A PXY-Mediated Transcriptional Network Integrates Signaling Mechanisms to Control Vascular Development in Arabidopsis

First author: Margot Smit; Affiliations: Wageningen University and Research (瓦赫宁根大学和研究中心): Wageningen, Netherlands

Corresponding author: Peter Etchells

Vascular meristems generate the majority of biomass in higher plants. They constitute a bifacial stem cell population from which xylem and phloem are specified on opposing sides by positional signals. The PHLOEM INTERCALATED WITH XYLEM (PXY) receptor kinase promotes vascular cell division and organisation. However, how these functions are specified and integrated is unknown. Here, a putative PXY-mediated transcriptional regulatory network comprised of 690 transcription factor-promoter interactions was mapped. Among these interactions was a feed-forward loop containing transcription factors WUSCHEL HOMEOBOX RELATED 14 (WOX14) and TARGET OF MONOPTEROS 6 (TMO6), which each regulate the expression of a third transcription factor, LATERAL ORGAN BOUNDARIES DOMAIN 4 (LBD4). PXY signalling in turn regulates the WOX14, TMO6, LBD4 loop to control vascular proliferation. Genetic interaction between LBD4 and PXY suggests that LBD4 marks the phloem-procambium boundary, thus defining the shape of the vascular bundle. These data collectively support a novel mechanism that influences recruitment of cells into the phloem lineage, and defines the role of PXY signalling in this context to the arrangement of vascular tissue.

维管分生组织产生高等植物主要的生物量。这些维管分生组织构成一个双面的干细胞群体，从中根据空间位置信号会在两侧分别分化出木质部和韧皮部。PXY受体激酶促进维管细胞的分裂和组织形成。然而，PXY蛋白实现其功能的具体分子机制还不清楚。本文中，作者揭示了一个PXY介导的转录调控网络，涉及了690个转录因子-启动子互作关系。在这些互作关系中存在一个正向调控环，其包含转录因子WOX14和TMO6，而这两个转录因子都能够调控另一个转录因子LBD4的表达。因此，PXY信号通路通过调控WOX14、TMO6以及LBD4环来控制植物维管的增殖。LBD4基因与PXY基因之间的遗传互作证明LBD4能够标记韧皮部与原形成层之间的边界，因此定义了维管束的形态。本文的研究揭示了一个影响细胞被招募到韧皮部的新的分子机制，同时也揭示了PXY信号通路在该情况下对于维管组织排列的作用。

通讯：Peter Etchells (https://www.dur.ac.uk/research/directory/staff/?id=11639)

个人简介：1995-1999年，圣安德鲁斯大学，学士；1999-2003年，爱丁堡大学，博士；2003-2004年，牛津大学，博士后；2004-2007年，约翰·英尼斯中心，博士后。

研究方向：植物维管组织的发育。

doi: https://doi.org/10.1105/tpc.19.00562

Journal: Plant Cell

First Published: December 05, 2019