Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
Planta. 2010 Jan;231(2):411-24. doi: 10.1007/s00425-009-1059-3. Epub 2009 Nov 22.
Using transcript profile analysis, we explored the nature of the stem cell niche in roots of maize (Zea mays). Toward assessing a role for specific genes in the establishment and maintenance of the niche, we perturbed the niche and simultaneously monitored the spatial expression patterns of genes hypothesized as essential. Our results allow us to quantify and localize gene activities to specific portions of the niche: to the quiescent center (QC) or the proximal meristem (PM), or to both. The data point to molecular, biochemical and physiological processes associated with the specification and maintenance of the niche, and include reduced expression of metabolism-, redox- and certain cell cycle-associated transcripts in the QC, enrichment of auxin-associated transcripts within the entire niche, controls for the state of differentiation of QC cells, a role for cytokinins specifically in the PM portion of the niche, processes (repair machinery) for maintaining DNA integrity and a role for gene silencing in niche stabilization. To provide additional support for the hypothesized roles of the above-mentioned and other transcripts in niche specification, we overexpressed, in Arabidopsis, homologs of representative genes (eight) identified as highly enriched or reduced in the maize root QC. We conclude that the coordinated changes in expression of auxin-, redox-, cell cycle- and metabolism-associated genes suggest the linkage of gene networks at the level of transcription, thereby providing additional insights into events likely associated with root stem cell niche establishment and maintenance.
利用转录谱分析，我们探索了玉米（Zea mays）根中干细胞生态位的本质。为了评估特定基因在生态位的建立和维持中的作用，我们干扰了生态位，并同时监测了假设为必需的基因的空间表达模式。我们的结果使我们能够将基因活性定量和定位到生态位的特定部分：静止中心（QC）或近轴分生组织（PM），或两者兼而有之。这些数据指向与生态位的指定和维持相关的分子、生化和生理过程，包括 QC 中代谢、氧化还原和某些细胞周期相关转录本的表达减少，整个生态位中生长素相关转录本的富集，QC 细胞分化状态的对照，细胞分裂素在生态位 PM 部分的特定作用，维持 DNA 完整性的修复机制以及基因沉默在生态位稳定化中的作用。为了为上述和其他假设在生态位指定中发挥作用的转录本提供额外支持，我们在拟南芥中过表达了在玉米根 QC 中高度富集或减少的代表性基因（八种）的同源物。我们得出结论，与生长素、氧化还原、细胞周期和代谢相关基因的表达协调变化表明转录水平上基因网络的连接，从而为与根干细胞生态位建立和维持相关的事件提供了更多的见解。
