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Results This result indicated an up-regulation of the achromobactin-like siderophore under high oxygen conditions. The situation in Psg1a differs from this considerably. In Psg1a, the total amount of siderophore production was not influenced by oxygen supply. However the amount of fluorescence differed: Under low oxygen conditions, less fluorescence was produced than under high oxygen conditions. These results indicated a differential regulation of siderophore production in Psg1a and Pss22. 5.3 Influence of siderophore production on biocontrol activity and epiphytic fitness of Pss22d In order to study the influence of siderophore production on the antagonism between Pss22d and Psg1a, the siderophore mutants of Pss22d were tested for their ability to suppress growth (and disease development) of Psg1a in planta. Bacteria were applied by wound inoculation technique. After punching soybean leaves with a sterile needle, 5 µl of bacterial suspension were applied to the fresh wounds and allowed to dry in. The inoculations were assigned as follows (Fig.23): A B C D E F G H I Fig. 23. Symptom development 14 days after wound inoculation. After punching soybean leaves with a sterile needle, 5 µl of bacterial suspension were applied to the fresh wounds and allowed to dry in. 14 days later the symptom development was assessed. Inoculations were as follows: A-E single inoculations with A: Psg1a; B: Pss22d; C: Pss22d∆Pvd; D: Pss22d∆Ach; E: Pss22d∆Sid; F-I Co-inoculation of Psg1a in combination with F: Pss22d; G: Pss22d∆Pvd; H: Pss22d∆Ach; I: Pss22d∆Sid 69
Results A-E represents single inoculations with A: Psg1a; B: Pss22d; C: Pss22d∆Pvd; D: Pss22d∆Ach, and E: Pss22d∆Sid. F-I showed the results for co-inoculation experiments of Psg1a in combination with F: Pss22d; G: Pss22d∆Pvd; H: Pss22d∆Ach; I: Pss22d∆Sid. In the co-inoculation experiments, antagonist and pathogen were mixed at a ratio of 2:1. Symptom development was investigated 14 days post inoculation (Fig.23). Only when a single inoculation of Psg1a was applied, a clear formation of chlorosis could be observed (Fig.23A). Wounds inoculated with the antagonistic strains alone symptom-free (Fig.23B-E). Wounds co-inoculated with antagonist and pathogen showed mostly no symptoms, while on some single wounds a strongly reduced symptom development could be observed (for example Fig.23G, uppermost wound). Determination of CFU per wound did not give any evidence for a different performance of Pss22d wild type and its siderophore mutants. Therefore data were grouped in Figure 24. In the co-inoculation experiments, pathogen population size was reduced by one order of magnitude as compared to the single inoculation of Psg1a. Since wound inoculation technique could potentially interfere with the impact of siderophores due to a possible iron leakage from wound exudates, the in planta epiphytical fitness of Pss22d and its siderophore mutants was investigated in a spray inoculation experiment. Preliminary results indicated a reduction of population size for the siderophore mutants as compared to the wild type (Tab. 10). While both single mutants reached a cell density one order of magnitude below the wild type, the double mutant was reduced by two orders of magnitude. A repetition of this experiment showed a very similar outcome for Pss22d∆Pvd; however, growth of Pss22d∆Sid was reduced only by one order of magnitude and that of Pss22d∆Ach was not affected at all. 70
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Siderophore production of Pseudomon
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Acknowledgements This project was s
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Abbreviations Ach achromobactin-lik
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Contents 4.1.2 Pseudomonas syringae
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Contents 5.3 Influence of sideropho
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Introduction 2 Introduction Like hu
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Introduction In contrast to the rhi
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Introduction 2.1.2 Host, pathogen a
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Introduction The relationship betwe
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Introduction developement of resist
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Introduction Fe 2+ + H 2 O 2 → Fe
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Introduction 1997a; May et al., 199
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Introduction Pss22d demonstrated a
Page 27 and 28: Introduction 2.4 Aim of this study
Page 29 and 30: Material and Methods Tab. 4. Antibi
Page 31 and 32: Material and Methods Iron-free 5b m
Page 33 and 34: Material and Methods Solution3, car
Page 35 and 36: Material and Methods 3.6 Plasmids T
Page 37 and 38: Material and Methods PCR-Screening
Page 39 and 40: Material and Methods on ice for 10
Page 41 and 42: Material and Methods stained in eth
Page 43 and 44: Material and Methods 4.2.5.3 Conver
Page 45 and 46: Material and Methods 4.2.5.9 Ligati
Page 47 and 48: Material and Methods strains were s
Page 49 and 50: Material and Methods 9.5). For sign
Page 51 and 52: Material and Methods gentle shaking
Page 53 and 54: Material and Methods columns were w
Page 55 and 56: Results 5 Results 5.1 Analysis of s
Page 57 and 58: Results The 13-kb open reading fram
Page 59 and 60: Results If integration is due to a
Page 61 and 62: Results Yersiniabactin is a siderop
Page 63 and 64: Results Next, a large number of tra
Page 65 and 66: Results Nevertheless the site of tr
Page 67 and 68: Results Achr2_KpnI_rev binding site
Page 69 and 70: Results Interestingly the mutant Ps
Page 71 and 72: Results XAD4-purification yielded i
Page 73 and 74: Results After changing the mobile p
Page 75 and 76: Results P P A Fig. 21. Isoelectic f
Page 77: Results reduced in comparison to th
Page 81 and 82: Results Tab. 10. Development of pop
Page 83 and 84: Results Tab. 11. Distribution of th
Page 85 and 86: Discussion bacteria with redundande
Page 87 and 88: Discussion 6.2 Possible regulation
Page 89 and 90: Discussion stationary phase transit
Page 91 and 92: Discussion and bacterium (Loper et
Page 93 and 94: Literature Bultreys, A., Gheysen, I
Page 95 and 96: Literature Galperin, M. Y. (2006).
Page 97 and 98: Literature Mazzola, M. (2002). Mech
Page 99 and 100: Literature Schubert, S., Rakin, A.,
Page 101: Literature Zou, J., Rodriguez-Zas,
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