosomic for a given Chinese Spring chromosome, or nullisomic for 5B and monotelosomic simultaneously. The Chinese Spring telosome in the hybrids permitted the evaluation of autosyndesis of chromosomes of the tested species. In addition, several Chinese Spring eu- and aneuhaploids were produced. Genotypes of T. cylindricum Ces., T. juvenale Thell., T. triunciale (L.) Raspail, T. ovatum (L.) Raspail, T. columnare (Zhuk.) Morris et Sears, T. triaristatum (Willd.) Godr. et Gren., and T. rectum (Zhuk.) comb. nov. were all shown to have suppressive effects on heterogenetic pairing in hybrids lacking 5B or 3AS, whereas T. kotschyi (Boiss.) Bowden had no effect. It was concluded that diploid-like meiosis in these species is due to genetic regulation. A number of these genotypes promoted heterogenetic pairing in the presence of 5B. A model is presented to explain this dichotomous behavior of the tested genotypes. Monotelosomic-3AL haploids had a greater amount of pairing than did euhaploid Chinese Spring, which substantiated the presence of a pairing suppressor(s) on the 3AS arm. Evidence is presented that shows that T. juvenale does not have a genome homologous with the D genome of T. aestivum.

THE CYTOGENETIC STRUCTURE OF A 56-CHROMOSOME DERIVATIVE FROM A CROSS BETWEEN TRITICUM AESTIVUM AND AGROPYRON ELONGATUM (2n = 70)

1976 ◽  
Vol 18 (2) ◽  
pp. 271-279 ◽  
Author(s):  
Jan Dvořák
Keyword(s):  
Triticum Aestivum ◽  
Chromosome Pairing ◽  
Chinese Spring ◽  
Wheat Chromosome ◽  
Agropyron Elongatum ◽  
Synthetic Genome ◽  
Chromosome Associations ◽  
Chromosome Segments ◽  
The Relationship ◽  
Chromosome 3B

Chromosome pairing was studied in a number of hybrids involving a 56-chromosome wheat-Agropyron derivative, PW 327. PW 327 originated from the cross, Triticum aestivum cv. Chinese Spring (Chinese Spring × A. elongatum, 2n = 70). In hybrids between PW 327 and T. aestivum a number of multivalent chromosome associations were formed at metaphase I. These multivalents result from interchanges which occurred among wheat chromosomes 1A, 1D, 2A, 2D, 4D and 6D of PW 327. One chromosome of the Agropyron chromosome set of PW 327 occasionally pairs with wheat chromosome 3B. The rest of the Agropyron chromosomes present in PW 327 do not pair with the chromosomes of T. aestivum. It is proposed that the set of Agropyron chromosomes present in PW 327 is not an intact genome of decaploid A. elongatum but rather a modified synthetic genome combining chromosomes and/or chromosome segments from different genomes of the Agropyron parent. The incorporation of duplication-deletions into synthetic genomes of natural polyploids is discussed and it is shown that the set of Agropyron chromosomes which is present in PW 327 carries at least one such duplication-deletion. Pairing between chromosomes of diploid and decaploid A. elongatum was studied in a 56-chromosome hybrid from a cross between an amphiploid, T. aestivum × A. elongatum (2n = 14), and PW 327. It appeared that at least four chromosomes of these two Agropyrons occasionally paired with each other in this hybrid in which the diploidizing system of wheat was active. The relationship between chromosomes of diploid and decaploid A. elongatum is discussed.

scholarly journals Equivalence of the A genome of bread wheat and that of Triticum urartu

1976 ◽  
Vol 27 (1) ◽  
pp. 69-76 ◽  
Author(s):  
Victor Chapman ◽  
T. E. Miller ◽  
Ralph Riley
Keyword(s):  
Triticum Aestivum ◽  
Hexaploid Wheat ◽  
Homoeologous Pairing ◽  
Triticum Urartu ◽  
B Genome ◽  
Chromosome 5B ◽  
A Genome ◽  
Telocentric Chromosomes ◽  
Mother Cells ◽  
Pairing Behaviour

