Symbiont derived resistant to fungal pathogens

Aphids are one of the world’s major insect pests, causing serious economics damage to crops worldwide. The most common form of aphid control is chemical insecticides although these are effective they are increasingly compromised by resistant insects. There is also a trend to decease the use of chemicals and promote the use of more environmentally friendly biological controls. Entomopathogenic fungi contribute to rapid declines in aphid populations and could play a vital role in aphid control, but using fungal agents is complex and we understand very little about how aphids respond to these pathogens. The Pea aphid genome project revealed that aphids don’t have most of the genes previously thought to be important for the recognition, signalling and killing of microbes in insects. There is also very little evidence that aphids have a dramatic immune response when challenged by pathogens.
This lack of standard immune genes maybe a result the aphid coevolution with Buchnera aphidcola, an essential nutrients symbiont, that provides the aphid host with essential amino acids. These immune genes may have been detrimental to the symbiosis and have been lost during the evolution of aphids.
However it is clear that aphids are not defenceless and show resistance to a number of natural enemies including entomopathogenic fungi. This resistance is not due to the insect genotype but is determined by the presence of secondary symbiotic bacteria such as Regiella insecticola. Although the role of R. insecticola in resistance to fungal infection is well established the mechanism by which resistance is delivered if not understood or characterised.
The aim of this PhD project is to understand how R. insecticola makes aphids resistant to fungal pathogens. The project will use high-throughput sequencing, comparative genomics and expression analysis to identify and describe bacterial and insect genes involved in the process.


Training:
The student will gain expertise in molecular biology, microbial analysis and culture, high-throughput sequencing and RNA-Seq analysis. The student will work closely with collaborators in the UK. A broad generic training program is also in place for postgraduate students ranging from Bioinformatics through to intellectual property and business.