Using natural variation in Nicotiana attenuata to elucidate its defense response against herbivory

Plants have shaped Earth's history, forming a large part of biomass and serving as key food sources for heterotrophs. Insects, especially herbivores, drive the evolution of plant defenses. Recognized since the 18th century, these interactions led to the field of chemical ecology in the 19th century. This dissertation examines plant-herbivore interactions in Nicotiana attenuata, focusing on the jasmonic acid (JA) pathway. It identifies genetic variation in the NaJAR4 gene, affecting JA-Ile levels and revealing a growth-defense trade-off. Transcriptome analysis shows NaJAR4 is part of a defense-response network, with mutations buffered by this network, allowing persistence under varying herbivory. Seed collections show variable frequencies of NaJAR4 variants, indicating balancing selection. The study also explores volatile organic compounds (VOCs), finding natural variation in the NaLIS gene affects linalool emission and impacts Manduca sexta predation and oviposition. This highlights the dynamic interplay of genetic diversity, environmental factors, and herbivore behavior in plant adaptation.