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The Role of Cuticular Waxes in the Prepenetration Processes of Blumeria Graminis F.Sp. Hordei Der Einfluss Kutikulärer Wachse A

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The Role of Cuticular Waxes in the Prepenetration Processes of Blumeria Graminis F.Sp. Hordei Der Einfluss Kutikulärer Wachse A The role of cuticular waxes in the prepenetration processes of Blumeria graminis f.sp. hordei Der Einfluss kutikulärer Wachse auf die Präpenetrationsprozesse von Blumeria graminis f.sp. hordei Dissertation zur Erlangung des naturwissenschaftlichen Doktorgrades der Graduate School of Life Sciences, Julius-Maximilians-Universität Würzburg, Klasse Integrative Biology vorgelegt von Anton Hansjakob aus München Würzburg 2012 Eingereicht am: …………………………………………………………… Mitglieder des Promotionskomitees: Vorsitzender: Prof. Dr. Dr. Martin Müller 1. Betreuer: Dr. Ulrich Hildebrandt 2. Betreuer: Prof. Dr. Markus Riederer 3. Betreuer: Prof. Dr. Roy Gross Tag des Promotionskolloquiums: ………………………………………. Doktorurkunden ausgehändigt am: …………………………………….. Table of contents Table of contents .......................................................................................................... i Summary ..................................................................................................................... iv Zusammenfassung ...................................................................................................... vi Acknowledgements....................................................................................................viii Statement of author contributions..............................................................................ix 1 Introduction ......................................................................................................... 1 1.1 The plant cuticle........................................................................................... 1 1.2 Blumeria graminis ........................................................................................ 3 1.3 The prepenetration processes of Blumeria graminis .................................. 6 1.4 Prepenetration processes of Blumeria graminis on native and artificial surfaces .................................................................................................................... 7 1.5 Aims of this work.......................................................................................... 9 2 Very-long-chain aldehydes promote in vitro prepenetration processes of Blumeria graminis in a dose- and chain length-dependent manner......................... 13 2.1 Abstract...................................................................................................... 13 2.2 Introduction ............................................................................................... 14 2.3 Material and Methods ............................................................................... 16 2.4 Results........................................................................................................ 19 2.4.1 Composition of barley and wheat leaf cuticular waxes..................... 19 2.4.2 Surface structures and contact angles............................................... 20 2.4.3 Prepenetration processes of B. graminis on native leaf surfaces and on wax-coated glass slides................................................................................. 21 2.5 Discussion................................................................................................... 31 2.5.1 Prepenetration processes on wheat and barley leaves..................... 32 2.5.2 The Formvar® resin-based in vitro system......................................... 32 2.5.3 Very-long-chain alkanes, alkanols, alkyl esters, fatty acids and the prepenetration processes.................................................................................. 34 2.5.4 Very-long-chain aldehydes and B. graminis prepenetration processes 35 2.6 Acknowledgements.................................................................................... 37 2.7 Supporting information.............................................................................. 38 3 Wax matters: absence of very-long-chain aldehydes from the leaf cuticular wax of the glossy11 mutant of maize compromises the prepenetration processes of Blumeria graminis ...................................................................................................... 39 3.1 Abstract...................................................................................................... 39 3.2 Introduction ............................................................................................... 40 3.3 Materials and Methods.............................................................................. 41 i 3.4 Results ........................................................................................................44 3.4.1 Cuticular leaf wax coverage and composition ...................................44 3.4.2 Leaf surface wettability and wax crystal structure ............................45 3.4.3 Masking of the gl11 phenotype .........................................................48 3.4.4 Mimicking of the gl11 phenotype......................................................49 3.4.5 Supplementing gl11 wax with n-hexacosanal....................................51 3.5 Discussion...................................................................................................51 3.6 Acknowledgements....................................................................................55 4 Appressorium morphogenesis and cell cycle progression are linked in the grass powdery mildew fungus Blumeria graminis ..............................................................56 4.1 Abstract ......................................................................................................56 4.2 Introduction................................................................................................57 4.3 Material and Methods................................................................................58 4.4 Results ........................................................................................................62 4.4.1 Spatiotemporal behaviour of B. graminis nuclei during prepenetration...................................................................................................62 4.4.2 The presence of very-long-chain aldehydes affects nuclear migration in B. graminis conidia .........................................................................................65 4.4.3 Spatial uncoupling of nuclear division and cytokinesis......................67 4.4.4 Cell cycle and morphogenesis............................................................67 4.5 Discussion...................................................................................................71 4.6 Conclusions.................................................................................................75 4.7 Acknowledgements....................................................................................76 4.8 Supporting information..............................................................................76 5 Surface dependent gene expression of barley powdery mildew fungus Blumeria graminis f.sp. hordei during the prepenetration processes ......................................82 5.1 Introduction................................................................................................82 5.2 Material and Methods................................................................................83 5.3 Results ........................................................................................................98 5.3.1 Kinetics of B. graminis conidia development.....................................98 5.3.2 Library screening for differentially expressed transcripts by reverse Northern blot analysis........................................................................................99 5.3.3 Confirmation of differentially expressed transcripts by RT-qPCR ...102 5.3.4 Cloning of transcript A1....................................................................105 5.4 Discussion.................................................................................................107 6 Summarizing discussion ...................................................................................113 6.1 The Formvar ® resin based in vitro system in comparison with other in vitro systems and native leaf surfaces..........................................................................113 6.1.1 Contact angles..................................................................................113 6.1.2 Effects on B. graminis conidia..........................................................115 ii 6.2 The impact of cuticular wax constituents on B. graminis prepenetration processes..............................................................................................................117 6.2.1 Very-long-chain aldehydes in vitro ..................................................117 6.2.2 Host-pathogen co-evolution ............................................................119 6.2.3 Primary alcohols, alkyl esters and fatty acids in vitro ......................119 6.2.4 Very-long-chain fatty acids do not inhibit germination and differentiation ..................................................................................................120 6.2.5 Very-long-chain aldehydes in vivo ................................................... 121 6.2.6 Mimicking of leaf wax phenotypes ..................................................122 6.3 Cuticular waxes and cutin provide chemical signals for phytopathogenic fungi 124 6.4 Morphogenesis and cell cycle are linked during B. graminis prepenetration processes..............................................................................................................126
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