A PtrLBD39-mediated transcriptional network regulates tension wood formation in Populus trichocarpa

Jing Yu; Chenguang Zhou; Danning Li; Shuang Li; Ying-Chung Jimmy Lin; Jack P Wang; Vincent L Chiang; Wei Li

doi:10.1016/j.xplc.2021.100250

A PtrLBD39-mediated transcriptional network regulates tension wood formation in Populus trichocarpa

Plant Commun. 2021 Oct 20;3(1):100250. doi: 10.1016/j.xplc.2021.100250. eCollection 2022 Jan 10.

Authors

Jing Yu¹, Chenguang Zhou¹, Danning Li¹, Shuang Li¹, Ying-Chung Jimmy Lin^{1

2}, Jack P Wang^{1

3}, Vincent L Chiang^{1

3}, Wei Li¹

Affiliations

¹ State Key Laboratory of Tree Genetics and Breeding, Northeast Forestry University, Harbin 150040, China.
² Department of Life Sciences and Institute of Plant Biology, College of Life Science, National Taiwan University, Taipei, Taiwan 10617, China.
³ Department of Forestry and Environmental Resources, Forest Biotechnology Group, North Carolina State University, Raleigh, NC 27695, USA.

Abstract

Tension wood (TW) is a specialized xylem tissue formed in angiosperm trees under gravitational stimulus or mechanical stresses (e.g., bending). The genetic regulation that underlies this important mechanism remains poorly understood. Here, we used laser capture microdissection of stem xylem cells coupled with full transcriptome RNA-sequencing to analyze TW formation in Populus trichocarpa. After tree bending, PtrLBD39 was the most significantly induced transcription factor gene; it has a phylogenetically paired homolog, PtrLBD22. CRISPR-based knockout of PtrLBD39/22 severely inhibited TW formation, reducing cellulose and increasing lignin content. Transcriptomic analyses of CRISPR-based PtrLBD39/22 double mutants showed that these two genes regulate a set of TW-related genes. Chromatin immunoprecipitation sequencing (ChIP-seq) was used to identify direct targets of PtrLBD39. We integrated transcriptomic analyses and ChIP-seq assays to construct a transcriptional regulatory network (TRN) mediated by PtrLBD39. In this TRN, PtrLBD39 directly regulates 26 novel TW-responsive transcription factor genes. Our work suggests that PtrLBD39 and PtrLBD22 specifically control TW formation by mediating a TW-specific TRN in Populus.

Keywords: cellulose; chromatin immunoprecipitation sequencing; lignin; tension wood; transcriptional regulatory network; transcriptomics.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Biomechanical Phenomena
Gene Expression Regulation, Plant* / physiology
Gene Regulatory Networks* / physiology
Genes, Plant* / genetics
Genes, Plant* / physiology
Laser Capture Microdissection
Populus* / genetics
Populus* / physiology
Wood* / genetics
Wood* / physiology
Xylem