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.

Characterization of genomes of timothy (Phleum pratense L.). I. Karyotypes and C-banding patterns in cultivated timothy and two wild relatives

Genome ◽  
1991 ◽  
Vol 34 (1) ◽  
pp. 52-58 ◽  
Author(s):  
Q. Cai ◽  
M. R. Bullen
Keyword(s):  
Phleum Pratense ◽  
Wild Relatives ◽  
Banding Patterns ◽  
C Banding ◽  
B Genome ◽  
A Genome ◽  
Cultivated Species ◽  
Genome Donors ◽  
Phleum Pratense L

In an attempt to know the phylogeny of timothy (Phleum pratense), the cultivated species and two wild relatives, Phleum alpinum and Phleum bertolonii, were karyotyped with conventional and Giemsa C-banding methods. In the hexaploid P. pratense (2n = 6x = 42), two sets of seven chromosomes were indistinguishable from each other both in morphology and in banding patterns and the third set of seven was found to be differentiated from them. Two genomes, A and B, were tentatively established. The banded karyotype in diploid P. alpinum (2n = 2x = 14) was close to the A genome, which was tetraploid in P. pratense, and the karyotype in P. bertolonii (2n = 2x = 14) was analogous to the B genome in P. pratense, which suggests these species were the genome donors of P. pratense.Key words: chromosome, genome, allopolyploid, Giemsa C-banding.

A TENTATIVE IDENTIFICATION OF CHROMOSOMES PRESENT IN TETRAPLOID TRITICALE BASED ON HETEROCHROMATIC BANDING PATTERNS

1978 ◽  
Vol 20 (2) ◽  
pp. 199-204 ◽  
Author(s):  
J. P. Gustafson ◽  
K. D. Krolow
Keyword(s):  
Secale Cereale ◽  
Banding Pattern ◽  
Triticum Turgidum ◽  
Staining Technique ◽  
Wheat Genome ◽  
Banding Patterns ◽  
Tentative Identification ◽  
C Banding ◽  
B Genome ◽  
Secale Cereale L

Three tetraploid triticales were analysed by C-banding techniques in order to establish their chromosome constitutions. All three tetraploid triticales contained seven rye chromosomes with the banding pattern of Secale cereale L. A mixture of A- and B-genome chromosomes from Triticum turgidum L. constituted the wheat genome present in the tetraploid triticales. Triticale Trc 4x3 contained 1A, 2B, 3A, 4A, 5B, 6A, and 7B. Triticale Trc 4x2 contained 1A, 2B, 3B, 4B, 5B, 6A, and 7B, while triticale Trc 4x5 contained 1A, 2B, 3B, 4A, 5A, 6A, and 7B. The reliability of the staining technique is subject to errors in identification, which are 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.

Identification of wheat and tritordeum chromosomes by genomic in situ hybridization using total Hordeum chilense DNA as probe

Genome ◽  
1999 ◽  
Vol 42 (6) ◽  
pp. 1194-1200 ◽  
Author(s):  
M J González ◽  
A Cabrera
Keyword(s):  
Triticum Aestivum ◽  
In Situ Hybridization ◽  
Hexaploid Wheat ◽  
Chromosome Complement ◽  
Dna Probe ◽  
Hordeum Chilense ◽  
B Genome ◽  
A Genome ◽  
The Individual

