Qi Dongmei, Wen Qingqing, Meng Ze, Yuan Shan, Guo Hong, Zhao Hongtao, Cui Sujuan
Hebei Key Laboratory of Molecular and Cellular Biology, Hebei Normal University, Hebei, 050024, China.
Key Laboratory of Molecular and Cellular Biology of Ministry of Education, Hebei Normal University, Hebei, 050024, China.
Plant J. 2020 Nov;104(4):901-916. doi: 10.1111/tpj.14967. Epub 2020 Sep 7.
Rice (Oryza sativa L.) endosperm provides the developing embryo with nutrients and provides human beings with a staple food. The embryo eventually develops into a new sporophyte generation. Despite their important roles, the molecular mechanisms underlying early-stage endosperm and embryo development remain elusive. Here, we established the fundamental functions of rice OsLFR, an ortholog of the Arabidopsis SWI/SNF chromatin-remodeling complex (CRC) component LFR. OsLFR was expressed primarily in the rice spikelets and seeds, and the OsLFR protein was localized to the nucleus. We conducted genetic, cellular and molecular analyses of loss-of-function mutants and transgenic rescue lines. OsLFR depletion resulted in homozygous lethality in the early seed stage through endosperm and embryo defects, which could be successfully recovered by the OsLFR genomic sequence. Cytological observations revealed that the oslfr endosperm had relatively fewer free nuclei, had abnormal and arrested cellularization, and demonstrated premature programed cell death: the embryo was reduced in size and failed to differentiate. Transcriptome profiling showed that many genes, involved in DNA replication, cell cycle, cell wall assembly and cell death, were differentially expressed in a knockout mutant of OsLFR (oslfr-1), which was consistent with the observed seed defects. Protein-protein interaction analysis showed that OsLFR physically interacts with several putative rice SWI/SNF CRC components. Our findings demonstrate that OsLFR, possibly as one component of the SWI/SNF CRC, is an essential regulator of rice seed development, and provide further insights into the regulatory mechanism of early-stage rice endosperm and embryo development.
水稻（Oryza sativa L.）胚乳为发育中的胚提供营养，并为人类提供主食。胚最终发育成新的孢子体世代。尽管它们具有重要作用，但胚乳和胚早期发育的分子机制仍不清楚。在这里，我们确定了水稻OsLFR的基本功能，它是拟南芥SWI/SNF染色质重塑复合体（CRC）组分LFR的直系同源物。OsLFR主要在水稻小穗和种子中表达，且OsLFR蛋白定位于细胞核。我们对功能缺失突变体和转基因拯救系进行了遗传、细胞和分子分析。OsLFR缺失通过胚乳和胚缺陷导致种子早期纯合致死，而OsLFR基因组序列可成功挽救这种致死现象。细胞学观察表明，oslfr胚乳的游离核相对较少，细胞化异常并停滞，且出现过早的程序性细胞死亡：胚体积减小且未能分化。转录组分析表明，许多参与DNA复制、细胞周期、细胞壁组装和细胞死亡的基因在OsLFR敲除突变体（oslfr-1）中差异表达，这与观察到的种子缺陷一致。蛋白质-蛋白质相互作用分析表明，OsLFR与几种假定的水稻SWI/SNF CRC组分发生物理相互作用。我们的研究结果表明，OsLFR可能作为SWI/SNF CRC的一个组分，是水稻种子发育的关键调节因子，并为水稻胚乳和胚早期发育的调控机制提供了进一步的见解。
