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

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.

1981 ◽  
Vol 23 (4) ◽  
pp. 655-669 ◽  
Author(s):  
D. R. Knott

A procedure was carried out to transfer to an A or B chromosome of wheat (Triticum aestivum L.), a segment of chromosome 2D carrying the gene Sr6 for resistance to stem rust (Puccinia graminis tritici Eriks. and Henn.). The objectives were to make Sr6 available for breeding in durum wheat (Triticum turgidum L.) and to study dosage effects with Sr6. Plants were produced that had 14 pairs of chromosomes (the A and B genomes) plus an added chromosome 2D carrying Sr6, either as a whole chromosome or as an isosome or telosome. Seeds from these plants were irradiated with thermal neutrons and the M1 progeny were used as male parents in crosses with the durum cultivar Kubanka. Progeny that carried Sr6 and were resistant to stem rust were examined cytologically for the presence of translocations. Five translocations were obtained and then transferred to the hexaploid level by backcrossing. Homozygous lines were produced and four were analyzed in crosses with the Chinese Spring monosomics. In two of them the segment of the A or B genome chromosome had apparently been lost as a result of crossing over. In a third line the translocation involved 2D and its homoeologue 2A. In the final line it appeared that a segment of 2D had been inserted into chromosome 7B. When the chromosome carrying this translocation was transferred to the hexaploid level a position effect occurred that affected the expression of Sr6.


1980 ◽  
Vol 18 (5-6) ◽  
pp. 465-482 ◽  
Author(s):  
K. M. Soliman ◽  
J. E. Bernardin ◽  
C. O. Qualset

1986 ◽  
Vol 28 (2) ◽  
pp. 294-297 ◽  
Author(s):  
E. D. P. Whelan ◽  
R. L. Conner ◽  
J. B. Thomas ◽  
A. D. Kuzyk

A translocation between a common wheat (Triticum aestivum L.) chromosome and chromosome 6 of Elytrigia pontica (Podp.) Holub conferred resistance to feeding by Eriophyes (= Aceria) tulipae Keifer, the mite vector of wheat streak mosaic virus and the wheat spot mosaic agent. Resistance was dominant, but differential transmission occurred between the pollen and the egg. Transmission of resistance through the pollen was low, about 3% in 'Cadet', 'Rescue', and 'Winalta', but significantly higher in 'Norstar' (9.1%). Significant differences also were detected in transmission through the egg. 'Cadet' had the highest transmission (50.9%) and 'Rescue' the lowest (40.5%). However, there were no significant differences among varieties in the frequencies of resistance (50.3–54.5%) in the F2. Less than 10% of the F2 plants were homozygous resistant. Selfed progeny from monosomic or disomic F1 plants from crosses between the homozygous translocation and group-6 monosomics all segregated for susceptibility. Meiotic studies of 25 susceptible F2 plants from these F1 monosomics showed that 21 were either monosomic or disomic and only 4 were nullisomic, indicating that the translocation did not involve any of the group-6 homoeologues. The translocation is considered to be a noncompensating translocation involving a whole arm of chromosome 6 of E. pontica.Key words: wheat, mite (wheat curl), translocation, Triticum.


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