Anti-Herbivore Resistance Changes in Tomato with Elevation.

Area of Science:

• Ecology
• Plant Science
• Entomology

Background:

• Local adaptation of host plants to climate influences insect-plant interactions.
• Elevational gradients present diverse climatic conditions affecting plant defense strategies.

Purpose of the Study:

• To investigate how local adaptations of tomato plants (Solanum lycopersicum var. cerasiforme and S. pimpinellifolium) to elevational gradients affect plant defense and insect herbivory.
• To test the hypothesis that lower-elevation plants possess higher defensive compounds and greater resistance to insect herbivory.

Main Methods:

• Evaluated plant defense responses and herbivore growth (Helicoverpa zea) on tomato accessions from 100 to 3000 m.
• Quantified total phenolic content, polyphenol oxidase, trypsin protease inhibitors, and leaf trichome density.
• Assessed tradeoffs between constitutive and induced plant defenses.

Main Results:

• Plant resistance to insect herbivory was stronger in middle and high-elevation accessions, contrary to the initial hypothesis.
• Total phenolic content increased with elevation in both damaged and undamaged leaves, correlating with enhanced plant resistance.
• No clear elevational gradient was observed for defensive proteins or leaf trichome density.

Conclusions:

• Plant resistance to insect herbivory is augmented by increased phenolic content with elevation, suggesting local adaptation.
• Tradeoffs between constitutive and induced defenses exist in tomato genotypes.
• Plant defense plasticity may play a crucial role in insect herbivore range expansion under climate change.