Gene expression patterns underlying changes in xylem structure and function in response to increased nitrogen...

Area of Science:

• Plant Biology
• Forestry Science
• Molecular Biology

Background:

• Nitrogen is crucial for plant growth and development.
• Xylogenesis, the formation of wood, is a key process in plant secondary growth.
• Understanding how nitrogen impacts xylogenesis is vital for forestry and agriculture.

Purpose of the Study:

• To investigate the effects of varying nitrogen availability on xylogenesis in hybrid poplar (Populus trichocarpa x deltoides H11-11).
• To correlate anatomical and hydraulic changes in xylem with gene expression patterns.

Main Methods:

• Hybrid poplar saplings were treated with high or adequate nitrogen levels for 33 days.
• Xylem anatomy and hydraulic properties were analyzed.
• Transcriptome analysis was performed on developing xylem tissue.

Main Results:

• High nitrogen led to increased radial growth, wider vessels and fibres, and thinner fibre walls in secondary xylem.
• Xylem in high nitrogen plants showed higher transport efficiency but increased susceptibility to cavitation.
• Differential gene expression analysis revealed 388 genes affected, including those in nitrogen/carbohydrate metabolism and xylem differentiation.
• Genes regulating secondary cell wall deposition were downregulated in high nitrogen plants.

Conclusions:

• Nitrogen availability significantly influences hybrid poplar xylem structure, function, and gene expression.
• Altered xylem traits under high nitrogen conditions present a trade-off between hydraulic efficiency and drought resilience.
• Identified gene candidates offer insights into the molecular mechanisms controlling xylem development and response to nitrogen.