Difference between revisions of "Phototropism in Arabidopsis"
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<date>1 Oct 2014</date> | <date>1 Oct 2014</date> | ||
</teaser> | </teaser> | ||
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<newstitle> Localizing phototropism in Arabidopsis</newstitle> | <newstitle> Localizing phototropism in Arabidopsis</newstitle> | ||
<teaser> | <teaser> | ||
Together with the group of Christian Fankhauser from the CIG at UNIL, CBG post-doc Tim Hohm showed that the sites of light perception for phototropism is | Together with the group of Christian Fankhauser from the CIG at UNIL, CBG post-doc Tim Hohm showed that the sites of light perception for phototropism is | ||
| − | located in the upper hypocotyl, where asymmetric elongation occurs. Thus, in contrast to monocots where a phototropism signal is sent from the leaves to the stem, in Arabidopsis it all happens "on site". The paper has | + | located in the upper hypocotyl, where asymmetric elongation occurs. Thus, in contrast to monocots where a phototropism signal is sent from the leaves to the stem, in Arabidopsis it all happens "on site". The paper has been published in |
<a href="http://www.cell.com/current-biology"> Current Biology</a> | <a href="http://www.cell.com/current-biology"> Current Biology</a> | ||
<date>27 Sept 2013</date> | <date>27 Sept 2013</date> | ||
Revision as of 16:21, 1 October 2014
Introduction
Being sessile organisms, plants posses various mechanisms to react to different and changing environmental stimuli. One of these mechanisms allows plants to adjust their growth direction to the direction of incoming blue light. This phototropic response involves sensing of light by photoreceptors, here mainly the membrane-associated proteins phot1 and phot2 kk2006a, redirection of the flux of the hormone auxin bbpm2004a,etls2006a,nbps2003a,pbbm2004a, as well as other downstream signaling events ddri2010a,flds2003a,ikmn2008a,hs2007a,lshp2006a,week2008a. Although these key players in phototropism in Arabidopsis thaliana are known, detailed means of interaction remain hidden.
The current view on phototropism can be summarized as follows: phototropism is a blue light- initiated process with its response being fluence rate dependent. For simplicity, here only low fluence rates of maximally 0.1 μmol m-2s -1 are considered—a scenario in which the phototropic response depends mostly on the activity of the photo receptor phot1. Under these fluence conditions, the second receptor of the same family, phot2, can be neglected. In addition, the two cryptochromes cry1 and cry2 have a mild effect on phototropism kk2006a but are not further considered here.
Open Questions
Considering the fact that during phototropism a lateral auxin gradient with its maximum on the shaded side is formed, the question arises how it is possible that such a gradient is established. Here, it is of special interest why the maximum of the gradient is located on the shaded side since the original blue light stimulus is applied to the opposite side and photo-activation seems to be positively fluence correlated. Still, one can argue that the light absorption of a tissue like a dark grown hypocotyl (with a diameter of about 250μm) hardly absorbs any light but then one would need to question why a gradient is formed at all.
In the course of this project, it is planned to investigate this gradient formation relying on both, experimental techniques as well as computational modeling, collaborating with the groups of Richard Smith and Christian Fankhauser as part of the Plant Growth project from SystemsX.ch.
References
<biblio>
- bbpm2004a pmid=14730061
- ddri2010a pmid=20071603
- etls2006a pmid=16371470
- flds2003a pmid=14645723
- hs2007a pmid=16906793
- ikmn2008a pmid=18378899
- kk2006a pmid=16870491
- lshp2006a pmid=16777956
- nbps2003a pmid=12827205
- pbbm2004a pmid=15208397
- week2008a pmid=20031918
</biblio>
