RIKEN Plant Science Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa 230-0045, Japan.
Development. 2010 Jan;137(1):63-71. doi: 10.1242/dev.035840.
Amplification of genomic DNA by endoreduplication often marks the initiation of cell differentiation in animals and plants. The transition from mitotic cycles to endocycles should be developmentally programmed but how this process is regulated remains largely unknown. We show that the plant growth regulator auxin modulates the switch from mitotic cycles to endocycles in Arabidopsis; high levels of TIR1-AUX/IAA-ARF-dependent auxin signalling are required to repress endocycles, thus maintaining cells in mitotic cycles. By contrast, lower levels of TIR1-AUX/IAA-ARF-dependent auxin signalling trigger an exit from mitotic cycles and an entry into endocycles. Our data further demonstrate that this auxin-mediated modulation of the mitotic-to-endocycle switch is tightly coupled with the developmental transition from cell proliferation to cell differentiation in the Arabidopsis root meristem. The transient reduction of auxin signalling by an auxin antagonist PEO-IAA rapidly downregulates the expression of several core cell cycle genes, and we show that overexpressing one of the genes, CYCLIN A2;3 (CYCA2;3), partially suppresses an early initiation of cell differentiation induced by PEO-IAA. Taken together, these results suggest that auxin-mediated mitotic-to-endocycle transition might be part of the developmental programmes that balance cell proliferation and cell differentiation in the Arabidopsis root meristem.
基因组 DNA 通过内复制的扩增常常标志着动植物细胞分化的开始。从有丝分裂周期到内周期的转变应该是发育编程的，但这个过程如何被调节在很大程度上仍然未知。我们表明，植物生长调节剂生长素调节拟南芥中从有丝分裂周期到内周期的转变；高水平的 TIR1-AUX/IAA-ARF 依赖性生长素信号需要抑制内周期，从而使细胞保持在有丝分裂周期中。相比之下，较低水平的 TIR1-AUX/IAA-ARF 依赖性生长素信号触发有丝分裂周期的退出和内周期的进入。我们的数据进一步表明，这种生长素介导的有丝分裂到内周期转变的调节与拟南芥根分生组织中从细胞增殖到细胞分化的发育转变紧密耦合。生长素拮抗剂 PEO-IAA 对生长素信号的短暂抑制迅速下调了几个核心细胞周期基因的表达，我们表明，过表达其中一个基因，CYCLIN A2;3 (CYCA2;3)，部分抑制了由 PEO-IAA 诱导的早期细胞分化的开始。总之，这些结果表明，生长素介导的有丝分裂到内周期的转变可能是平衡拟南芥根分生组织中细胞增殖和细胞分化的发育程序的一部分。
