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Article|01 May 2021|OPEN
Transcriptomic and epigenomic remodeling occurs during vascular cambium periodicity in Populus tomentosa
Bo Chen1,2,4, Huimin Xu3, Yayu Guo1,2,3, Lukas Schreiber5, Paul Grünhofer5, Jinxing Lin1,2,3 & Ruili Li1,3,2,
1Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Forestry University, Beijing 100083, China
2College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China
3College of Biological Sciences, China Agricultural University, Beijing 100193, Chin
4Institute of Tree Development and Genome Editing, Beijing Forestry University, Beijing 100083, China
5Institute of Cellular and Molecular Botany, University of Bonn, Kirschallee 1, D-53115 Bonn, Germany

Horticulture Research 8,
Article number: 102 (2021)
doi: 10.1038/hortres.2021.102
Views: 227

Received: 13 Sep 2020
Revised: 20 Feb 2021
Accepted: 08 Mar 2021
Published online: 01 May 2021

Abstract
Trees in temperate regions exhibit evident seasonal patterns, which play vital roles in their growth and development. The activity of cambial stem cells is the basis for regulating the quantity and quality of wood, which has received considerable attention. However, the underlying mechanisms of these processes have not been fully elucidated. Here we performed a comprehensive analysis of morphological observations, transcriptome profiles, the DNA methylome, and miRNAs of the cambium in Populus tomentosa during the transition from dormancy to activation. Anatomical analysis showed that the active cambial zone exhibited a significant increase in the width and number of cell layers compared with those of the dormant and reactivating cambium. Furthermore, we found that differentially expressed genes associated with vascular development were mainly involved in plant hormone signal transduction, cell division and expansion, and cell wall biosynthesis. In addition, we identified 235 known miRNAs and 125 novel miRNAs. Differentially expressed miRNAs and target genes showed stronger negative correlations than other miRNA/target pairs. Moreover, global methylation and transcription analysis revealed that CG gene body methylation was positively correlated with gene expression, whereas CHG exhibited the opposite trend in the downstream region. Most importantly, we observed that the number of CHH differentially methylated region (DMR) changes was the greatest during cambium periodicity. Intriguingly, the genes with hypomethylated CHH DMRs in the promoter were involved in plant hormone signal transduction, phenylpropanoid biosynthesis, and plant–pathogen interactions during vascular cambium development. These findings improve our systems-level understanding of the epigenomic diversity that exists in the annual growth cycle of trees.