Evolution of plant specialized metabolites: beyond ecological drivers

Plants produce a highly diverse array of specialized metabolites. Traditionally, the evolution of these metabolites has been studied primarily through the lens of plants' ecological interactions with herbivores, pathogens, and pollinators, as many of them exhibit defense and/or attraction functions. However, increasing evidence suggests that many specialized metabolites, along with their precursors, also act as cellular signals that regulate cell growth and differentiation. We propose that these intrinsic functions are at least equally important factors in shaping the evolution of plant chemical defenses. We further discuss how future research that combines modern single-cell techniques and evolutionary genomics will provide novel insights into the evolutionary process of specialized metabolism diversification.