SUMMARYLines of Triticum aestivum Chinese Spring (2n = 6x = 42) which were ditelocentric or doubly ditelocentric, in turn, for the 14 chromosomes of the A and B genomes were pollinated by Triticum urartu (2n = 14). The behaviour of the marked telocentric chromosomes was scored in the 14 distinct hybrids obtained from these pollinations. In 6 of the hybrids in which different A genome chromosomes were marked by telocentrics there were from 50 to 80% of the pollen mother cells in which the telocentrics were paired. In the seven hybrids in which different B genome chromosomes were marked the telocentrics were never paired. It was concluded that the genome of T. urartu matched very closely the A genome of hexaploid wheat and that it did not correspond, as had been proposed by Johnson, to the B genome. The pairing behaviour of the 14 T. aestivum × T. urartu hybrids was compared with earlier results obtained from hybrids between T. aestivum and T. boeoticum. It was proposed that the higher trivalent frequencies seen in the T. boeoticum hybrids could be due to homoeologous pairing and that the genotype of T. boeoticum has the capacity partly to suppress the activity of the Ph locus of chromosome 5B of wheat, as a result of which homoeologous pairing is normally prevented.

Biochemical data bearing on the relationship between the genome of Triticum urartu and the A and B genomes of the polyploid wheats

Genome ◽  
1988 ◽  
Vol 30 (4) ◽  
pp. 576-581 ◽  
Author(s):  
K. Kerby ◽  
J. Kuspira ◽  
B. L. Jones
Keyword(s):  
Amino Acid ◽  
Triticum Turgidum ◽  
Amino Acid Sequences ◽  
Triticum Monococcum ◽  
Triticum Urartu ◽  
B Genome ◽  
Genome Donor ◽  
A Genome ◽  
The Relationship ◽  
Donor Species

To determine whether the Triticum urartu genome is more closely related to the A or B genome of the polyploid wheats, the amino acid sequence of its purothionin was compared to the amino acid sequences of the purothionins in Triticum monococcum, Triticum turgidum, and Triticum aestivum. The residue sequence of the purothionin from T. urartu differs by five and six amino acid substitutions respectively from the α1 and α2 forms coded for by genes in the B and D genomes, and is identical to the β form specified by a gene in the A genome. Therefore, the T. urartu purothionin is either coded by a gene in the A genome or a chromosome set highly homologous to it. The results demonstrate that at least a portion of the T. urartu and T. monococcum genomes is homologous and probably identical. A variety of other studies have also shown that T. urartu is very closely related to T. monococcum and, in all likelihood, also possesses the A genome. Therefore, it could be argued that either T. urartu and T. monococcum are the same species or that T. urartu rather than T. monococcum is the source of the A genome in T. turgidum and T. aestivum. Except for Johnson's results, our data and that of others suggest a revised origin of polyploid wheats. Specifically, the list of six putative B genome donor species is reduced to five, all members of the Sitopsis section of the genus Aegilops.Key words: Triticum monococcum, Triticum urartu, polyploid wheats, genomes A and B, purothionins.

EFFECT OF THE REMOVAL OF GENES PROMOTING HOMOEOLOGOUS CHROMOSOME PAIRING ON CHROMOSOME PAIRING IN TRITICUM AESTIVUM × TRITICUM URARTU AMPHIPLOIDS

1978 ◽  
Vol 20 (4) ◽  
pp. 539-544 ◽  
Author(s):  
J. Dvořák
Keyword(s):  
Triticum Aestivum ◽  
Chromosome Pairing ◽  
Chinese Spring ◽  
Homoeologous Pairing ◽  
Homoeologous Chromosome ◽  
Triticum Urartu ◽  
The Poor ◽  
Homoeologous Chromosome Pairing ◽  
Chromosome Arm ◽  
Specific Strain

