Endoreplication is a type of cell cycle where genome replication occurs without mitosis. An increase of ploidy level by endoreplication is often associated with cell enlargement and an enhanced plant growth. Here we report Arabidopsis thaliana subclass I ACTIN DEPOLYMERIZING FACTORs (ADFs) and vegetative ACTIN2/8 as novel regulators of endoreplication. A. thaliana has 11 ADF members that are divided into 4 subclasses. Subclass I consists of four members, ADF1, -2, -3, and -4, all of which constitutively express in various tissues. We found that both adf4 knockout mutant and transgenic plants in which expressions of all of four subclass I ADFs are suppressed (ADF1-4Ri) showed an increased leaf area of mature first leaves, which was associated with a significant increase of epidermal pavement cell area. Ploidy analysis revealed that the ploidy level was significantly increased in mature leaves of ADF1-4Ri. The increased ploidy was also observed in roots of adf4 and ADF1-4Ri, as well as in dark-grown hypocotyls of adf4. Furthermore, double mutants of vegetative ACT2 and ACT8 (act2/8) exhibited an increase of leaf area and ploidy level in mature leaves. Therefore, actin-relating pathway could regulate endoreplication. The possible mechanisms that actin and ADFs regulate endoreplication are discussed.

Endoreplication 是一种细胞周期，其中基因组复制发生而没有有丝分裂。通过内复制增加倍性水平通常与细胞增大和植物生长增强有关。在这里，我们报告拟南芥亚类 I 肌动蛋白解聚因子 (ADF) 和营养性 ACTIN2/8 作为内复制的新型调节剂。A. thaliana有 11 个 ADF 成员，分为 4 个亚类。子类 I 由四个成员ADF1、-2、-3和-4 组成，所有这些成员都在各种组织中组成型表达。我们发现adf4敲除突变体和转基因植物中所有四个亚类 I ADF 的表达s 被抑制 ( ADF1-4Ri ) 显示成熟第一叶的叶面积增加，这与表皮铺面细胞面积的显着增加有关。倍性分析表明，ADF1-4Ri成熟叶片的倍性水平显着增加。增加的倍性也在根观察ADF4和ADF1-4Ri，在黑暗生长的下胚轴以及ADF4。此外，植物性ACT2和ACT8 的双突变体( act2/8) 表现出成熟叶中叶面积和倍性水平的增加。因此，肌动蛋白相关通路可以调节内复制。讨论了肌动蛋白和 ADF 调节内复制的可能机制。