Table 2.
Karyotype of pachytene chromosomes in potato (S. tuberosum)
| Parameter | Chromosomea | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 2b | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | Total | |
| Absolute length (μm) | 81.73 ± 14.40 | 55.15 ± 11.09 | 55.88 ± 8.70 | 56.54 ± 9.31 | 39.80 ± 6.65 | 50.31 ± 8.74 | 42.61 ± 7.41 | 44.66 ± 7.55 | 49.80 ± 8.61 | 41.22 ± 6.34 | 37.71 ± 7.55 | 40.72 ± 6.48 | 596.13 ± 98.50 |
| Relative length (%) | 13.70 ± 0.69 | 9.22 ± 0.70 | 9.39 ± 0.38 | 9.49 ± 0.43 | 6.68 ± 0.35 | 8.43 ± 0.37 | 7.15 ± 0.40 | 7.49 ± 0.45 | 8.35 ± 0.26 | 6.93 ± 0.30 | 6.30 ± 0.44 | 6.84 ± 0.30 | 100 |
| DNA contentc (Mb) | 115.09 ± 5.78 | 77.48 ± 5.88 | 78.91 ± 3.22 | 79.72 ± 3.60 | 56.13 ± 2.90 | 70.84 ± 3.10 | 60.06 ± 3.38 | 62.95 ± 3.74 | 70.14 ± 2.17 | 58.23 ± 2.53 | 52.95 ± 3.73 | 57.50 ± 2.52 | 840 |
| Relative DAPI fluorescenced (%) | 11.88 ± 1.16 | 8.33 ± 1.03 | 8.41 ± 0.82 | 10.39 ± 0.49 | 7.26 ± 0.69 | 8.12 ± 0.65 | 7.67 ± 0.61 | 6.70 ± 0.82 | 9.88 ± 0.56 | 7.36 ± 1.14 | 5.86 ± 0.72 | 8.14 ± 0.69 | 100 |
| DNA contente (Mb) | 99.82 ± 9.73 | 70.01 ± 8.68 | 70.63 ± 6.91 | 87.27 ± 4.13 | 60.95 ± 5.78 | 68.24 ± 5.50 | 64.43 ± 5.16 | 56.29 ± 6.91 | 82.98 ± 4.67 | 61.82 ± 9.58 | 49.18 ± 6.02 | 68.37 ± 5.84 | 840 |
| Centromere indexf (%) | 23.28 ± 2.49 | 9.27 ± 2.61 | 21.01 ± 6.21 | 32.46 ± 4.63 | 45.59 ± 3.41 | 24.69 ± 5.84 | 30.97 ± 1.28 | 34.44 ± 6.79 | 40.52 ± 3.90 | 35.80 ± 1.17 | 48.88 ± 1.99 | 47.15 ± 1.19 | |
| Heterochromatin (%) | 30.96 ± 1.88 | 33.70 ± 4.97g | 32.80 ± 5.13 | 23.08 ± 8.56 | 39.07 ± 4.71 | 30.25 ± 3.30 | 35.10 ± 6.37 | 33.78 ± 5.03 | 30.90 ± 6.92 | 41.78 ± 8.42 | 36.38 ± 5.91 | 32.33 ± 5.39 | 32.80 ± 2.80h |
aChromosomes were ordered and numbered according to their corresponding linkage groups (van Os et al. 2006)
bThe rDNA section of chromosome 2 was included in the measurements
cEstimation of the DNA content of each chromosome was based on relative length and the assumption that (1) the haploid genome size of potato is 840 Mb; (2) the euchromatic and heterochromatic regions contain equal amounts of DNA (Mb/μm). Thus, the DNA content would be underestimated for relatively heterochromatic chromosomes and overestimated for relatively euchromatic chromosomes
dRelative DAPI fluorescence density measurements for each bivalent
eEstimation of the DNA content of each chromosome was based on relative DAPI fluorescence and the assumption that (1) the haploid genome size of potato is 840 Mb; (2) the euchromatic and heterochromatic regions contain unequal amounts of DNA (Mb/μm)
fCentromere index was percentage of short arm/total chromosome length (Levan et al. 1964)
gValue includes NOR
hPercentage heterochromatin in TCC