NO, hydrogen sulfide does not come first during tomato response to high salinity

Area of Science:

• Plant Physiology
• Abiotic Stress Response
• Molecular Signaling

Background:

• High salinity poses a significant threat to agricultural productivity, impacting crop yields worldwide.
• Tomato (Solanum lycopersicum) serves as a model organism for studying plant responses to abiotic stresses like salinity.
• Nitric oxide (NO) and hydrogen sulfide (H2S) are key signaling molecules involved in plant stress responses.

Purpose of the Study:

• To elucidate the signaling pathway between nitric oxide (NO) and hydrogen sulfide (H2S) in tomato plants subjected to salt stress.
• To determine the order of action (upstream or downstream) of NO and H2S in the salt stress response cascade.
• To investigate the role of NO and H2S in mitigating oxidative stress and enhancing salinity tolerance in tomatoes.

Main Methods:

• Application of NO-donor and H2S-donor compounds to tomato plants.
• Quantification of NO and H2S accumulation in roots and leaves after NaCl treatment.
• Measurement of transcript levels of H2S-synthesizing enzymes.
• Analysis of the signaling cross-talk between NO and H2S under salt stress conditions.

Main Results:

• An NO donor increased H2S levels by 12-18.9%, while an H2S donor increased NO levels by 10% in roots.
• NO accumulated in roots one hour after NaCl treatment, preceding H2S accumulation which started two hours later.
• NO significantly stimulated H2S accumulation in roots and leaves, but H2S did not stimulate NO accumulation.
• NO accumulation correlated with increased transcript levels of genes encoding H2S-synthesizing enzymes.

Conclusions:

• Hydrogen sulfide (H2S) acts downstream of nitric oxide (NO) in the signaling pathway during tomato salt stress response.
• The NO-H2S signaling cascade plays a crucial role in mitigating oxidative stress induced by high salinity.
• This NO-dependent H2S signaling enhances the overall salinity tolerance of tomato plants.