State Key Laboratory of Hybrid Rice, College of Life Science, Wuhan University, Wuhan, 430072, China.
Laboratory of Brassicaceae, Wuhan Institute of Vegetable Science, Wuhan, 430345, China.
New Phytol. 2014 Jan;201(1):66-79. doi: 10.1111/nph.12472. Epub 2013 Sep 10.
Polycomb group (PcG) proteins are gene repressors that help to maintain cellular identity during development via chromatin remodeling. Fertilization-independent endosperm (FIE), a member of the PcG complex, operates extensively in plant development, but its role in rice has not been fully investigated to date. We report the isolation and characterization of a PcG member in rice, which was designated OsFIE2 for Oryza sativa Fertilization-Independent Endosperm 2. OsFIE2 is a single-copy gene in the rice genome and shows a universal expression pattern. The OsFIE2 RNAi lines displayed pleiotropic phenotypes in vegetative and reproductive organ generation. In unfertilized lines, endosperm formation could be triggered without embryo formation, which indicates that FIE is indeed involved in the suppression of autonomous endosperm development in rice. Furthermore, lateral root generation was promoted early in the roots of OsFIE2 RNAi lines, whereas the primary root was premature and highly differentiated. As the root tip stem cell differentiated, QHB, the gene required for stem cell maintenance in the quiescent center, was down-regulated. Our data suggest that the OsFIE2-PcG complex is vital for rice reproduction and endosperm formation. Its role in stem cell maintenance suggests that the gene is functionally conserved in plants as well as animals.
多梳组 (PcG) 蛋白是基因沉默因子，通过染色质重塑帮助在发育过程中维持细胞身份。无融合生殖胚乳 (FIE)，PcG 复合物的一个成员，在植物发育中广泛发挥作用，但迄今为止，其在水稻中的作用尚未得到充分研究。我们报告了水稻中 PcG 成员的分离和鉴定，该成员被命名为 OsFIE2，代表水稻无融合生殖胚乳 2。OsFIE2 是水稻基因组中的单拷贝基因，表现出普遍的表达模式。OsFIE2 RNAi 系在营养和生殖器官发生中表现出多效表型。在未受精的系中，没有胚胎形成也可以触发胚乳形成，这表明 FIE 确实参与了对水稻自主胚乳发育的抑制。此外，OsFIE2 RNAi 系的侧根生成在根早期被促进，而主根则提前且高度分化。随着根尖干细胞分化，维持干细胞的 QHB 基因下调。我们的数据表明，OsFIE2-PcG 复合物对水稻繁殖和胚乳形成至关重要。其在干细胞维持中的作用表明该基因在植物和动物中具有功能保守性。
