Sensitivity of flow cytometry to detect DNA differences in monotelosomic and wheat-rye translocation wheat lines

The nuclear DNA contents of different wheat monotelosomic and wheat-rye translocation lines were estimated using a laser-based Coulter flow cytometer. Nuclei were isolated from two-week-old seedlings and stained with 4, 6-diamidino- 2-phenylindole (DAPI). Analysis was performed using tetraploid wheat as an internal standard to determine the sensitivity of flow cytometry in detecting small DNA differences. DNA differences were attributed to a missing single arm for each chromosome in monotelosomic lines. In wheat-rye translocation lines, a higher DNA containing rye chromosome arm (1RS) substitute for a lower DNA containing wheat chromosome arm (1BS). The mean fluorescence intensities of different wheat lines indicated significant differences. All monotelosomic lines except 1BL showed significantly lower amounts of nuclear DNA compared to Chinese Spring wheat. There was no statistically significant difference among the different monotelosomic lines studied. One pair of near-isogenic wheat-rye translocation lines indicated a higher DNA amount in wheat-rye translocated line than in the complete wheat line. The second pair did not reflect this difference. Upon cytological analysis, the near isogenic wheat line in this pair observed to contain the wheat-rye translocation. These results provided evidence for the sensitivity of flow cytometric techniques in detecting aneuploid plants.