Nucleocytoplasmic interactions stabilize ploidy level in wheat interspecific hybrids

Genome ◽  
1991 ◽  
Vol 34 (6) ◽  
pp. 983-987 ◽  
Author(s):  
S. S. Maan ◽  
T. R. Endo
Keyword(s):  
Interspecific Hybrids ◽  
Triticum Turgidum ◽  
Triticum Aestivum L ◽  
Meiotic Metaphase ◽  
D Genome ◽  
Ploidy Levels ◽  
Aegilops Squarrosa ◽  
Functional Advantage ◽  
Mother Cells ◽  
Nucleocytoplasmic Interactions

The cytoplasm of Aegilops squarrosa L. (2n = 14; DD) is compatible with the nuclei of Triticum aestivum L. (2n = 42; AABBDD) and the pentaploid F1 (2x = 35; AABBD), but not with the euploid nucleus of Triticum turgidum L. (2n = 28; AABB). To identify D-genome chromosomes with the genes conditioning differential nucleocytoplasmic compatibility, ae and sq 5x F1, having cytoplasms of T. aestivum and Ae. squarrosa, respectively, were reciprocally crossed to the seven doubled ditelosomics (d-dts) of the D-genome chromosomes (including four control crosses of d-dts 1A, 1B, and sq 5x F1). The 32 progeny were examined for the presence or absence of unpaired telosomes, monosomes, and the maximum number of bivalents at the meiotic metaphase I in the pollen mother cells for comparison with the transmission of ae and sq male and ae and sq female gametes carrying different numbers of D-genome chromosomes. The sq gametes with 1D, 5D, and other D-genome chromosomes had a strong functional advantage. In contrast, the ae gametes with 1D and other D genome chromosomes, except 5D, had a functional disadvantage. The sq and ae 5x F1 transmitted chromosome 5D through 80.0 and 72.2% of the male and 58.6 and 44.8% of the female gametes, respectively. We concluded that the sq gametes tended to increase and ae gametes tended to reduce the ploidy levels of the progeny.Key words: preferential gamete transmission, alloplasmic wheat, Triticum, Aegilops, polyploidy, aneuploidy.

A cytological and molecular analysis of D-genome chromosome retention following F2–F6 generations of hexaploid×tetraploid wheat crosses

2018 ◽  
Vol 69 (2) ◽  
pp. 121 ◽  
Author(s):  
Sriram Padmanaban ◽  
Peng Zhang ◽  
Mark W. Sutherland ◽  
Noel L. Knight ◽  
Anke Martin
Keyword(s):  
Durum Wheat ◽  
Tetraploid Wheat ◽  
Triticum Aestivum L ◽  
Food Crops ◽  
Cytological Analysis ◽  
Genome Chromosome ◽  
D Genome ◽  
Ploidy Levels ◽  
F2 Generation ◽  
Global Food

Both hexaploid bread wheat (AABBDD) (Triticum aestivum L.) and tetraploid durum wheat (AABB) (T. turgidum spp. durum) are highly significant global food crops. Crossing these two wheats with different ploidy levels results in pentaploid (AABBD) F1 lines. This study investigated the differences in the retention of D chromosomes between different hexaploid × tetraploid crosses in subsequent generations by using molecular and cytological techniques. Significant differences (P < 0.05) were observed in the retention of D chromosomes in the F2 generation depending on the parents of the original cross. One of the crosses, 2WE25 × 950329, retained at least one copy of each D chromosome in 48% of its F2 lines. For this cross, the retention or elimination of D chromosomes was determined through several subsequent self-fertilised generations. Cytological analysis indicated that D chromosomes were still being eliminated at the F5 generation, suggesting that in some hexaploid × tetraploid crosses, D chromosomes are unstable for many generations. This study provides information on the variation in D chromosome retention in different hexaploid × tetraploid wheat crosses and suggests efficient strategies for utilising D genome retention or elimination to improve bread and durum wheat, respectively.

scholarly journals Comparative Mapping of Genes for Brittle Rachis in Triticum

2011 ◽  
Vol 41 (No. 2) ◽  
pp. 39-44 ◽  
Author(s):  
N. Watanabe ◽  
N. Takesada ◽  
Y. Fujii ◽  
P. Martinek
Keyword(s):  
Triticum Turgidum ◽  
Aegilops Tauschii ◽  
Dominant Gene ◽  
Introgression Line ◽  
Triticum Aestivum L ◽  
Grass Species ◽  
Brittle Rachis ◽  
D Genome ◽  
Adaptive Value ◽  
Group 3

