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The Roles of Polar Auxin and Calcium Transport in the Gravitropic Response of Maize Roots

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The Roles of Polar Auxin and Calcium Transport in the Gravitropic Response of Maize Roots Order Number 8824647 The roles of polar auxin and calcium transport in the gravitropic response of maize roots Young, Linda Mull, Ph.D. The Ohio State University, 1988 Copyright ©1988 by Young, Linda Mull. All rights reserved. 300 N. Zeeb Rd. Ann Arbor, MI 48106 THE ROLES OF POLAR AUXIN AND CALCIUM TRANSPORT IN THE GRAVITROPIC RESPONSE OF MAIZE ROOTS DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of the Ohio State University By Linda Mull Young, B.A., M.S. ***** The Ohio State University 1988 Dissertation Committees Approved by M. G. Cline M. L. Evans G. L. Floyd Advisor F. D. Sack Department of Botany Copyright by Linda Mull Young 1988 To the Crew of Challenger - may your spirit of adventure live in us always. ACKNOWLEDGMENTS I wish to acknowledge my advisor, Dr. Michael L. Evans for his encouragement and advice in the preparation of this manuscript and during the performance of the research upon which it is based. I am truly thankful for this opportunity to work with and learn from such an outstanding scientist. I wish to extend my gratitude to the members of my committee for their valued opinions during the course of this research and their helpful suggestions during the preparation of this dissertation. Special thanks are extended to Dr. Rainer Hertel whose enthusiasm is contagious. Not only did Rainer suggest many of the experiments described here, but he has also instilled in me some of his scientific curiosity. Rainer's unique approach to research has shown me how satisfying scientific investigation can be. I wish to thank my friends and co-workers: Mark Fondren, Karl Hasenstein, John Kiss, June Lee, Chuck iii Stinemetz, Rosemary White and Rick Yang. Their suggestions, help and support have been invaluable. Finally, I wish to thank my parents for their encouragement and patience. I also thank and acknowledge my husband, Curtis for his support and understanding during the difficult times. His love and unwavering belief in my abilities helped to make this dissertation possible. VITA March 31, 1960........... Born - Latrobe, Pennsylvania 1982...... .... ............B.A., Wittenberg University Springfield, Ohio Biology and Chemistry 1985...................... M.S., The Ohio State University Columbus, Ohio Botany 1985 - Present............. Research and Teaching Associate Department of Botany The Ohio State University Columbus, Ohio PUBLICATIONS Mull, Linda L. 1985. An examination of calcium flux patterns in maize root tip protoplasts. Master's Thesis. Young, LM ML Evans 1987. Correlations between gravitropic curvature and auxin transport across root tips of Zea mays. ASGSB Bulletin 1_: 29. Young, LM ML Evans 1988. Correlations between gravitropic curvature and auxin transport across root tips of Zea mays. Plant Physiol. 86: 67, suppl. v Evans, ML, CL Stinemetz, LM Young and WM Fondren 1988. The role of calcium in the response of roots to auxin and gravity. In: Plant Growth Substances 1988. Springer Verlag, ed. R. Pharis. FIELDS OF STUDY Major Field: Botany Studies in Plant Physiology - Michael L. Evans vi TABLE OF CONTENTS DEDICATION................................................. ii ACKNOWLEDGMENTS.......................................... iii VITA ..................................................... LIST OF TABLES............................................ ix LIST OF FIGURES........................................... xi LIST OF ABBREVIATIONS...................................xiii INTRODUCTION................................................ 1 CHAPTER I. THE NATURE OF AUXIN TRANSPORT IN G RAVI STIMULATED ROOTS OF ZEA MAYS................... 26 Introduction..................................... 26 Materials and Methods.............................28 Results.......................................... 36 Discussion....................................... 78 II. CORRELATIONS BETWEEN GRAVITROPIC CURVATURE AND AUXIN TRANSPORT ACROSS GRAVISTIMULATED ROOTS OF ZEA MAYS................... 96 Introduction..................................... 96 Materials and Methods............................ 97 Results......................................... 100 Discussion....................... 112 vii III. POSSIBLE AUXIN TRANSPORT/CALCIUM TRANSPORT INTERACTIONS............................. 133 Introduction..................................... 133 Materials and Methods ............... 134 Results.......................................... 139 Discussion....................................... 158 SUMMARY.................................................... 