Fig 1.
Representative histogram and karyogram of Z. mays.
(A) Representative histogram from FCM measurement of the nuclear DNA amount of Z. mays ‘AL Bandeirante’ from suspensions stained with propidium iodide. Channel 200 shows the G0/G1 peak of ‘CE-777’ (internal standard), 2C = 5.57 pg and CV = 3.20%, and channel 219 the G0/G1 peak of sample ‘AL Bandeirante’, 2C = 6.10 pg and CV = 3.80%. (B) Representative karyogram of Z. mays. Prometaphase obtained from root meristem treated with 1.75 mM HU for 18 h and 3 μM APM for 4 h, followed by Feulgen reaction. The further preparations display stoichiometrically stained chromosomes with well-defined telomeric, centromeric and secondary constriction portions, which are prerequisites for morphometric characterization and determination of area, OD and IOD. Bar = 10 μm. (C) Ideogram assembled based on chromosome morphometry. Relative arm length and arm ratio are respectively shown to the right of the chromosome representation. Bar = 10 μm.
Table 1.
Mean 2C DNA value of each maize chromosome arm and satellite portions in pg (± standard deviation) and in 1C bp.
Fig 2.
Comparison between chromosomal 1C DNA amount (in bp) of the present study (ICM, Z. mays ‘AL Bandeirante’; black square), sequencing data (Z. mays ‘B73’; red triangle) (http://ensembl.gramene.org/Zea_mays/Location/Genome?r=1:8001-18000) and ICM data (Z. mays ‘Black Mexican Sweet Corn’; green circle) [19].
Note that all values measured for ‘Black Mexican Sweet Corn’, except for chromosome 10 (1C = 0.234 × 109 bp), and by sequencing were lower when compared to ‘AL Bandeirante’. Sequencing values ranged from 1C = 0.301 × 109 bp (chromosome 1) to 1C = 0.150 × 109 bp (chromosome 10). Chromosomal DNA values for ‘AL Bandeirante’ ranged from 1C = 0.393 × 109 bp (chromosome 1) to 1C = 0.188 × 109 bp (chromosome 10). Values converted to bp, considering that 1 pg of DNA corresponds to 0.978 × 109 [49].