背景回顾：In plants, vascular stem cells located in the cambium continuously undergo self-renewal and differentiation during secondary growth. Recent advancements in cell sorting techniques have enabled access to the transcriptional regulatory framework of cambial cells. 

提出问题：However, mechanisms underlying the robust control of vascular stem cells remain unclear.

主要研究：Here, we identified a new cambium-related regulatory module through co-expression network analysis using multiple transcriptome datasets obtained from an ectopic vascular cell transdifferentiation system using Arabidopsis cotyledons, VISUAL. 

结果1-BEH3鉴定：The cambium gene list included a gene encoding the transcription factor BES1/BZR1 Homolog 3 (BEH3), whose homolog BES1 negatively affects vascular stem cell maintenance. 

结果2-功能缺失突变：Interestingly, null beh3 mutant alleles showed a large variation in their vascular size, indicating that BEH3 functions as a stabilizer of vascular stem cells. 

结果3-遗传学实验：Genetic analysis revealed that BEH3 and BES1 perform opposite functions in the regulation of vascular stem cells and the differentiation of vascular cells in the context of the VISUAL system. 

结果4-生化实验：At the biochemical level, BEH3 showed weak transcriptional repressor activity and functioned antagonistically to other BES/BZR members by competing for binding to the brassinosteroid (BR) response element. 

结果5-模型构建：Furthermore, mathematical modeling suggested that the competitive relationship between BES/BZR homologs leads to the robust regulation of vascular stem cells.

 摘 要 

在植物中，维管干细胞位于形成层中，在次生生长过程中能够持续不断的进行自我更新和分化。最近在细胞分选技术方面的发展，使得研究形成层细胞的转录调控框架成为可能。但是，有关维管干细胞的稳定调控机制还不清楚。本文中，作者利用拟南芥子叶异位维管细胞转分化系统（VISUAL）测得了多个转录组，并通过共表达网络的构建鉴定了一个新的形成层相关的调控模块。形成层基因列表中包含了一个编码BES1/BZR1同源物BEH3的转录因子，该蛋白的同源蛋白BES1能够负作用于维管干细胞的维持。有趣的是，无义beh3突变体等位基因在其维管细胞大小特征上表现出极大的变异，说明BEH3可能发挥稳定维管干细胞的功能。基于VISUAL系统中的遗传学实验显示，BEH3和BES1在调控维管干细胞和维管细胞分化方面存在相反的功能。在生化层面，BEH3表现出较弱的转录抑制活性，并且通过竞争性结合到油菜素内酯（BR）响应元件，与其它的BES/BZR成员存在拮抗作用。此外，数学模型表明，BES/BZR同源物之间的竞争关系形成了对维管干细胞的稳健调控。