Sex pheromone biosynthesis in moth pests : From gene discovery to biotechnological production
Author
Summary, in English
Moths (Lepidoptera) are some of the most economically important pests in human agriculture. Conventional insecticides used for management promote insecticide resistance in addition to cause human- and environmental harm. This emphasises an inescapable need for sustainable alternatives and integrated practices. Moths rely on species-specific female-emitted sex pheromones for communication and reproduction, a chemical ecology paradigm that can be used for pest control, either by trapping males with pheromone baits or masking female pheromone trails with their own pheromones. Such an approach does not carry any risk for humans, other species or the environment, and has proven successful for many crops. Pheromones can be made biotechnologically with a potential for green and efficient production, using moth pheromone biosynthesis enzymes expressed in for example yeast.
The ultimate aim of this work has been to advance development of biotechnological production of pheromones for pest management. To this end, the yeast Yarrowia lipolytica was extensively engineered for efficient production of two pheromones, (Z)-11-hexadecenol and (Z)-9-tetradecenol, which can be applied in pest management of several moth species.
Another focus, serving to develop biotechnological pheromone production, has been to investigate sex pheromone biosynthesis in three economically important moth pests: the sugarcane borer Diatraea saccharalis, the oriental fruit moth Grapholita molesta and the tomato leafminer Tuta absoluta. The focus was on characterisation of genes for desaturases, which produce double bonds in the pheromones of these species. Methods used have been 1) the identification of pheromone precursors by gas chromatography/mass spectrometry analyses of fatty acids in the moth female pheromone gland, and to trace the fate of isotope-labelled pheromone precursors applied to the pheromone gland, 2) transcriptome and expression analysis of candidate genes encoding enzymes in pheromone biosynthesis, and 3) functional characterisation of those genes in heterologous expression assays or by gene-deletion in the insect. For D. saccharalis, genes for both desaturases and a reductase involved in producing the main and minor pheromone components were characterised, and heterologous expression of genes and production of pheromone components demonstrated in yeast. For G. molesta, a unique desaturase has been identified, the first Δ8 desaturase in lepidopteran pheromone biosynthesis. The role of the desaturase was confirmed by CRISPR/Cas9 knock-out of the gene, creating a pheromone-deficient moth. For T. absoluta, the conventional biosynthesis pathway elucidation methodology has proved to be insufficient, revealing that either pheromone precursors or biosynthesis are different to what is common for most Lepidoptera. Interestingly, transcriptome analysis showed that this species does not have a desaturase in the lepidopteran-specific Δ11/10 lineage, otherwise frequently found in moth genomes. This collection of results provides insights into lepidopteran pheromone biosynthesis and evolution, especially of unusual pheromone structures in Tortricidae and Gelechiidae. The results also pave the way for more sustainable control of a pest on one of the world’s biggest crops (D. saccharalis on sugarcane) and for studying pheromone biosynthesis in tortricid moths, major fruit pests around the world.
The ultimate aim of this work has been to advance development of biotechnological production of pheromones for pest management. To this end, the yeast Yarrowia lipolytica was extensively engineered for efficient production of two pheromones, (Z)-11-hexadecenol and (Z)-9-tetradecenol, which can be applied in pest management of several moth species.
Another focus, serving to develop biotechnological pheromone production, has been to investigate sex pheromone biosynthesis in three economically important moth pests: the sugarcane borer Diatraea saccharalis, the oriental fruit moth Grapholita molesta and the tomato leafminer Tuta absoluta. The focus was on characterisation of genes for desaturases, which produce double bonds in the pheromones of these species. Methods used have been 1) the identification of pheromone precursors by gas chromatography/mass spectrometry analyses of fatty acids in the moth female pheromone gland, and to trace the fate of isotope-labelled pheromone precursors applied to the pheromone gland, 2) transcriptome and expression analysis of candidate genes encoding enzymes in pheromone biosynthesis, and 3) functional characterisation of those genes in heterologous expression assays or by gene-deletion in the insect. For D. saccharalis, genes for both desaturases and a reductase involved in producing the main and minor pheromone components were characterised, and heterologous expression of genes and production of pheromone components demonstrated in yeast. For G. molesta, a unique desaturase has been identified, the first Δ8 desaturase in lepidopteran pheromone biosynthesis. The role of the desaturase was confirmed by CRISPR/Cas9 knock-out of the gene, creating a pheromone-deficient moth. For T. absoluta, the conventional biosynthesis pathway elucidation methodology has proved to be insufficient, revealing that either pheromone precursors or biosynthesis are different to what is common for most Lepidoptera. Interestingly, transcriptome analysis showed that this species does not have a desaturase in the lepidopteran-specific Δ11/10 lineage, otherwise frequently found in moth genomes. This collection of results provides insights into lepidopteran pheromone biosynthesis and evolution, especially of unusual pheromone structures in Tortricidae and Gelechiidae. The results also pave the way for more sustainable control of a pest on one of the world’s biggest crops (D. saccharalis on sugarcane) and for studying pheromone biosynthesis in tortricid moths, major fruit pests around the world.
Department/s
Publishing year
2024-04-22
Language
English
Full text
Document type
Dissertation
Publisher
Lund University
Topic
- Biological Sciences
Keywords
- Lepidoptera
- Moths
- Sex pheromones
- Biosynthesis
- Desaturases
- Gene characterisation
- Transcriptomics
- Heterologous expression
- Biotechnology
- integrated pest management
Status
Published
Research group
- Pheromone Group
ISBN/ISSN/Other
- ISBN: 978-91-8104-011-1
- ISBN: 978-91-8104-010-4
Defence date
17 May 2024
Defence time
13:00
Defence place
Blå Hallen, Ekologihuset, Sölvegatan 37.
Opponent
- Iva Pichová (PhD)