Non-invasive imaging of defence responses in plants

Jasmonic and salicylic acids are key hormones involved in plant responses to pests and pathogens. Existing fluorescence-based approaches to imaging plant defence hormones are constrained by the need for external illumination and by autofluorescence of plant tissues, while luminescence-based ones require exogenous substrates. Here, we use jasmonate- and salicylate-responsive promoters to engineer autoluminescent plants that report hormone signalling activity with up to a 53-fold contrast. Using consumer-grade cameras, we image reporter Arabidopsis thaliana and Nicotiana benthamiana plants throughout normal development and in response to pest and pathogen attacks, visualising local and systemic responses. Because the luminescence is self-sustained, these reporters enable non-invasive, substrate-free imaging of defence signalling over extended time courses without specialised equipment.