Behavior of an Alien Telocentric Chromosome in Callus Culture of Wheat
Tissue culture can cause changes in chromosome number and structure. An alien telocentric addition from Elytrigia intermedia subsp. barbulata (Schur.) A. Löve that confers purple aleurone pigment and blue seed color in common wheat (Triticum aestivum L.) was used as a phenotypic marker of the telocentric chromosome to investigate the behavior of that chromosome in primary regenerants from calli of immature wheat embryos cultured for various durations. Six embryos from a plant that was a ditelocentric addition yielded 155 primary regenerants with 507 heads. Twenty-six (5.1%) heads segregated 58.5% white to 41.5% blue seeds, indicating that the heads were monotelocentric additions and that there had been telocentric loss. Similar culture of 15 F1 hybrid embryos that were monotelocentric additions yielded 424 plants with 858 heads. Seventeen (2.0%) heads produced only white seeds, i.e., telocentric loss, and seven (0.8%) heads only blue seeds, i.e., telocentric gain. The other 834 F1 hybrid heads segregated about 74% white to 26% blue seeds, a frequency clearly different from that of the nonhybrid monotelocentric additions. The overall frequency of heads showing changes involving the telocentric chromosome was 3.7% (based on examination of seed from 1365 heads of 579 primary regenerants extracted from calli of both sets of cultured embryos). The duration of culture had no obvious relationship with the frequency with which the alien telocentric chromosome was eliminated or added.
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