Influence of elevated CO₂ concentration on disease development in tomato

Area of Science:

• Plant pathology
• Plant physiology
• Molecular biology

Background:

• Phytophthora parasitica causes root rot in Lycopersicon esculentum (tomato).
• Elevated atmospheric carbon dioxide (CO2) concentrations are a significant environmental change.
• Understanding plant responses to pathogens under changing CO2 levels is crucial.

Purpose of the Study:

• To investigate the impact of elevated CO2 on tomato susceptibility to P. parasitica.
• To analyze defense-related gene expression in tomato plants under different CO2 conditions during infection.

Main Methods:

• Tomato plants (Lycopersicon esculentum) were grown at ambient (350 ppm) and elevated (700 ppm) CO2 concentrations.
• Plants were infected with Phytophthora parasitica (root rot).
• Defense-related gene expression (pathogenesis-related and wound-response) and hormone levels (salicylic acid, abscisic acid) were measured.

Main Results:

• Tomato plants exhibited increased tolerance to P. parasitica at elevated CO2.
• No significant difference in overall pathogenesis-related (PR) or wound-response gene expression was observed between CO2 treatments.
• PR mRNAs increased in infected roots at elevated CO2, while wound-response mRNAs were not induced. Leaf PR and wound-response transcripts correlated with salicylic and abscisic acid levels, respectively.
• CO2 had minimal effect on the timing or levels of PR and wound-response mRNAs in infected plants.

Conclusions:

• Elevated CO2 confers a degree of tolerance to Phytophthora parasitica in tomato plants.
• This tolerance may involve CO2's effects on PR protein transcription or turnover, or enhanced photosynthesis and water use efficiency.
• Further research is needed to elucidate the precise mechanisms underlying CO2-mediated plant defense.