The vascular-cambium-specific transcription factor PtrSCZ1 and its homologue regulate cambium activity and affect xylem development in .

INTRODUCTION

Vascular cambium proliferates and differentiates into the secondary xylem (wood), enabling the perennial increase in stem diameter for wood formation. In our previous study, we identified 95 vascular-cambium-specific (VCS) transcription factors (TFs) in .

METHODS

In this study, we characterized the function of the highly vascular cambium-expressed heat shock TF among these VCSs, PtrSCZ1, using -overexpressing transgenic lines and gene-edited mutants in .

RESULTS

Overexpressing or its homolog (, ) led to enhanced cambium activity, increased stem diameter, and a larger xylem proportion. CRISPR-based mutants of and exhibited phenotypes opposite to the and plants. This suggests that and redundantly promote cambium activity and secondary growth, leading to increased radial growth in . Overexpression and knockout of and significantly affected the expression of key regulatory factors of cambium (, , , , , and ) and disrupted cell wall-related gene expression. This demonstrates that and may function in cambium division activity by regulating these key cambium-associated transcription factors for wood formation.

DISCUSSION

Our work identifies and as promising target genes for enhancing wood yield through molecular breeding, and illustrates the role of vascular cambium systems in understanding lateral meristem development.