Department of Plant Sciences, Laboratory of Molecular Biology, Wageningen University, 6708 PB Wageningen, The Netherlands.
Unité de Recherche en Génomique Végétale, UMR INRA 1165, Université d'Evry Val d'Essonne, ERL CNRS 8196, Saclay Plant Sciences, 91057 Evry, France.
Plant Cell. 2017 Sep;29(9):2183-2196. doi: 10.1105/tpc.17.00366. Epub 2017 Aug 30.
Root growth is modulated by environmental factors and depends on cell production in the root meristem (RM). New cells in the meristem are generated by stem cells and transit-amplifying cells, which together determine RM cell number. Transcription factors and chromatin-remodeling factors have been implicated in regulating the switch from stem cells to transit-amplifying cells. Here, we show that two paralogs encoding plant-specific histone deacetylases, HDT1 and HDT2, regulate a second switch from transit-amplifying cells to expanding cells. Knockdown of () results in an earlier switch and causes a reduced RM cell number. Our data show that HDT1/2 negatively regulate the acetylation level of the () locus and repress the expression of in the RM and elongation zone. Overexpression of in the RM phenocopies the phenotype. Conversely, knockout of partially rescues the root growth defect of These results suggest that by repressing the expression of , HDT1/2 likely fine-tune gibberellin metabolism and they are crucial for regulating the switch from cell division to expansion to determine RM cell number. We propose that HDT1/2 function as part of a mechanism that modulates root growth in response to environmental factors.
根的生长受到环境因素的调节，并且依赖于根分生组织（RM）中的细胞产生。分生组织中的新细胞由干细胞和过渡扩增细胞产生，这两者共同决定了 RM 细胞的数量。转录因子和染色质重塑因子已被牵涉到调节干细胞向过渡扩增细胞的转变。在这里，我们表明，编码植物特异性组蛋白去乙酰化酶的两个同源物 HDT1 和 HDT2，调节从过渡扩增细胞到扩展细胞的第二个转变。（）的敲低导致更早的转变，并导致 RM 细胞数量减少。我们的数据表明，HDT1/2 负调控（）基因座的乙酰化水平，并在 RM 和伸长区抑制的表达。在 RM 中过表达（）可模拟（）表型。相反，（）的敲除部分挽救了（）的根生长缺陷。这些结果表明，通过抑制的表达，HDT1/2 可能精细调节赤霉素代谢，它们对于调节从细胞分裂到扩展的转变以确定 RM 细胞数量至关重要。我们提出 HDT1/2 作为响应环境因素调节根生长的机制的一部分发挥作用。
