Journal Article

Red Light-Aphototropic (rap) Mutants Lack Red Light-Induced Chloroplast Relocation Movement in the Fern <i>Adiantum capillus-veneris</i>

Akeo Kadota and Masamitsu Wada

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 40, issue 2, pages 238-247
Published in print January 1999 | ISSN: 0032-0781
Published online January 1999 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/oxfordjournals.pcp.a029533
Red Light-Aphototropic (rap) Mutants Lack Red Light-Induced Chloroplast Relocation Movement in the Fern Adiantum capillus-veneris

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Two physiologically distinct classes of phytochrome seem to regulate the many diverse red light-stimulated responses in the fern haplophase. The classes include dichroic phytochrome and non-dichroic phytochrome [Kadota et al. (1989) Plant CellPhysiol. 30: 523]. The responses regulated by the former show action dichroism under polarized light while those regulated by the latter do not. The involvement of dichroic phytochrome is particularly evident in phototropism and the chloroplast relocation response. In the present work, red-light aphototropic (rap) mutants of the fern Adiantum capillus-veneris were isolated and their photoresponses were characterized. Five rap mutants, rap2, rap7, rap32, rap33, rap39 were obtained. The rap mutants lacked red light polarotropism but still retained normal blue light phototropism and polarotropism. Treatment with biliverdin, a precursor of phytochrome chromophore had no effect on the red-light aphototropic nature of rap mutants. Analyses on the other photoresponses revealed that phytochrome-mediated chloroplast relocation movement was missing in the mutants whereas the response induced by blue light was normal. Phytochrome regulation of spore germination, tip growth and cell division were also normal in the rap strains. These results indicate that phototropism and chloroplast relocation movement share the same dichroic phytochrome and the following signal transduction steps. Moreover, it shows that this pathway is distinct from that controlling spore germination, tip growth and cell division. The rap mutants may have defect(s) in the photoreceptor molecule itself, in the binding mechanism to a stable structure, or in elements involved early in the dichroic phytochrome-mediated signal transduction pathway.

Keywords: Adiantum capillus-veneris (fern); Blue light response; Chloroplast movement; Photomutant; Phototropism; Phytochrome (dichroic)

Journal Article.  0 words. 

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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