CSIRO Agriculture and Food, Canberra, Australian Capital Territory, Australia.
Xinjiang Key Laboratory of Biological Resources and Genetic Engineering, School of Life Science and Technology, Xinjiang University, Urumqi, P. R. China.
Nat Plants. 2023 Nov;9(11):1848-1861. doi: 10.1038/s41477-023-01536-4. Epub 2023 Oct 9.
Prevention of autonomous division of the egg apparatus and central cell in a female gametophyte before fertilization ensures successful reproduction in flowering plants. Here we show that rice ovules of Polycomb repressive complex 2 (PRC2) Osfie1 and Osfie2 double mutants exhibit asexual embryo and autonomous endosperm formation at a high frequency, while ovules of single Osfie2 mutants display asexual pre-embryo-like structures at a lower frequency without fertilization. Earlier onset, higher penetrance and better development of asexual embryos in the double mutants compared with those in Osfie2 suggest that the autonomous endosperm facilitated asexual embryo development. Transcriptomic analysis showed that male genome-expressed OsBBM1 and OsWOX8/9 were activated in the asexual embryos. Similarly, the maternal alleles of the paternally expressed imprinted genes were activated in the autonomous endosperm, suggesting that the egg apparatus and central cell convergently adopt PRC2 to maintain the non-dividing state before fertilization, possibly through silencing of the maternal alleles of male genome-expressed genes.
在受精前防止卵子器官和中央细胞的自主分裂，确保了开花植物的成功繁殖。在这里，我们发现，多梳抑制复合物 2（PRC2）Osfie1 和 Osfie2 双突变体的水稻胚珠以高频率表现出无性胚胎和自主胚乳形成，而单 Osfie2 突变体的胚珠以较低频率在没有受精的情况下表现出无性类胚胎结构。与 Osfie2 相比，双突变体中无性胚胎的起始更早、穿透性更强且发育更好，这表明自主胚乳促进了无性胚胎的发育。转录组分析表明，雄性基因组表达的 OsBBM1 和 OsWOX8/9 在无性胚胎中被激活。同样，父本表达的印迹基因的母本等位基因在自主胚乳中被激活，这表明卵子器官和中央细胞通过沉默雄性基因组表达基因的母本等位基因，在受精前趋同采用 PRC2 来维持非分裂状态。
