Fig 1.
Cytological observations of pollen morphology.
(A) Anther phenotypes of diploid (left) and autotetraploid (right) rice. (B and C) 1% I2-KI staining of the pollen grains of diploid and autotetraploid rice. Bar = 200 μm.
Fig 2.
Semi-thin sections showing anther development in 02428-4x.
(A) Premeiotic interphase, (B-H) meiosis stage, (I-J) single microspore stage, (K, L) mature pollen. Ep, En, ML and Ta indicate the epidermis, endothecium, middle layer and tapetum, respectively. The red arrow indicates the degenerated middle layer. Bars = 50 μm.
Fig 3.
Abnormal anther locule during anther development of autotetraploid rice.
(A) Premeiotic interphase, (B-C) meiosis stage, (G) single microspore stage, (H) mature pollen, (B) double vascular bundle (VB). (D, E, F, I, J) abnormal anther locule of each stage. The red arrow indicates the abnormal anther locule. Bars = 50 μm.
Fig 4.
Abnormal tapetum during anther development in autotetraploid rice.
(A, B) Giant tapetal cells (A) and prevacuolation of giant tapetal cells (B) during premeiotic interphase. (C-E) Redundant tapetal cells (C) and tapetum degenerating along with the middle layer (D, E) during meiosis. (F, G) Unbalanced tapetum size after meiosis. (H, I) Tapetum cytoplasm that is not deeply stained at the microspore stage. (J, K) Degeneration of the tapetum (J) and abnormal proliferation (K) during the microspore stage. (L) Arrested microspores and larger endothecium in the mature pollen stage. En, ML and Ta indicate the endothecium, middle layer and tapetum, respectively. The red arrow indicates the abnormalities. Bars = 50 μm.
Table 1.
The homozygous DNA polymorphisms between autotetraploid (02428-4x) and diploid (02428-2x) rice.
Fig 5.
Distribution of methylated transposable element genes in 02428-4x.
Table 2.
Differentially expressed genes associated with copy number variations in autotetraploid rice.
Fig 6.
Protein-protein interactions of candidate meiosis-related genes in autotetraploid rice.
Group 1 genes: genes related to DNA polymorphisms and that exhibit differential expression patterns. Group 2 genes: genes related to DNA methylation and that exhibit differential expression patterns. Group 3 genes: genes related to DNA polymorphisms and DNA methylation.
Fig 7.
A hypothesis model of low seed set in autotetraploid rice.
Blue line indicated the action for the next step. Black line means it cause bad effect to pollen and embryo sac fertility. Red line indicated that the low seed set may cause by multiple factors.