Transcriptome and Low-Affinity Sodium Transport Analysis Reveals Salt Tolerance Variations between Two Poplar Trees

Area of Science:

• Plant Biology
• Molecular Biology
• Environmental Stress Physiology

Background:

• Salinity stress is a major agricultural problem limiting plant growth and productivity.
• Understanding the molecular basis of plant salt tolerance is crucial for developing resilient crops.
• Poplar species offer a model system to investigate differential responses to salt stress.

Purpose of the Study:

• To investigate the molecular and physiological mechanisms underlying differential salt tolerance in two poplar species.
• To compare transcriptional profiles and ionic transport characteristics in response to salt stress.
• To identify key genes and pathways contributing to enhanced salinity resistance.

Main Methods:

• RNA-sequencing to analyze gene expression profiles in poplar roots under salt stress.
• Physiological and pharmacological analyses to assess ionic transport and metabolic responses.
• Comparative study of two poplar species, *Populus alba* and *Populus russkii*, with differing salt sensitivities.

Main Results:

• *Populus alba* showed higher expression of energy metabolism genes, indicating robust defense activation.
• The high-affinity K+ transporter1;2 (HKT1;2) in *P. alba* demonstrated superior Na+ transport capacity, maintaining shoot K+/Na+ homeostasis.
• Genes for ethylene and abscisic acid synthesis were upregulated in *P. alba* but downregulated in *P. russkii*.
• Increased antioxidant enzyme activity (POD, APX, GR) and glycine-betaine content were observed in *P. alba* under salt stress.

Conclusions:

• *Populus alba* possesses enhanced salt tolerance attributed to coordinated energy metabolism, efficient Na+ sequestration, and hormonal regulation.
• The study highlights the role of HKT1;2 in maintaining ion homeostasis under salinity.
• Findings provide valuable insights for improving salt tolerance in crops and woody plants.