Publicação
Molecular and biotechnological approaches to essential oils production in thymus caespititius
| Resumo: | Thymus caespititius is an aromatic plant from the NW Iberian Peninsula and from the Azores and Madeira archipelagos. In this species chemical polymorphism in the essential oils has been described, with seven well defined chemotypes, namely thymol, carvacrol, α-terpineol, sabinene, and the mixed chemotypes thymol/sabinene, thymol/carvacrol and thymol/sabinene/carvacrol. T. caespititius essential oils already proved to have antimicrobial, antioxidant activity and acetylcholinesterase inhibition, and more recently they were shown to have high nematicidal activity against the pinewood nematode Bursaphelenchus xylophilus, namely the carvacrol and thymol rich oils. Since this species is not used commercially, the oils diversity observed results only from natural evolution; however, the molecular mechanisms underlying such chemical diversity are not yet clear. In this work were used molecular and biotechnological approaches to understand the basis for chemical diversity of T. caespititius’ essential oils. Five T. caespititius in vitro cultures from plants with different chemotypes were established, allowing having enough plant material for the following studies. This advantageous in vitro system avoids plant material collection from the natural habitat and the controlled growth conditions reduce the sources of variability known to affect essential oil composition. Terpenes are the main group components identified in T. caespititius essential oils. However the molecular basis of their synthesis has not yet been fully understood. Given this, the genes encoding enzymes of monoterpene biosynthesis were searched and identified in the five established in vitro genotypes and latter their expression level was assessed. It has been shown that biotic (pathogens, herbivores) and abiotic (temperature, light quality, nutrients type and availability) factors could influence the essential oil composition as well as the genes involved in their biosynthesis. So, nutrient composition and Botrytis cinerea fungal extracts were assayed in in vitro cultures to study the biosynthesis and accumulation of terpenes in this aromatic species. Collectively, it was demonstrated that the conditions established in this work also step up the possibility of using T. caespititius shoot cultures as an experimental model to investigate the terpene biosynthesis and accumulation in plants. The large biomass increase obtained in vitro advance the possibility of using large-scale in vitro production of desirable secondary metabolites. The terpene synthase genes identified and characterized here were a small contribution to understanding how these genes evolved, are regulated and function in Lamiaceae |
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| Autores principais: | Mendes, Marta Daniela de Sá |
| Assunto: | Teses de doutoramento - 2014 |
| Ano: | 2014 |
| País: | Portugal |
| Tipo de documento: | tese de doutoramento |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | Thymus caespititius is an aromatic plant from the NW Iberian Peninsula and from the Azores and Madeira archipelagos. In this species chemical polymorphism in the essential oils has been described, with seven well defined chemotypes, namely thymol, carvacrol, α-terpineol, sabinene, and the mixed chemotypes thymol/sabinene, thymol/carvacrol and thymol/sabinene/carvacrol. T. caespititius essential oils already proved to have antimicrobial, antioxidant activity and acetylcholinesterase inhibition, and more recently they were shown to have high nematicidal activity against the pinewood nematode Bursaphelenchus xylophilus, namely the carvacrol and thymol rich oils. Since this species is not used commercially, the oils diversity observed results only from natural evolution; however, the molecular mechanisms underlying such chemical diversity are not yet clear. In this work were used molecular and biotechnological approaches to understand the basis for chemical diversity of T. caespititius’ essential oils. Five T. caespititius in vitro cultures from plants with different chemotypes were established, allowing having enough plant material for the following studies. This advantageous in vitro system avoids plant material collection from the natural habitat and the controlled growth conditions reduce the sources of variability known to affect essential oil composition. Terpenes are the main group components identified in T. caespititius essential oils. However the molecular basis of their synthesis has not yet been fully understood. Given this, the genes encoding enzymes of monoterpene biosynthesis were searched and identified in the five established in vitro genotypes and latter their expression level was assessed. It has been shown that biotic (pathogens, herbivores) and abiotic (temperature, light quality, nutrients type and availability) factors could influence the essential oil composition as well as the genes involved in their biosynthesis. So, nutrient composition and Botrytis cinerea fungal extracts were assayed in in vitro cultures to study the biosynthesis and accumulation of terpenes in this aromatic species. Collectively, it was demonstrated that the conditions established in this work also step up the possibility of using T. caespititius shoot cultures as an experimental model to investigate the terpene biosynthesis and accumulation in plants. The large biomass increase obtained in vitro advance the possibility of using large-scale in vitro production of desirable secondary metabolites. The terpene synthase genes identified and characterized here were a small contribution to understanding how these genes evolved, are regulated and function in Lamiaceae |
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