Genetic induction of structural changes in barley chromosomes added to common wheat by a gametocidal chromosome derived from Aegilops cylindrica

A gametocidal chromosome, chromosome 2C derived from Aegilops cylindrica, w as introduced into six wheat-barley addition lines to establish chromosome- mutation-inducing lines. These lines, except the one for chromosome 4H, had a pair of respective barley chromosomes and one 2C chromosome (22 "+1'); t he line for 4H was doubly monosomic for chromosome 4H and chromosome 2C (21 "+2'). In these lines, chromosome breaks were expected to occur in the gam etes lacking chromosome 2C. The selfed and backcrossed progeny of these lin es were cytologically investigated by in situ hybridization and N-banding. Various types of structural aberration like deletion and translocation were detected for all barley chromosomes with frequencies ranging from 10.8% to 27.9%. The highest frequency of aberrations occurred in chromosome 4H with most of the breakpoints localized in or near the centromeric region. A sim plified procedure of in situ hybridization used in this study was suitable for the large-scale screening for barley chromosome aberrations in the back ground of wheat.