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SUMMARY Plants produce a staggering array of chemicals that are the basis for organismal function and important human nutrients and medicines. However, it is poorly defined how these compounds evolved and are distributed across the plant kingdom, hindering a systematic view and understanding of plant chemical diversity. Recent advances in plant genome/transcriptome sequencing have provided a well‐defined molecular phylogeny of plants, on which the presence of diverse natural products can be mapped to systematically determine their phylogenetic distribution. Here, we built a proof‐of‐concept workflow where previously reported diverse tyrosine‐derived plant natural products were mapped onto the plant tree of life. Plant chemical‐species associations were mined from literature, filtered, evaluated through manual inspection of over 2500 scientific articles, and mapped onto the plant phylogeny. The resulting “phylochemical” map confirmed several highly lineage‐specific compound class distributions, such as betalain pigments and Amaryllidaceae alkaloids. The map also highlighted several lineages enriched in dopamine‐derived compounds, including the orders Caryophyllales, Liliales, and Fabales. Additionally, the application of large language models, using our manually curated data as a ground truth set, showed that post‐mining processing can largely be automated with a low false‐positive rate, critical for generating a reliable phylochemical map. Although a high false‐negative rate remains a challenge, our study demonstrates that combining text mining with language model‐based processing can generate broader phylochemical maps, which will serve as a valuable community resource to uncover key evolutionary events that underlie plant chemical diversity and enable system‐level views of nature's millions of years of chemical experimentation. 

l-Tyrosine is an essential amino acid for protein synthesis and is also used in plants to synthesize diverse natural products. Plants primarily synthesize tyrosine via TyrA arogenate dehydrogenase (TyrAa or ADH), which are typically strongly feedback inhibited by tyrosine. However, two plant lineages, Fabaceae (legumes) and Caryophyllales, have TyrA enzymes that exhibit relaxed sensitivity to tyrosine inhibition and are associated with elevated production of tyrosine-derived compounds, such as betalain pigments uniquely produced in core Caryophyllales. Although we previously showed that a single D222N substitution is primarily responsible for the deregulation of legume TyrAs, it is unknown when and how the deregulated Caryophyllales TyrA emerged. Here, through phylogeny-guided TyrA structure–function analysis, we found that functionally deregulated TyrAs evolved early in the core Caryophyllales before the origin of betalains, where the E208D amino acid substitution in the active site, which is at a different and opposite location from D222N found in legume TyrAs, played a key role in the TyrA functionalization. Unlike legumes, however, additional substitutions on non-active site residues further contributed to the deregulation of TyrAs in Caryophyllales. The introduction of a mutation analogous to E208D partially deregulated tyrosine-sensitive TyrAs, such as Arabidopsis TyrA2 (AtTyrA2). Moreover, the combined introduction of D222N and E208D additively deregulated AtTyrA2, for which the expression in Nicotiana benthamiana led to highly elevated accumulation of tyrosine in planta. The present study demonstrates that phylogeny-guided characterization of key residues underlying primary metabolic innovations can provide powerful tools to boost the production of essential plant natural products. 

Tremendous chemical diversity is the hallmark of plants and is supported by highly complex biochemical machinery. Plant metabolic enzymes originated and were transferred from eukaryotic and prokaryotic ancestors and further diversified by the unprecedented rates of gene duplication and functionalization experienced in land plants. Unlike microbes, which have frequent horizontal gene transfer events and multiple inputs of energy and organic carbon, land plants predominantly rely on organic carbon generated from CO 2 and have experienced very few, if any, gene transfers during their recent evolutionary history. As such, plant metabolic networks have evolved in a stepwise manner and on existing networks under various evolutionary constraints. This review aims to take a broader view of plant metabolic evolution and lay a framework to further explore underlying evolutionary mechanisms of the complex metabolic network. Understanding the underlying metabolic and genetic constraints is also an empirical prerequisite for rational engineering and redesigning of plant metabolic pathways. Expected final online publication date for the Annual Review of Plant Biology, Volume 72 is May 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.