Action spectra of the light-growth response in three behavioral mutants of Phycomyces.
Null-point action spectra of the light-growth response were measured for three mutants of Phycomyces blakesleeanus (Burgeff) and compared with the action spectrum of the wild type (WT). The action spectrum for L150, a recently isolated "night-blind" mutant, differs from the WT spectrum. The L150 action spectrum has a depression near 450 nm and small alterations in its long-wavelength cutoff, the same spectral regions where its photogravitropism action spectrum is altered. This indicates that the affected gene product influences both phototropism and the light-growth response. For L85, a "hypertropic" (madH) mutant, the light-growth-response action spectrum is very similar to that of WT even though the photogravitropism action spectrum of L85 has been shown previously to be altered in the near-UV region. The affected gene product in this mutant appears to affect phototropic transduction but not light-growth-response transduction. The action spectrum of C110, a "stiff" (madE) mutant, differs significantly from the WT spectrum near 500 nm, the same spectral region where sporangiophores of madE mutants have been shown to have small alterations in second-derivative absorption spectra. This indicates that the madE gene product may be physically associated with a photoreceptor complex, as predicted by system-analysis studies.
Ensminger
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Department of Physics, Syracuse University, NY 13244-1130, USA.
Lipson
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D005800:Genes, Fungal; D018522:Gravitropism / Q000235:genetics* / Q000528:radiation effects; D008027:Light; D009154:Mutation; D018524:Phototropism / Q000235:genetics* / Q000528:radiation effects; D010800:Phycomyces / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects*; D015398:Signal Transduction / Q000235:genetics