Lecture23 - 1. Abscisic acid is a single compound unlike...

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1. Abscisic acid is a single compound unlike the auxins, gibberellins, and cytokinins. 2. In 1963, abscisic acid was first identified and characterized by Addicott and his colleagues. They were studying compounds responsible for the abscission of fruits (cotton). Two compounds were isolated and called abscisin I and abscisin II . Abscisin II is presently called abscisic acid (ABA) 3. Two other groups at about the same time discovered the same compound. One group headed by Wareing was studying bud dormancy in woody plants. The other group led by Steveninck was studying abscission of flowers and fruits from lupine. 4. Plant physiologists agreed to call the compound abscisic acid
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ABA is a naturally occurring compound in plants. It is a sesquiterpenoid (15-carbon)
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1. ABA biosynthesis takes place in chloroplasts and other plastids It makes sense that biosynthesis primarily occurs in the leaves. 2. The production of ABA is stimulated by stresses such as water loss and freezing temperatures. 3. ABA-deficient mutants have been found in both maize and Arabidopsis . A 40C carotenoid
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Breakdown of the C40 carotenoid 1. An asymmetric cleavage reaction--> C15 + C25 2. Further oxidation of the cleaved C15 product into ABA-aldehyde and ABA Synthesis of NCED is rapidly Induced by water stress O
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ABA can be inactivated by further oxidation or conjugation Conjugation not only renders ABA inactive but also alters its polarity and cellular distribution Free ABA: cytosol ABA-GE: vacuole
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Transport of ABA 1. Transport of ABA occurs through both the xylem and phloem . However, it is usually much more abundant in the phloem sap.
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This note was uploaded on 11/30/2011 for the course BIOLOGY 321 taught by Professor Min during the Winter '11 term at University of Michigan.

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Lecture23 - 1. Abscisic acid is a single compound unlike...

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