Comparison of two different flow cytometer systems in detecting dna difference among ditelosomic wheat lines

The nuclear DNA contract of a wheat ditelosomic lines were estimated by a laser-based Coulter instrument (LBCI) and an arc lamp-based Partec instrument (ABPI). Nuclei were isolated from two-week-old seedling and stained with 4', 6-diamidino-2-phenylindole (DAPI). Flow analysis was performed using both internal (tetraploid wheat) and external (Chinese Spring wheat) standards to compare the sensitivity of both of the cytometers. The mean fluorescence intensities of different wheat lines indicated significant differences. Comparison using internal and external standards revealed similar results with the LBCI but not with ABPI. Both the Coulter and Partec instruments indicated similar DNA content difference when used with an internal standard. The wheat-rye addition line indicated a significantly higher amount of DNA while ditelosomic lines showed significantly lower amounts of DNA compared to Chinese spring wheat. For external standard analysis, titration curves established the requirement of different amounts of fluorochrome for each cytometer. External standard analysis with LBCI appeared to be more consistent due to ABPI having stabilization problems, which interfered with external standard analysis. A high degree of variation between the runs was noted with ABPI. ABPI analysis was equivalent in with the LBCI in detecting small DNA difference with an internal standard, but not with an external standard. The results provided further potential of the flow cytometric technique to rapidly screen aneuploid and euploid stocks.