Chromosome pairing in Triticum aestivum cv. Chinese Spring × T. urartu hybrids lacking chromosome arm 5AS or 5BS was shown to be lower than in similar hybrids involving euploid Chinese Spring. Amphiploids were produced from crosses of Chinese Spring, ditelosomic 5AL, and ditelosomic 5BL with a specific strain of T. urartu. The absence of asynapsis in the amphiploids lacking chromosome arm 5AS or 5BS provides evidence that the poor chromosome pairing observed in the corresponding F1 hybrids was due to suppression of homoeologous pairing and not to general asynapsis. This conclusion is supported by the finding that heterogenetic chromosome pairing, as evidenced by the frequency of multivalents, was lower in the ditelo 5BL × T. urartu amphiploids than in the amphiploids from the cross Chinese Spring × T. urartu.

The phylogeny of the polyploid wheats Triticum aestivum (bread wheat) and Triticum turgidum (macaroni wheat)

Genome ◽  
1987 ◽  
Vol 29 (5) ◽  
pp. 722-737 ◽  
Author(s):  
K. Kerby ◽  
J. Kuspira
Keyword(s):  
Triticum Aestivum ◽  
Triticum Turgidum ◽  
Diploid Species ◽  
Triticum Monococcum ◽  
Aegilops Speltoides ◽  
Triticum Urartu ◽  
B Genome ◽  
Aegilops Longissima ◽  
A Genome ◽  
Genome Donors

The phylogeny of the polyploid wheats has been the subject of intense research and speculation during the past 70 years. Various experimental approaches have been employed to ascertain the diploid progenitors of these wheats. The species having donated the D genome to Triticum aestivum has been unequivocally identified as Aegilops squarrosa. On the basis of evidence from many studies, Triticum monococcum has been implicated as the source of the A genome in both Triticum turgidum and Triticum aestivum. However, numerous studies since 1968 have shown that Triticum urartu is very closely related to Triticum monococcum and that it also carries the A genome. These studies have prompted the speculation that Triticum urartu may be the donor of this chromosome set to the polyploid wheats. The donor of the B genome to Triticum turgidum and Triticum aestivum remains equivocal and controversial. Six different diploid species have been implicated as putative B genome donors: Aegilops bicornis, Aegilops longissima, Aegilops searsii, Aegilops sharonensis, Aegilops speltoides, and Triticum urartu. Until recently, evidence presented by different researchers had not permitted an unequivocal identification of the progenitor of the B genome in polyploid wheats. Recent studies, involving all diploid and polyploid wheats and putative B genome donors, lead to the conclusion that Aegilops speltoides and Triticum urartu can be excluded as B genome donors and that Aegilops searsii is the most likely source of this chromosome set. The possibility of the B genome having arisen from an AAAA autotetraploid or having a polyphyletic origin is discussed. Key words: phylogeny; Triticum aestivum; Triticum turgidum; A, B, and D genomes.

CHROMOSOME DIFFERENTIATION IN POLYPLOID SPECIES OF ELYTRIGIA, WITH SPECIAL REFERENCE TO THE EVOLUTION OF DIPLOID-LIKE CHROMOSOME PAIRING IN POLYPLOID SPECIES

1981 ◽  
Vol 23 (2) ◽  
pp. 287-303 ◽  
Author(s):  
J. Dvořák
Keyword(s):  
Triticum Aestivum ◽  
Special Reference ◽  
Normal Level ◽  
Chromosome Pairing ◽  
Chinese Spring ◽  
Triticum Aestivum L ◽  
Polyploid Species ◽  
Chromosome Differentiation

