To my dearest and beloved one, my daughter Sana ‘ There is one great truth on this planet: whoever you are, or whatever it is that you do, when you really want something, it's because that desire originated in the soul of the universe. The soul of the world is nourished by people's happiness. When you want something, all the universe conspires in helping you to achieve it, And no heart has ever suffered when it goes in search of its dream. ’ Paulo Coelho Promoters: Prof. dr. ir. Marie-Christine Van Labeke Department of Plant Production, Ghent University, Ghent, Belgium Dr. ir. Jan De Riek Institute for Agricultural and Fisheries Research, Unit Plant (ILVO), Melle, Belgium Members of the examination board: Prof. dr. ir. Stefaan De Smet (Chair) Ghent university, Ghent, Belgium Prof. dr. Kevin Folta University of Florida, Gainesville, USA Prof. dr. Els Van Damme Ghent Universty, Ghent, Belgium Prof. dr. ir. Kathy Steppe Ghent Universty, Ghent, Belgium Prof. dr. ir. Wannes Keulemans KULeuven, Leuven, Belgium Dean: Prof. dr. ir. Guido Van Huylenbroeck Rector: Prof. dr. Paul Van Cauwenberge Farzaneh RAZAVI Molecular & Physiological Responses to Drought Stress in Fragaria sp. Thesis submitted in fulfilment of the requirements for the degree of Doctor (PhD) in Applied Biological Sciences Nederlandse vertaling van de titel van dit proefschrift: Moleculaire en Fysiologische Reacties op Droogtestress bij Aardbei Razavi F. (2012). Molecular & Physiological Responses to Drought Stress in Fragaria sp. ISBN-number: 978-90-5989-570-6 The author and the PhD promoters give the authorisation to consult and to copy parts of this work for personal use only. Every other use is subject to the copyright laws. Permission to reproduce any material contained in this work should be obtained from the author ACKNOWLEDGEMENT ‘ The teacher gives not of his wisdom, but rather of his faith and lovingness’ ‘Khalil Gibran’ First of all, I am grateful to my promoter Prof. dr. ir. Marie Chrisitine Van Labeke and I would like to give my sincere thanks to her support and for her great enthusiasm, inspiration, and efforts to support my doctoral research. I acknowledge all that I have learnt from Prof. Van Labeke during my PhD and I deeply thank her for providing many opportunities for my research progress, with her great expertise I could realize the production of my thesis. I would also like to thank my co-promoter, dr. ir. Jan De Riek, who advised my research steps in the best way at ILVO (Plant Science Unit). He provided me with all the facilities that I needed in my molecular research and I am deeply thankful to Jan and his team in this institute for their great expertise and contribution to my research. I am pleased to thank everyone who supported me in ILVO, Dr. ir. Johan Van Huylenbroeck, Dr. ir. Kristiaan Van Laecke, Dr. ir. Ellen De Keyser, Dr. ir. Emmy Dhooghe and Prof. dr. ir. Erik Van Bockstaele. Also I will never forget the help I received from Mrs. Veerle Bouyssens and Mrs. Laurence Desmet for their all technical support in ILVO. I am grateful to all members of my examination committee for the time they spent for the evaluation of my thesis and for their thoughtful comments. I want to take all those who have contributed in any way in my thesis. Thank all my colleagues in the laboratory of In Vitro Biology and Horticulture in the Department of Plant Production in Ghent University. Machteld, Thea, Christophe, Mieke, Patricia, Ellen, ir. Linda Zamariola, ir. Annelies Christiaens, ir. Katrien De Dauw and ir. Lien De Hauwere, thanks to you all not only for your kind helps and support, but also for being so nice and friendly. I would like to express gratitude to Prof. Kevin Folta from The University of Florida for his support during my internship in his lab and thanks to his colleagues for providing a stimulating environment in which to learn. Prof. Folta, you taught me to be a positive and brave researcher. I would also like to show my appreciation to Prof. Wannes Keulemans from KULeuven for his kind support in helping me to fulfil all procedures for starting my education in Belgium, and also allowing access and use of their lab facilities in my pre-doctoral program. I should mention that this PhD could not be accomplished without the financial support of Iranian Ministry of Science and Ministry of Agriculture, BOF and FWO grants from Ghent University. Special thanks to the academic staff of Iranian Ministry of Agriculture, Seed and Plants Improvement Institute (SPII), who supported me, particularly thanks to my colleague Dr. Hamid Abdollahi for all his support and also to all my other colleagues in the research institute of Chahar-Mahal province. And I will never forget to thank my friends : Lina M.A., Maryam H.H., Nasrin G.H., and Sheida K.A., and all my other dear friends in Belgium. Thanks to them all. Above all I would like to highlight that I would not be here without the support of my beloved family. My parents and my sisters, Fereshteh, Samira and Mahsa, I cannot say how much I miss you and how much I wish you were here with me. Thanks to my husband Reza for his patience, support and for encouraging me during the hard moments. And finally I have the most special thanks to my dearest, my daughter Sana. My honey Sana, I am greatly indebted to you and I will do my best to be a great mother with more time for you from now on. Farzaneh RAZAVI Gent, December 2012 TABLE OF CONTENTS List of abbreviations & acronyms…………………………………………………………………..........i Thesis outline.………………………………………………………………………………………….vii CHAPTER 1: Water deficit stress and strawberry (Fragaria) response to drought ...................... 1 1.1 Introduction ................................................................................................................................... 3 1.2 The genus Fragaria ....................................................................................................................... 4 1.3 Economic importance and nutritional value of strawberries ......................................................... 4 1.4 Water deficit and plant responses to drought stress ...................................................................... 5 1.4.1 Introduction ............................................................................................................................ 5 1.4.2 Effect of water deficit on plant physiology, growth characteristics and cellular structure .... 7 1.4.3 Effect of water deficit on plant metabolites............................................................................ 8 1.4.4 Signalling during drought stress ........................................................................................... 17 1.5 Epigenetic control of plant response to drought stress; non-coding RNA (miRNA and siRNA) and plant drought tolerance ......................................................................................................... 33 1.6 Genotype variation in plant response to water deficit ................................................................. 34 1.7 Osmotic stress (dehydration and salt stress) in strawberry (Fragaria spp.): an overview .......... 34 1.8 Recommended genomics and genetics approaches for studying of drought tolerance in Fragaria ....................................................................................................................................... 36 1.8.1 Introduction .......................................................................................................................... 36 1.8.2 Structural and functional genomics ...................................................................................... 37 1.8.3 Functional molecular biology ............................................................................................... 37 1.8.4 Transgenic system and genetic engineering ......................................................................... 38 1.9 Conclusions ................................................................................................................................. 39 CHAPTER 2: Evaluation of chlorophyll fluorescence as a probe for drought stress in strawberry ............................................................................................................................................ 41 2.1 Introduction ................................................................................................................................. 43 2.2 Materials and Methods ................................................................................................................ 44 2.2.1 Plant material, water treatments and environmental conditions ........................................... 44 2.2.2 Leaf water potential .............................................................................................................. 45 2.2.3 Measurement of chlorophyll fluorescence ........................................................................... 45 2.2.4 Measurement of morphological traits ................................................................................... 45 2.2.5 Statistical analysis ................................................................................................................ 46 2.3 Results ......................................................................................................................................... 46 2.3.1 Climatic data......................................................................................................................... 46