The brittle rachis phenotype is of adaptive value in wild grass species because it causes spontaneous spike shattering. The genes on the homoeologous group 3 chromosomes determine the brittle rachis in Triticeae. A few genotypes with brittle rachis have also been found in the cultivated Triticum. Using microsatellite markers, the homoeologous genes for brittle rachis were mapped in hexaploid wheat (Triticum aestivum L.), durum wheat (Triticum turgidum L. conv. durum /Desf./) and Aegilops tauschii Coss. On chromosome 3AS, the gene for brittle rachis, Br<sub>2</sub>, was linked with the centromeric marker, Xgwm32, at the distance of 13.3 cM. Br<sub>3 </sub>was located on chromosome 3BS and linked with the centromeric marker,<br />Xgwm72 (14.2 cM). Br<sub>1 </sub>was located on chromosome 3DS. The distance from the centromeric marker Xgdm72 was 23.6 cM. The loci Br<sub>1</sub>, Br<sub>2</sub> and Br<sub>3</sub> determine disarticulation of rachides above the junction of the rachilla with the rachis so that a fragment of rachis is attached below each spikelet. The rachides of Ae. tauschii are brittle at every joint, so that the mature spike disarticulates into barrel type. The brittle rachis was determined by a dominant gene, Br<sup>t</sup>, which was linked to the centromeric marker, Xgdm72 (19.7 cM), on chromosome 3DS. A D-genome introgression line, R-61, was derived from the cross Bet Hashita/Ae. tauschii, whose rachis disarticulated as a wedge type. The gene for brittle rachis of R-61, tentatively designated as Br<sup>61</sup>, was distally located on chromosome 3DS, and was linked with the centromeric marker, Xgdm72 (27.5 cM). We discussed how the brittle rachis of R-61 originated genetically. &nbsp; &nbsp;

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.

Analysis of induced homoeologous pairing in hybrids between 6x triticale ph1 mutant and Triticum aestivum L.

1986 ◽  
Vol 28 (5) ◽  
pp. 696-700 ◽  
Author(s):  
Nicolás Jouve ◽  
Benito Giorgi
Keyword(s):  
Triticum Aestivum ◽  
Triticum Aestivum L ◽  
Wheat Breeding ◽  
Hexaploid Triticale ◽  
D Genome ◽  
Level Of Involvement ◽  
Mother Cells ◽  
Homoeologous Chromosomes ◽  
Different Doses ◽  
Induced Homoeologous Pairing

The meiotic behaviour of three hexaploid triticale × Triticum aestivum L. hybrids having different doses of ph1 mutant alleles was investigated using C-band staining of pollen mother cells at first metaphase. D-genome chromosomes that were clearly distinguished by their small size and unbanded response to Giemsa staining were increasingly promoted to pair with the homoeologous chromosomes of the A and B genomes in the absence of Ph1 genes. However, the wheat–rye associations were not enhanced when one or two ph1 alleles were present. The distribution of meiotic configurations was significantly different for each chromosome in the ph1/ph1 hybrid. Thus, 1B did not form multivalents in this hybrid, and the remaining identified chromosomes differed significantly in the level of involvement in tri-, quadri-, or quinque-valents. The hybrids should be of value for hexaploid and wheat breeding programs.Key words: Triticale, Triticum aestivum, C-banding, ph1 mutants.

Chromosomal location in common wheat of a gene (Cmcl) from Aegilops squarrosa that conditions resistance to colonization by the wheat curl mite

Genome ◽  
1989 ◽  
Vol 32 (6) ◽  
pp. 1033-1036 ◽  
Author(s):  
E. D. P. Whelan ◽  
J. B. Thomas
Keyword(s):  
Mosaic Virus ◽  
Common Wheat ◽  
Chromosomal Location ◽  
Dominant Gene ◽  
Triticum Aestivum L ◽  
Wheat Streak Mosaic Virus ◽  
D Genome ◽  
Wheat Curl Mite ◽  
Aegilops Squarrosa ◽  
Homozygous Resistant

