Enhanced luciferin entry causes rapid wound-induced light emission in plants expressing high levels of luciferase.
In-vivo imaging of transgenic tobacco plants (Nicotiana tobacum L.) expressing firefly luciferase under the control of the Arabidopsis phenylalanine ammonialyase 1 (PAL1)-promoter showed that luciferase-catalyzed light emission began immediately after the substrate luciferin was sprayed onto the leaves and reached a plateau phase after approximately 60 min. This luminescence could easily be detected for up to 24 h after luciferin application although the light intensity declined continuously during this period. A strong and rapid increase in light emission was observed within the first minutes after wounding of luciferin-sprayed leaves. However, these data did not correlate with luciferase activity analysed by an in-vitro enzyme assay. In addition, Arabidopsis plants expressing luciferase under the control of the constitutive 35S-promoter showed similar wound-induced light emission. In experiments in which only parts of the leaves were sprayed with luciferin solutions, it was shown that increased uptake of luciferin at the wound site and its transport through vascular tissue were the main reasons for the rapid burst of light produced by preformed luciferase activity. These data demonstrate that there are barriers that restrict luciferin entry into adult plants, and that luciferin availability can be a limiting factor in non-invasive luciferase assays.
Nass
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Leibniz Institute of Plant Biochemistry, Department of Stress- and Developmental Biology, Halle, Saale, Germany. nnass@ipb-halle.de
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D017360:Arabidopsis / Q000201:enzymology / Q000378:metabolism*; D001483:Base Sequence; D017931:DNA Primers; D049454:Firefly Luciferin / Q000378:metabolism*; D008156:Luciferases / Q000235:genetics*; D030821:Plants, Genetically Modified / Q000378:metabolism; D010947:Plants, Toxic; D014026:Nicotiana / Q000201:enzymology / Q000378:metabolism*
D017931:DNA Primers; D049454:Firefly Luciferin; D008156:Luciferases