Plant phototropic growth.
Plants are photoautotrophic sessile organisms that use environmental cues to optimize multiple facets of growth and development. A classic example is phototropism - in shoots this is typically positive, leading to growth towards the light, while roots frequently show negative phototropism triggering growth away from the light. Shoot phototropism optimizes light capture of leaves in low light environments and hence increases photosynthetic productivity. Phototropins are plasma-membrane-associated UV-A/blue-light activated kinases that trigger phototropic growth. Light perception liberates their protein kinase domain from the inhibitory action of the amino-terminal photosensory portion of the photoreceptor. Following a series of still poorly understood events, phototropin activation leads to the formation of a gradient of the growth hormone auxin across the photo-stimulated stem. The greater auxin concentration on the shaded compared with the lit side of the stem enables growth reorientation towards the light. In this Minireview, we briefly summarize the signaling steps starting from photoreceptor activation until the establishment of a lateral auxin gradient, ultimately leading to phototropic growth in shoots.
Centre for Integrative Genomics, Faculty of Biology and Medicine, Génopode Building, University of Lausanne, CH-1015 Lausanne, Switzerland. Electronic address: christian.fankhauser@unil.ch.
Christian
C
Fankhauser
Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, Bower Building, University of Glasgow, Glasgow G12 8QQ, UK.
John M
JM
Christie
D017360:Arabidopsis / Q000254:growth & development* / Q000378:metabolism / Q000528:radiation effects; D007210:Indoleacetic Acids / Q000378:metabolism; D056949:Phototropins / Q000378:metabolism / Q000528:radiation effects; D018524:Phototropism; D063245:Plant Development; D014466:Ultraviolet Rays
D007210:Indoleacetic Acids; D056949:Phototropins