Blue Skies, Tough Choices: How Blue Light Shapes Plant Growth-Defence Trade-offs
Supervisors:
Prof John Christie, School of Molecular Biosciences, University of Glasgow
Dr Paul Birch, The James Hutton Institute
Project Summary:
Plants must continuously balance the competing demands of growth and defence. Blue light plays a pivotal role in this process, regulating adaptive responses such as phototropism, leaf positioning, chloroplast movement, and stomatal opening through the action of phototropin blue-light receptor kinases, particularly phototropin 1 (phot1). Recent evidence suggests that phot1 also influences plant immunity, acting as a key regulator of the trade-off between growth and defence. This balance is agriculturally important because pathogens can exploit these signalling pathways to promote disease. For example, Phytophthora infestans, the causal agent of potato late blight, suppresses host defence responses by manipulating phot1 signalling.
This project will investigate the molecular mechanisms by which phot1 coordinates growth and defence responses through its substrate, the immune regulator SWAP70. Building on our recent discovery that SWAP70 is directly phosphorylated by phot1 in response to blue light, the student will identify phot1-dependent phosphorylation sites in SWAP70, determine how phosphorylation affects its localisation and function, and generate transgenic Arabidopsis lines expressing wild-type SWAP70 or phospho-null/-mimetic variants. The functional significance of SWAP70 phosphorylation will then be assessed in both light-signalling and pathogen-response assays, including INF1-triggered cell death in Nicotiana benthamiana.
The student will be jointly based within interdisciplinary teams at the University of Glasgow and the James Hutton Institute, receiving training in molecular biology, plant genetics, confocal microscopy, plant physiology, and plant pathology. This project will provide fundamental insights into how environmental light signals influence disease susceptibility and plant performance, with potential applications for improving crop resilience, disease resistance, and productivity.