The hedgehog signalling pathway has long been assumed to exist exclusively in animal lineages. However, we have recently discovered evidence for an orthologous plant signalling pathway with profound effects on development. Hedgehog is a peptide secreted from cells as a short-range signalling molecule. The lipidation of hedgehog is catalysed by Hedgehog acyl transferase () and is essential for its function. We have identified mutants in the putative plant homologue of , named acyl transferase (VAT), and deduced that loss-of-function mutants are embryo lethal, underlining the importance of this pathway to plants.
Interestingly the expression of VAT is largely unaffected by abiotic stress but is strongly down regulated following exposure to pathogens. In mutant plants lacking R-proteins, required to initiate immunity in responses to secreted pathogen effectors, expression of VAT is elevated. This suggests that plants supress the VAT controlled developmental pathway to promote immunity, while pathogens, via effectors, target the VAT pathway to either supress immunity or promote plant growth. This suggests that VAT is a hitherto unidentified regulatory nexus underpinning the trade-off between growth and immunity.
This project will aim to:
Generate and characterise weak mutant alleles of VAT to determine what effects VAT has on post-embryonic growth and development.
Identify the peptide substrate for VAT by , co-purification, yeast secretion assay and phage display.
Investigate the mechanistic basis of how acts to regulate plant development.
Investigate whether increased or decreased pathway action can help to promote immunity against bacterial and oomycete pathogens.
Identify the mechanism underlying how pathogens promote increased pathway action.
This project will provide training in molecular biology, protein biochemistry, quantitative plant developmental and immunity biology, plant transformation, mass spectrometry proteomics, yeast secretion assays and phage display.