Metabolic engineering in mint plants: increasing essential oil yield through genetic manipulation of biosynthetic pathways

This studentship is an excellent opportunity to become part of an international Global Challenges Research Fund
project to enhance the yield of high-value essential oil compounds in Mentha (mint) plants in order to produce elite
mint varieties for cultivation and commercial exploitation by local farming communities in rural Uganda. Different
Mentha species have been shown to preferentially accumulate particular oil components, with the terpenoid
compounds menthol and carvone being most abundant in peppermint (M. x piperita) and spearmint (M. spicata)
respectively, and these are used extensively in a broad range of foodstuffs, beverages, cosmetics and medicinal
products. Other essential oil compounds such as nepetalactone, the active ingredient in catnip, are produced in the
closely related Nepeta genus and research has shown that nepetalactone has good insect repellence qualities, making
it an excellent candidate for the developmental of low-cost mosquito repellents in order to reduce the incidence of
malaria.
The biosynthetic pathways for menthol, carvone and nepetalactone are well-understood, and this project will employ
plant metabolic engineering via genetic modification to enhance the yield of these compounds in the essential oils.
Using advanced modular DNA assembly techniques such as the Golden Gate cloning system, key enzymes involved in
the biosynthesis of menthol, carvone or nepetalactone will be manipulated by overexpression or down-regulation
using RNA interference in order to optimise the production and accumulation of these compounds in transgenic plants.
This will involve the creation of single and multi-gene constructs using different combinations of promoters,
terminators and regulation mechanisms to identify the optimum combination of genetic modifications to maximise oil
compound yield. Oil composition will be analysed by GC-MS and lines producing optimum oil profiles will be selected
for growth trials in Uganda.
Transgenic lines sent to our partner organisations in Uganda will be cultivated and the oils extracted and sold directly
or used for the development of local food, beverage and cosmetic products. Through partnerships established
between Cardiff and Makerere Universities and with our local business partner organisation CEMPOP, this project will
ensure that sustainable financial benefits accrue principally to local communities in Uganda, via cooperative groups
set up to grow, harvest and exploit new mint crops.
The student will join a dynamic team of scientists working on the BBSRC GCRF-funded project and will be supervised
by a highly-experienced plant molecular biologist and a world-class biological chemist.