Oryza sativa RNA-Dependent RNA Polymerase 6 Contributes to Double-Strand Break Formation in Meiosis
Oryza sativa RNA-Dependent RNA Polymerase 6 Contributes to Double-Strand Break Formation in Meiosis
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DOI：
10.1105/tpc.20.00213
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发表时间：
2020-10-01
期刊：
影响因子：
11.6
通讯作者：
Cheng, Zhukuan
中科院分区：
文献类型：
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作者：
Liu, Changzhen;Shen, Yi;Cheng, Zhukuan
OsRDR 6在减数分裂过程中起着重要作用，可能与其介导小RNA合成有关，而RNA依赖性RNA聚合酶6（RNA-dependent RNA polymerase 6，RDR 6）是小RNA生物合成途径的核心成分，但其在减数分裂中的功能尚不清楚。在这里，我们报告了一个新的等位基因OsRDR 6（Osrdr 6-meiossis [Osrdr 6-mei]），它导致减数分裂特异性表型在水稻（水稻）。在Osrdr 6-mei中，减数分裂双链断裂（DSB）形成被部分阻断。我们通过将Osrdr 6-mei与敲除突变体Osrdr 6-edit杂交，创建了具有更严重表型的双等位基因突变体Osrdr 6-bi。在Osrdr 6-bi成熟母细胞中，观察到24个单价体，未检测到组蛋白H2 AX磷酸化灶。与野生型相比，Osrdr 6-mei中21个核苷酸的小RNA的数量显著降低，而24个核苷酸的小RNA的数量显著增加。在OsRDR 6-mei中发现了数千个差异甲基化区域（DMR），这意味着OsRDR 6在DNA甲基化中起重要作用。在Osrdr 6-mei中有457个基因表达下调，包括3个基因：CENTRAL REGION COMPONENT 1、P31（comet）和O. Sativa SOLO DANCERS，与DSB形成有关。有趣的是，下调的基因与高水平的24-核苷酸小RNA相关，但与DMR的相关性较低。因此，我们推测Osrdr 6突变体中小RNA表达的改变导致减数分裂期间DSB形成的缺陷，这可能不直接依赖于RNA指导的DNA甲基化。
OsRDR6 plays a crucial role in meiosis that might be related to its function in mediating small RNA genesis.RNA-dependent RNA polymerase 6 (RDR6) is a core component of the small RNA biogenesis pathway, but its function in meiosis is unclear. Here, we report a new allele of OsRDR6 (Osrdr6-meiosis [Osrdr6-mei]), which causes meiosis-specific phenotypes in rice (Oryza sativa). In Osrdr6-mei, meiotic double-strand break (DSB) formation is partially blocked. We created a biallelic mutant with more severe phenotypes, Osrdr6-bi, by crossing Osrdr6-mei with a knockout mutant, Osrdr6-edit. In Osrdr6-bi meiocytes, 24 univalents were observed, and no histone H2AX phosphorylation foci were detected. Compared with the wild type, the number of 21-nucleotide small RNAs in Osrdr6-mei was dramatically lower, while the number of 24-nucleotide small RNAs was significantly higher. Thousands of differentially methylated regions (DMRs) were discovered in Osrdr6-mei, implying that OsRDR6 plays an important role in DNA methylation. There were 457 genes downregulated in Osrdr6-mei, including three genes, CENTRAL REGION COMPONENT1, P31(comet), and O. sativa SOLO DANCERS, related to DSB formation. Interestingly, the downregulated genes were associated with a high level of 24-nucleotide small RNAs but less strongly associated with DMRs. Therefore, we speculate that the alteration in expression of small RNAs in Osrdr6 mutants leads to the defects in DSB formation during meiosis, which might not be directly dependent on RNA-directed DNA methylation.