相对于动物干细胞，植物有其自身干细胞版本。植物干细胞，或分裂组织，可以发育成几乎所有细胞类型。植物的地上部分，例如花、叶和种子是由枝条顶端分生组织（SAM）产生的，SAM是位于茎的顶端的特种分生组织。与动物干细胞不同，只要植物在生长，枝条顶端分生组织就能分化成任何种类细胞。尽管干细胞非常重要，但他们的分子构成却一直是科学家的难题。
加洲大学河滨分校的G.V. Reddy及其同事通过研究模式植物拟南芥，鉴定了所有在植物干细胞表达的基因。他们同时精确指出了在分生细胞和调控植物分生细胞死亡的壁龛细胞中表达的基因。此结果将有助于科学家更好地理解干细胞主导的分子路径，并为培育更好的作物和植物品种开创道路。研究也将帮助科学家深刻理解一些基础问题，例如什么决定干细胞身份，为什么植物和动物的干细胞都能转变为特定细胞。（生物谷Bioon.com）
生物谷推荐原始出处：
PNAS March 3, 2009, doi: 10.1073/pnas.0900843106
Gene expression map of the Arabidopsis shoot apical meristem stem cell niche
Ram Kishor Yadav, Thomas Girke, Sumana Pasala, Mingtang Xie and G. Venugopala Reddy,1
1 Center for Plant Cell Biology and Department of Botany and Plant Sciences, 2150 Batchelor Hall, University of California, Riverside, CA 92521.
Despite the central importance of stem cells in plant growth and development, the molecular signatures associated with them have not been revealed. Shoot apical meristems (SAMs) harbor a small set of stem cells located at the tip of each plant and they are surrounded by several million differentiating cells. This imposes a major limitation in isolating pure populations of stem cells for genomic analyses. We have developed a system to isolate pure populations of distinct cell types of the SAMs, including stem cells. We have used this system to profile gene expression from 4 different cell samples of SAMs. The cell sample-specific gene expression profiling has resulted in a high-resolution gene expression map to reveal gene expression networks specific to individual spatial domains of SAMs. We demonstrate that the cell sample-specific expression profiling is sensitive in identifying rare transcripts expressed in a few specific subsets of cells of SAMs. Our extensive RNA in situ analysis reveals that the expression map can be used as a predictive tool in analyzing the spatial expression patterns of genes and it has led to the identification of unique gene expression patterns within the SAMs. Furthermore, our work reveals an enrichment of DNA repair and chromatin modification pathways in stem cells suggesting that maintenance of genome stability and flexible chromatin may be crucial for stem cell function. The gene expression map should guide future reverse genetics experiments, high-resolution analyses of cell–cell communication networks and epigenetic modifications.
