Molecular evidence for the origin and evolution of chromosome 4A in polyploidy wheats

1985 ◽  
Vol 27 (2) ◽  
pp. 246-250 ◽  
Author(s):  
A. Lane Rayburn ◽  
B. S. Gill

The chromosomes of polyploid Triticum species and the putative donor diploid species were analyzed by in situ hybridization with a repeated DNA sequence clone pSc 119 isolated from rye and also found in wheat. In Triticum aestivum cv. Chinese Spring, chromosome 4A showed one terminal site in the short arm and one terminal and two interstitial sites of hybridization in the long arm. Triticum turgidum contained a 4A chromosome identical to 'Chinese Spring' with respect to hybridization sites. Chromosome 4A of the timopheevi wheats differed from 4A of 'Chinese Spring' in that the site of the sequence on the short arm was subterminal rather than terminal. Of the A-, B-, and D-genome progenitor species, only potential B-genome donors Aegilops speltoides and Aegilops sharonensis each showed a chromosome with hybridization sites similar to 4A. This suggested that 4A belongs to the B genome. Moreover, with regard to this sequence, chromosome 4A has undergone only minor changes during the evolution of the polyploid wheats.Key words: wheat evolution, in situ hybridization, biotin labeling.

Genetics ◽  
2003 ◽  
Vol 164 (2) ◽  
pp. 665-672 ◽  
Author(s):  
Zhi-Jun Cheng ◽  
Minoru Murata

AbstractFrom a wild diploid species that is a relative of wheat, Aegilops speltoides, a 301-bp repeat containing 16 copies of a CAA microsatellite was isolated. Southern blot and fluorescence in situ hybridization revealed that ∼250 bp of the sequence is tandemly arrayed at the centromere regions of A- and B-genome chromosomes of common wheat and rye chromosomes. Although the DNA sequence of this 250-bp repeat showed no notable homology in the databases, the flanking or intervening sequences between the repeats showed high homologies (>82%) to two separate sequences of the gag gene and its upstream region in cereba, a Ty3/gypsy-like retroelement of Hordeum vulgare. Since the amino acid sequence deduced from the 250 bp with seven CAAs showed some similarity (∼53%) to that of the gag gene, we concluded that the 250-bp repeats had also originated from the cereba-like retroelements in diploid wheat such as Ae. speltoides and had formed tandem arrays, whereas the 300-bp repeats were dispersed as a part of cereba-like retroelements. This suggests that some tandem repeats localized at the centromeric regions of cereals and other plant species originated from parts of retrotransposons.


Genome ◽  
1993 ◽  
Vol 36 (3) ◽  
pp. 489-494 ◽  
Author(s):  
Yasuhiko Mukai ◽  
Yumiko Nakahara ◽  
Maki Yamamoto

Common wheat, Triticum aestivum, is an allohexaploid species consisting of three different genomes (A, B, and D). The three genomes were simultaneously discriminated with different colors. Biotinylated total genomic DNA of the diploid A genome progenitor Triticum urartu, digoxigenin-labeled total genomic DNA of the diploid D genome progenitor Aegilops squarrosa, and nonlabeled total genomic DNA of one of the possible B genome progenitors Ae. speltoides were hybridized in situ to metaphase chromosome spreads of Triticum aestivum cv. Chinese Spring. For detection, only two fluorochromes, fluorescein and rhodamine, were used. The A, B, and D genomes were simultaneously detected by their yellow, brown, and orange fluorescence, respectively. The genomic fluorescence in situ hybridization pattern of chromosome 4A of cv. Chinese Spring wheat showed that the distal 32% of the long arm was derived from a B genome chromosome. Furthermore, by using two highly repeated sequence probes, pSc 119.2 and pAsl, and two fluorochromes simultaneously, we were able to identify all B and D genome chromosomes and chromosomes 1A, 4A, and 5A of wheat.Key words: common wheat, in situ hybridization, multicolor fluorescence.


Genome ◽  
1999 ◽  
Vol 42 (4) ◽  
pp. 706-713 ◽  
Author(s):  
Concha Linares ◽  
Antonio Serna ◽  
Araceli Fominaya

