PMC

Pollen sterility caused by the interaction of different pollen sterility loci. a Pollen phenotypes of Taichung65-4×. b Pollens of a hybrid with interaction at Sa locus. c Pollens of a hybrid with interaction at Sb locus. d Pollens of a hybrid with interaction at Sc locus. e Pollens of a hybrid with double loci (SaSb) interaction. f Pollens of a hybrid with triple loci (SaSbSc) interaction. g Pollens of a hybrid (T449-4× × E1-4×) with no-interaction at Sa and Sb pollen sterility loci, but interaction exists at Sc pollen sterility locus. h Pollens of a hybrid (T449-4× × E24-4×) with no-interaction at Sa and Sb pollen sterility loci, but interaction exists at Sc pollen sterility locus. i Pollens of a hybrid (T449-4× × E24-4×), with no-interaction at Sa, Sb and Sc pollen sterility loci. Bars = 10 μm

Relationship between differentially expressed genes, pollen sterility loci, and polyploidy. A, Expression levels of differentially expressed genes in four pairwise comparisons: (1) E1-4x versus E1-2x, (2) E245-4x versus E245-2x (polyploidy effect), (3) diploid hybrid (Taichung65 × E245) that is heterozygous at the Sa, Sb, and Sc pollen sterility loci (DF₁) versus E1-2x and E245-2x (pollen sterility loci interactions), and (4) autotetraploid hybrid (Taichung65-4x × E245-4x) that is heterozygous at the Sa, Sb, and Sc pollen sterility loci (TF₁) versus DF₁ (the effect of polyploidy, pollen sterility loci interactions, and the combined effect of polyploidy and pollen sterility loci interactions). B, Effect of allelic interactions between the Sa, Sb, and Sc pollen sterility loci (IE), polyploidy effect (PE), and the combined effect of polyploidy and pollen sterility loci interactions (IPE) on gene expression patterns during meiosis. C, Venn diagram represents the differentially expressed genes in the s meiosis of the parental lines, the diploid hybrid, and the autotetraploid hybrid that were putatively associated with PE (type I), IE (type II), and PE + IE + IPE (type III) factors.

Pollen abortion stages of autotetraploid rice hybrids with allelic interactions at Sa, Sb and Sc pollen sterility loci. a-d, Abnormal pollen development in a hybrid with interaction at Sa pollen sterility locus. a Tetrad stage, one microspore degradation. b Tetrad stage, two microspores degradation. c Tetrad stage, morphological abnormalities. d Tetrad stage, callose remained after completion of meiosis. e-h, Abnormal pollen development in a hybrid with interaction at Sb pollen sterility locus. e Metaphase II, spindle abnormalities. f Metaphase II, spindle abnormalities. g Metaphase II, spindle abnormalities. h Tetrad stage, one microspore degradation. i-l, Abnormal pollen development in a hybrid with the interaction of Sc pollen sterility locus. i Tetrad stage, microspore degradation. j Tetrad stage, microspore degradation. k Tetrad stage, microspore degradation. l Tetrad stage, cell shrinkage. m-p, Abnormal pollen development in a hybrid with interactions at SaSb pollen sterility loci. m Tetrad stage, one microspore degradation. n Tetrad stage, two microspores degradation. o Middle microspore stage, cell shrinkage. p Middle microspore stage, cell shrinkage. q-t, Abnormal pollen development in a hybrid with the interactions of SaSbSc pollen sterility loci. q Dyad stage, cell shrinkage. r Dyad stage, cell shrinkage. s Tetrad stage, cell shrinkage. t Middle microspore stage, cell shrinkage. Bars = 40 μm

Venn diagram representing the overlap between down-regulated genes associated with polyploidy effect (PE), effect of allelic interactions between the Sa, Sb, and Sc pollen sterility loci (IE), and the combined effect of polyploidy and pollen sterility loci interactions (IPE) factors (http://bioinfogp.cnb.csic.es/tools/venny/; ).