Department of Plant Biology and Genome Center, University of California, Davis, Davis, CA 95616, USA.
Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA.
Cell Rep. 2019 Jul 9;28(2):342-351.e4. doi: 10.1016/j.celrep.2019.06.041.
Plant xylem cells conduct water and mineral nutrients. Although most plant cells are totipotent, xylem cells are unusual and undergo terminal differentiation. Many genes regulating this process are well characterized, including the Vascular-related NAC Domain 7 (VND7), MYB46, and MYB83 transcription factors, which are proposed to act in interconnected feedforward loops (FFLs). Less is known regarding the molecular mechanisms underlying the terminal transition to xylem cell differentiation. Here, we generate whole-root and single-cell data, which demonstrate that VND7 initiates sharp switching of root cells to xylem cell identity. Based on these data, we identified 4 candidate VND7 downstream target genes capable of generating this switch. Although MYB46 responds to VND7 induction, it is not among these targets. This system provides an important model to study the emergent properties that may give rise to totipotency relative to terminal differentiation and reveals xylem cell subtypes.
植物木质部细胞输送水分和矿物质养分。虽然大多数植物细胞具有全能性，但木质部细胞很特殊，会经历终末分化。许多调节这个过程的基因已经得到很好的描述，包括与血管相关的 NAC 结构域蛋白 7（VND7）、MYB46 和 MYB83 转录因子，它们被认为在相互连接的前馈环（FFLs）中发挥作用。关于木质部细胞终末分化的分子机制知之甚少。在这里，我们生成了全根和单细胞数据，这些数据表明 VND7 启动了根细胞向木质部细胞身份的急剧转变。基于这些数据，我们鉴定出 4 个候选的 VND7 下游靶基因，它们能够产生这种转变。尽管 MYB46 对 VND7 的诱导有反应，但它不在这些靶基因之列。这个系统为研究相对于终末分化出现的全能性的涌现特性提供了一个重要模型，并揭示了木质部细胞亚型。
