Chemoproteomic\nProfiling Reveals Chlorogenic Acid\nas a Covalent Inhibitor of <i>Arabidopsis</i> Dehydroascorbate\nReductase 1

Chlorogenic acid (CA) is an abundant plant secondary\nmetabolite\nwith promising allelopathic effects on weed growth. However, the molecular\ntargets and mechanism of action of CA in plants remain elusive. Here,\nwe report the employment of a clickable photoaffinity probe in identifying\nthe protein targets of CA in <i>Arabidopsis</i> seedling\nproteomes. CA specifically binds <i>Arabidopsis</i> dehydroascorbate\nreductase 1 (<i>At</i>DHAR1), an enzyme responsible for\nascorbate regeneration in plants, by covalent alkylating Cys20 within\nthe catalytic center, thereby inhibiting its activity. In vivo application\nof CA reduced the pool size and redox state of ascorbate, leading\nto H<sub>2</sub>O<sub>2</sub> accumulation in <i>Arabidopsis</i> seedlings. In agreement with these results, CA significantly induced\nthe upregulation of antioxidant enzymes and downregulation of proteins\ninvolved in water transport and photosynthesis, as evidenced by quantitative\nproteomics. Taken together, this study revealed DHAR1 as a functional\ntarget underlying CA’s allelopathic activity in plants, which\nopens new opportunities for the development of novel herbicides from\nnaturally existing resources.