The evolution of tyrosine-enriched metabolism and the convergent origin of betalain pigments

As sessile organisms, plants have exploited metabolic systems to produce a plethora of diverse specialised metabolites. Specialised metabolites are critical for survival in particular ecological niches and are often taxonomically restricted. In flowering plants, one remarkable example of a taxonomically restricted specialised metabolite occurs in the angiosperm order Caryophyllales. Here, an unusual class of metabolites known as betalain pigments can replace the otherwise ubiquitous anthocyanin pigments. In contrast to the phenylalanine‐derived anthocyanins, betalains are tyrosine‐derived pigments which contain the chromophore betalamic acid. The origin of betalain pigments within Caryophyllales and their mutual exclusion with anthocyanin pigments has been the subject of considerable research. In recent years, numerous discoveries, accelerated by ‐omic scale data, phylogenetics and synthetic biology, have shed light on the origin and evolution of the betalain biosynthetic pathway in Caryophyllales. These advances include the elucidation of novel biosynthetic steps in the betalain pathway, identification of co-opted transcriptional regulators for betalain synthesis, and the resolution of the molecular evolution within key biosynthetic genes. In this talk I will outline how we have used comparative phylotransciptomic approaches:  1) to resolve the emergence of novel biosynthetic pathways including the convergent origin of the betalain biosynthetis pathway; 2) to pinpoint wholesale shifts in aromatic amino-acid usage as a evolutionary foundation for metabolic innovation, and 3) to highlight a role for operonic-like structures in the regulation of the betalain pathway in Caryophyllales.

More information on Dr Samuel Brockington