Triticum aestivum L. em Thell ditelosomics 7AL and 7DS and T. aestivum-Elytrigia elongata (Host) Holub (2n = 2x = 14) ditelosomic additions were crossed with "E. elongata 4x" (2n = 4x = 28), E. caespitosa (C. Koch) Nevski (2n = 4x = 28), and E. intermedia (Host) Nevski (2n = 6x = 42). The effect of each Elytrigia genotype on homoeologous (heterogenetic) chromosome pairing was assessed by comparing the pairing frequencies of T. aestivum cv. Chinese Spring telosomes 7AL and 7DS in the hybrids with the pairing frequency of telosome 7AL in haploid Chinese Spring. The genotype of "E. elongata 4x" had no effect on heterogenetic pairing in the hybrids. Although some genotypes of E. caespitosa and E. intermedia promoted heterogenetic pairing in the hybrids, others had no effect. Telosome VS of E. elongata interacted in a complementary fashion with the genotype of "E. elongata 4x," but not with the genotypes of Chinese Spring and E. caespitosa, and it promoted heterogenetic pairing. In hybrids in which the wheat diploidizing genes were active at the normal level, the E. elongata telosomes paired with chromosomes of "E. elongata 4x" in 5.8% to 24.6% of the cells, with chromosomes of E. caespitosa in 0.0% to 1.0% of the cells, and with chromosomes of E. intermedia in 0.0% to 2.8% of the cells. A model of chromosome differentiation is discussed and special attention is devoted to the origin of diploid-like pairing in polyploid species.

EFFECT OF RYE ON HOMOEOLOGOUS CHROMOSOME PAIRING IN WHEAT × RYE HYBRIDS

1977 ◽  
Vol 19 (3) ◽  
pp. 549-556 ◽  
Author(s):  
J. Dvořák
Keyword(s):  
Triticum Aestivum ◽  
Chromosome Pairing ◽  
Chinese Spring ◽  
Triticum Aestivum L ◽  
Homoeologous Chromosome ◽  
Wheat Genotype ◽  
Hybrid Plants ◽  
Homoeologous Chromosome Pairing ◽  
Secale Cereale L ◽  
Polygenic System

The number of chiasmata per cell at metaphase I was scored in eight haploid plants of Triticum aestivum L. emend. Thell. cv. 'Chinese Spring' and 100 hybrid plants of Chinese Spring × Secale cereale L. Mean chiasma frequency per cell ranged from 0.00 to 3.59 in the hybrids and from 0.17 to 0.35 in the haploids. Since the same wheat genotype was present in both the haploids and hybrids, it is concluded that some of the rye genotypes promoted homoeologous chromosome pairing. The absence of distinct segregation classes among the hybrids suggests that these genes constitute a polygenic system.

The origin of wheat chromosomes 4A and 4B and their genome reallocation

1983 ◽  
Vol 25 (3) ◽  
pp. 210-214 ◽  
Author(s):  
J. Dvořák
Keyword(s):  
Triticum Aestivum ◽  
Banding Pattern ◽  
The Other ◽  
Evolutionary Lineage ◽  
C Banding ◽  
B Genome ◽  
A Genome

Triticum aestivum chromosome "4A" is, like the B genome chromosomes, extensively heterochromatic while the remaining six A genome chromosomes are not. In the presence of the Ph gene it does not pair with any chromosome of einkorn wheats, T. monococcum and T. urartu, the source of the A genome. It is shown here that the same chromosome is also present in T. timopheevii which represents the other evolutionary lineage of wheats. The "4A" chromosomes of T. timopheevii and T. aestivum pair poorly with each other, like the B genome chromosomes of the two lineages, while the remaining A genome chromosomes, except for one arm, pair relatively well. Hence, in both lineages chromosome "4A" has the attributes of the B genome chromosomes, not of the A genome chromosomes. The C-banding pattern of chromosome "4A" of T. aestivum and T. timopheevii closely resembles the C-banding pattern of a chromosome of T. speltoides and less closely chromosome 4B1 of T. sharonense. On the basis of this and other evidence it is concluded that this chromosome was contributed by a species of the section Sitopsis and, consequently, belongs to the B genome. Additionally, there is evidence that the chromosome that was originally designated "4B" belongs to the A genome.

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