A repetitive sequence, pAs17, was isolated from Avena strigosa (As genome) and characterized. The insert was 646 bp in length and showed 54% AT content. Databank searches revealed its high homology to the long terminal repeat (LTR) sequences of the specific family of Ty1-copia retrotransposons represented by WIS2-1A and Bare. It was also found to be 70% identical to the LTR domain of the WIS2-1A retroelement of wheat and 67% identical to the Bare-1 retroelement of barley. Southern hybridizations of pAs17 to diploid (A or C genomes), tetraploid (AC genomes), and hexaploid (ACD genomes) oat species revealed that it was absent in the C diploid species. Slot-blot analysis suggested that both diploid and tetraploid oat species contained 1.3 × 104 copies, indicating that they are a component of the A-genome chromosomes. The hexaploid species contained 2.4 × 104 copies, indicating that they are a component of both A- and D-genome chromosomes. This was confirmed by fluorescent in situ hybridization analyses using pAs17, two ribosomal sequences, and a C-genome specific sequence as probes. Further, the chromosomes involved in three C-A and three C-D intergenomic translocations in Avena murphyi (AC genomes) and Avena sativa cv. Extra Klock (ACD genomes), respectively, were identified. Based on its physical distribution and Southern hybridization patterns, a parental retrotransposon represented by pAs17 appears to have been active at least once during the evolution of the A genome in species of the Avena genus.Key words: chromosomal organization, in situ hybridization, intergenomic translocations, LTR sequence, oats.


Genome ◽  
1990 ◽  
Vol 33 (1) ◽  
pp. 30-39 ◽  
Author(s):  
J. Dvořák ◽  
P. Resta ◽  
R. S. Kota

The genome allocation of the Triticum aestivum L. chromosomes denoted 4A and 4B was based on an erroneous inference. Since neither chromosome pairs with the chromosomes of putative ancestors of wheat, molecular tools were employed to clarify the origin of the two chromosomes. Disomic substitutions for T. aestivum chromosomes 4A or 4B by chromosomes 4 from T. speltoides (Tausch) Gren., a putative ancestor of the wheat B genome, T. longissimum (Schweinf. et Muschl.) Bowden (a close relative of T. speltoides), or T. monococcum L. ssp. aegilopoides (Link) Thell., a close relative of the ancestor of the wheat A genome, were produced. The ability of the substituted chromosome to compensate in the disomic substitution lines, the C-banding patterns of the chromosomes, electrophoretic alleles at the Adh-1 and Lpx-1 loci, and in situ hybridization with an interspersed repeated sequence all were consistent in showing that the chromosome previously denoted as 4A belongs to the B genome and the chromosome previously denoted as 4B is a rearranged chromosome of the A genome. Chromosome 4A is consequently reallocated to the B genome and chromosome 4B to the A genome in T. turgidum L. em. Morris et Sears and T. aestivum. To reflect the fact that the chromosome previously denoted as 4B has only a homoeologous relationship to chromosome 4A of T. urartu (the ancestor of the A genome in polyploid wheats), the chromosome is designated 4Aa.Key words: repeated nucleotide sequence, alcohol dehydrogenase, lipoxygenase, in situ hybridization, chromosome evolution.


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Liuyang Fu ◽  
Qian Wang ◽  
Lina Li ◽  
Tao Lang ◽  
Junjia Guo ◽  
...  

Abstract Background Chromosomal variants play important roles in crop breeding and genetic research. The development of single-stranded oligonucleotide (oligo) probes simplifies the process of fluorescence in situ hybridization (FISH) and facilitates chromosomal identification in many species. Genome sequencing provides rich resources for the development of oligo probes. However, little progress has been made in peanut due to the lack of efficient chromosomal markers. Until now, the identification of chromosomal variants in peanut has remained a challenge. Results A total of 114 new oligo probes were developed based on the genome-wide tandem repeats (TRs) identified from the reference sequences of the peanut variety Tifrunner (AABB, 2n = 4x = 40) and the diploid species Arachis ipaensis (BB, 2n = 2x = 20). These oligo probes were classified into 28 types based on their positions and overlapping signals in chromosomes. For each type, a representative oligo was selected and modified with green fluorescein 6-carboxyfluorescein (FAM) or red fluorescein 6-carboxytetramethylrhodamine (TAMRA). Two cocktails, Multiplex #3 and Multiplex #4, were developed by pooling the fluorophore conjugated probes. Multiplex #3 included FAM-modified oligo TIF-439, oligo TIF-185-1, oligo TIF-134-3 and oligo TIF-165. Multiplex #4 included TAMRA-modified oligo Ipa-1162, oligo Ipa-1137, oligo DP-1 and oligo DP-5. Each cocktail enabled the establishment of a genome map-based karyotype after sequential FISH/genomic in situ hybridization (GISH) and in silico mapping. Furthermore, we identified 14 chromosomal variants of the peanut induced by radiation exposure. A total of 28 representative probes were further chromosomally mapped onto the new karyotype. Among the probes, eight were mapped in the secondary constrictions, intercalary and terminal regions; four were B genome-specific; one was chromosome-specific; and the remaining 15 were extensively mapped in the pericentric regions of the chromosomes. Conclusions The development of new oligo probes provides an effective set of tools which can be used to distinguish the various chromosomes of the peanut. Physical mapping by FISH reveals the genomic organization of repetitive oligos in peanut chromosomes. A genome map-based karyotype was established and used for the identification of chromosome variations in peanut following comparisons with their reference sequence positions.


