Genomic insights into the evolution of plant chemical defense.

Plant trait evolution can be impacted by common mechanisms of genome evolution, including whole-genome and small-scale duplication, rearrangement, and selective pressures. With the increasing accessibility of genome sequencing for non-model species, comparative studies of trait evolution among closely related or divergent lineages have supported investigations into plant chemical defense. Plant defensive compounds include major chemical classes, such as terpenoids, alkaloids, and phenolics, and are used in primary and secondary plant functions. These include the promotion of plant health, facilitation of pollination, defense against pathogens, and responses to a rapidly changing climate. We discuss mechanisms of genome evolution and use examples from recent studies to impress a stronger understanding of the link between genotype and phenotype as it relates to the evolution of plant chemical defense. We conclude with considerations for how to leverage genomics, transcriptomics, metabolomics, and functional assays for studying the emergence and evolution of chemical defense systems.