Chromosome structural changes and their role in the evolution of tetraploid wheats

Genome ◽  
1989 ◽  
Vol 32 (2) ◽  
pp. 257-261 ◽  
Author(s):  
Kaz. Noda ◽  
Ge Koulin
Keyword(s):  
Key Words ◽  
Structural Changes ◽  
Triticum Dicoccoides ◽  
Aegilops Speltoides ◽  
Banding Patterns ◽  
Tetraploid Wheats ◽  
B Genome ◽  
Triticum Boeoticum

The possibility that chromosomal interchanges present in the Timopheevi group (AAGG) are responsible for the differentiation of two different groups of tetraploid wheats, the Emmer group (AABB) and the Timopheevi (AAGG) group, has been examined. Chromosomes of Triticum dicoccoides (2n = 28, AABB) and six interchange types of the Timopheevi group (2n = 28, AAGG) were studied by N-banding. The banding patterns of the G genome were distinct from those of the B genome. The banding patterns of the G genome chromosomes of the interchange types were similar to the basic banding patterns of the G genome except those of interchanged chromosomes. No intermediate banding patterns between the B and G genomes were observed. These interchanges might have occurred after establishment of the basic karyotype of the G genome and would not be related to the differentiation of AABB and AAGG from a progenitor tetraploid, such as amphidiploid (AASS) between Aegilops speltoides (SS) and Triticum boeoticum (AA).Key words: tetraploid wheats, N-banding, interchange.

Screening wild progenitors of wheat for salinity stress at early stages of plant growth: insight into potential sources of variability for salinity adaptation in wheat

2018 ◽  
Vol 69 (7) ◽  
pp. 649 ◽  
Author(s):  
Jafar Ahmadi ◽  
Alireza Pour-Aboughadareh ◽  
Sedigheh Fabriki-Ourang ◽  
Ali-Ashraf Mehrabi ◽  
Kadambot H. M. Siddique
Keyword(s):  
Salinity Stress ◽  
Principal Component ◽  
Wild Relatives ◽  
Aegilops Speltoides ◽  
Tolerance Mechanisms ◽  
B Genome ◽  
Oxidative Balance ◽  
Triticum Boeoticum ◽  
Extensive Collection ◽  
Wild Progenitors

Wild relatives of wheat have served as a pool of genetic variation for understanding salinity tolerance mechanisms. Two separate experiments were performed to evaluate the natural diversity in root and shoot Na+ exclusion and K+ accumulation, and the activity of four antioxidant enzymes within an extensive collection of ancestral wheat accessions. In the initial screening experiment, salinity stress (300 mm NaCl) significantly increased Na+ concentration in roots and leaves and led to a significant decline in root and shoot fresh weights, dry weights, and K+ contents. Principal component analysis of the 181 accessions and 12 species identified three first components accounted for 63.47% and 78.55% of the variation under salinity stress. We identified 12 accessions of each species with superior tolerance to salinity for further assessment of their antioxidant defence systems in response to salinity. Both mild (250 mm NaCl) and severe (350 mm NaCl) levels of salinity significantly increased activities of four enzymes, indicating an enhanced antioxidant-scavenging system for minimising the damaging effects of H2O2. Some of the wild relatives—Aegilops speltoides (putative B genome), Ae. caudata (C genome), Ae. cylindrica (DC genome) and Triticum boeoticum (Ab genome)—responded to salinity stress by increasing antioxidants as the dominant mechanism to retain oxidative balance in cells. Further evaluation of salt-tolerance mechanisms in these superior wild relatives will help us to understand the potential of wheat progenitors in the development of more salt-tolerant varieties.

Repetitive DNAs of wild emmer wheat (Triticum dicoccoides) and their relation to S-genome species: molecular cytogenetic analysis

Genome ◽  
2002 ◽  
Vol 45 (2) ◽  
pp. 391-401 ◽  
Author(s):  
Olga Raskina ◽  
Alexander Belyayev ◽  
Eviatar Nevo
Keyword(s):  
Repetitive Dna ◽  
Triticum Dicoccoides ◽  
Wild Emmer Wheat ◽  
Emmer Wheat ◽  
Wild Emmer ◽  
Banding Technique ◽  
Banding Patterns ◽  
Genome Species ◽  
B Genome ◽  
Copia Retrotransposons