Genome ◽  
1996 ◽  
Vol 39 (3) ◽  
pp. 535-542 ◽  
Author(s):  
Concha Linares ◽  
Juan González ◽  
Esther Ferrer ◽  
Araceli Fominaya

A physical map of the locations of the 5S rDNA genes and their relative positions with respect to 18S–5.8S–26S rDNA genes and a C genome specific repetitive DNA sequence was produced for the chromosomes of diploid, tetraploid, and hexaploid oat species using in situ hybridization. The A genome diploid species showed two pairs of rDNA loci and two pairs of 5S loci located on both arms of one pair of satellited chromosomes. The C genome diploid species showed two major pairs and one minor pair of rDNA loci. One pair of subtelocentric chromosomes carried rDNA and 5S loci physically separated on the long arm. The tetraploid species (AACC genomes) arising from these diploid ancestors showed two pairs of rDNA loci and three pairs of 5S loci. Two pairs of rDNA loci and 2 pairs of 5S loci were arranged as in the A genome diploid species. The third pair of 5S loci was located on one pair of A–C translocated chromosomes using simultaneous in situ hybridization with 5S rDNA genes and a C genome specific repetitive DNA sequence. The hexaploid species (AACCDD genomes) showed three pairs of rDNA loci and six pairs of 5S loci. One pair of 5S loci was located on each of two pairs of C–A/D translocated chromosomes. Comparative studies of the physical arrangement of rDNA and 5S loci in polyploid oats and the putative A and C genome progenitor species suggests that A genome diploid species could be the donor of both A and D genomes of polyploid oats. Key words : oats, 5S rDNA genes, 18S–5.8S–26S rDNA genes, C genome specific repetitive DNA sequence, in situ hybridization, genome evolution.


Genome ◽  
1997 ◽  
Vol 40 (4) ◽  
pp. 582-587 ◽  
Author(s):  
R. J. Snowdon ◽  
W. Köhler ◽  
A. Köhler

Using fluorescence in situ hybridization, we located ribosomal DNA loci on prometaphase chromosomes of the diploid species Brassica rapa and Brassica oleracea and their amphidiploid Brassica napus. Based on comparisons of chromosome morphology and hybridization patterns, we characterized the individual B. napus rDNA loci according to their presumed origins in the Brassica A and C genomes. As reported in other studies, the sum of rDNA loci observed on B. rapa (AA genome) and B. oleracea (CC genome) chromosomes was one greater than the total number of loci seen in their amphidiploid B. napus (AACC). Evidence is presented that this reduction in B. napus rDNA locus number results from the loss of the smallest A genome rDNA site in the amphidiploid.Key words: Brassica, fluorescence in situ hybridization, ribosomal DNA, rDNA.


Genome ◽  
1995 ◽  
Vol 38 (4) ◽  
pp. 747-751 ◽  
Author(s):  
J. M. Leggett ◽  
G. S. Markhand

Genomic in situ hybridization using total genomic DNA extracted from the C genome diploid species Avena eriantha (2n = 2x = 14, genome CpCp) was used to identify monosomics (2n = 6x − 1 = 41) of the constituent genomes of the hexaploid cultivated oat A. sativa L. cv. Sun II (2n = 6x = 42, genomes AACCDD). The results demonstrate 3 AD/C and 6 C/AD chromosome translocations, indicate that five of the missing monosomics are derived from the C genome, and show that there are duplicates within the partial monosomic series. Chromosome polymorphisms between some monosomic lines are also demonstrated.Key words: Avena, monosomics, genomic in situ hybridization, genomic identification.


Genome ◽  
1995 ◽  
Vol 38 (5) ◽  
pp. 946-950 ◽  
Author(s):  
Juan Zhang ◽  
Bernd Friebe ◽  
Bikram S. Gill

Genomic in situ hybridization to somatic metaphase chromosomes of hexaploid wheat cv. Chinese Spring using biotinylated maize genomic DNA as a probe revealed the existence of amplified maize DNA sequences in five pairs of chromosomes. The in situ hybridization sites were located on chromosomes 1A, 7A, 2B, 3B, and 7B. One pair of in situ hybridization sites was also observed in hexaploid oat. The locations and sizes of in situ hybridization sites varied among progenitor species.Key words: Triticum aestivum, Zea mays, shared DNA sequences, genomic in situ hybridization.


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