Simulating ozone detoxification in the leaf apoplast through the direct reaction with ascorbate

Area of Science:

• Plant physiology
• Biochemistry
• Environmental science

Background:

• Ozone (O3) is a significant atmospheric pollutant impacting plant health.
• Ascorbate (ASC) is a key antioxidant within plant cells.
• The apoplast, the aqueous space surrounding plant cells, plays a role in pollutant interaction.

Purpose of the Study:

• To develop a mathematical model for semi-quantifying ozone detoxification by ascorbate in the plant apoplast.
• To analyze the influence of various physico-chemical factors on ozone's interaction with apoplastic ascorbate.
• To assess the protective capacity of apoplastic ascorbate against ozone uptake in plants.

Main Methods:

• Development of a mathematical model simulating ozone uptake and reaction with ascorbate.
• Inclusion of parameters such as ASC regeneration, replenishment, and sub-cellular distribution.
• Analysis of physico-chemical factors including stomatal conductance, apoplast pH, and reaction stoichiometry.
• Model validation using experimental observations.

Main Results:

• The model quantifies ozone detoxification via direct reaction with apoplastic ascorbate.
• Simulations indicate sufficient apoplastic ASC concentration to scavenge substantial ozone under environmental conditions.
• Physico-chemical characteristics significantly influence ozone flux to the plasmalemma.
• Significant inter-taxa variation exists in the protective role of apoplastic ASC.

Conclusions:

• Apoplastic ascorbate provides a significant first line of defense against ozone entering plant leaves.
• Plant species exhibit differing capacities for ozone protection mediated by apoplastic ascorbate.
• Further investigation into the chemistry of ozone reactions within the cell wall is warranted.