Atmospheric H₂S exposure does not affect stomatal aperture in maize

Area of Science:

• Plant physiology
• Plant biochemistry
• Environmental science

Background:

• Sulfur is essential for plant function.
• Hydrogen sulfide (H₂S) may act as a gasotransmitter regulating stomatal aperture.
• H₂S is hypothesized to be metabolized into cysteine, causing stomatal closure.

Purpose of the Study:

• To investigate the role of H₂S in regulating stomatal aperture in maize.
• To determine if atmospheric H₂S influences stomatal closure.
• To assess H₂S as a sulfur source for maize growth.

Main Methods:

• Maize plants were exposed to subtoxic atmospheric H₂S levels.
• Plants were grown with or without sulfate supply to the roots.
• Biomass, sulfur content (sulfate, glutathione, cysteine), leaf area, stomatal density, stomatal resistance, and transpiration rates were measured.

Main Results:

• Maize utilized H₂S as a sulfur source, alleviating growth reduction in sulfate-deprived plants.
• H₂S fumigation increased shoot sulfate, glutathione, and cysteine levels.
• No significant changes were observed in leaf area, stomatal density, stomatal resistance, or transpiration rate.

Conclusions:

• Atmospheric H₂S does not affect stomatal aperture or transpiration rate in maize.
• H₂S functions as a sulfur nutrient, not a gaseous signal molecule controlling stomatal aperture in maize.
• The hypothesis that H₂S metabolism into cysteine causes stomatal closure is not supported in maize.