Iowa State University Capstones, Theses and Graduate Theses and Dissertations Dissertations 2015 Investigating the roles of diterpenoids in rice- Xanthomonas oryzae interactions Xuan Lu Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/etd Part of the Agriculture Commons, and the Plant Sciences Commons Recommended Citation Lu, Xuan, "Investigating the roles of diterpenoids in rice-Xanthomonas oryzae interactions" (2015). Graduate Theses and Dissertations. 14912. https://lib.dr.iastate.edu/etd/14912 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Investigating the roles of diterpenoids in rice-Xanthomonas oryzae interactions by Xuan Lu A dissertation submitted to the graduate faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Major: Plant Biology Program of Study Committee: Reuben J. Peters, Major Professor Gwyn Beattie Gustavo MacIntosh Alan Myers Bing Yang Iowa State University Ames, Iowa 2015 Copyright © Xuan Lu, 2015. All rights reserved. ii TABLE OF CONTENTS Page ABSTRACT ............................................................................................................... iv CHAPTER 1 GENERAL INTRODUCTION ....................................................... 1 Rice–Xanthomonas oryzae Interactions ............................................................ 1 Ecological Function of Secondary Metabolites ............................................. 2 Terpenoids ......................................................................................................... 2 Gibberellin ..................................................................................................... 4 Rice Phytoalexins .............................................................................................. 5 Organization of Dissertation and Author Contribution .................................. 7 References ......................................................................................................... 8 Figures ......................................................................................................... 12 CHAPTER 2 AN ENT-KAURENE DERIVED DITERPENOID VIRULENCE FACTOR FROM XANTHOMONAS ORYZAE PV. ORYZICOLA ..... 15 Abstract ......................................................................................................... 15 Introduction .................................................................................................... 16 Results ......................................................................................................... 18 Discussion ......................................................................................................... 24 Materials and Methods ........................................................................................ 26 Acknowledgements .............................................................................................. 32 References ......................................................................................................... 32 Figures ......................................................................................................... 35 Supplementary Results ......................................................................................... 39 Supplementary Table ........................................................................................... 41 CHAPTER 3 FUNCTIONAL CONSERVATION OF THE CAPACITY FOR ENT-KAURENE BIOSYNTHESIS AND AN ASSOCIATED OPERON IN CERTAIN RHIZOBIA .............................................................................................. 42 Abstract ......................................................................................................... 42 Introduction .................................................................................................... 43 Results ......................................................................................................... 45 Discussion ......................................................................................................... 52 Materials and Methods ........................................................................................ 53 Acknowledgements .............................................................................................. 57 References ......................................................................................................... 58 Table ........................................................................................................ 62 Figures ......................................................................................................... 62 iii CHAPTER 4 PHYSIOLOGICAL FUNCTION AND METABOLITES LEVEL OF DITERPENOIDS IN RICE DEFENSE ............................................................... 65 Abstract ......................................................................................................... 65 Introduction .................................................................................................... 66 Results ......................................................................................................... 70 Discussion ......................................................................................................... 79 Materials and Methods ......................................................................................... 80 References ......................................................................................................... 85 Figures ......................................................................................................... 89 Supplemental Results ........................................................................................... 96 CHAPTER 5 INVESTIGATING THE BIOLOGICAL FUNCTION OF PHYTOCASSANES IN RICE DEFENSE ................................................................ 99 Abstract ......................................................................................................... 99 Introduction .................................................................................................... 99 Results ......................................................................................................... 101 Discussion ......................................................................................................... 103 Materials and Methods ......................................................................................... 104 Acknowledgements .............................................................................................. 106 References ......................................................................................................... 106 Figures ......................................................................................................... 107 CHAPTER 6 EXPLORATION OF ORYZALIDE-RELATED DITERPENOIDS IN RICE DEFENSE WITH GENOME EDITING TECHNOLOGY ........................ 111 Abstract ......................................................................................................... 111 Introduction .................................................................................................... 111 Results ......................................................................................................... 113 Discussion ......................................................................................................... 116 Materials and Methods ........................................................................................ 117 Acknowledgements .............................................................................................. 118 References ......................................................................................................... 119 Figures ......................................................................................................... 120 CHAPTER 7 CONCLUSIONS AND FUTURE DIRECTIONS ........................... 124 Conclusions ......................................................................................................... 124 Future Directions ................................................................................................ 125 References ......................................................................................................... 128 Figures ......................................................................................................... 129 ACKNOWLEDGMENTS ......................................................................................... 130 iv ABSTRACT Secondary metabolites play a significant role in mediating plant-microbe interactions. Rice (Oryza sativa) is one of the most important staple crops. Once rice is attacked by microbial pathogens, it will produce phytoalexins antibiotics to defend against enemies such as the bacterial pathogen Xanthomonas oryzae. Diterpenoids provide a rich source of metabolites mediating rice-X. oryzae interaction. First, gibberellin (GA), as complex diterpenoid phytohormone, besides the profound effects on plant growth and development, it has been shown to negatively regulate rice defense. Interestingly, we found a putative GA biosynthetic gene