Amplification of heterochromatic knob size in callus culture by unequal sister chromatid exchange

摘要

Tissue culture and in vitro plant regeneration systems have provided alternative means for mass proliferation of several plant species. Several reports have given evidence that successful plant regeneration from maize embryo-derived callus cultures isgenotype dependent (see Fluminhan and Aguiar-Perecin, 1998). In addition, tissue and cell culture systems have been useful for studies on the effect of stress on chromosome stability. Chromosome breakage associated with hetero-chromatin regions has beenobserved in plant species, as for instance the occurrence of breakpoints on chromosome arms containing heterochromatic knobs detected by meiotic studies of regenerated maize plants (Lee and Phillips, Genome 29:122-128, 1987).