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Ethylene and Senescence Matt Mckechnie. Properties Hormone – only gas of the five classic plant hormones Structure –hydrocarbon.

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Presentation on theme: "Ethylene and Senescence Matt Mckechnie. Properties Hormone – only gas of the five classic plant hormones Structure –hydrocarbon."— Presentation transcript:

1 Ethylene and Senescence Matt Mckechnie

2 Properties Hormone – only gas of the five classic plant hormones Structure –hydrocarbon

3 Historical facts Ancient Egypt –fig gashing Ancient China –burned incense to ripen pears Neljubow (1901) –coal lamps Cousins (1910) –oranges Gane (1934) –natural product Burg & Thimann (1959) –quantification McKeon et al. (1995) –biosynthetic pathway

4 Functions Stimulates bromelliad, pineapple flower induction Induction of femaleness in flowers Stimulates flower opening Stimulates fruit ripening Stimulates the release of dormancy. Stimulates shoot and root growth and differentiation (triple response) May have a role in adventitious root formation Stimulates leaf and fruit abscission

5 Senescence Plants age productively because as tissues senesce they produce enzymes necessary to recycle valuable materials and reroute the subunits to areas for use by active growth in some other place, at some other time or in the next generation

6 Biosynthesis of ethylene from methionine –from the Yang cycle to AdoMet -while consuming 1 ATP to ACC (limiting step) –via ACC synthase to ethylene –via ACC oxidase

7 Senescence- mechanism Hormonal response –Climacteric Protein synthesis –For limited/controlled hydrolysis Transport –To seeds, active growth areas or storage

8 Controlling Senescence cytokinins and gibberellins –seeds, roots High [CO 2 ] –Limits respiration Harsh Chemicals (florists) –Antifungal agents-sodium benzoate –Anti-ethylene agents (silver nitrate)

9 Detecting Ethylene Quantitatively –Gas chromatography sensitive down to parts per trillion

10 Detecting Ethylene Qualitatively –Bioassays for best results: triple response in pea seedlings other bioassays –epinasty of tomato leaves –root hair formation –leaf abscission

11 Associated research SAGs response vs. different stresses and hormone treatments –ethylene –detached leaves in the dark were most affected Indicated by older and younger leaves reacting similarly –four new SAGs were isolated


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