Evolution of Plant Metabolism: A (Bio)synthesis
Résumé
Title: Evolution of plant metabolism: A (bio)synthesis Studying the evolution of metabolism is technically challenging. A novel study combining in silico metabolic maps and phylogenomics allows reconstructing the diversification of plant metabolism across one billion years of evolution. Text: Following the initial primary endosymbiotic event leading to the evolution of the chloroplast approximately a billion years ago, plants (Viridiplantae or Chloroplastida) have evolved into a tremendous diversity of organisms such as green algae, mosses or ferns [1]. Each of these lineages has evolved prominent developmental and physiological innovations linked to the colonization of new ecological niches. Although roots and flowers will come to everyone's mind when asked for plant innovations, one can hardly argue against specific metabolites, say caffeine, as iconic lineage-specific novelties. Besides such recent evolution, metabolic novelties that evolved at deep nodes in the plant phylogeny may have played essential roles in the evolution of extremely diverse and successful plant lineages such as the land plants. However, while scoring for the presence or absence of a given macroscopic trait-such as roots or flowers-is relatively straightforward, determining the distribution of metabolites requires the use of sophisticated and time-consuming approaches, hindering the description of the plant metabolism in an evolutionary perspective. In their work published in this issue of Current Biology Cannell et al. [2] overcome these limitations and propose a comprehensive view of the plant metabolism evolution. To do so, the authors first computed metabolic maps on eight focal taxa belonging to the major plant lineages. Rather than reflecting the presence or absence of a given enzymatic property, reconstructing biosynthesis pathways allow inferring whether the "modules" are present and thus the metabolic end-product. Mapping these predictions on the plant phylogeny, the authors were able to propose gains and losses of specific metabolic pathways in an untargeted manner. The initial set of eight species, although covering a large diversity of lineages, made the approach very sensitive to misannotation or assemblies. To strengthen their conclusions the authors included a total of 72 diverse plant genomes in an OrthoFinder run, identifying orthologs across all the species, and later added 305 transcriptomes. With these orthogroups, the authors were able to predict the evolution of the plant metabolism. Some of these predictions reflected the known evolutionary pattern of well-described metabolic pathways, such as the gain of thalianol biosynthesis in the Arabidopsis thaliana lineage [3] others turned out to be much more surprizing. Revisiting the evolution of plant hormones Gibberellins (GAs) are plant hormones regulating multiple developmental processes. Their biosynthesis is well described in angiosperms. Initial phylogenetic studies conducted on the biosynthetic enzymes on the model moss Physcomitrella patens, and metabolomics survey, suggested that active GAs (derivative of GA12) were not produced in mosses, suggesting that their evolution was specific to the vascular plants [4]. Here the authors discovered in liverworts and hornworts, the other two bryophyte clades, the entire suit of enzymes
Domaines
Sciences du Vivant [q-bio]
Origine : Fichiers produits par l'(les) auteur(s)
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