PagMYB31 coordinates cambial cell proliferation and differentiation in poplar wood formation

Zhang et al. explore the regulation of cambium division and differentiation in poplar.

Yanhui Zhang and Quanzi Li, State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, Beijing, China

Background: In trees such as poplar (Populus spp.), wood formation involves cell division of the vascular cambium, xylem cell expansion, secondary cell wall (SCW) deposition, and programmed cell death. The ability of cambial cells to continue to divide is critical for the stems, branches, and trunks of woody plants to grow in diameter (radial growth). Therefore, understanding how plants regulate cambial cells has implications for producing trees with improved wood growth. The WUSCHEL-homeobox transcription factor WOX4 has been identified as a central regulator of cambial cell division and NAC and MYB transcription factors have been identified as key regulators of secondary cell wall thickening. However, our current knowledge on how cambial cell proliferation and differentiation are coordinately regulated is still limited.

Question: We wanted to identify which gene is involved in regulating cambium cell division and differentiation (xylem development), and understand how it regulates cambial cell proliferation and differentiation in poplar (Populus alba × Populus glandulosa).

Findings: Phenotypic characterization of mutant and overexpressing transgenic plants demonstrated that the transcription factor PagMYB31 positively regulates cambial cell proliferation and negatively regulates xylem cell expansion and secondary cell wall biosynthesis. We find that PagMYB31 plays an important role in maintaining vascular cambium homeostasis in multiple pathways to promote or inhibit WOX4 expression. We also find that PagMYB31 inhibits the expansion of cambial cells and xylem cells, and wall thickening of xylem cells, demonstrating its essential role in balancing cambial meristematic fate and differentiation. PagMYB31 can directly regulate key genes controlling cambial cell proliferation and xylem development, placing PagMYB31 at the center of the regulatory network coordinating wood formation.

Next steps: This study shows that PagMYB31 has opposite functions in regulating cambial cell proliferation and xylem development (cell expansion and wall thickening). Further analyses will be carried out to uncover what upstream cues or factors regulate PagMYB31, and explore strategies for breeding trees with augmented growth.


Yanhui Zhang, Song Chen, Linghua Xu, Shimin Chu, Xiaojing Yan, Lanying Lin, Jialong Wen, Bo Zheng, Su Chen, Quanzi Li. (2024). Transcription factor PagMYB31 positively regulates cambium activity and negatively regulates xylem development in poplar.