Molecular Characterization of Plant Defense Responses to Erwinia carotovora

......................................................................................... 9 INTRODUCTION .................................................................................... 10 Perception of the pathogen ................................................................. 11 Gene-for-gene interactions ........................................................ 11 General elicitors ..................................................................... 12 Receptors ............................................................................ 12 Plant defense responses ..................................................................... 15 Early events of plant defense ..................................................... 15 Local and systemic defense responses .......................................... 16 The wound response ............................................................... 16 Reactive oxygen species .......................................................... 17 Defense signals ..................................................................... 18 Salicylic acid ............................................................... 18 Jamonates and C-6 volatiles ............................................. 20 Ethylene ..................................................................... 21 Cross-talk between signal pathways .................................... 23 Pathogenesis-related proteins ..................................................... 23 Phytoalexins ......................................................................... 24 Phenylpropanoids ................................................................... 24 Model of study ............................................................................... 25 The phytopathogen Erwinia carotovora subsp. carotovora .................. 25 The plant hosts ...................................................................... 26 AIMS OF THE STUDY ............................................................................. 28 MATERIALS AND METHODS ................................................................... 29 Biological material ........................................................................... 29 Methods ....................................................................................... 29 RESULTS AND DISCUSSION .................................................................... 30 Plant cell wall degrading enzymes from Erwinia carotovora synergistically induce SA-independent plant defense responses (I) .................. 30 The role PCDWEs as elicitors of plant defense ................................. 30 PCDWE-induced resistance is SA-independent ................................ 31 Identification, isolation and characterization of potato target genes .................. 33 Novel potato receptor-like protein kinases induced by E.c. carotovora (II) ............................................................. 33 Isolation and sequence analysis of PRKs ............................... 33 PRK-3 may be generated by alternative splicing ...................... 34 Expression of PRK transcripts ........................................... 35 A novel potato defense-related alcohol dehydrogenase induced by Erwinia carotovora (III) ............................................. 36 Identification, isolation and characterization of drd-1 ............... 36 Biochemical characterization of DRD-1 ................................ 36 Downregulation of photosystem I by Erwinia carotovora derived elicitors correlates with H2O2 accumulation in chloroplasts of potato plants (IV) ................................................................ 40 Isolation and characterization of psaD ................................. 40 Functional characterization of photosystem I ......................... 40 Downregulation of photosystem I correlates with hydrogen peroxide accumulation ................................. 41 Transgenic plants producing N-oxoacyl-homoserine lactone exhibit enhanced resistance to E.c. carotovora (V)...................................... 43 Generation of transgenic plants producing N-oxoacyl-homoserine lactone........................................... 43 Enhanced resistance to E.c. carotovora in OHL-producing plants..................................................... 44 CONCLUDING REMARKS ........................................................................ 46 ACKNOWLEDGEMENTS ......................................................................... 48 REFERENCES ........................................................................................ 50