Comparative morpho-anatomical and ecological aspects of desiccation-tolerant vascular plants Dissertation zur Erlangung des akademischen Grades doctor rerum naturalium (Dr. rer. nat.) der Mathematisch-Naturwissenschaftlichen Fakultät der Universität Rostock vorgelegt von Nikola S. Korte, geboren am 12.06.1981 in Oldenburg (Oldb) Februar 2012 1. Gutachter Prof. Dr. Stefan Porembski Universität Rostock Allgemeine und Spezielle Botanik Wismarsche Str. 8 D-18051 Rostock 2. Gutachter Prof. Dr. Wilhelm Barthlott Universität Bonn Nees-Institut für Biodiversität der Pflanzen Venushügelberg 22 D-53115 Bonn Datum der Verteidigung: 29.06.2012 Datum der Einreichung: 24.02.2012 Index 1. Introduction ...................................................................................................................... 1 1.1. Definition and brief history of desiccation tolerance ............................................ 1 1.2. Geographic and ecological aspects of desiccation-tolerant vascular plants .......... 5 1.3. Taxonomic and evolutionary aspects of desiccation-tolerant vascular plants ....... 7 1.4. Relevance of desiccation tolerance research ....................................................... 10 1.5. Objectives of the doctoral thesis .......................................................................... 11 2. Anatomical analysis of turgescent and semi-dry resurrection plants using X-ray micro-computed tomography (μCT) ................................................................................. 13 2.1. Abstract ................................................................................................................ 13 2.2. Introduction ......................................................................................................... 13 2.3. Material and Methods .......................................................................................... 17 2.4. Results ................................................................................................................. 20 2.5. Discussion ............................................................................................................ 25 3. A morpho-anatomical characterization of Myrothamnus moschatus under the aspect of desiccation tolerance........................................................................................... 27 3.1. Abstract ................................................................................................................ 27 3.2. Introduction ......................................................................................................... 27 3.3. Material and Methods .......................................................................................... 28 3.3.1. Plant material .................................................................................................... 28 3.3.2. Rehydration ...................................................................................................... 28 3.3.3. Leaf and wood anatomy ................................................................................... 29 3.4. Results ................................................................................................................. 29 3.4.1. Rehydration ...................................................................................................... 29 3.4.2. Leaf morphology, leaf and wood anatomy ....................................................... 30 3.5. Discussion ............................................................................................................ 34 4. Leaf anatomical traits of desiccation-tolerant vascular plants: a comparative analysis ................................................................................................................................. 38 4.1. Abstract ................................................................................................................ 38 4.2. Introduction ......................................................................................................... 38 4.3. Material and Methods .......................................................................................... 40 ______________________________________________________________________ 4.3.1. Plant material .................................................................................................... 40 4.3.2. Visualization of dry plant material ................................................................... 41 4.3.3. Visualization of rehydrated plant material ....................................................... 41 4.3.4. Shrinkage of leaves during dehydration ........................................................... 42 4.4. Results ................................................................................................................. 42 4.4.1. Cyperaceae........................................................................................................ 42 4.4.2. Velloziaceae...................................................................................................... 47 4.4.3. Myrothamnaceae .............................................................................................. 50 4.4.4. The desiccation-sensitive species ..................................................................... 52 4.5. Discussion ............................................................................................................ 57 4.5.1. Lack of a morpho-anatomical syndrome in desiccation-tolerant vascular plants .................................................................................................................................... 57 4.5.2. Important adaptive morpho-anatomical traits................................................... 60 4.5.3. The dominance of monocots among desiccation-tolerant angiosperms ........... 63 4.5.4. Phylogeny and morpho-anatomical adaptations to desiccation tolerance ........ 64 4.5.5. Links between morpho-anatomical traits and other adaptive levels................. 65 5. First non-destructive leaf growth rate determination of desiccation-tolerant, mat-forming monocots ....................................................................................................... 70 5.1. Abstract ................................................................................................................ 70 5.2. Introduction ......................................................................................................... 70 5.3. Material and Methods .......................................................................................... 71 5.4. Results ................................................................................................................. 73 5.5. Discussion ............................................................................................................ 74 5.5.1. Absolute growth rate ........................................................................................ 74 5.5.2. Leaf-marking method ....................................................................................... 75 5.5.3. Absolute vs. relative growth rate ...................................................................... 76 6. Outlook ............................................................................................................................ 77 7. Summary ......................................................................................................................... 80 8. Zusammenfassung .......................................................................................................... 82 9. References........................................................................................................................ 85 List of Figures ................................................................................................................... 100 List of Tables ..................................................................................................................... 102 ______________________________________________________________________ Appendix ........................................................................................................................... 103 List of publications ................................................................................................... 103 Statement on the candidates’ contribution................................................................ 104 List of contributions to conferences ......................................................................... 106 Grants and scholarships ............................................................................................ 107 Selbständigkeitserklärung ......................................................................................... 108 Danksagung .............................................................................................................. 109 ______________________________________________________________________ Chapter 1 1. Introduction 1.1. Definition and brief history of desiccation tolerance Desiccation tolerance can be defined as “the ability to dry to equilibrium with moderately dry air and then resume normal function when rehydrated” (Alpert & Oliver 2002). In other words, desiccation-tolerant plants dehydrate, remain in the desiccated state for days or months, turn green upon rehydration and become functional again (Fig. 1). Since its first discovery in rotifers by Leeuwenhoek in 1702 this phenomenon has long been the matter of