Plant Hormones and Signal Transduction植物激素与信号转导

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1、Lecture 5Plant hormonesandSignal transductionPLSC 452/5521/23/14Department of Plant SciencesNeal Stewart LabBrain teaser Little Johnny nails a sign 90 cm off the ground to a tree outside of his clubhouse that says “no girls allowed.” If the tree grows 12 cm every year, at what height will the sign b

2、e when Little Johnny returns as Big Johnny in 15 years?Overview Define “hormone” as a functional compound. What is the function and importance of hormones? Know the major plant hormones Understand real-world application of hormones Importance of hormones for tissue culture: introductionWhat is a hor

3、mone? Biochemical which regulates growth based on biological and environmental influences Synonyms: Plant hormones, plant growth regulators (PGRs), phytohormones Regulate growth and development Mobile throughout plant Environment and stress responsiveMajor plant hormones Auxin Greek: auxein; to grow

4、 or increase Cytokinin cytokinesis (cell division) Abscisic acid abscission Jasmonic acid found in jasmine oil Gibberellic acid pathogen Gibberella Ethylene chemical brother to ethanol Brassinosteroids derived from Brassica spp.Finding plant hormonesObservational:Darwin stumbles on auxin Noticed gra

5、ss tips grow toward light With tip growth responded to light Without tip growth had no responseMutation screening: (aka forward genetics) Dwarf plants are can be hormone deficientABRC teaching tools websiteGeneral hormone biochemistry Present in all cells at various levels Classes of hormones work i

6、n signal cascades Hormone-receptor interactions Respond to a host of factors and biological needs Abiotic Water stress Light Nutrient deficiency Biotic Growth Development Herbivore stressHormone biosynthesisMade from four biosynthetic pathways: Terpenoids AMP + IPP (cytokinins) Carotenoid breakdown

7、(abscisic acid) Diterpene (gibberellic acid) Triterpene (brassinosteroids) Fatty acids (jasmonic acid) Tryptophan (auxins) Methionine (ethylene)KEGG database: :/Auxins Greek: auxein; to grow or increase Apical dominance growth Cell elongation Hormone level very important2, 4-dichlorophenoxyacetic Ac

8、id :/ :/=104205Taiz and Zeiger. 2002. Plant Physiology, 3rd Ed.Auxin: Apical dominanceCytokinin Cytokinesis (cell division) Accidently added degraded DNA to medium Organization and development of xylem tissue Response to light Lateral growth of shoots Open stomata :/KinetinApplication: cotton sprayi

9、ng Adding cytokinins to young cotton increase drought-resistance Arizona 31% US cotton, highest yield acre-1Auxin and cytokinin ratio importance Auxin alone = Large cells (no division) Cytokinin alone = Cells have no change Auxin + Cytokinin = Normal cell growth and division Auxin + Cytokinin = Shoo