ANALYSIS OF MULTIPLE PHOTORECEPTOR PIGMENTS FOR PHOTOTROPISM IN A MUTANT OF Arabidopsis thaliana

Abstract

Abstract— The shape of the fluence‐response relationship for the phototropic response of the JK224 strain of Arabidopsis thaliana depends on the fluence rate and wavelength of the actinic light. At low fluence rate (0.1 μmol m‐2s‐1), the response to 450‐nm light is characterized by a single maximum at about 9 μmol m‐2. At higher fluence rate (0.4 μmol m‐2s‐1), the response shows two maxima, at 4.5 and 9 μmol m‐2. The response to 510‐nm light shows a single maximum at 4.5 μmol m‐2. Unilateral preirradiation with high fluence rate (25 μmol m‐2s‐1) 510‐nm light eliminates the maximum at 4.5 μmol m‐2 in the fluence response curve to a subsequent unilateral 450‐nm irradiation, while the second maximum at 9 μmol m‐2 is unaffected. Based on these results, it is concluded that a single photoreceptor pigment has been altered in the JK224 strain of Arabidopsis thaliana.