NSFDEB-NERC; Collaborative Resource; A phytochemical "tug-of-war" and its impact on organismal diversification and niche occupancy in Caryophyllales

Our proposed work seeks to understand the step-wise evolution of complex specialized metabolic traits in
flowering plants, and to explore how the evolution of such traits influence subsequent adaptation and
diversification in flowering plants. To address these questions, we will focus on the flowering plant order
Caryophyllales, which is well recognized for extraordinary adaptations to extreme environments and
unusually high diversity of metabolites derived from the amino-acid Tyrosine. Our central hypothesis is
that changes in availability and abundance of Tyrosine in Caryophyllales has led to the evolution of
numerous lineage-specific tyrosine-derived metabolites that in turn has profoundly influenced the
adaptation and diversification of species within Caryophyllales. To test this hypothesis, we will build an
evolutionary framework for Caryophyllales, that integrates transcriptomic, genomic, and metabolic
datasets, with patterns of trait evolution, on a macroevolutionary scale. Specifically, we will: 1) perform
an extensive survey to establish the occurrence and distribution of tyrosine-derived metabolic traits across
Caryophyllales; 2) examine the association of these tyrosine-derived metabolic traits with organismal
adaptation and diversification patterns; and 3) determine the evolutionary genetic mechanisms responsible
for the biosynthesis of these metabolites. On completion of the proposed work, we expect to have
comprehensively described the extent of tyrosine-enriched metabolism in Caryophyllales, to have defined
the degree to which they are associated with organismal diversification patterns across Caryophyllales,
and to have resolved the stepwise evolutionary assembly of the genetic pathways underlying complex
tyrosine-derived metabolic traits.

Understanding the evolution of complex traits is a fundamental challenge for biologists, as the stepwise
fashion by which such traits have evolved is not always readily apparent. Furthermore, the connections
between the various stages of complex trait assembly (e.g. genetic, biochemical, and morphological) and
subsequent organismal diversification patterns are not well explored, with methodological approaches
still in their infancy. Recent advances in phylogenetics, with the integration of -omic scale data, now
provide timely opportunities to marry the assembly of complex traits with lineage-specific and nichespecific
organismal diversification. Specialized metabolites are chemicals that confer adaptive advantages
in certain ecological and evolutionary contexts. The stepwise nature of the biosynthetic pathways
underlying complex specialized metabolites ensure that they are especially tractable for reconstructing
stepwise evolution of complexity. While the phylogenetically restricted distributions of specialized
metabolites are fundamental to resolving the influence of complex traits on niche-specific and lineagespecific
organismal adaptation and diversification. Our approach, using the tyrosine-enriched specialized
metabolism in Caryophyllales as a model system, therefore has the potential to lead to new and
fundamental insights into the causes and consequences of the evolutionary assembly of complex traits at a
variety of evolutionary scales.

The proposed work sits at the interface of phylogenetics, evolutionary biology, and specialized plant
metabolism, and consequently will influence a number of frontiers in scientific discovery. Numerous
tyrosine-derived metabolites are important in human health and nutrition. Our work will reveal genetic
components that help improve industrial production of betalain pigments and further help to elucidate
biosynthesis pathways of a number of plant-derived alkaloids with pharmaceutical values, such as
catecholamines, isoquinoline, and benzylisoquinoline alkaloids. The international collaboration among
the Minnesota, Wisconsin, Michigan, and Cambridge (UK) teams will provide multidisciplinary training
opportunities for students and postdocs in addressing broader evolutionary questions by applying various
omics and biochemical methods in a phylogenetic framework. All data and analytical tools generated by
the project will be made freely available within six months via NCBI SRA and genome databases, after
quality control and processing. Phylogenomics workshops at professional society meetings, a K-12
summer camp module, and multiple public outreach modules are planned for both the US and UK
institutions, which will bring these concepts to the public, and highlight the importance of biodiversity
with respect to high-value plant chemicals.