Dopamine biosynthesis in plants

Dopamine, an essential human neurotransmitter, also plays important roles in plant-microbe interactions and abiotic stress tolerance in plants. Although dopamine biosynthesis is well-characterized in humans, it remains largely unclear in plants. Through metabolite-based genome-wide association studies, we identified a dopamine biosynthetic gene cluster in Brachypodium distachyon comprising two tyrosine decarboxylase genes and three putative polyphenol oxidase genes. Biochemical and knockout mutant analyses revealed that dopamine biosynthesis proceeds primarily via tyramine as an intermediate, and dopamine oxidation leads to tissue browning in B. distachyon. Homolog searches and enzymatic assays suggest that the dopamine biosynthetic pathway is likely conserved across numerous plant species. This discovery provides valuable insights into plant dopamine biosynthesis with potential applications in reducing food browning, improving plant stress resilience, and bioengineering valuable compounds. Overall design: RNAseq profiling of 2- and 4-week-old Brachypodium distachyon Bd21-3 roots and shoots. These plants were grown in a hydroponic system.