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Ethylene PowerPoint Presentation

Ethylene

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Ethylene

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  1. Ethylene Abscission of fruits, flowers and leaves

  2. The Discovery of Ethylene • The oldest identified growth regulator • Was used by the ancient Egyptians to cause fig ripening • The Chinese burned incense in closed rooms to cause pear ripening • Discovered in 1901 by Dimitry Neljubow • In 1910 H. H. Cousins showed that plants can produce their own ethylene • Discovery of Ethylene's role in abscission was in 1917 by S Doubt • In 1934 ethylene was shown as a natural plant product

  3. Functions of Ethylene • Stimulates shoot & root growth & differentiation • Stimulates the release of dormancy • May have a role in adventitious root formation • Stimulates bromiliad flower induction • Induction of femaleness in dioecious flowers • Stimulates flower opening • Stimulates flower & leaf senescence • Stimulates fruit ripening • Stimulates leaf, fruit and flower abscission

  4. Ethylene transport • Transported as a gas • Diffuses through the airspace • Transported in the cytosol • Travels from cell to cell in the symplast and phloem

  5. Measurement of Ethylene • Epinasty of leaves • Flower senescence • Root hair formation • Leaf abscission • Triple response • Gas chromatography

  6. Biosynthesis of Ethylene • Ethylene is produced from L-methionine in higher plants • Methionine is activated by ATP to form S-sdenosylmethionine • ACC is the rate limiting step of ethylene production and its activity is regulated by factors such as wounding, drought stress, flooding and auxin

  7. Stress induced Ethylene • Ethylene is the stress hormone • Wounding • Flooding • Drought • Chilling • Heating

  8. Three phases of leaf abscission • Leaf maintenance phase • Shedding induction phase • Shedding phase

  9. Ethylene’s Affects • Cross section of a cabbage • Stored in a room containing apples • Ethylene produced from the apples caused abscission of the leaves from the stalk, even though the cabbage was immature

  10. Ethephon O ll ll Cl-----CH2----CH2----P----OH + OH-  CH2===CH2 + H2PO4- + Cl- l l O- Ethephon Ethylene • Stable at low pH, but at neutral or high pH, breaks down to give off ethylene • Mixing with water is a convenient method of exposing plants to high doses of ethylene

  11. Characterization of a non-abscission mutant in Lupinus angustifolius. I. Genetic and Structural aspects Jon Clements and Craig Atkins American Journal of Botany 88(1): 31-42, 2001

  12. Lupinus angustifolius (Abs-) • Spontaneous mutant (Abs-) that does not abscise any organ, but still maintains normal patterns of growth and senescence • A recessive single gene mutation • This mutant is specific to abscission, and may be caused by a lack or delay in the expression of hydrolytic enzymes which are specifically associated with abscission zone differentiation and separation

  13. Biotechnology Relevance • Delays in fruit ripening • Delays in petal fading • Delays in abscission • Abscission limits yield and fiber quality of cotton