INHERITED SEX-MOSAIC IN MAN

Abstract

Introgression of agronomically important traits from barley to wheat is important for the improvement of wheat. Also, knowledge about precise location of genes in barley chromosomes is a prerequisite for map based gene isolation. The isolated genes would be introduced into wheat by crop transformation and consequently improve wheat. Many attempts have been conducted to achieve chromosome mediated introgressions from barley to wheat and to construct chromosome maps of barley showing physical locations of genes in the past. In the present study I have developed an alternative chromosome mutation inducing system capable of producing barley/wheat translocations and deletions in barley chromosome. The following is the summary. 1)In the attempt to induce breakage in barley chromosomes, I introduced a gametocidal chromosome 2C into six wheat barley addition lines. Chromosome 2C, from Aegilops cylindrica, which is a related species of wheat, has a gametocidal action causing chromosome breakage in the progeny of the monosomic 2C addition line of Chinese Spring wheat. The critical plants (21″+H″+2C′), disomic for each of barley chromosomes and monosomic for the 2C chromosome, were obtained. 2)The six critical lines were either selfed or backcrossed with the respective wheat barley addition lines. The selfed and backcrossed progeny of these lines were cytologically investigated by N banding and FISH using the barley probe HvT01 that is specific to the subterminal repeats of barley chromosomes. Various types of structural aberrations, most of which were deletions and translocations, were detected for all barley chromosomes with frequencies ranging from 10.8% to 27.9%. 3)Chromosome 7H was chosen to investigate the distribution of the breakpoints in the aberrations. Reciprocal crosses were made between the mutation inducing common wheat line (or critical lines) (21″+7H″+2C′) and the 7H addition line of common wheat (21″+7H″) to obtain more 7H deletions and 7H/wheat translocations. There were various types of aberrations as observed in the previous study. The breakpoints of these deletions and translocations appeared to distribute along the entire length of chromosome 7H.