A LATERAL ROOT DEFECT IN THE WAG1-1;WAG2-1 DOUBLE MUTANT OF ARABIDOPSIS

Graduate School ETD Form 9 (Revised 12/07) PURDUE UNIVERSITY GRADUATE SCHOOL Thesis/Dissertation Acceptance This is to certify that the thesis/dissertation prepared By Entitled For the degree of Is approved by the final examining committee: Chair To the best of my knowledge and as understood by the student in the Research Integrity and Copyright Disclaimer (Graduate School Form 20), this thesis/dissertation adheres to the provisions of Purdue University’s “Policy on Integrity in Research” and the use of copyrighted material. Approved by Major Professor(s): ____________________________________ ____________________________________ Approved by: Head of the Graduate Program Date Steven D. Rowland A Lateral Root Defect in the wag1-1/wag2-1 Double Mutant of Arabidopsis Master of Science John C. Watson Stephen Randall Ellen Chernoff John C. Watson Simon Atkinson 04/20/11 Graduate School Form 20 (Revised 9/10) PURDUE UNIVERSITY GRADUATE SCHOOL Research Integrity and Copyright Disclaimer Title of Thesis/Dissertation: For the degree of Choose your degree I certify that in the preparation of this thesis, I have observed the provisions of Purdue University Executive Memorandum No. C-22, September 6, 1991, Policy on Integrity in Research.* Further, I certify that this work is free of plagiarism and all materials appearing in this thesis/dissertation have been properly quoted and attributed. I certify that all copyrighted material incorporated into this thesis/dissertation is in compliance with the United States’ copyright law and that I have received written permission from the copyright owners for my use of their work, which is beyond the scope of the law. I agree to indemnify and save harmless Purdue University from any and all claims that may be asserted or that may arise from any copyright violation. ______________________________________ Printed Name and Signature of Candidate ______________________________________ Date (month/day/year) *Located at http://www.purdue.edu/policies/pages/teach_res_outreach/c_22.html A Lateral Root Defect in the wag1-1/wag2-1 Double Mutant of Arabidopsis Master of Science Steven D. Rowland 05/02/11 A LATERAL ROOT DEFECT IN THE WAG1-1;WAG2-1 DOUBLE MUTANT OF ARABIDOPSIS A Thesis Submitted to the Faculty of Purdue University by Steven D. Rowland In Partial Fulfillment of the Requirements for the Degree of Master of Science August 2011 Purdue University Indianapolis, Indiana ii This work is dedicated to my parents Steve and Donna Rowland, and to my sister Melissa. iii ACKNOWLEDGMENTS I would like to thank Dr. John C. Watson for giving me the opportunity to pursue graduate work in his laboratory. The advice and insights he has given me during my time here are invaluable, and he has been a great influence in my development as a scientist. I would like to thank Dr. Stephen Randall for all his advice and input during my time here. I would also like to thank Dr. Ellen Chernoff for all the aid she has given me in learning to be a better microscopist. Her instruction was invaluable and this work would not have been possible without her. I also need to thank Kay Cheek for her input and advice as both a fellow scientist and a friend. Finally, I need to thank my parents who have always driven me to pursue the things I loved, and always supported me no matter where those things may have led. iv TABLE OF CONTENTS Page LIST OF FIGURES vi LIST OF ABBREVIATIONS viii ABSTRACT ix INTRODUCTION 1 Root System Architecture of Plants 1 Arabidopsis Root Anatomy 2 Lateral Root Development 5 Root Waving 10 Protein Serine/Threonine Kinases 11 MATERIAL AND METHODS 14 Plant Material and Growth Conditions 14 Emerged Lateral Root Quantification 14 Staging of Lateral Root Primordia 15 Germination 16 Promoter Activity and Lateral Organ Density 16 LR and LRP Density in Zone 1 and Zone 2 17 Lateral Root and Lateral Root Primordia Patterning 17 v Page Methyl Jasmonate Treatment 18 Calcium Blockers 18 RESULTS 19 Lateral Root and Lateral Root Primordia in wag1;wag2 19 Root Waving and Lateral Root Development 23 Lateral Root Response to Hormone and Inhibitor Treatments 25 Genetic Analysis of WAG1 and WAG2 in Lateral Root Development 30 DISCUSSION 33 Lateral Root and Lateral Root Primordia in wag1;wag2 33 Root Waving and Lateral Root Development 36 Lateral Root Response to Hormone and Inhibitor Treatments 38 Genetic Analysis of WAG1 and WAG2 in Lateral Root Development 41 FUTURE DIRECTIONS 44 FIGURES 48 LIST OF REFERENCES 64 APPENDIX. 69 vi LIST OF FIGURES Figure Page Figure 1 Lateral Root Initiation Pathway 48 Figure 2 Schematic of the PsPK3-like Proteins 49 Figure 3 wag1;wag2 has Increased Lateral Roots 50 Figure 4 wag1;wag2 has Increased LRP Formation 51 Figure 5 WAG1 and WAG2 Promoter Activity 52 Figure 6 wag1;wag2 has Increased LR Formation 53 Figure 7 wag1;wag2 LRP Density is Increased 54 Figure 8 LO Position and Patterning 55 Figure 9 Inter-Lateral Organ Distance 56 Figure 10 Germination Rate 57 Figure 11 Auxin Response 58 Figure 12 Auxin Induction of LR Formation 59 Figure 13 LR and LRP Development with MeJA Treatment 60 Figure 14 wag1;wag2 has Decreased Emeregence on MeJA 61 Figure 15 Calcium Inhibitors Reduce wag1;wag2 LR Formation 62 Figure 16 Genetic Analysis of wag1;wag2 LR Pathway 63 vii Appendix Figure Page Figure A.1 Increased Meristem Size in wag1;wag2 78 Figure A.2 wag1;wag2 has an Increased Meristem Size 79 viii LIST OF ABBREVIATIONS ABA Abcisic Acid ARG Altered Response to Gravity AUX Auxin Resistance AXR Auxin Resistant IL Inner Layer LAX Like AUX1 LO Lateral Organ LR Lateral Root / Roots LRP Lateral Root Primordium / Primordia OL Outer Layer PAT Polar Auxin Transport PGM Phosphoglucomutase PID PINOID PIN Pin Formed RSA Root System Architecture TIR Transport Inhibitor Response [...]