Table 1.
Observed pathways of seed formation in Ranunculus kuepferi.
| N |
Ploidy |
Genome contribution of sperm nuclei to endosperm | |||||
|---|---|---|---|---|---|---|---|
| seed | polar nuclei | sperm nuclei | Embryo | Endosperm | |||
| Diploid | |||||||
| Sexual | A | 663 | 2 | 1 | 1Cx(m) + 1Cx(p) | 2Cx(m) + 1Cx(p) | 1 reduced |
| BIII | AB | 4 | 2 | 1 or 2 | 2Cx(m) + 1Cx(p)/2Cx(m) + 2Cx(p) | 4Cx(m) + 1Cx(p)/4Cx(m) + 2Cx(p) | 1 reduced/1 unreduced |
| A2 | 30 | 2 | 1 | 2Cx(m) | 4Cx(m) + 1Cx(p) | 1 reduced | |
| Asexual | A3 | 2 | 2 | 1 or 2 | 2Cx(m) | 4Cx(m) + 2Cx(p) | 2 reduced or 1 unreduced |
| A4 | 2 | 2 | 2 | 2Cx(m) | 4Cx(m) + 3Cx(p) | 2 reduced (∼ 1.5Cx)* | |
| Triploid | |||||||
| Sexual | B | 6 | 2 | 1 | 1Cx(m) + 2Cx(p)/2Cx(m) + 1Cx(p) | 2Cx(m) + 2Cx(p)/4Cx(m) + 1Cx(p) | 1 reduced (diploid/haploid sperm nuclei) |
| BIII*** | BB | 6 | 2 | 2 | 3Cx(m) + 1Cx(p) | 6Cx(m) + 6Cx(p)/6Cx(m) + 4Cx(p)/6Cx(m) + 2Cx(p) | endosperm polyploidization, 2 reduced (diploid/haploid sperm nucleus) |
| B2 | 101 | 2 | 1 or 2 | 3Cx(m) | 6Cx(m) + 2Cx(p)/6Cx(m) + 1Cx(p) | 1 reduced (diploid/haploid sperm nucleus) | |
| B3 | 12 | 2 | 1 or 2 | 3Cx(m) | 6Cx(m) + 5Cx(p)/6Cx(m) + 4Cx(p) | 2 reduced (∼ 2.5Cx)*/2 reduced | |
| Asexual | B4 | 2 | 2 | 1 or 2 | 3Cx(m) | 6Cx(m) + 3Cx(p) | 1 unreduced or 2 reduced (∼ 1.5Cx)* |
| B5 | 2 | 2 | 2 | 3Cx(m) | 6Cx(m) + 6Cx(p) | 2 unreduced | |
| D1 | 2 | 2 | 1 | 3Cx(m) | 12Cx(m) + 3Cx(p) | endosperm polyploidization + 1 unreduced | |
| Tetraploid | |||||||
| Sexual | C | 118 | 2 | 1 | 2Cx(m) + 2Cx(p) | 4Cx(m) + 2Cx(p) | 1 reduced |
| BIII | CB | 33 | 2 | 1 or 2 | 4Cx(m) + 2Cx(p)/4Cx(m) + 4Cx(p) | 8Cx(m) + 2Cx(p)/8Cx(m) + 4Cx(p) | 1 unreduced/2 reduced |
| C2 | 1258 | 2 | 1 | 4Cx(m) | 8Cx(m) + 2Cx(p) | 1 reduced | |
| C3 | 400 | 2 | 1 or 2 | 4Cx(m) | 8Cx(m) + 4Cx(p) | 2 reduced or 1 unreduced | |
| C4 | 58 | 2 | 2 | 4Cx(m) | 8Cx(m) + 6Cx(p) | 2 reduced (∼3Cx)*, ** | |
| Asexual | C5 | 24 | 2 | 2 | 4Cx(m) | 8Cx(m) + 8Cx(p) | 2 unreduced or endosperm poyploidization, ** |
| C6 | 16 | 2 | 0 | 4Cx(m) | 8Cx(m) | autonomous endosperm | |
| D2 | 25 | 2 | 1 | 4Cx(m) | 8Cx(m) + 1Cx(p) | 1 reduced diploid | |
| D3 | 35 | 2 | 1 or 2 | 4Cx(m) | 8Cx(m) + 3Cx(p) | 1 reduced (∼3Cx)* | |
| D4 | 4 | 2 | 1 | 4Cx(m) | 16Cx(m) + 4Cx(p) | endosperm polyploidization + 1 unreduced | |
Cx, ploidy after DNA content (Greilhuber et al., 2005); m, maternal genome contribution; p, paternal genome contribution; * after unbalanced pollen meiosis; ** also trinucleate endosperm possible (C4: 12Cm + 2Cp, C5: 12Cm + 4Cp; see also Talent and Dickinson 2007); *** only possible variants of observed cases presented.