We have analyzed the chromosomal GISH molecular banding patterns of three populations of the wild allopolyploid wheat Triticum dicoccoides in an attempt to unravel the evolutionary relationships between highly repetitive DNA fractions of T. dicoccoides and proposed diploid progenitors of the B genome. Aegilops speltoides showed almost complete affinity of its repetitive DNA to C-heterochromatin of T. dicoccoides, whereas other S-genome species demonstrated relatedness only to distal heterochromatin. This substantiates the priority of Ae. speltoides as the most similar to the wheat B-genome donor in comparison with other Sitopsis species. Using molecular banding technique with DNA of different Aegilops species as a probe permits tracing of the origin of each heterochromatin cluster. Molecular banding analysis reveals polymorphism between three wild emmer wheat populations. Comparison of molecular banding patterns with chromosomal distribution of the Ty1-copia retrotransposons, which constitute a large share of T. dicoccoides genome, makes it possible to propose that the activity of transposable elements may lie in the background of observed intraspecific polymorphism.Key words: Aegilops, evolution, heterochromatin, Ty1-copia retrotransposons, Triticum.

scholarly journals Chromosome banding patterns and the origin of the B genome in wheat

1974 ◽  
Vol 24 (1) ◽  
pp. 103-108 ◽  
Author(s):  
A. T. Natarajan ◽  
N. P. Sarma
Keyword(s):  
Hexaploid Wheat ◽  
Chromosome Banding ◽  
Tetraploid Wheat ◽  
Aegilops Speltoides ◽  
Banding Patterns ◽  
B Genome ◽  
Genome Donors

SUMMARYThe distribution of heterochromatic regions in the chromosomes of diploid, tetraploid and hexaploid wheat shows that the B genome possesses characteristic large blocks. Though analyses of probable B genome donors indicate that Aegilops speltoides has a pattern of distribution of heterochromatin nearest to the B genome chromosomes, a polyphyletic origin of tetraploid wheat seems more plausible.

Pairing affinities of the B- and G-genome chromosomes of polyploid wheats with those of Aegilops speltoides

Genome ◽  
2000 ◽  
Vol 43 (5) ◽  
pp. 814-819 ◽  
Author(s):  
S Rodríguez ◽  
B Maestra ◽  
E Perera ◽  
M Díez ◽  
T Naranjo
Keyword(s):  
Chromosome Pairing ◽  
Interspecific Hybrids ◽  
Triticum Turgidum ◽  
Aegilops Speltoides ◽  
Meiotic Pairing ◽  
Triticum Timopheevii ◽  
C Banding ◽  
Tetraploid Wheats ◽  
B Genome ◽  
Metaphase I

Chromosome pairing at metaphase I was studied in different interspecific hybrids involving Aegilops speltoides (SS) and polyploid wheats Triticum timopheevii (AtAtGG), T. turgidum (AABB), and T. aestivum (AABBDD) to study the relationships between the S, G, and B genomes. Individual chromosomes and their arms were identified by means of C-banding. Pairing between chromosomes of the G and S genomes in T. timopheevii × Ae. speltoides (AtGS) hybrids reached a frequency much higher than pairing between chromosomes of the B and S genomes in T. turgidum × Ae. speltoides (ABS) hybrids and T. aestivum × Ae. speltoides (ABDS) hybrids, and pairing between B- and G-genome chromosomes in T. turgidum × T. timopheevii (AAtBG) hybrids or T. aestivum × T. timopheevii (AAtBGD) hybrids. These results support a higher degree of closeness of the G and S genomes to each other than to the B genome. Such relationships are consistent with independent origins of tetraploid wheats T. turgidum and T. timopheevii and with a more recent formation of the timopheevi lineage.Key words: Triticum turgidum, Triticum timopheevii, Aegilops speltoides, meiotic pairing, evolution, C-banding.

scholarly journals Molecular variation in chloroplast DNA regions in ancestral species of wheat.

