Appropriate cell cycle regulation is crucial for achieving coordinated development and cell differentiation in multicellular organisms. In Arabidopsis, endoreduplication is often observed in terminally differentiated cells and several reports have shown its molecular mechanisms. Auxin is a key factor for the mode transition from mitotic cell cycle to endocycle; however, it remains unclear if and how auxin maintains the endocycle mode. In this study, we reanalyzed root single-cell transcriptome data and reconstructed cell cycle trajectories of the mitotic cell cycle and endocycle. With progression of the endocycle, genes involved in auxin synthesis, influx and efflux were induced at the specific cell phase, suggesting that auxin concentration fluctuated dynamically. Such induction of auxin-related genes was not observed in the mitotic cell cycle, suggesting that the auxin fluctuation plays some roles in maintaining the endocycle stage. In addition, the expression level of CYCB1;1, which is required for cell division in the M phase, coincided with the expected amount of auxin and cell division. Our analysis also provided a set of genes expressed in specific phases of the cell cycle. Taking these findings together, reconstruction of single-cell transcriptome data enables us to identify properties of the cell cycle more accurately.

中文翻译：

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时间序列单细胞RNA-Seq数据揭示了周期内生长素的波动。

适当的细胞周期调节对于在多细胞生物中实现协调的发育和细胞分化至关重要。在拟南芥中，经常在终末分化的细胞中观察到核内复制，并且一些报告显示了其分子机制。生长素是从有丝分裂细胞周期到内周期模式转变的关键因素。然而，目前尚不清楚植物生长素是否以及如何维持内循环模式。在这项研究中，我们重新分析了根单细胞转录组数据，并重建了有丝分裂细胞周期和内周期的细胞周期轨迹。随着内循环的进行，在特定的细胞相中诱导了涉及植物生长素合成，内流和外排的基因，这表明植物生长素的浓度是动态变化的。在有丝分裂细胞周期中未观察到这种与生长素相关基因的诱导，提示生长素的波动在维持内皮周期阶段中起一定作用。此外，M期细胞分裂所需的CYCB1; 1的表达水平与生长素和细胞分裂的预期数量相吻合。我们的分析还提供了一组在细胞周期特定阶段表达的基因。综合这些发现，单细胞转录组数据的重建使我们能够更准确地鉴定细胞周期的特性。