Table_2_Arabidopsis ZUOTIN RELATED FACTOR1 Proteins Are Required for Proper Embryonic and Post-Embryonic Root Development.xlsx

The H2A/UBIQUITIN-binding proteins AtZRF1a/b have been reported as key regulators involved in multiple processes of Arabidopsis plant growth and development. Yet, the cellular and molecular mechanisms underlying the mutant phenotype remain largely elusive. Here we show that loss-of-function of AtZRF1a/b causes defective root elongation and deformed root apical meristem organization in seedlings. The premature termination of the primary root in the atzrf1a;atzrf1b double mutant is associated with an advanced onset of endoreduplication and subsequent consumption of reservoir stem cells. Cytological analyses using cell type-specific markers and florescent dyes indicate that AtZRF1a/b are involved in maintenance of proper cell layer organization, determinacy of cell identity, and establishment of auxin gradient and maximum at the root tip. During embryogenesis AtZRF1a/b act dominantly in regulating the maintenance of ground tissue initial cells and production of lateral root cap. Lastly, quantitative real-time polymerase chain reaction analysis shows mis-expression of some key genes involved in regulating cell patterning, cell proliferation and/or hormone pathways. Our results provide important insight into AtZRF1a/b function in cell fate determinacy and in establishment and maintenance of proper stem cell reservoir during embryonic and post-embryonic root development.

H2A/泛素结合蛋白AtZRF1a/b已被报道为参与调控拟南芥植物生长与发育多个过程的关键调节因子。然而，关于突变体表型的细胞和分子机制仍鲜有探究。本研究揭示，AtZRF1a/b功能的丧失会导致幼苗根伸长缺陷及根尖分生组织形态异常。在atzrf1a;atzrf1b双突变体中，初生根的过早终止与内复制提前发生以及储备干细胞消耗有关。利用细胞类型特异性标记和荧光染料进行的细胞学分析表明，AtZRF1a/b参与维持适当的细胞层组织结构、细胞身份的确定性以及建立根尖的赤霉素梯度及最大值。在胚胎发生过程中，AtZRF1a/b在调节初始分生组织细胞的维持和侧生根冠的产生中起主导作用。最后，定量实时聚合酶链式反应分析显示，一些参与调控细胞图案、细胞增殖及/或激素途径的关键基因表达出现异常。本研究结果对AtZRF1a/b在细胞命运确定性、胚胎及胚后根发育过程中正确干细胞储备的建立与维持方面的功能提供了重要见解。