Variability of chromosomal DNA contents in maize (Zea mays L.) inbred and hybrid lines

The flow karyotypes of different maize (Zea mays L.) inbred and hybrid lines were analyzed. The accumulation and isolation of large quantities of high-quality metaphase chromosomes from root tips was achieved from many kinds of maize lines. The chromosome suspensions were prepared by a simple slicing method from synchronized maize root tips and analyzed by flow cytometry. Variations of experimental flow karyotypes were detected among inbred and hybrid lines in terms of the positions and/or the numbers of chromosome peaks. The 2C DNA amount among eight inbred lines ranged from 5.09 to 5.52 pg. The selection of appropriate maize lines is critical for sorting specific single chromosome types. At least five different chromosome types can be discriminated and sorted from five maize lines. The variability of DNA content in maize chromosome 1 was 9.1%, ranging from 0.685 to 0.747 pg. Differences were detected in the DNA content of homologous chromosome I of hybrid lines.