Wheat streak mosaic is a destructive disease of wheat caused by wheat streak mosaic virus. Wheat streak mosaic virus is vectored by the wheat curl mite (Eriophyes tulipae Keifer). A single dominant gene conditioning resistance to colonization by the mite vector was transferred from Aegilops squarrosa L. to a synthetic amphiploid (AC PGR 16635) and then to common wheat (Triticum aestivum L. em. Thell.) through backcrossing. Because of its origin, the transferred gene was probably located in the D genome. Monosomics 1D through 7D were crossed with a homozygous resistant line with the pedigree Norstar*4/AC PGR 16635. Both 41- and 42-chromosome F1 plants were identified and selfed to obtain F2 seed. The observed proportion of resistant and susceptible plants in 6 of the 7 F2 families from monosomics, and in all 7 of the F2s from disomics, did not deviate significantly from a 3:1 ratio. However, the proportion of resistant plants from the F2 of monosomic 6D was significantly (p < 0.01) in excess of this ratio and susceptible plants from this family were nullisomic for all or part of 6D. In crosses with standard ditelosomic stocks, telocentrics from a ditelosomic derivative of susceptible individual of this F2 paired with 6D(L) but failed to pair with 6D(S). The F2 of heterozygous resistant plants that were monotelodisomic for the long arm of 6D(L) segregated approximately 19 resistant to 1 susceptible, while those from monotelodisomics for the short arm segregated normally (3 resistant to 1 susceptible, p = 0.27). These data show that the gene Cmcl for mite resistance is located on the short arm of chromosome 6D. Key words: Aegilops squarrosa, wheat streak mosaic virus.

scholarly journals Screening of Diverse Ethiopian Durum Wheat Accessions for Aluminum Tolerance

Agronomy ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 440
Author(s):  
Edossa Fikiru Wayima ◽  
Ayalew Ligaba-Osena ◽  
Kifle Dagne ◽  
Kassahun Tesfaye ◽  
Eunice Magoma Machuka ◽  
...  
Keyword(s):  
Durum Wheat ◽  
Bread Wheat ◽  
Rapid Method ◽  
Triticum Turgidum ◽  
Aluminum Tolerance ◽  
Acid Soils ◽  
Triticum Aestivum L ◽  
D Genome ◽  
Potential Source ◽  
Seminal Roots

Acid soils and associated Al3+ toxicity are prevalent in Ethiopia where normally Al3+-sensitive durum wheat (Triticum turgidum ssp durum Desf.) is an important crop. To identify a source of Al3+ tolerance, we screened diverse Ethiopian durum germplasm. As a center of diversity for durum wheat coupled with the strong selection pressure imposed by extensive acid soils, it was conceivable that Al3+ tolerance had evolved in Ethiopian germplasm. We used a rapid method on seedlings to rate Al3+ tolerance according to the length of seminal roots. From 595 accessions screened using the rapid method, we identified 21 tolerant, 180 intermediate, and 394 sensitive accessions. When assessed in the field the accessions had tolerance rankings consistent with the rapid screen. However, a molecular marker specific for the D-genome showed that all accessions rated as Al3+-tolerant or of intermediate tolerance were hexaploid wheat (Triticum aestivum L.) that had contaminated the durum grain stocks. The absence of Al3+ tolerance in durum has implications for how Al3+ tolerance evolved in bread wheat. There remains a need for a source of Al3+-tolerance genes for durum wheat and previous work that introgressed genes from bread wheat into durum wheat is discussed as a potential source for enhancing the Al3+ tolerance of durum germplasm.

Interactions between the scs and Vi genes in alloplasmic durum wheat

Genome ◽  
1994 ◽  
Vol 37 (2) ◽  
pp. 210-216 ◽  
Author(s):  
S. S. Maan
Keyword(s):  
Male Sterility ◽  
Chromosomal Location ◽  
Triticum Turgidum ◽  
Meiotic Chromosome ◽  
Seed Viability ◽  
Triticum Aestivum L ◽  
Male Sterile ◽  
Genome Chromosome ◽  
D Genome ◽  
Alien Cytoplasm

