Apical-root apoplastic acidification affects cell wall extensibility in wheat under salinity stress

Area of Science:

• Plant Physiology
• Molecular Biology
• Agronomy

Background:

• Plant salt tolerance is linked to root growth rate.
• Root growth depends on cell wall properties and apoplastic pH.
• The interplay of these factors under salinity stress is not well understood.

Purpose of the Study:

• To investigate apoplastic pH, cell wall extensibility, and expansin expression in response to salinity stress.
• To compare salt-sensitive and salt-tolerant cultivars.
• To elucidate the role of expansins in maintaining root growth under saline conditions.

Main Methods:

• Assessed apoplastic pH in root elongation zones of two cultivars under varying NaCl concentrations.
• Measured pH-dependent cell wall extensibility.
• Analyzed expansin gene expression.

Main Results:

• Salt treatment reduced apoplastic pH in both cultivars.
• Optimal pH for cell wall loosening differed between cultivars and treatments.
• A specific pH (5.0) mitigated cell wall stiffening in tolerant plants but worsened it in sensitive plants.
• Salinity altered expansin expression, impacting cell wall extensibility differently at pH 5.0 and 6.0.

Conclusions:

• Expansins play a differential role in cell wall loosening at specific pH levels under salinity stress.
• Understanding these pH-dependent mechanisms is crucial for improving plant salt tolerance.
• Targeting expansin activity could enhance root growth in saline environments.