title: Biophoton imaging: a nondestructive method for assaying R gene responses.
abstract: Plant disease resistance (R) proteins of the nucleotide binding-leucine rich repeat class are responsible for pathogen recognition and activation of defense signaling networks leading to the hypersensitive response (HR). Genetically, R-protein signaling appears to be integrated through a limited set of common downstream components. However, the timing of development of visible HR is unique to individual R proteins. By utilizing the phenomena of ultraweak photon emission from leaves undergoing an incompatible interacttion, a powerful nondestructive and facile assay is described to compare timing of defense responses elicited by different R proteins. We demonstrate that ultraweak photon emission, or "biophoton generation," is demonstrated to be associated with hypersensitive cell death. Biophoton emission requires an intact R signaling network and increases in cytosolic calcium and nitric oxide, but elevated reactive oxygen species are not necessary. Importantly, the assay is robust and applicable to a range of incompatible interactions in various plant species. The ability to assay R responses nondestructively in real time and a chosen genetic background makes this technique amenable to subtle genetic dissection of plant defense responses.
authors.affiliation: Department of Agricultural Science, Imperial College London, Wye Campus, Wye TN25 5AH, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Bennett
authors.forename: Monaz
authors.initials: M
authors.lastname: Mehta
authors.forename: Murray
authors.initials: M
authors.lastname: Grant
mesh_terms: D017360:Arabidopsis / Q000502:physiology; D002118:Calcium / Q000502:physiology; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D017343:Genes, Plant / Q000502:physiology*; D007113:Immunity, Innate / Q000235:genetics; D008163:Luminescent Measurements / Q000379:methods*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D017785:Photons; D010935:Plant Diseases / Q000382:microbiology; D018515:Plant Leaves / Q000502:physiology; D018521:Plant Physiological Phenomena; D011549:Pseudomonas; D016897:Respiratory Burst / Q000502:physiology; D015398:Signal Transduction
chemical_list: D019001:Nitric Oxide Synthase; D002118:Calcium