PDF(Pubmed)
Abstract：
Wood formation involves consecutive developmental steps, including cell division of vascular cambium, xylem cell expansion, secondary cell wall (SCW) deposition, and programmed cell death. In this study, we identified PagMYB31 as a coordinator regulating these processes in Populus alba × Populus glandulosa and built a PagMYB31-mediated transcriptional regulatory network. PagMYB31 mutation caused fewer layers of cambial cells, larger fusiform initials, ray initials, vessels, fiber and ray cells, and enhanced xylem cell SCW thickening, showing that PagMYB31 positively regulates cambial cell proliferation and negatively regulates xylem cell expansion and SCW biosynthesis. PagMYB31 repressed xylem cell expansion and SCW thickening through directly inhibiting wall-modifying enzyme genes and the transcription factor genes that activate the whole SCW biosynthetic program, respectively. In cambium, PagMYB31 could promote cambial activity through TRACHEARY ELEMENT DIFFERENTIATION INHIBITORY FACTOR (TDIF)/PHLOEM INTERCALATED WITH XYLEM (PXY) signaling by directly regulating CLAVATA3/ESR-RELATED (CLE) genes, and it could also directly activate WUSCHEL HOMEOBOX RELATED4 (PagWOX4), forming a feedforward regulation. We also observed that PagMYB31 could either promote cell proliferation through the MYB31-MYB72-WOX4 module or inhibit cambial activity through the MYB31-MYB72-VASCULAR CAMBIUM-RELATED MADS2 (VCM2)/PIN-FORMED5 (PIN5) modules, suggesting its role in maintaining the homeostasis of vascular cambium. PagMYB31 could be a potential target to manipulate different developmental stages of wood formation.
摘要：
木材的形成涉及连续的发育步骤，包括血管形成层的细胞分裂，木质部细胞扩增,次生细胞壁（SCW）沉积，和程序性细胞死亡。在这项研究中,我们将PagMYB31确定为调节白杨×甘杜叶杨中这些过程的协调者，并建立了PagMYB31介导的转录调节网络。PagMYB31突变导致形成层细胞减少，较大的梭形首字母，射线首字母,船只,纤维和射线细胞，和增强木质部细胞SCW增厚，表明PagMYB31正调节形成层细胞增殖，负调节木质部细胞扩增和SCW生物合成。PagMYB31通过直接抑制壁修饰酶基因和激活整个SCW生物合成程序的转录因子基因来抑制木质部细胞扩增和SCW增厚，分别。在形成层中，PagMYB31可以通过直接调节CLAVATA3/ESR相关（CLE）基因，通过与XYLEM（PXY）信号传导的TRACHEMENT分化抑制因子（TDIF）/PHLOEM促进形成层活性，它还可以直接激活WUSCHELHOMEOBOXRELATED4（PagWOX4），形成前馈调节。我们还观察到PagMYB31可以通过MYB31-MYB72-WOX4模块促进细胞增殖，或通过MYB31-MYB72-血管相关的MADS2（VCM2）/PIN-FORMED5（PIN5）模块抑制形成层活动，提示其在维持血管形成层稳态中的作用。PagMYB31可能是操纵木材形成的不同发育阶段的潜在靶标。
