Table 3.
Placement and chi-square significance of microsatellite distribution inside and outside of ORFs from GSSRs, BSSRs, and ESSRs of carrot*
| Repeat type | GSSRs | BSSRs | ESSRs | |||
|---|---|---|---|---|---|---|
| χ2 | p (df = 1) | χ2 | p (df = 1) | χ2 | p (df = 1) | |
| Dinucleotide | 2.79 | 0.10 | 0.23 | 0.63 | 60.89 | 0.00 |
| Trinucleotide | 0.14 | 0.71 | 4.55 | 0.03 | 1.30 | 0.25 |
| Tetranucleotide | 18.00 | 0.00 | 2.96 | 0.09 | 17.06 | 0.00 |
| Pentanucleotide | 2.00 | 0.16 | 0.04 | 0.84 | 3.57 | 0.06 |
| Hexanucleotide | 0.00 | 1.00 | 0.14 | 0.71 | 0.42 | 0.52 |
| Total | 2.73 | 0.10 | 0.15 | 0.70 | 29.70 | 0.00 |
* A minimum of 6 repeat units (r.u.) for dinucleotides, 4 r.u. for trinucleotides, and 3 r.u. for tetra-, penta-, hexa-, hepta-,and octanucleotides were used as parameters for searching microsatellites in genomic and EST sequence of carrot. Chi-square distributions indicate observed SSR motif types inside versus outside ORFs as compared to posterior probabilities. χ2 = chi-squared statistic; df = degrees of freedom. Observed distributions generally fit those expected (p ≥0.05) except for tetranucleotides for GSSRs (from a hybridization-based enrichment of genomic library), and trinucleotides for BSSRs (from BAC end sequence). For ESSRs (from ESTs) the observed distributions only fit expected ones for tri-, penta-, and hexanucleotide repeats, with observed occurrence of di- and tetranucleotide repeats occurring much more often outside ORFs than expected.