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Abscission

Abscission. a. b. c. Figure 1. a, Premature abscission of poinsettia flower. b, Abscission zone (AZ) development in the induced abscission system. C, Longitudinal section of the AZ (stained with calcofluor). Definition : Separation of plant organs from the mother plant

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Abscission

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  1. Abscission

  2. Abscission a b c Figure 1. a, Premature abscission of poinsettia flower. b, Abscission zone (AZ) development in the induced abscission system. C, Longitudinal section of the AZ (stained with calcofluor) • Definition: Separation of plant organs from the mother plant • Problem: Loss of final product quality and yield in agriculture and horticulture • Our Aim: Elucidate the mechanism of the abscission process to make an improved plant without abscission or with delayed abscission • Main feature: Cell separation including breakdown of • middle lamella accompanying modification of cell wall • components

  3. Why poinsettia? Why abscission? Why Minnesota? • Poinsettia is the most important potted plant in Norway • 6 million plants produced every year • NGF (The Norwegian Grower’s Association) identified poinsettia as the main target for research, and specifed the areas • Flower abscission • Virus • White fly • The Norwegian Reseach Council (NFR) funded a large Strategic Programme coordinated by Prof. Roar Moe from 2002-2005 • NFR funded another project 2004-2007 (Reidunn Aalen, UiO) • Fulbright scholarship 2009-2010 to Trine H-E as a visiting scientist at UMN to work with Jerry D. Cohen and Gary Gardner at the Dept of Horticultural Sciences, UMN: two highly distinguished scientists in the auxin field Abscission

  4. Flowers of poinsettia Abscission From Rasolomanana 2008 • Flowers in the centre of the red bracts • 3rd order flowers used in all experiments = 6 identical buds/star

  5. Induction of abscission • Decapitating the buds to intiate abscission • Initiated in 7 days under winter conditions (under low light) • 98-100 % induction if done accurately Abscission

  6. Abscission Control Induced abscission Natural abscission

  7. Abscission THE HORMONE STORY

  8. Decapitation must be accurate! • Cut position extremely important • Applications of • IAA • ABA • GA3 • Ethylene • Combinations of two Abscission From Munster 2006

  9. Hormone interactions • Hypothesis based on experiments with 3 cut positions and applications of IAA, ABA, GA3 Abscission Mathiesen et al in prep

  10. So I came to Minnesota… Abscission

  11. Auxin transport studies • Distribution of IAA in buds verified • Next step was to verify if the auxin protects the AZ from developing through auxin transport from the anthers and top of the bud to the AZ • N-(1-Naphtyl)Phthalamic acid (NPA) inhibits auxin transport Abscission

  12. We decided it would be cool to analyze the whole plants: • Analyze whole plants of poinsettia to get IAA distribution of the whole plant, incl flowers – an IAA map of poinsettia • This is feasible because poinsettia is vegetatively propagated and has an early responsiveness to short days to induce flowering Abscission

  13. Plants analyzed: non-flowering, flowering and past anthesis (abscised) Abscission

  14. The plants were carefully harvested and each piece (50-150 mg) was carefully labeled Abscission

  15. Acknowledgements • Thanks to Jerry and Gary for hosting me! • Thanks to Xing, Sumaira and Peng for helping out in the lab! • Thanks to the members of Jerry’s, Gary’s and Adrian’s groups for their help, friendship and support • Thanks to John Erwin for helping me aquire poinsettias • Thanks to Roger for the help in the greenhouses • Thanks to my husband Odd Arne for helping me with the statistics Abscission Thanks to all of you! Thanks to Fulbright!

  16. THANK YOU FOR YOUR ATTENTION ! Abscission

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