HYBRIDS BETWEEN A DIPLOID AGROPYRON ELONGATUM AND AEGILOPS SQUARROSA

1971 ◽  
Vol 13 (1) ◽  
pp. 90-94 ◽  
Author(s):  
J. Dvořák
Keyword(s):  
Chromosome Pairing ◽  
Agropyron Elongatum ◽  
B Genome ◽  
Hybrid Plants ◽  
Aegilops Squarrosa ◽  
High Degree

Hybrids were obtained in crosses between Aegilops squarrosa and Agropyron elongatum (2x) but not in crosses between Ag. elongatum and Ae. speltoides and T. boeoticum, respectively. Chromosome pairing revealed a rather high degree of homoeology between the genomes of Ae. squarrosa and Ag. elongatum. The average pairing was 10.7′ + 1.5″ + 0.027″′ per cell with a range of from 0 to 5 pairs. All F1 hybrid plants were sterile with very low pollen fertility.It is proposed that the A and D genomes of wheat are more closely related to the genomes of section Elytrigia of the genus Agropyron than is the B genome.

The genomic relationship of the diploid Bromus variegatus to Bromus inermis

1984 ◽  
Vol 26 (4) ◽  
pp. 469-474 ◽  
Author(s):  
K. C. Armstrong
Keyword(s):  
Chromosome Pairing ◽  
Diploid Species ◽  
Bromus Inermis ◽  
Genomic Relationship ◽  
Diploid Genome ◽  
B Genome ◽  
Hybrid Plants ◽  
Relationship Of ◽  
Genomic Model

The diploid species Bromus variegatus Bieb. was crossed to Bromus inermis Leyss (4x, 8x). Chromosome pairing in each of the six F1 hybrid plants of B. variegatus × B. inermis (4x) fit a 2:1 genomic model of chromosome pairing, which indicated that the B. variegatus genome was more closely related to the A or B genome of B. inermis than A and B were related to each other. A breakdown of microsporocytes was observed in the B. variegatus × B. inermis (8x) hybrid. However, chromosome pairing suggested that the B. variegatus genome was differentiated from the A and B genomes of octoploid B. inermis.Key words: Bromus, diploid, genome, affinity.

THE HOMOEOLOGY OF AEGILOPS MUTICA CHROMOSOMES

1968 ◽  
Vol 10 (3) ◽  
pp. 620-626 ◽  
Author(s):  
J. K. Jones ◽  
B. N. Majisu
Keyword(s):  
Triticum Aestivum ◽  
Chromosome Pairing ◽  
Homoeologous Pairing ◽  
D Genome ◽  
Ancestral Species ◽  
B Genome ◽  
Triticum Species ◽  
Aegilops Squarrosa

Chromosome pairing in Aegilops squarrosa × Ae. mutica hybrids was almost regular and exceeded the pairing in hybrids between Ae. mutica and Sitopsis species of Aegilops, and between Ae. mutica and diploid Triticum species. The Ae. mutica genome is homoeologous with the A, S(B) and D genomes present in wheat, and the evidence reported and reviewed does not suggest that this genome is homoeologous with the B genome of Triticum aestivum in particular. The chromosomes of Ae. mutica appear to have considerable homoeology with the D genome of Ae. squarrosa, and the general homoeology may indicate that it is an ancestral species in the Triticinae. Analysis of chromosome pairing in triploid hybrids supports the hypothesis that factors in Ae. mutica do not independently produce additional homoeologous pairing other than that permitted by the suppression of regulation.

Intergeneric hybrids between Triticum aestivum and three crested wheatgrasses: Agropyron mongolicum, A. michnoi, and A. desertorum

Genome ◽  
1990 ◽  
Vol 33 (5) ◽  
pp. 663-667 ◽  
Author(s):  
Qin Chen ◽  
Joseph Jahier ◽  
Yvonne Cauderon
Keyword(s):  
Triticum Aestivum ◽  
Chromosome Pairing ◽  
Adult Stage ◽  
Meiotic Chromosome ◽  
Intergeneric Hybrids ◽  
Species Hybrid ◽  
Hybrid Necrosis ◽  
Hybrid Plants ◽  
High Degree ◽  
First Time

Three hybridizations of Triticum aestivum cv. Chinese Spring (CS) (2n = 42) with Agropyron mongolicum (2n = 14), A. michnoi (2n = 28), and A. desertorum (2n = 28) are reported for the first time. Hybrid embryos were obtained at frequencies of 0.24, 1.13, and 2.05%, respectively. The hybrid plants obtained from pollinating CS by A. mongolicum had the expected chromosome number of 2n = 4x = 28, but as a result of hybrid necrosis, none could be raised to the adult stage. Hybrids CS × A. michnoi and CS × A. desertorum both had 2n = 5x = 35 chromosomes. The average meiotic chromosome pairing per cell was 7.04 I + 12.14 II + 1.06 III + 0.07 IV + 0.02 V + 0.02 VI and 9.29 I + 11.05 II + 1.14 III + 0.05 IV, respectively. Their analysis leads to the conclusions that (i) the two Agropyron genomes in the hybrids share a high degree of homology, thus revealing that tetraploid Agropyron species are true autoploids (genome constitution PPPP) and (ii) gene(s) in the Agropyron species suppress the activity of the homoeologous pairing control system of wheat. The possibility of gene transfer from Agropyron to wheat is discussed.Key words: intergeneric hybrids, Triticum aestivum, Agropyron species, hybrid necrosis, chromosome pairing.

