CHROMOSOME INSTABILITY OF WHEAT BARLEY DITELOSOMIC ADDITION LINES IN TISSUE-CULTURE

The chromosome instability of some Chinese Spring/Betzes addition line s was studied in sexually propagated plants and in plants propagated i n tissue culture. A total of 197 regenerant plants were raised after p ropagation in tissue culture from six Chinese Spring/Bezes wheat/barle y ditelosomic addition lines (1H beta 3HS, 3HL, 6HS, 6HL and 7HS) isol ated by Islam (1983). The highest regeneration frequency was detected in the 3HL and 6HL addition lines. Cytological analyses of seed obtain ed on the regenerants showed that 49.8% of the seeds examined containe d 42+2t chromosomes, 46.6% had 42 chromosomes, while 3.6% contained va rious numbers of chromosomes (42+1t, 41, 43). The loss of the addition ed pair of telocentric barley chromosomes was most frequent in progeny regenerated from the 3HL line, where 88.4% of the seed examined had a chromosome number of 42. However, when propagated sexually 3HL proved to be one of the most stable wheat/barley ditelosomic addition lines; 93.1% of the seed analysed contained 42+2t chromosomes. The least sta ble addition line among the sexually propagated plants was the 7HS add ition line, where only 15.4 % of the seed contained the additioned bar ley telocentric chromosomes.