Two nuclear genes, vitality (Vi) on an A- or B-genome chromosome and species cytoplasm specific (scs) on a 1DL telosome from Triticum aestivum L. or a telosome from Aegilops uniaristata Vis. (un telosome), improved compatibility between the nucleus of Triticum turgidum L. var. durum and the cytoplasm of Ae. longissima S. &M. or Ae. uniaristata. To study interactions between Vi and scs and to determine the chromosomal location of Vi, 29-chromosome fertile plants were crossed with 13 D-genome disomic-substitution (d-sub) lines [except 5D(5A)] of 'Langdon' durum. F1 and backcross progenies were examined for meiotic chromosome number and pairing, fertility, and plant vigor. In 11 crosses, Vi restored seed viability but produced double-monosomics (d-monos) with greatly reduced growth and vigor. In contrast, crosses involving 1D(1A) and 1D(1B) d-sub lines produced d-monos with normal vigor and anthesis but nonfunctional pollen. A backcross of 1D + 1A d-mono F1 and 1D(1A) d-sub lines produced 11 male steriles; 3 had 13 II + 1 II 1D + 1 I 1A, 2 had 13 II + 2 I, 1 had 13 II + 1 II 1D(1A), and 5 were not examined. Crosses of 1D + 1A d-mono F1 with control durum, lo durum (with 1DL), and un durum (with un telosome) lines produced 16 male-sterile d-monos and 14 fertiles with 14 II + 1 I 1D, showing that 15-chromosome female gametes transmitted monosomes 1A and 1D. However, BC2F1's from 1D + 1B d-mono × fertile line with un telosome included 20 male-sterile d-monos, 6 fertile triple monosomics (13 II + 1 I 1D + 1 I 1B + t I un telosome), and 1 fertile plant with a 1B/1D translocation. Unlike d-mono 1A + 1D, d-mono 1B + 1D did not transmit 15-chromosome female gametes with monosomes 1D and 1B. Additional backcrosses also indicated that homozygous scs caused male sterility in 1D(1A) and 1D(1B) d-subs and that the procedure used was not suitable for the chromosomal location of Vi.Key words: alien cytoplasm, nucleocytoplasmic interactions, 1B/1D translocation, aneuploidy, cytoplasmic male sterility.

EFFECTS OF THE D GENOME ON MILLING AND BAKING PROPERTIES OF WHEAT

1969 ◽  
Vol 49 (3) ◽  
pp. 255-263 ◽  
Author(s):  
E. R. Kerber ◽  
K. H. Tipples
Keyword(s):  
Triticum Aestivum ◽  
Triticum Durum ◽  
Triticum Aestivum L ◽  
High Quality ◽  
D Genome ◽  
Aegilops Squarrosa ◽  
The Common ◽  
Triticum Durum Desf ◽  
Synthetic Hexaploids ◽  
Baking Performance

The common hexaploid wheat Triticum aestivum L. emend. Thell. ssp. vulgare MacKey cv. Canthatch (2n = 42 = AABBDD), the tetraploid component (2n = 28 = AABB) extracted from it, Triticum durum Desf., cv. Stewart 63 (2n = 28 = AABB) and five synthetic hexaploids (2n = 42 = AABBDD) produced by combining the extracted tetraploid with Aegilops squarrosa (2n = 14 = DD) were tested for several milling and baking properties. Compared with Canthatch, a bread wheat of high quality, the extracted tetraploid had extremely poor baking characteristics; it was very similar to Stewart 63. The baking performance of the synthetic hexaploids was much superior to that of the extracted tetraploid but considerably inferior to that of Canthatch. The results substantiated the supposition that the D genome derived from Ae. squarrosa has contributed the desirable milling and baking properties which distinguish hexaploid bread wheats from those of the tetraploid group.

scholarly journals The Development and Meiotic Behavior of Asymmetrical Isochromosomes in Wheat

Genetics ◽  
1997 ◽  
Vol 145 (4) ◽  
pp. 1155-1160
Author(s):  
Adam J Lukaszewski
Keyword(s):  
Triticum Aestivum ◽  
Hexaploid Wheat ◽  
Triticum Aestivum L ◽  
Meiotic Metaphase ◽  
Meiotic Behavior ◽  
Pollen Mother Cells ◽  
Chromosome Arm ◽  
Mother Cells ◽  
Metaphase I

To determine which segments of a chromosome arm are responsible for the initiation of chiasmate pairing in meiosis, a series of novel isochromosomes was developed in hexaploid wheat (Triticum aestivum L.). These isochromosomes are deficient for different terminal segments in the two arms. It is proposed to call them “asymmetrical.” Meiotic metaphase I pairing of these asymmetrical isochromosomes was observed in plants with various doses of normal and deficient arms. The two arms of an asymmetrical isochromosome were bound by a chiasma in only two of the 1134 pollen mother cells analyzed. Pairing was between arms of identical length whenever such were available; otherwise, there was no pairing. However, two arms deficient for the same segment paired with a frequency similar to that of normal arms, indicating that the deficient arms retained normal capacity for pairing. Pairing of arms of different length was prevented not by the deficiency itself, but rather, by the heterozygosity for the deficiency. Whether two arms were connected via a centromere in an isochromosome or were present in two different chromosomes had no effect on pairing. This demonstrates that in the absence of homology in the distal regions of chromosome arms, even if relatively short, very long homologous segments may remain unrecognized in meiosis and will not be involved in chiasmate pairing.

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