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Updated: Feb 15, 2026

Xylem Water Distribution in Woody Plants Visualized with a Cryo-scanning Electron Microscope
Published on: June 20, 2019
The LkMTA2/LkMTB8-LkERF1-LkEXPA8 cascade regulates xylem cell expansion in larch
Zhongrui Lyu1, Yunhui Xie1, Kaikai Zhang1
1State Key Laboratory of Tree Genetics and Breeding & Key Laboratory of Tree Breeding and Cultivation, National Forestry and Grassland Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, 100091, China.
Abstract:
Cell expansion is a critical determinant of the final shape and size of wood cells. In this study, the role of N6-methyladenosine (m6A), an abundant mRNA modification, in regulating xylem cell expansion was investigated. Treatment with the m6A methylation inhibitor STM2457 triggered global m6A hypomethylation in larch and significantly enlarged the xylem cell cross-sectional area. Analysis of m6A-seq data indicated that the hypomethylated m6A peaks were primarily localized within coding sequences and correlated with decreased transcript abundance. Among these transcripts, we identified a gene associated with xylem cell expansion, ETHYLENE-RESPONSIVE FACTOR 1 (LkERF1), whose overexpression in poplar reduced the xylem cell cross-sectional area. We characterized MRNA ADENOSINE METHYLASE 2 (LkMTA2) and METHYLTRANSFERASE B8 (LkMTB8), whose overexpression in poplar resulted in a significant reduction in vessel lumen cross-sectional area. LkMTA2 and LkMTB8 form a heterodimeric complex, which enhances the mRNA stability and abundance of LkERF1 via m6A hypermethylation, while LkERF1 directly represses the expression of EXPANSIN A8 (LkEXPA8), a key regulator of cell expansion. These findings provide novel insights into the LkMTA2/LkMTB8-LkERF1-LkEXPA8 cascade in regulating xylem cell expansion and reveal a molecular link between m6A RNA modification and wood formation.
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