Investigating the Diversity of Latex Metabolites in Species of the Euphorbia Genus
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Park, Se Jin
The Euphorbiaceae family is one of the largest angiosperm families with its largest genus Euphorbia, containing about 2000 species. This genus is characterized by the presence of laticifers and latex. Latex is a milky fluid with diverse secondary metabolites but especially enriched with terpenes. Many of these metabolites, especially diverse terpenes, are used by the Euphorbias as a defense mechanism against herbivores. Although Euphorbia is a large genus, it is relatively understudied at the metabolomic and genomic level compared to other Euphorbiaceae genera. The goal of this research was to establish a foundation for further investigation into latex, laticifers and their contribution to species diversity in the Euphorbia genus. Towards this goal, first, I performed a metabolomics study of 18 Euphorbia species. Next, two model Euphorbias – Euphorbia peplus and Euphorbia lathyris – were selected for further analysis based on previous biochemical studies.We confirmed their identity and estimated their genome size using maturase K (matK) and flow cytometry analysis, respectively. Further, a latex metabolite extraction protocol was standardized and used for assessing the diversity of metabolites from the latex of the two Euphorbia model species using a machine learning approach. The metabolite networking analysis suggested that the Euphorbia latex has a diverse network of secondary metabolites, from which we identified 13 unique terpenes. Finally, to understand the genetic causes of the metabolic diversity, de novo assembled transcriptomes were used to identify terpene synthase genes. Phylogenetic analysis revealed that the Euphorbiaceae family and the Euphorbia genus have conserved terpene synthase subfamilies in relation to other plant families that were studied. The results indicate that the Euphorbia latex is highly diversified while having relatively conserved proteins that are responsible for producing the latex metabolic diversity.
Euphorbiaceae; Euphorbia; laticifer; latex; maturase K(matK)
dissertation or thesis