Cytological evidence bearing on the origin of the B genome in polyploid wheats

Genome ◽  
1988 ◽  
Vol 30 (1) ◽  
pp. 36-43 ◽  
Author(s):  
K. Kerby ◽  
J. Kuspira
Keyword(s):  
Dna Hybridization ◽  
Triticum Turgidum ◽  
Root Tip ◽  
Cytological Evidence ◽  
B Genome ◽  
Genome Donor ◽  
The One ◽  
Genome Donors ◽  
Tip Cells ◽  
Root Tip Cells

To help elucidate the origin of the B genome in polyploid wheats, karyotypes of Triticum turgidum, Triticum monoccum, and all six purported B genome donors were compared. The analysis utilized a common cytological procedure that employed the most advanced equipment for the measurement of chromosome lengths at metaphase in root tip cells. A comparison of the karyotypes of T. turgidum and T. monococcum permitted the identification of B genome chromosomes of T. turgidum. These consist of two SAT pairs, one ST pair, three SM pairs, and one M pair of homologues. Comparisons of the chromosomes of the B genome of T. turgidum with the karyotypes of the six putative B genome donors showed that only the karyotype of Aegilops searsii was similar to the one deduced for the donor of the B genome in T. turgidum, suggesting that Ae. searsii is, therefore, the most likely donor of the B genome to the polyploid wheats. Support for this conclusion has been derived from geographic, DNA-hybridization, karyotype, morphological, and protein data reported since 1977. Reasons why the B genome donor has not been unequivocally identified are discussed.Key words: phylogeny, karyotypes, Triticum turgidum, Triticum monococcum, B genome, B genome donors.

Aluminium causes variable responses in actin filament cytoskeleton of the root tip cells of Triticum turgidum

PROTOPLASMA ◽  
2005 ◽  
Vol 225 (3-4) ◽  
pp. 129-140 ◽  
Author(s):  
G. Frantzios ◽  
B. Galatis ◽  
P. Apostolakos
Keyword(s):  
Actin Filament ◽  
Triticum Turgidum ◽  
Root Tip ◽  
Tip Cells ◽  
Root Tip Cells

A DICENTRIC WHEAT CHROMOSOME IN DIVISION

1954 ◽  
Vol 32 (3) ◽  
pp. 491-502 ◽  
Author(s):  
J. W. Morrison
Keyword(s):  
Extra Chromosome ◽  
Wheat Chromosome ◽  
Chiasma Formation ◽  
Root Tip ◽  
Anther Wall ◽  
Somatic Variation ◽  
Root Tips ◽  
The One ◽  
Tip Cells ◽  
Root Tip Cells

A dicentric chromosome was observed in the F2 progeny of an interspecific wheat cross. It is suggested that: the dicentric arose from breakage and fusion of two nonhomologous univalent chromosomes in the preceding meiosis. Because only a few bridges were observed in root tips, anther wall tissue, and in sectioned ovaries, it was concluded that the dicentric persisted in the plant because of parallel separation of the chromatids. Somatic variation was observed in some root tip cells. At meiosis, the dicentric was invariably paired with its two homologues and both centromeres were effective in orientation on the plate. Chains-of-five and even rings-of-five were formed in one spike. In another, the loss of one chromosome arm prevented such associations but several forms of trivalents occurred. In one spike, internal chiasmata were formed in the intercentric region of the chromosome. On the chiasmatype theory of crossing over this should have caused bridges at succeeding stages. Besides the lack of bridges, in some cells at AI there was definite evidence that the dicentric was breaking apart and forming an extra chromosome. To explain this phenomenon it is suggested that the effect of the one centromere was nullified by the other and the full consequences of chromatid breakage and reunion in chiasma formation were not fulfilled.

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