Phototropin

Phototropins are blue light photoreceptor proteins (more specifically, flavoproteins) that mediate phototropism responses across many species of algae,[1] fungi and higher plants.[2] Phototropins can be found throughout the leaves of a plant. Along with cryptochromes and phytochromes they allow plants to respond and alter their growth in response to the light environment. When phototropins are hit with blue light, they induce a signal transduction pathway that alters the plant cells' functions in different ways.

Phototropins are part of the phototropic sensory system in plants that causes various environmental responses in plants. Phototropins specifically will cause stems to bend towards light[3] and stomata to open.[4] In addition phototropins mediate the first changes in stem elongation in blue light prior to cryptochrome activation.[5] Phototropins are also required for blue light mediated transcript destabilization of specific mRNAs in the cell.[6]

Phototropins also regulate the movement of chloroplasts within the cell,[7][8] notably chloroplast avoidance. It was thought that this avoidance serves a protective function to avoid damage from intense light,[9] however an alternate study argues that the avoidance response is primarily to increase light penetration into deeper mesophyll layers in high light conditions.[10] Phototropins may also be important for the opening of stomata.[11]

  1. ^ Veetil, S.K; Mittal, C; Ranjan, P; Kateriya, S (July 2011). "A conserved isoleucine in the LOV1 domain of a novel phototropin from the marine alga Ostreococcus tauri modulates the dark state recovery of the domain". Biochim Biophys Acta. 1810 (7): 675–82. doi:10.1016/j.bbagen.2011.04.008. PMID 21554927.
  2. ^ Li, F. W., Rothfels, C. J., Melkonian, M., Villarreal, J. C., Stevenson, D. W., Graham, S. W., Wong, G. K. S., Mathews, S., & Pryer, K. M. (2015). The origin and evolution of phototropins. Frontiers in Plant Science, 6(AUG). https://doi.org/10.3389/fpls.2015.00637
  3. ^ Price (2009). Molecular Basis of Botanical Biology. Phoenix Publishing. p. 213.
  4. ^ Price (2009). Molecular Basis of Botanical Biology. Phoenix Publishing. p. 213.
  5. ^ Folta, Kevin (2001). "Unexpected Roles for Cryptochrome 2 and Phototropin Revealed by High-resolution Analysis of Blue Light-mediated Hypocotyl Growth Inhibition". The Plant Journal. 26 (5): 471–78. doi:10.1046/j.1365-313x.2001.01038.x. PMID 11439133.
  6. ^ Brighton; et al. (2006). "Role of phototropin in the differential expression of blue light mediated mRNAs". International Journal of Molecular Botany. 72 (54): 672–691.
  7. ^ Wada M, Kagawa T, Sato Y (2003). "Chloroplast movement". Annu Rev Plant Biol. 54: 455–68. doi:10.1146/annurev.arplant.54.031902.135023. PMID 14502999.
  8. ^ DeBlasio SL, Luesse DL, Hangarter RP (September 2005). "A plant-specific protein essential for blue-light-induced chloroplast movements". Plant Physiol. 139 (1): 101–14. doi:10.1104/pp.105.061887. PMC 1203361. PMID 16113226.
  9. ^ Kasahara, M., Kagawa, T., Olkawa, K., Suetsugu, N., Miyao, M., & Wada, M. (2002). Chloroplast avoidance movement reduces photodamage in plants. Nature, 420(6917). https://doi.org/10.1038/nature01213
  10. ^ Wilson, S., & Ruban, A. v. (2020). Rethinking the influence of chloroplast movements on non-photochemical quenching and photoprotection. Plant Physiology, 183(3). https://doi.org/10.1104/pp.20.00549
  11. ^ Smith, Garland (2010). Fundamentals of Biomolecular Botany (2 ed.). Fisher Press. p. 340.