Suppression of homologous pairing between chromosomes of A and B genomes of 4x and 6x wheats by Hordeum californicum Covas and Stebbins

Genome ◽  
1988 ◽  
Vol 30 (1) ◽  
pp. 8-11
Author(s):  
H. S. Balyan ◽  
G. Fedak
Keyword(s):  
Chromosome Pairing ◽  
Chinese Spring ◽  
Chiasma Frequency ◽  
Mother Cell ◽  
Triticum Turgidum ◽  
Regulatory Gene ◽  
Intergeneric Hybrids ◽  
Homologous Pairing ◽  
Meiotic Analysis ◽  
Hybrid Plants

Three hybrids of Triticum turgidum cv. Ma with Hordeum californicum × T. aestivum cv. Chinese Spring amphiploid were obtained at a frequency of 1.6% of the pollinated florets. Meiotic analysis of the hybrid plants revealed an average chiasma frequency per pollen mother cell ranging from 15.27 to 17.60. The lower than expected chromosome pairing in the hybrid plants was attributed to the suppression of pairing between homologous wheat chromosomes by pairing regulatory gene(s) in H. californicum.Key words: intergeneric hybrids, Hordeum californicum, Triticum turgidum, meiosis, chromosome pairing.

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.

scholarly journals Banana contains a diverse array of endogenous badnaviruses

2005 ◽  
Vol 86 (2) ◽  
pp. 511-520 ◽  
Author(s):  
Andrew D. W. Geering ◽  
Neil E. Olszewski ◽  
Glyn Harper ◽  
Benham E. L. Lockhart ◽  
Roger Hull ◽  
...  
Keyword(s):  
Nuclear Genome ◽  
Synonymous Substitution ◽  
Selective Constraint ◽  
Musa Balbisiana ◽  
Reading Frame ◽  
B Genome ◽  
Species Analysis ◽  
Breeding Programmes ◽  
Distinct Sequence ◽  
High Degree

Banana streak disease is caused by several distinct badnavirus species, one of which is Banana streak Obino l'Ewai virus. Banana streak Obino l'Ewai virus has severely hindered international banana (Musa spp.) breeding programmes, as new hybrids are frequently infected with this virus, curtailing any further exploitation. This infection is thought to arise from viral DNA integrated in the nuclear genome of Musa balbisiana (B genome), one of the wild species contributing to many of the banana cultivars currently grown. In order to determine whether the DNA of other badnavirus species is integrated in the Musa genome, PCR-amplified DNA fragments from Musa acuminata, M. balbisiana and Musa schizocarpa, as well as cultivars ‘Obino l'Ewai’ and ‘Klue Tiparot’, were cloned. In total, 103 clones were sequenced and all had similarity to open reading frame III in the badnavirus genome, although there was remarkable variation, with 36 distinct sequences being recognized with less than 85 % nucleotide identity to each other. There was no commonality in the sequences amplified from M. acuminata and M. balbisiana, suggesting that integration occurred following the separation of these species. Analysis of rates of non-synonymous and synonymous substitution suggested that the integrated sequences evolved under a high degree of selective constraint as might be expected for a living badnavirus, and that each distinct sequence resulted from an independent integration event.

scholarly journals Comparative mapping in intraspecific populations uncovers a high degree of macrosynteny between A- and B-genome diploid species of peanut

BMC Genomics ◽  
2012 ◽  
Vol 13 (1) ◽  
pp. 608 ◽  
Author(s):  
Yufang Guo ◽  
Sameer Khanal ◽  
Shunxue Tang ◽  
John E Bowers ◽  
Adam F Heesacker ◽  
...  
Keyword(s):  
Comparative Mapping ◽  
Diploid Species ◽  
B Genome ◽  
High Degree

Genome constitution of the Australian hexaploid grass Elymus scabrus (Poaceae: Triticeae)

Genome ◽  
1993 ◽  
Vol 36 (1) ◽  
pp. 147-151 ◽  
Author(s):  
J. Torabinejad ◽  
R. J. Mueller
Keyword(s):  
Chromosome Pairing ◽  
Interspecific Hybrids ◽  
Intergeneric Hybrid ◽  
Meiotic Pairing ◽  
Genome Constitution ◽  
Psathyrostachys Juncea ◽  
Hybrid Plants ◽  
Thinopyrum Bessarabicum ◽  
Mother Cells ◽  
Metaphase I

