Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences and Viikki Plant Science Centre, University of Helsinki, 00014 Helsinki, Finland.
Institute of Biotechnology, HiLIFE, University of Helsinki, 00014 Helsinki, Finland.
Science. 2024 Nov 8;386(6722):646-653. doi: 10.1126/science.adj8752. Epub 2024 Nov 7.
Wood constitutes the largest reservoir of terrestrial biomass. Composed of xylem, it arises from one side of the vascular cambium, a bifacial stem cell niche that also produces phloem on the opposing side. It is currently unknown which molecular factors endow cambium stem cell identity. Here we show that TRACHEARY ELEMENT DIFFERENTIATION INHIBITORY FACTOR (TDIF) ligand-activated PHLOEM INTERCALATED WITH XYLEM (PXY) receptors promote the expression of CAMBIUM-EXPRESSED AINTEGUMENTA-LIKE (CAIL) transcription factors to define cambium stem cell identity in the root. By sequestrating the phloem-originated TDIF, xylem-expressed PXY confines the TDIF signaling front, resulting in the activation of CAIL expression and stem cell identity in only a narrow domain. Our findings show how signals emanating from cells on opposing sides ensure robust yet dynamically adjustable positioning of a bifacial stem cell layer.
木材构成了陆地生物量的最大储存库。它由木质部组成，起源于维管形成层的一侧，维管形成层是一个双面的茎干细胞巢，在另一侧也产生韧皮部。目前还不知道哪些分子因素赋予形成层干细胞身份。在这里，我们表明，木质部衍生的 PHLOEM INTERCALATED WITH XYLEM (PXY) 受体激活的 TRACHEARY ELEMENT DIFFERENTIATION INHIBITORY FACTOR (TDIF) 配体促进 CAMBIUM-EXPRESSED AINTEGUMENTA-LIKE (CAIL) 转录因子的表达，以确定根中形成层干细胞的身份。通过隔离源自韧皮部的 TDIF，木质部表达的 PXY 限制了 TDIF 信号前缘，从而仅在一个狭窄的区域激活 CAIL 表达和干细胞身份。我们的发现表明，来自相对侧细胞的信号如何确保双面茎干细胞层的强大但动态可调定位。
