背景回顾：Cellular heterogeneity is a hallmark of multicellular organisms. During shoot regeneration from undifferentiated callus, only a select few cells, called progenitors, develop into shoot. 

提出问题：How these cells are selected and what governs their subsequent progression to a patterned organ system is unknown. 

主要发现：Using Arabidopsis thaliana, we show that it is not just the abundance of stem cell regulators but rather the localization pattern of polarity proteins that predicts the progenitor’s fate. 

结果1-CUC2-XTH9：A shoot-promoting factor, CUC2, activated the expression of the cell-wall-loosening enzyme, XTH9, solely in a shell of cells surrounding the progenitor, causing different mechanical stresses in these cells.  

结果2-机械应力冲突促进祖细胞的细胞极性：This mechanical conflict then activates cell polarity in progenitors to promote meristem formation. Interestingly, genetic or physical perturbations to cells surrounding the progenitor impaired the progenitor and vice versa. 

结论：These suggest a feedback loop between progenitors and their neighbors for shoot regeneration in the absence of tissue-patterning cues.

 摘 要 

细胞异质性是多细胞生物的一个特征。在未分化的愈伤组织进行芽再生过程中，只有被称为祖细胞的少数细胞能够再生发育成芽。这些细胞是如何被选择的，以及什么赋予了这些细胞随后进入模式建成，最终形成一套完整的器官体系。本文中，作者以拟南芥为研究对象，发现相比于干细胞调控因子的丰度，极性蛋白的定位更有可能预测祖细胞的命运。一个促进芽形成的因子CUC2能够在祖细胞周边的细胞壳中激活细胞壁松弛酶XTH9的表达，从而导致这些细胞产生不同的机械应力。接着，这种机械应力的冲突会激活祖细胞的细胞极性，从而以促进分生组织的形成。有趣的是，通过遗传或者物理破坏祖细胞的周边细胞，能够破坏祖细胞，反之亦然。这些结果表明，在没有组织模式建成时，祖细胞及其周边细胞存在一个反馈回路，作用于芽再生。

 Kalika Prasad