Catecholamines, such as dopamine, norepinephrine (noradrenaline) and epinephrine (adrenaline), are well-known neurotransmitters in animals and are also specialised metabolites in plants. The biosynthesis of catecholamines and their precursor, L-DOPA, in animals and plants very likely represents an example of convergent evolution. L-DOPA and catecholamines are also likely to have evolved multiple times within plants, in some lineages accumulating to exceptionally high levels. Functional studies so far support an adaptive role for these compounds’ roles in biotic and abiotic defence as well as involvement in the regulation of carbohydrate mobilisation. However, evolutionary and functional insights are hindered by the lack of knowledge about the biosynthesis of these compounds.
The proposed project aims to elucidate the biosynthetic pathways to L-DOPA and catecholamines in three species representing at least two evolutionary origins of these compounds: Beta vulgaris (Amaranthaceae), Mucuna pruriens (Fabaceae) and Vicia faba (Fabaceae). This research will allow the comparison of biosynthesis at different evolutionary scales (Plantae/Animalia, Amaranthaceae/Fabaceeae, within-Fabaceae) in order to look for patterns in the molecular mechanisms underlying the basis of this convergence and to investigate why these patterns exist. Knowledge of the genes encoding the enzymes of the biosynthetic pathway will also be essential in providing the genetic tools to carry out well-controlled functional studies of these compounds in planta, as well as to provide insights for the bioengineering of important dopamine-derived alkaloids, such as morphine.
Results from this project will represent the first time that the catecholamine biosynthetic pathway has been elucidated in any plant species and will provide the foundation from which to understand the evolution and function of these compounds. Furthermore, this pathway encompasses fundamental reactions in tyrosine metabolism that are currently poorly understood, thus the elucidation of the enzymes catalysing these reactions promises to provide novel insights into our understanding of derived biosynthetic pathways.
The primary researchers will be the principal investigator, Hester Sheehan, and the mentor, Heidi Halbwirth, Associate Professor at Technisches Universität Vienna.
