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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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