Small GTP-binding protein PdRanBP regulates vascular tissue development in poplar

Area of Science:

• Plant molecular biology
• Forest genetics

Background:

• Ectopic expression of Ran-binding protein (RanBP) in Arabidopsis increases axillary buds and reduces apical dominance.
• The function of RanBP in poplar, a species with significant secondary growth, is not well understood.

Purpose of the Study:

• To isolate and functionally characterize the Populus deltoides RanBP gene (PdRanBP).
• To investigate the role of PdRanBP in poplar growth and development through ectopic expression.

Main Methods:

• Isolation and ectopic expression of the PdRanBP gene in hybrid poplar.
• Analysis of gene expression patterns in different poplar tissues.
• Assessment of plant growth parameters, including branching, cell cycle progression, and secondary growth zones.

Main Results:

• PdRanBP is primarily expressed in leaf buds and tissues involved in secondary wall expansion (immature xylem and phloem).
• Overexpression of PdRanBP in poplar led to increased branching, a higher proportion of cells in G2 phase, retarded growth, and reduced secondary xylem/phloem zones.
• Downregulation of PdRanBP promoted stem height, secondary growth, and expression of cell wall biosynthesis genes.

Conclusions:

• PdRanBP plays a role in regulating both apical and radial growth in poplar trees.
• PdRanBP may control cell division during cell cycle progression.
• PdRanBP is identified as a nuclear protein associated with vascular tissue development in Populus deltoides.