... protein-serine/threonine kinases (2,58) Protein kinases are enzymes that transfer the gamma phosphate of ATP or GTP to a substrate protein (58) This transfer often results in the activation or inactivation of the substrate (58) AGCVIIIa protein kinases are distinguished from other AGC kinases by a conserved DFD motif, and a variable insertion within the catalytic domain (58) Many AGCVIIIa kinases have not been associated... as lateral roots The initiation and development of lateral roots has been well defined WAG1 and WAG2 are protein-serine/threonine kinases from Arabidopsis that are closely related to PINOID and suppress root waving The wag1;wag2 double mutants exhibit a strong root waving phenotype on vertical hard agar plates only seen in wild-type roots when the seedlings are grown on inclined plates Here an additional... layers damaging the primary root in the process (53) As the lateral root continues to develop, LAX3 transports auxin into the overlying tissue layer causing the breakdown of the cell walls and allowing for the lateral root to eventually emerge from the primary root without damage After the auxin maximum is formed and the pericycle founder cells re-enter the cell cycle, they begin anticlinal division (along... components of the medium also contribute to the waving pattern of seedling roots For example, roots will not wave in the absence of sucrose (21,54) The levels of ethylene present also modulate the amount of root waving (21,36,54) Protein Serine/Threonine Kinases The AGCVIIIa subfamily of kinases in Arabidopsis is a part of the eukaryotic group of regulatory kinases (58) AGCVIII kinases are protein-serine/threonine... columnella cells, auxin is moved into the lateral root cap by PIN3 and PIN4 (3) Auxin in the lateral root cap is moved shootward through the epidermal cell layer via the protein PIN2 (1,39) Mutations in PIN2 demonstrated a role for auxin transport in proper gravitropic response, as the roots of PIN2 loss -of- function mutants displayed an agravitropic phenotype (1,39) In the transition zone auxin transported... contact and avoidance of a barrier in the soil, can alter RSA significantly, typically resulting in the formation of new lateral roots on specific sides of the primary root, associated with the direction of avoidance (48) Biotic factors 2 also affect RSA, such as bacteria (infectious or not) and fungi (44) The ways in which the RSA is altered is almost as varied as the number of biotic factors that can affect... was nearly twice that of inclined Col-0 seedlings and vertical wag1;wag2 seedlings The average inter-LO distance between inclined Col-0 and vertical wag1;wag2 was not statistically different These data strongly suggest that the root waving of the wag1;wag2 double mutant affects the spatial pattern of LR and LRP De Smet et al (2007) previously showed waving roots have 51% of their LR positioned on the. .. additional root phenotype in the wag1;wag2 mutant is reported The wag1;wag2 double mutant displays both an increased total number and density of emerged lateral roots (approximately 1.5-fold) An increased LRP density of 1.5-fold over wild-type is observed To ascertain the role of WAG1 and WAG2 in lateral root development we examined promoter activity in the WAG1::GUS and WAG2::GUS lines The WAG1 promoter... only in pericycle cells that had previously been primed and activate the lateral root developmental program (9,18,19,20,42) Additionally an auxin maximum continues to accumulate in the actively dividing cells, which up regulates Like AUX1 (LAX) 3 in the cells of the adjacent tissue layer (53) LAX3 is an auxin influx protein, and, in the case of the initially 7 dividing pericycle cells, imports auxin into... present in low amounts the root system will alter its architecture by increasing the amount of branching or increasing root elongation (33,44,46,59) Availability of a carbon source, such as glucose, also alters the RSA When glucose is readily available, roots will increase branching, growth rate and root hair development, significantly altering their architecture (38) Mechanical stimulation, such as contact . ETD Form 9 (Revised 12/07) PURDUE UNIVERSITY GRADUATE SCHOOL Thesis/ Dissertation Acceptance This is to certify that the thesis/ dissertation prepared By Entitled For the degree of Is approved. Integrity and Copyright Disclaimer Title of Thesis/ Dissertation: For the degree of Choose your degree I certify that in the preparation of this thesis, I have observed the provisions of Purdue. all materials appearing in this thesis/ dissertation have been properly quoted and attributed. I certify that all copyrighted material incorporated into this thesis/ dissertation is in compliance