Total genomic Hordeum chilense DNA probe was hybridized to somatic chromosome spreads of Triticum aestivum 'Chinese Spring' and to four advanced tritordeum lines, the latter being the fertile amphiploid between H. chilense and durum wheat (2n = 6x = 42, AABBHchHch). The probe hybridized strongly to the B-genome chromosomes and to one or two bands on the A-genome chromosomes present in both wheat and tritordeum alloploids. Bands on chromosomes 1D, 2D, and 7D from hexaploid wheat were also detected. Genomic H. chilense DNA probe identified 16 chromosome pairs of the chromosome complement of hexaploid wheat and all A- and B-genome chromosomes present in the tritordeum amphiploids. The in situ hybridization patterns observed correspond to those previously reported in wheat by both N-banding and in situ hybridization with the GAA-satellite sequence (Pedersen and Langridge 1997), allowing the identification of these chromosomes. Variation among the tritordeum amphiploids for hybridization sites on chromosomes 2A, 4A, 6A, 7A, 4B, 5B, and 7B was observed. Despite of this polymorphism, all lines shared the general banding pattern. When used as probe, total H. chilense genomic DNA labeled the H. chilense chromosomes over their lengths allowing the identification of 14 H. chilense chromosomes present in the tritordeum amphiploids. In addition, chromosome-specific telomeric, interstial, and centromeric hybridization sites were observed. These hybridization sites coincide with N-banded regions in H. chilense allowing the identification of the individual H. chilense chromosomes in one of the amphiploid. The N-banded karyotypes of H. chilense (accessions H1 and H7) are presented.Key words: Hordeum chilense, Triticum aestivum, chromosome identification, in situ hybridization, N-banding.

The analysis of meiosis of the B genome in common wheat

1985 ◽  
Vol 27 (1) ◽  
pp. 17-22 ◽  
Author(s):  
N. Jouve ◽  
J. M. Gonzalez ◽  
A. Fominaya ◽  
E. Ferrer
Keyword(s):  
Triticum Aestivum ◽  
Common Wheat ◽  
Triticum Aestivum L ◽  
Genome Chromosome ◽  
Meiotic Analysis ◽  
C Banding ◽  
Meiotic Chromosomes ◽  
B Genome ◽  
Whole Genomes ◽  
Chromosome Arm

Two intervarietal hybrids of common wheat, Triticum aestivum L., are meiotically analyzed using the C-banding staining method. The C-banding pattern of nine meiotic chromosomes (4A, 7A, and the seven of the B genome) permitted their unequivocal recognition at first metaphase plates. The pairing frequency of each B-genome chromosome arm was scored. Data on the pairing frequency of the arms, separately considered, are applied to calculate expected pairing of whole chromosomes and whole genomes. The application of mathematical models to predict the genome pairing using either equal or different frequencies per chromosome arm is discussed.Key words: meiotic analysis, Triticum aestivum L., C-banding.

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.

Molecular evidence for Triticum speltoides as a B-genome progenitor of wheat (Triticum aestivum)

Genome ◽  
1996 ◽  
Vol 39 (3) ◽  
pp. 543-548 ◽  
Author(s):  
Hassan Mat Daud ◽  
J. P. Gustafson
Keyword(s):  
Southern Blot ◽  
Blot Hybridization ◽  
The Other ◽  
Molecular Evidence ◽  
Dot Blot ◽  
Specific Sequence ◽  
Polyploid Wheat ◽  
B Genome ◽  
Genome Donor ◽  
A Genome

In polyploid wheat, the origin of the B-genome donor has remained relatively unknown in spite of a number of investigations attempting to identify the parental species. A project was designed to isolate and clone a genome-specific DNA sequence from Triticum speltoides L. to determine if that species could be the B-genome donor. A cloning scheme involving the prescreening of 1-kb fragments followed by colony, dot blot, and Southern blot hybridization screenings was used to isolate a speltoides-specific sequence (pSp89.XI). The methods used allowed for rapid isolation of a genome-specific sequence when screened against total DNA from closely related species. Subsequent analyses showed that the sequence was barely detected in any of the other genomes of the annual Sitopsis section. The results of dot blot and Southern blot analyses established that (i) the sequence pSP89.XI, specific to T. speltoides relative to the other species of the Sitopsis section, was present in the genomes of tetraploid and hexaploid wheat, (ii) the relative abundance of pSp89.XI seemed to decrease from the diploid to the polyploid wheats, and (iii) the existence of a related, but modified B genome in polyploid wheat compared with that in modern T. speltoides was probable. Key words : genome-specific, DNA.