Eight intergeneric hybrid plants were obtained between Elymus scabrus (2n = 6x = 42, SSYY??) and Australopyrum pectinatum ssp. retrofractum (2n = 2x = 14, WW). The hybrids were vegetatively vigorous but reproductively sterile. Examination of pollen mother cells at metaphase I revealed an average of 16.63 I, 5.29 II, 0.19 III, and 0.05 IV per cell for the eight hybrids. The average chiasma frequency of 6.77 per cell in the above hybrids strongly supports the presence of a W genome from A. pectinatum ssp. retrofractum in E. scabrus. Meiotic pairing data of some other interspecific hybrids suggest the existence of the SY genomes in E. scabrus. Therefore, the genome constitution of E. scabrus should be written as SSYYWW. Two other hybrid plants resulted from Elymus yezoensis (2n = 4x = 28, SSYY) crosses with A. pectinatum ssp. pectinatum (2n = 2x = 14, WW). Both were weak and sterile. An average of 0.45 bivalents per cell were observed at metaphase I. This clearly indicates a lack of pairing between W genome of Australopyrum and S or Y genomes of E. yezoensis. In addition, six hybrid plants of E. scabrus with Psathyrostachys juncea (2n = 2x = 14, NN) and one with Thinopyrum bessarabicum (2n = 2x = 14, JJ) were also obtained. The average bivalents per cell formed in both combinations were 2.84 and 0.70, respectively. The results of the latter two combinations showed that there is no N or J genome in E. scabrus.Key words: wide hybridization, chromosome pairing, genome analysis, Australopyrum, Elymus.

A AND B GENOME HOMOEOLOGIES IN TETRAPLOID AND OCTOPLOID CYTOTYPES OF BROMUS INERMIS

1979 ◽  
Vol 21 (1) ◽  
pp. 65-71 ◽  
Author(s):  
K. C. Armstrong
Keyword(s):  
Chromosome Pairing ◽  
Convincing Evidence ◽  
Bromus Inermis ◽  
Open Pollination ◽  
Homoeologous Chromosome ◽  
Genome Chromosome ◽  
B Genome ◽  
Homoeologous Chromosome Pairing ◽  
A Genome ◽  
Structural Differences

Homoeology between the A and B genomes of allotetraploid (2n = 4x = 28) AiAiBiBi and autoallooctoploid (2n = 8x = 56) AIAIAIAIBIBIBIBI cytotypes of B. inermis Leyss. was studied in a tetraploid F1 hybrid (AeAeAiBi) from 4x B. erectus × 4x B. inermis and in a haplo-triploid (AIeAIeBI) which occurred spontaneously in the F2 from open-pollination among plants of the hexaploid F1 hybrid (AeAeAIAIBIBI) from 4x B. erectus × 8x B. inermis. Chromosome pairing at metaphase I in both the tetraploid (AeAeAiBi) and haplo-triploid (AIeAIeBI) indicated that for each A genome chromosome there was a corresponding B genome homoeologue. There was no convincing evidence of gross structural differences between the two homoeologous genomes. The frequency of trivalent formation in the haplo-triploid was approximately one-half that found in two pentaploids (2n = 5x = 35) AIeAIeAIBIBI. This indicates that the pairing affinity between the A and B genomes is one-half that between homologues as expressed by trivalent formation in triploids of the type AAB and AAA. Homoeologous chromosome pairing (A with B) may be controlled by a gene which is hemizygous ineffective.

Low glucosinolate Brassica juncea breeding line revealed to be nullisomic

Genome ◽  
2001 ◽  
Vol 44 (4) ◽  
pp. 738-741 ◽  
Author(s):  
B F Cheng ◽  
G Séguin-Swartz ◽  
D J Somers ◽  
G Rakow
Keyword(s):  
Brassica Juncea ◽  
Interspecific Cross ◽  
Meiotic Behaviour ◽  
Breeding Line ◽  
Pollen Mother Cells ◽  
Chromosomal Segregation ◽  
B Genome ◽  
Hybrid Plants ◽  
Mother Cells ◽  
Metaphase I

The low glucosinolate Brassica juncea breeding line 1058 was derived from a BC1F3 plant of an interspecific cross between high glucosinolate Indian B. juncea (genome AABB, 2n = 36) line 60143 and B. rapa (genome AA, 2n = 20) canola strain CZY. Line 60143 had 2n = 36 chromosomes (18 bivalents at metaphase I) and strain CZY had 2n = 20 chromosomes (10 bivalents). Line 1058 was nullisomic, with 2n - 2 = 34 chromosomes, with 17 bivalents formed at metaphase I and an even chromosomal segregation of 17:17 at anaphase I. In F1 hybrid plants of the cross 1058 × CZY, 98.3% of the pollen mother cells had 10 bivalents and seven univalents. This is evidence that plants of line 1058 are nullisomic, missing one pair of B-genome chromosomes.Key words: low glucosinolate mustard, meiotic behaviour, cytogenetics.

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