Red-light-induced positive phototropism in Arabidopsis roots

• Published in: Planta 2001-02, Vol.212 (3), p.424-430
• Main Authors: Ruppel, Nicholas J., Hangarter, Roger P., Kiss, John Z.
• Format: Article
• Language: English
• Subjects: Arabidopsis - genetics; Arabidopsis - physiology; Arabidopsis - radiation effects; Biological and medical sciences; Curvature; Fluence; Fundamental and applied biological sciences. Psychology; Gravitropism; Gravitropism - physiology; Hypocotyls; Life Sciences (General); Light; Movements; Phototropism; Phototropism - physiology; Plant cells; Plant physiology and development; Plant roots; Plant Roots - physiology; Plant Roots - radiation effects; Plants; Root growth; Seedlings; Space life sciences
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/s004250000410

The interaction between light and gravity is critical in determining the final form of a plant. For example, the competing activities of gravitropism and phototropism can determine the final orientation of a stem or root. The results reported here indicate that, in addition to the previously described blue-light-dependent negative phototropic response in roots, roots of Arabidopsis thaliana (L.) Heynh. display a previously unknown red-light-dependent positive phototropic response. Both phototropic responses in roots are considerably weaker than the graviresponse, which often masks phototropic curvature. However, through the use of mutant strains with impaired gravitropism, we were able to identify a red-light-dependent positive phototropic response in Arabidopsis roots. The redinduced positive phototropic response is considerably weaker than the blue-light response and is barely detectable in plants with a normal gravitropic response.