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Auxin

Auxin. Sandy Alkoutami, Rachel Guenter, Will Banish, and Taylor Black. Molecular Formula. C 10 H 9 NO 2. Background Information. The first plant hormone discovered by Frits Went in 1926 The most intensely studied molecule in plants

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Auxin

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  1. Auxin Sandy Alkoutami, Rachel Guenter, Will Banish, and Taylor Black

  2. Molecular Formula • C10H9NO2

  3. Background Information • The first plant hormone discovered by Frits Went in 1926 • The most intensely studied molecule in plants • Involved in almost every aspect of plant growth, such as cell division and specialization • Crucial for the correct foundation of root growth • IAA (indole-3-acetic acid) is a form of Auxin • One of the most prevalent and important forms of Auxin

  4. Origin in Plants • Auxin synthesis occurs in shoot apical meristem and young leaves • Produced in root apical meristems • Growing fruits and seeds contain high amounts of Auxin • However, it is still uncertain whether Auxin is produced of transported from maternal tissues

  5. Destination • Auxin is typically produced in shoot tips • Transported between cells down the stem of a plant (1 cm/hr) • Auxin moves from tip to base; never in the opposite direction • Polar transport • Polar transport in auxin results from the polar distribution of its transport proteins in cells

  6. Functions of Auxin • Promotes the production of lateral and adventitious roots • Controls the development of fruit • Enhances apical dominance • Promotes vascular differentiation • Retards leaf abscission • Stimulates stem elongation • Involved in phototropism

  7. Phototropism • Phototropism is the growth of a shoot toward or away from light • The shoot tip, which contains auxin, is responsible for the direction in which the shoot moves • The areas where the sun hits the shoot has the least amount of auxin; however, the shaded areas of the shoot have the most • The auxin in these areas respond to the lack of light by controlling the movement of the shoot towards the sun

  8. Cell Elongation • Auxin stimulates cell growth by binding to a receptor in the cell membrane • Acid growth hypothesis is a model reflecting this process • In the shoot’s region of elongation, auxin promotes the cell membrane’s proton pumps • Increases voltage across the membrane and lowers pH in cell wall • The increasing membrane potential promotes the uptake of ions in the cell • Enables osmosis which increases turgor • Increased turgor allow the cell to elongate

  9. Flowchart • Response • Growth proteins are synthesized • Transduction • A second messenger activates DNA binding protein which goes to the golgi and also activates an ATP synthase • Next step: auxin regulated gene in the nucleus

  10. Sources • http://www.cshperspectives.cshlp.org/content/2/10/a004572.full • http://www.plant-hormones.info/auxins.htm • http://pubs.acs.org/cen/news/83/i22/8322notw1.html • https://docs.google.com/viewer?a=v&q=cache:pt4NiTdCOlQJ:classes.uleth.ca/200603/biol4560a/xu.pdf+background+information+of+auxin&hl=en&gl=us&pid=bl&srcid=ADGEESj-Yw-8ggInhDRbOk8ZpgYJqnH2dvrjqXBntJy-poWnOnL1Gy19FYLqznEuNzMjbvA9QFFt3LLUdpTa0ad-86G8yQ9nLDt4F9RS3pDU0ZL4D2LDjzpdzD4d4eyVRi_2RGwDLAF0&sig=AHIEtbRKW1qcyKDEq1ycfIqHz2dI8VqXdw • http://auxin.hawaii-conference.com/sponsors • https://docs.google.com/viewer?a=v&q=cache:pteaMyuZlPYJ:rhsapbiology.wikispaces.com/file/view/Ch%255B1%255D.%2B39%2BPlant%2BResponses%2Bto%2BInternal%2Band%2BExternal%2BStimuli.ppt+&hl=en&gl=us&pid=bl&srcid=ADGEESgaZcxAeyYpEIwNimuEk2_K2q8t7P7tNtB_FA5FnBP51JDonk-FA2Eu_KMigKY-hW0M15j3i6nrjJpJkg1wDKFd0J4f_gLMoWGY4hKVfP0mSQURlWVEGX7OqvReenXlwgHRYN3B&sig=AHIEtbRrI6b6OzvZddRRwOWhSdFsDR0BaA • Campbell NA, Reece JB. 2011. Biology 9th ed. San Francisco (CA): Pearson/Benjamin Cummings

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