Detection of B Chromosomes in Rye Collected from Pakistan and China

The geographical distribution and frequency of rye plants with B chromosomes from Pakistan and China were investigated to examine whether or not rye plants in these areas have B chromosomes and to compare them with those from other countries. Of the six samples of weedy rye (Secale segetale) collected from northwestern Pakistan, two samples, one from Chitral and the other from Parwak, contained plants carrying B chromosomes with frequencies of 16.7 % and 3.3 %, respectively. On the other hand, one sample of cultivated rye (S. cereale) collected from southwestern China carried B chromosomes with a frequency of 41.7 %. The morphology of all detected B chromosomes was of the standard type, i.e., subtelocentric and about two-thirds as long as A chromosomes, and they displayed non-Mendelian inheritance. The present study suggested that B chromosome-carriers occur relatively commonly in weedy rye from northwestern Pakistan and in cultivated rye from southwestern China.