Table_3_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/UBIQUITIN结合蛋白AtZRF1a/b已被报道为参与调控拟南芥植物生长和发育多个过程的的关键调节因子。然而，其突变型表型的细胞和分子机制至今尚不明晰。本研究揭示了AtZRF1a/b功能缺失导致幼苗根伸长缺陷及根顶端分生组织结构异常。在atzrf1a;atzrf1b双突变体中，初级根的早期终止与内复制的提前发生及随后的储备干细胞消耗相关。通过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在维持适当的细胞层组织、决定细胞身份以及建立根尖处的生长素梯度和最大值中发挥作用。在胚胎发生过程中，AtZRF1a/b在调节基本组织原细胞的维持和侧根根冠的产生中起主导作用。最后，定量实时聚合酶链反应分析显示，一些涉及调控细胞模式、细胞增殖和/或激素途径的关键基因表达出现异常。我们的研究结果为理解AtZRF1a/b在细胞命运决定、胚胎和胚胎后根发育过程中维持适当的干细胞储备库中的作用提供了重要的见解。