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In vitro variation of B chromosomes was studied by examining the callus cells derived from the immature embryos from a cross of Chinese Spring wheat(Triticum aestivum L.) and Fin 7416 rye(Secale cereale L.) carrying two B chromosomes.In 40-d-old callus cells,the numbers of B chromosomes ranged from one to four in 65.6% of the cells observed.The distribution of B chromosome numbers was associated with the ploidy levels of the normal chromosomes(A chromosomes).The frequency of the cells with high numbers of B chromosomes(i.e.,three or four B chromosomes) in the amphiploid cells with 56 A chromosomes was greater than those in the haploid cells with 28 A chromosomes.Although structural changes in the rye A chromosomes were observed,cytological observation and genomic in situ hybridization demonstrated that the rye B chromosomes were conserved in morphological appearance following tissue culture.
In vitro variation of B chromosomes was studied by examining the callus cells derived from the immature embryos from a cross of Chinese Spring wheat (Triticum aestivum L.) and Fin 7416 rye (Secale cereale L.) carrying two B chromosomes. In 40-d -old callus cells, the numbers of B chromosomes ranged from one to four in 65.6% of the cells observed. The distribution of B chromosome numbers was associated with the ploidy levels of the normal chromosomes (A chromosomes). The frequency of the cells with high numbers of B chromosomes (ie, three or four B chromosomes) in the amphiploid cells with 56 A chromosomes were greater than those in the haploid cells with 28 A chromosomes.Although structural changes in the rye A chromosomes were observed, cytological observation and genomic in situ hybridization prototype that the rye B chromosomes were conserved in morphological appearance following tissue culture.