Genetics ◽  
1994 ◽  
Vol 137 (3) ◽  
pp. 883-889 ◽  
Author(s):  
N T Miyashita ◽  
N Mori ◽  
K Tsunewaki
Keyword(s):  
Chloroplast Dna ◽  
Restriction Enzymes ◽  
Triticum Dicoccoides ◽  
The Other ◽  
Major Type ◽  
Aegilops Speltoides ◽  
Triticum Timopheevi ◽  
Restriction Sites ◽  
D Values ◽  
Chloroplast Dna Regions

Abstract Restriction map variation in two 5-6-kb chloroplast DNA regions of five diploid Aegilops species in the section Sitopsis and two wild tetraploid wheats, Triticum dicoccoides and Triticum araraticum, was investigated with a battery of four-cutter restriction enzymes. A single accession each of Triticum durum, Triticum timopheevi and Triticum aestivum was included as a reference. More than 250 restriction sites were scored, of which only seven sites were found polymorphic in Aegilops speltoides. No restriction site polymorphisms were detected in all of the other diploid and tetraploid species. In addition, six insertion/deletion polymorphisms were detected, but they were mostly unique or species-specific. Estimated nucleotide diversity was 0.0006 for A. speltoides, and 0.0000 for all the other investigated species. In A. speltoides, none of Tajima's D values was significant, indicating no clear deviation from the neutrality of molecular polymorphisms. Significant non-random association was detected for three combinations out of 10 possible pairs between polymorphic restriction sites in A. speltoides. Phylogenetic relationship among all the plastotypes (plastid genotype) suggested the diphyletic origin of T. dicoccoides and T. araraticum. A plastotype of one A. speltoides accession was identical to the major type of T. araraticum (T. timopheevi inclusively). Three of the plastotypes found in the Sitopsis species are very similar, but not identical, to that of T. dicoccoides, T. durum and T. aestivum.

A Centromeric Tandem Repeat Family Originating From a Part of Ty3/gypsy-Retroelement in Wheat and Its Relatives

Genetics ◽  
2003 ◽  
Vol 164 (2) ◽  
pp. 665-672 ◽  
Author(s):  
Zhi-Jun Cheng ◽  
Minoru Murata
Keyword(s):  
In Situ Hybridization ◽  
Tandem Repeats ◽  
Diploid Species ◽  
Upstream Region ◽  
Aegilops Speltoides ◽  
Repeat Family ◽  
B Genome ◽  
Intervening Sequences ◽  
Wild Diploid Species

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.

Characterization of six wheat × Thinopyrum intermedium derivatives by GISH, RFLP, and multicolor GISH

Genome ◽  
2003 ◽  
Vol 46 (3) ◽  
pp. 490-495 ◽  
Author(s):  
F P Han ◽  
G Fedak ◽  
A Benabdelmouna ◽  
K Armstrong ◽  
T Ouellet
Keyword(s):  
Genomic Dna ◽  
Aegilops Tauschii ◽  
Rflp Analysis ◽  
Aegilops Speltoides ◽  
Thinopyrum Intermedium ◽  
B Genome ◽  
A Genome ◽  
Genetic Stocks ◽  
Disomic Addition Lines ◽  
Thinopyrum Elongatum

Restriction fragment length polymorphism (RFLP) analysis and multicolor genomic in situ hybridization (GISH) are useful tools to precisely characterize genetic stocks derived from crosses of wheat (Triticum aestivum) with Thinopyrum intermedium and Thinopyrum elongatum. The wheat × Th. intermedium derived stocks designated Z1, Z2, Z3, Z4, Z5, and Z6 were initially screened by multicolor GISH using Aegilops speltoides genomic DNA for blocking and various combinations of genomic DNA from Th. intermedium, Triticum urartu, and Aegilops tauschii for probes. The probing (GISH) results indicated that lines Z1 and Z3 were alien disomic addition lines with chromosome numbers of 2n = 44. Z2 was a substitution line in which chromosome 2D was substituted by a pair of Th. intermedium chromosomes; this was confirmed by RFLP and muticolour GISH. Z4 (2n = 44) contained two pairs of wheat – Th. intermedium translocated chromosomes; one pair involved A-genome chromosomes, the other involved D- and A-genome chromosomes. Z5 (2n = 44) contained one pair of wheat – Th. intermedium translocated chromosomes involving the D- and A-genome chromosomes of wheat. Z6 (2n = 44) contained one pair of chromosomes derived from Th. intermedium plus another pair of translocated chromosomes involving B-genome chromosomes of wheat. Line Z2 was of special interest because it has some resistance to infection by Fusarium graminearum.Key words: wheat, Thinopyrum intermedium, addition, substitution, and translocation lines, GISH, multicolor GISH, RFLP.

