Photobiological properties of the inhibition of etiolated Arabidopsis seedling growth by ultraviolet-B irradiation.
Alteration of 'normal' levels of ultraviolet-B light (UV-B, 280-320 nm) can affect plant chemical composition as well as growth; however, little is known about how plants perceive UV-B light. We have carried out fluence response curves, and demonstrated that the growth inhibition of etiolated Arabidopsis thaliana seedlings by low fluence UV light is specific to UV-B and not UV-A (320-390 nm). The response shows reciprocity between duration and intensity, at least over a limited range, and thus depends only on photon fluence and not on photon flux. The action spectrum for this response indicates a peak of maximum effectiveness at 290 nm, and response spectra at different fluences indicate that the most effective wavelength at 30,000 micromol m(-2) is 290 nm, whereas 300 nm light was the most effective at 100,000 micromol m(-2). This response occurs in mutant seedlings deficient in cryptochrome, phytochrome or phototropin, suggesting that none of the known photoreceptors is the major UV-B photoreceptor. Some null mutants in DNA repair enzymes show hypersensitivity to UV-B, suggesting that even at low fluence rates, direct damage to DNA may be one component of the response to UV-B.
Gardner
Gary
G
Department of Horticultural Science, University of Minnesota, St. Paul, MN 55108, USA. ggardner@umn.edu
Lin
Chentao
C
Tobin
Elaine M
EM
Loehrer
Heather
H
Brinkman
Doug
D
D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000528:radiation effects; D004260:DNA Repair; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D009154:Mutation; D036226:Seedlings / Q000254:growth & development / Q000528:radiation effects*; D015398:Signal Transduction; D014466:Ultraviolet Rays