Does elevated carbon dioxide universally alter phytohormone signaling?

Plants encounter countless challenges in the environment including insect and pathogen attack. Perception of attack and elicitation of defense is mediated largely by phytohormones. Human activities are increasing the concentration of CO₂, potentially altering the relationship between plants and herbivores. Previous studies in soybeans demonstrated elevated CO₂ modulates plant resistance through alterations in hormone signaling and defenses against herbivorous pests. To determine the impact of elevated CO₂ exposure across plant species, the magnitude and timing of three major hormone signaling pathways (jasmonic acid [JA], salicylic acid [SA], ethylene [ET]) were examined in different plant species and different cultivars of soybean under elevated CO₂ after artificial wounding. Accumulation of defense related transcripts and actual metabolite abundance (JA, SA) will be discussed. The modulation of JA and ET signaling transcripts and metabolites could explain differences in insect damage on plants grown under elevated CO₂ observed in previous studies.