176 LIST OF REFERENCES........................................180 viii LIST OF TABLES TABLE PAGE 1. Polar Auxin Transport Across Caps of Gravistimulated Roots...............................37 2. Time Course of the Development of Downward Auxin Transport Polarity..................42 3. Auxin Transport Across Tips of Intact and Decapped Roots in Vertical and Horizontal Positions........................................... 49 4. 3h _i a a Transport Across Isolated Root Caps or Meristems...................................52 5. Effect of KCN on Polarity of ^h - i a a Transport Across the Tips of Gravi­ stimulated Roots.................................... 55 6. Transport Across Intact Roots Treated with 10"5 m NPA............................ 60 7. 3fj_jAA Transport Across Isolated Root Caps Treated with 10“5 m NPA....................... 63 8. Basipetal Movement of 3h - i a a in Gravistimulated Roots Treated with 10"5 M NPA for 60 min............................. 65 9. Effect of PBA on Auxin Transport Polarity Across the Caps of Gravistimulated Roots......... 67 10. Effect of PBA on the Basipetal Transport of Auxin in Gravistimulated Roots.................69 11. 3r -a b a Transport Across Maize Root Tips...........72 ix 12. Transport of ^h -a b a and ^h - i a a Across Tips of Vertical Maize Roots Following Isotope Loading. ...................74 13. Gravicurvature of Control, Prestimulated and Prestimulated/ Rotated Roots....................................... 110 14. Auxin Transport Across the Caps of Control, Prestimulated and Prestimulated/Rotated Roots........................ 113 15. The Effect of Calmidazolium on Gravi- induced Transport of 45ca2+ Across Maize Root Tips..................................... 140 16. The Effect of Pretreatment of Root Caps with Calmidazolium on Gravi-induced 3h-IAA Redistribution in the Elongation Zone................................................. 142 17. The Effect of EGTA on ^h -i a a Transport Polarity Across the Caps of Gravi­ stimulated Roots. ..................................145 18. Simultaneous Transport of ^h -i a a and 45ca2+ Across the Caps of Gravistimulated Roots........ ...148 x LIST OF FIGURES FIGURE PAGE 1. Auxin Transport in Vertically- and Horizontally-Oriented Roots................... 16 2. The Inositol Trisphosphate Pathway............... 20 3. Time Course of the Development of Auxin Transport Across Caps of Gravistimulated Roots............................. 39 4. Comparison of the Rate of Downward Auxin Transport and the Rate of Upward Auxin Transport Across the Caps of Gravi­ stimulated Roots................................... 44 5. Measurement of Auxin Transport Polarity During Discrete Intervals of the Gravitropic Response...............................47 6. Structures of NPA and PBA......................... 58 7. Basipetal Transport of 3h -ABA and ^H-IAA in Vertical Roots........ 76 8. The Initial Gravitropic Response of Control Roots vs. Roots Pretreated with Inhibitors of Auxin Transport.............. 101 9. Extended Time Course of Gravitropic Curvature in Control Roots vs. Roots Pretreated with Inhibitors of Auxin Transport... 103 xi FIGURE PAGE 10. Short-Term Gravitropic Response of Control, Prestimulated and Prestimulated/ Rotated Roots.....................................105 11. Long-Term Gravitropic Response of Control, Prestimulated and Prestimulated/ Rotated Roots. ............... 107 12. Correlation Between Downward Auxin Transport Polarity and the Rate of Gravicurvature.................................. .116 13. Auxin Transport Polarity vs. Rate of Gravicurvature........................... 119 14. The Time Course of Development of Downward Calcium Transport Polarity Across the Caps of Gravistimulated Roots........ 150 15. A Comparison of Auxin and Calcium Transport Polarities as Determined from Dual Label Experiments...................... 153 16. A Comparison of Downward and Upward Calcium Transport in Gravistimulated Roots...... 156 17. A Comparison of the Basipetal Movement of 3H-IAA and 45Ca2+..............................159 18. A Comparison of Auxin and Calcium Transport Rates Across the Caps of Gravistimulated Roots.............................169 xii LIST OF ABBREVIATIONS CMZ Calmidazolium DMSO Dimethylsulfoxide EGTA Ethyleneglycol-bis-(amino ethyl ether) N, N'-tetraacetic acid 3h -IAA 3—(5 <n> -^HJ-Indolylacetic acid NPA Naphthylphthalamic acid PBA Pyrenoylbenzoic acid INTRODUCTION A REVIEW OF THE STUDY OF ROOT GRAVITROPISM Scientists have long been intrigued by the curvature of plant organs toward or away from the earth's gravitational pull, a phenomenon called gravitropism. This ability to sense the field of gravity and to use it for orienting the direction of growth is advantageous to plant survival. If a plant is displaced from its original position with respect to gravity, perception of the earth's gravitational field by the plant results in the alteration of root and stem growth patterns. Differential growth across these organs ultimately
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