Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 90187 Umeå, Sweden.
IRBV, Department of Biological Sciences, University of Montreal, 4101 Sherbrooke Est, Montreal H1X 2B2, QC, Canada.
Sci Adv. 2022 Dec 9;8(49):eabq2047. doi: 10.1126/sciadv.abq2047.
Endoreplication is an evolutionarily conserved mechanism for increasing nuclear DNA content (ploidy). Ploidy frequently scales with final cell and organ size, suggesting a key role for endoreplication in these processes. However, exceptions exist, and, consequently, the endoreplication-size nexus remains enigmatic. Here, we show that prolonged tissue folding at the apical hook in Arabidopsis requires endoreplication asymmetry under the control of an auxin gradient. We identify a molecular pathway linking endoreplication levels to cell size through cell wall remodeling and stiffness modulation. We find that endoreplication is not only permissive for growth: Endoreplication reduction enhances wall stiffening, actively reducing cell size. The cell wall integrity kinase THESEUS plays a key role in this feedback loop. Our data thus explain the nonlinearity between ploidy levels and size while also providing a molecular mechanism linking mechanochemical signaling with endoreplication-mediated dynamic control of cell growth.
内复制是一种进化上保守的增加核 DNA 含量（ploidy）的机制。ploidy 通常与最终细胞和器官的大小成比例，表明内复制在这些过程中起着关键作用。然而，也存在例外，因此，内复制-大小关联仍然是一个谜。在这里，我们表明拟南芥顶端弯钩处的组织长时间折叠需要在生长素梯度的控制下进行不对称的内复制。我们通过细胞壁重塑和刚度调节鉴定了一条将内复制水平与细胞大小联系起来的分子途径。我们发现，内复制不仅允许生长：内复制减少会增强细胞壁硬度，从而主动减小细胞大小。细胞壁完整性激酶 THESEUS 在这个反馈环中起着关键作用。因此，我们的数据解释了ploidy 水平和大小之间的非线性关系，同时也提供了一个分子机制，将机械化学信号与内复制介导的细胞生长的动态控制联系起来。
