The metabolite itaconate is a transcriptional and posttranslational modulator of plant metabolism, development, and stress response.

Itaconate, derived from the tricarboxylic acid cycle, is recognized as a key regulator of the immune response in mammals. Despite this well-characterized role, its presence and functions within plants have remained largely unexplored. Here, we identify itaconate as an endogenous metabolite in maize and and investigate its impact on development. Itaconate treatment has dose-dependent effects on growth in maize and seedlings. To characterize the mechanisms responsible for itaconate's regulation of plant development, we investigated its effects on roots using analysis of mutants and reporter lines, RNA sequencing, and two forms of protein-metabolite interaction assays. Our results demonstrate that itaconate covalently binds to proteins and substantially influences critical pathways in plants, including central carbon metabolism, phytohormone signaling, and oxidative stress response. This study expands the current understanding of itaconate's roles beyond the animal kingdom, providing a foundation for further research into its complex functions in plants.