Insect herbivory antagonizes leaf cooling responses to elevated temperature in tomato

Area of Science:

• Plant Biology
• Climate Change Biology
• Stress Physiology

Background:

• Global climate change intensifies abiotic stresses like heat waves, compounding biotic stress from pests.
• Plant hormones like jasmonate (JA) mediate stress resilience, but their interaction with heat stress is unclear.
• Rising temperatures can stimulate arthropod herbivore activity, increasing plant vulnerability.

Purpose of the Study:

• To investigate how wound-induced JA signaling interacts with elevated temperature (ET) in cultivated tomato (Solanum lycopersicum).
• To determine the role of heat shock protein 90 (HSP90) in mediating JA responses under ET.
• To understand the impact of combined heat and herbivory stress on plant adaptation and growth.

Main Methods:

• Simulated heat waves and controlled wounding (insect herbivory/mechanical) were applied to tomato plants.
• Jasmonate (JA) signaling pathways, including the JA receptor COI1, were analyzed.
• Leaf hyponasty, stomatal conductance, leaf temperature, photosynthesis, and growth were measured.
• Pharmacological inhibition of HSP90 was used to assess its role.

Main Results:

• Elevated temperature (ET) enhanced wound-induced JA responses, mediated by HSP90 increasing COI1 receptor accumulation.
• Wound-induced JA signaling blocked leaf hyponasty and evaporative cooling under ET.
• COI1-dependent stomatal closure occurred after wounding at ET, increasing leaf temperature and reducing photosynthesis and growth.
• HSP90 inhibition reversed these negative effects, mimicking JA-insensitive mutants.

Conclusions:

• Wound-induced JA signaling negatively impacts short-term plant adaptation to ET by impairing thermoregulation and photosynthesis.
• The interaction between HSP90, COI1, and JA signaling is crucial for plant responses to combined heat and herbivory stress.
• Antagonistic responses to combined insect herbivory and heat stress may worsen crop losses in a changing climate.