School of Biological Science and Technology, College of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan.
RIKEN Center for Sustainable Resource Science, Yokohama, 230-0045, Japan.
Plant Signal Behav. 2023 Dec 31;18(1):2153209. doi: 10.1080/15592324.2022.2153209. Epub 2022 Dec 28.
Cell size control is one of the prerequisites for plant growth and development. Recently, a GRAS family transcription factor, SCARECROW-LIKE28 (SCL28), was identified as a critical regulator for both mitotic and postmitotic cell-size control. Here, we show that is specifically expressed in proliferating cells and exerts its function to delay G2 progression during mitotic cell cycle in . Overexpression of provokes a significant enlargement of cells in various organs and tissues, such as leaves, flowers and seeds, to different extents depending on the type of cells. The increased cell size is most likely due to a delayed G2 progression and accelerated onset of endoreplication, an atypical cell cycle repeating DNA replication without cytokinesis or mitosis. Unlike , a rice ortholog of , SCL28 may not have a role in brassinosteroid (BR) signaling because sensitivity against brassinazole, a BR biosynthesis inhibitor, was not dramatically altered in mutant and -overexpressing plants. Collectively, our findings strengthen a recently proposed model of cell size control by SCL28 and suggest the presence of diversified evolutionary mechanisms for the regulation and action of SCL28.
细胞大小控制是植物生长和发育的前提条件之一。最近，一种GRAS 家族转录因子 SCARECROW-LIKE28（SCL28）被鉴定为有丝分裂和有丝分裂后细胞大小控制的关键调节因子。在这里，我们表明 特异性表达在增殖细胞中，并在拟南芥的有丝分裂细胞周期中发挥作用，延迟 G2 期进展。过表达 会引起各种器官和组织（如叶片、花朵和种子）中的细胞显著增大，其程度取决于细胞类型。细胞大小的增加很可能是由于 G2 期进展延迟和内复制（一种非典型的细胞周期，在没有胞质分裂或有丝分裂的情况下重复 DNA 复制）的起始加速所致。与 不同，拟南芥的 SCL28 水稻同源物可能在油菜素内酯（BR）信号转导中不起作用，因为油菜素唑（BR 生物合成抑制剂）对 突变体和过表达植物的敏感性没有明显改变。总的来说，我们的发现加强了 SCL28 细胞大小控制的最新模型，并表明 SCL28 的调节和作用存在多样化的进化机制。