scholarly journals Studies on the genetic diversity of pointed gourd using biochemical methods (Isozyme analysis)

1970 ◽  
Vol 34 (1) ◽  
pp. 123-141
Author(s):  
ASMMR Khan ◽  
MG Rabbani ◽  
MA Siddique ◽  
MA Islam
Keyword(s):  
Genetic Diversity ◽  
Acid Phosphatase ◽  
Key Words ◽  
Glutamate Oxaloacetate Transaminase ◽  
Banding Patterns ◽  
Biochemical Methods ◽  
Electrophoretic Patterns ◽  
Wide Range ◽  
Rf Values ◽  
Pointed Gourd

Biochemical characterizations of 64 pointedgourds were done using three isozyme viz., acid phosphatase, peroxidase and glutamate oxaloacetate transaminase. A wide range of diversity among the gremplasm based on their acid phosphatase, peroxidase and glutamate oxaloacetate transaminase isoenzyme banding patterns were observed. In respect of isoenzyme activity; 8 acid phosphatase, 7 peroxidase and 9 glutamate oxaloacetate transminase electrophoretic zymotypes were formed by 19, 11, and 19 bands at different Rf values varying from 0.19 to 0.82, 0.38 to 0.69 and 0.15 to 0.95, respectively. The wide range of similarity co-efficient of 0.0-80.0, 0.0-66.0, and 0.0-80.0 as found among the electrophoretic patterns in acid phosphatase, peroxidase, and glutamate oxaloacetate transminase, respectively, indicating wide genetic diversity among the accessions. Based on the polymorphic activity of these three enzymes, 27 combinations of electrophoretic zymotypes were identified, each of which can he equated to genotypes. Each of the groups consisted of one to eight genotypes. Sixty four accessions of pointed gourd were grouped into 12 clusters. The genotypes collected from the same location were grouped into different clusters. Key Words: Genetic diversity; pointed gourd; biochemical methods. DOI: 10.3329/bjar.v34i1.5762Bangladesh J. Agril. Res. 34(1) : 123-141, March 2009

Biochemical data bearing on the origin of the B genome in the polyploid wheats

Genome ◽  
1990 ◽  
Vol 33 (3) ◽  
pp. 360-368 ◽  
Author(s):  
K. Kerby ◽  
J. Kuspira ◽  
B. L. Jones ◽  
G. L. Lookhart
Keyword(s):  
Amino Acid ◽  
B Chromosome ◽  
Amino Acid Sequences ◽  
Chromosome 1 ◽  
Aegilops Speltoides ◽  
B Genome ◽  
Aegilops Longissima ◽  
Aegilops Sharonensis ◽  
A Genome ◽  
Genome Donors

For many years each of the species Aegilops bicornis, Aegilops longissima, Aegilops searsii, Aegilops sharonensis, Aegilops speltoides, and Triticum urartu has been implicated as the donor of the B genome in the polyploid wheats. Biochemical and cytological data have revealed that T. urartu possesses a genome similar to that of T. monococcum, and therefore it may be the source of the A genome in T. turgidum and T. aestivum. This revelation therefore excludes T. urartu from the list of putative B-genome donors. To determine which of the remaining species is the source of the B chromosome set, the amino acid sequences of their purothionins were compared with that of the α1 purothionin coded for by the Pur-1B gene on chromosome 1 in the B genome of T. turgidum and T. aestivum. The residue sequences of this protein from Ae. bicornis, Ae. longissima, Ae. searsii, Ae. sharonensis, and Ae. speltoides differed by 1, 6, 1, 1, and 2 amino acid substitutions, respectively, from the α1 protein. These results suggest that either Ae. bicornis, Ae. searsii, or Ae. sharonensis was the most likely donor of the B genome. If the B genome in the polyploid wheats is monophyletic in origin, the collective findings of this and other investigations indicate that Ae. searsii is the most likely donor. The possibility that the B genome in the polyploid wheats could have a polyphyletic origin is also discussed.Key words: polyploid wheats, putative B-genome donors, purothionins, monophyletic, polyphyletic.

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