Meiotic abnormalities in primary regenerants from callus culture of immature embryos of 'Norstar' winter wheat

Tissue culture can induce changes in chromosome structure and number in common wheat (Triticum aestivum L.). The type and frequency of such changes were evaluated in primary regenerants extracted from calli of four immature embryos of 'Norstar' winter wheat cultured for various durations. Meiotic analyses of samples from 18 or 19 primary regenerants from a single embryo cultured for 6, 10, or 14 weeks detected chromosomal changes in 17–20% of the samples. Analyses of 20 duplicate samples from these plants indicated that 7 (35%) plants were chimeras. Similar analyses for nine duplicate samples from plants extracted from an embryo cultured for 18 weeks failed to detect any chimeras, but meiotic abnormalities were much more frequent, with about one-half of the 46 plants sampled showing chromosomal structural changes; translocations were the most common abnormality. Plants regenerated from this embryo also were characterized by an abnormal chromosome, believed to contain a deletion, that was not considered to have been induced by tissue culture.Key words: tissue culture, meiotic abnormalities, Triticum aestivum, aneuploidy, translocations, chimeras.