Analysis of karyotypes and Giemsa C-banding patterns in eight species of Arachis

Genome ◽  
1987 ◽  
Vol 29 (1) ◽  
pp. 187-194 ◽  
Author(s):  
Q. Cai ◽  
S. Lu ◽  
C. C. Chinnappa
Keyword(s):  
Close Relationships ◽  
Diploid Species ◽  
Chromosome Morphology ◽  
Tetraploid Species ◽  
Interspecific Relationship ◽  
Banding Patterns ◽  
C Banding ◽  
B Genome ◽  
A Genome ◽  
Structural Differences

The karyotypes and Giemsa C-banding patterns of the chromosomes in eight species of Arachis L. have been studied. Six species are diploid with 20 chromosomes and two are tetraploid with 40 chromosomes. One diploid species (A. rigonii Krap. et Greg.) belongs to the sect. Erectoides and the rest belong to the sect. Arachis. Among the diploid species from the sect. Arachis, A. batizocoi Krap. et Greg, has a unique karyotype while others have similar karyotypes. Two tetraploid species, A. monticola Krap. et Greg, and A. hypogaea L., possess the most similar karyotypes. However, the diploid species, A. rigonii, from sect. Erectoides, has a karyotype distinguishable from those in sect. Arachis. The C-banding patterns of the chromosomes have been obtained for all the species. The centromeric bands have been found in all the chromosomes and the intercalary bands can be identified in a varied number of chromosomes among these complements. However, the telomeric bands only exist in one or two chromosomes. The comparison of banding patterns demonstrated that structural differences exist among the chromosomal complements of the species with similar chromosome morphology. The karyotype variation among the different species and interspecific relationship are discussed. It is suggested that all the diploid species with the A genome are closely related. There are close relationships between the tetraploid species and diploid species with the A or B genome within sect. Arachis. Key words: Arachis, cytology, karyotypes, Giemsa C-banding.

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.

ORIGIN AND TAXONOMY OF WHEAT IN THE LIGHT OF RECENT RESEARCH

2000 ◽  
Vol 48 (3) ◽  
pp. 301-313 ◽  
Author(s):  
A. F. Bálint ◽  
G. Kovács ◽  
J. Sutka
Keyword(s):  
Triticum Aestivum ◽  
Common Wheat ◽  
Divergent Evolution ◽  
Tetraploid Species ◽  
D Genome ◽  
B Genome ◽  
A Genome ◽  
The World ◽  
Donor Species ◽  
Exact Origin

There is still disagreement among scientists on the exact origin of common wheat (Triticum aestivum ssp. aestivum), one of the most important crops in the world. The first step in the development of the hexaploid aestivum group (ABD) may have been hybridisation between T. urartu (A), as pollinator, and a species related to the Sitopsis section of the Aegilops genus (S) as cytoplasm donor, leading to the creation of the tetraploid species T. turgidum ssp. dicoccoides (AB). The following step may have involved hybridisation between T. turgidum ssp. dicoccon (AB genome, cytoplasm donor), a descendant of T. turgidum ssp. dicoccoides, and Ae. tauschii (D genome, pollinator), resulting in the hexaploid species T. aestivum ssp. spelta (ABD) or some other hulled type. This form may have given rise to naked types, including T. aestivum ssp. aestivum (ABD). The ancestors of the tetraploid T. timopheevii (AG) may have been the diploid T. urartu (A genome, pollinator) and Ae. speltoides (S genome, cytoplasm donor). Species in the timopheevii group developed later than those in the turgidum group, as confirmed by the fact that the G genome is practically identical to the S genome of Ae. speltoides, while the more ancient B genome has undergone divergent evolution. Hybridisation between T. timopheevii (AG, cytoplasm donor) and T. monococcum (A m, pollinator) may have resulted in the species T. zhukovskyi (AGA m). Research into the relationships between the various species is of assistance in compiling the taxonomy of wheat and in avoiding misunderstandings arising from the fact that some species are known by two or more synonymous names.

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