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The Andes-endemic Barnadesioideae lineage is the oldest surviving and phylogenetically basal subfamily of the Asteraceae (Compositae), a prolific group of flowering plants with world-wide distribution (∼24,000 species) marked by a rich diversity of sesquiterpene lactones (STLs). Intriguingly, there is no evidence that members of the Barnadesioideae produce STLs, specialized metabolites thought to have contributed to the adaptive success of the Asteraceae family outside South America. The biosynthesis of STLs requires the intimate expression and functional integration of germacrene A synthase (GAS) and germacrene A oxidase (GAO) to sequentially cyclize and oxidize farnesyl diphosphate into the advanced intermediate germacrene A acid leading to diverse STLs. Our previous discovery of GAO activity conserved across all major subfamilies of Asteraceae, including the phylogenetically basal lineage of Barnadesioideae, prompted further investigation of the presence of the gateway GAS in Barnadesioideae. Herein we isolated two terpene synthases (BsGAS1/BsGAS2) from the basal Barnadesia spinosa (Barnadesioideae) that displayed robust GAS activity when reconstituted in yeast and characterized in vitro . Despite the apparent lack of STLs in the Barnadesioideae, this work unambiguously confirms the presence of GAS in the basal genera of the Asteraceae. Phylogenetic analysis reveals that the two BsGASs fall into two distinct clades of the Asteraceae's GASs, and BsGAS1 clade is only retained in the evolutionary closer Cichorioideae subfamily, implicating BsGAS2 is likely the ancestral base of most GASs found in the lineages outside the Barnadesioideae. Taken together, these results show the enzymatic capacities of GAS and GAO emerged prior to the subsequent radiation of STL-producing Asteraceae subfamilies. [ABSTRACT FROM AUTHOR]

Energy security and pollution are becoming critical issues in the context of climate change and the circular economy, calling for sustainable resources. Asteraceae species, commonly referred as the aster, daisy, composite, or sunflower family, are among the largest flowering plants with 23,000 species belonging to 1600 genera, and are a major source of biomass. Here we review botanical characteristics and applications of Asteraceae for bioenergy, remediation, nanotechnology, medicine, food and agriculture. Sunflower is the most used to produce bio-oils with a yearly production of 47 million tons. Sunflower is also used for phytoremediation of heavy metals such as cadmium, lead, uranium, and chromium. Artichoke, chicory, purple coneflower, and wormwood display medicinal potential with 27–103 bioactive compounds. Artemisia, calendula, and sunflower oil are precursors for cosmetic and perfume production. Asteraceae species exhibited high efficiencies of 90−96% for removal of remazol red, and reactive blue dyes. Asteraceae species are used for fabrication of nanoparticles, biochar, activated carbon and biocomposites. [ABSTRACT FROM AUTHOR]