Bislang ist ungeklärt, warum PNPs teils schmerzhaft und teils schmerzlos verlaufen. Die in der vorliegenden Arbeit untersuchte Hypothese lautete, dass ein Ungleichgewicht zwischen pro- und anti-inflammatorischen Zytokinen der unterschiedlichen Schmerzausprägung zugrunde liegt.Es wurden 32 Patienten mit schmerzhafter PNP, 20 Patienten mit schmerzloser PNP und 44 Kontrollpersonen auf die Expression und Produktion ausgewählter pro- und anti-inflammatorischer Zytokine untersucht. Zur Messung der Schmerzhaftigkeit wurden etablierte Schmerzfragebögen verwendet. Zusätzlich wurden nahezu alle Patienten mit der Allgemeinen Depressionsskala befragt. Die Diagnose, Ätiologie, Dauer, klinische Manifestation der PNP sowie die Medikation der Patienten wurde auf standardisierten Erhebungsbögen dokumentiert. Zur Messung der Zytokine wurde morgens Blut in EDTA- und Serummonovetten asserviert und entsprechend der Messmethodik weiterverarbeitet. Die relative Genexpression wurde aus Gesamt-RNA mittels reverser Transkription und quantitativer real-time PCR, die Serumproteine mittels enzyme-linked immunosorbant assay gemessen. Die Patienten mit schmerzhafter PNP hatten in der Mehrzahl Neuropathie-typische Plussymptome und mittelstarke Schmerzen, die eine starke bis sehr starke Behinderung darstellten. Die hier untersuchten Zytokinmuster bei Patienten mit schmerzhafter und schmerzloser PNP zeigten eine Verschiebung zu pro-inflammatorischen Zytokinen bei Patienten mit schmerzhafter PNP. Die Zytokinexpression der Patienten mit schmerzhafter PNP war im Vergleich zu Patienten mit schmerzloser PNP und Kontrollen bezüglich der IL-2 und TNF Expression und Produktion signifikant erhöht. Umgekehrt lagen bei Patienten mit schmerzloser PNP die Produktion und die Expression des IL-4 im Vergleich zu Patienten mit schmerzhafter PNP und Kontrollen höher. Die Expression des IL-10 lag bei Patienten mit schmerzloser PNP ebenfalls höher als bei Patienten mit schmerzloser PNP und Kontrollen, unterschied sich aber auf Proteinebene nicht in den drei Gruppen. Die einleitend gestellte Hypothese, dass der schmerzhafte oder schmerzlose Verlauf einer PNP durch unterschiedliche Zytokinprofile bedingt ist, kann durch die vorliegenden Ergebnisse gestützt werden. In Zusammenschau mit den Daten aus der Grundlagenforschung scheint einem pro-inflammatorischen Zytokinmuster eine entscheidende Rolle an der Entstehung und Aufrechterhaltung neuropathischer Schmerzen zuzukommen. Für TNF sind entsprechende pathophysiologische Wirkungen bekannt. Anti-inflammatorische Zytokine, wie IL-4 und IL-10 zeigten analgetische Wirkungen im Tierversuch. Die Mitwirkung des IL-2 an peripheren Opioid-Rezeptoren lässt eine endogene periphere Analgesie vermuten. Hieraus lassen sich Folgerungen für zukünftige Diagnostik und Therapie neuropathischer Schmerzen ziehen. Durch Erkennung von Zytokin-Imbalancen wären schmerzhafte PNPs früher einer adäquaten Therapie zuzuführen. Durch die Modulation von Zytokinprofilen im Rahmen schmerzhafter PNPs könnten sich zusätzlich therapeutische Möglichkeiten eröffnen. / BACKGROUND: Pain is a common symptom in peripheral neuropathies. The factors determining why some peripheral neuropathies are painful and others are not are incompletely understood. Pro-inflammatory cytokines have been implicated to play a crucial role in the generation of pain. OBJECTIVE: To investigate whether cytokine profiles differ between patients with painful or painless neuropathy. METHODS: In this prospective study, we analyzed blood mRNA and protein levels of the pro-inflammatory cytokines interleukin-2 (IL-2) and tumor necrosis factor-alpha (TNF) and the anti-inflammatory cytokines IL-4 and IL-10 in 32 patients with painful neuropathy, 20 patients with painless neuropathy, and 38 healthy control subjects, using quantitative real-time PCR and ELISA. RESULTS: Patients with a painful neuropathy had about twofold higher IL-2 mRNA (p = 0.001) and TNF mRNA (p < 0.0001) and protein levels (p = 0.009) than healthy control subjects and about twofold higher IL-2 and TNF mRNA (p = 0.03; p = 0.001) and protein levels (p = 0.04; p = 0.04) than patients with painless neuropathy. In contrast, mRNA levels of the anti-inflammatory cytokine IL-10 were about twofold higher in patients with painless neuropathy than in patients with painful neuropathy (p = 0.001) and controls (p = 0.004). IL-4 protein levels were 20-fold higher in patients with painless neuropathy (p < 0.0001) and 17-fold higher in patients with painful neuropathy (p < 0.0001) than in healthy control subjects. CONCLUSIONS: A pro-inflammatory cytokine profile seems to be associated with pain in the setting of a peripheral neuropathy, corroborating findings in animal models with experimental painful neuropathies. This may have implications for future treatment strategies.

Loose smut of barley, caused by fungal pathogen Ustilago nuda is one of the major concerns throughout the globe for barley producers. The infection takes place without exhibiting any obvious symptoms and an infected seed lot can only be identified at the heading stage when the fungal teliospores emerge at the place of crop. The percentage losses on yield are directly proportional to the occurrence of infection. Currently available detection methods include seed health testing protocols which are time-consuming and cumbersome. With the globalization of the international market and increased crop demand, development of rapid disease screening methodologies has become an essential focus in the field of plant pathology. The present study sought to develop a rapid probe-based detection method for screening of U. nuda with real-time qPCR. Two U. nuda specific primer pairs were compared using standard PCR alongside optimization of real-time qPCR assay. The advantage of high fidelity DNA polymerase for amplification of U. nuda genomic DNA was recorded. U. nuda genomic DNA was amplified and cloned into a vector which was further used for generation of a quantification curve with a specific probe. The qPCR assay developed in this study was successful in the detection of as little as 43 copies of U. nuda genomic DNA. With studies involving larger sample size and field samples, this assay can be improved for enhanced sensitivity and specificity which can help in monitoring infection from DNA extractions of barley seeds and further improving the current microscopic detection methods.

In unserer Studie sollte die Genauigkeit der PCR zur Bestimmung von Zytokinspiegeln ermittelt werden. Mittels Blutproben von mit A. Fumigatus infizierten Mäusen, sollte eine Aussage bezüglich der Immunantwort getroffen werden. Wir griffen TNF&#945;, IL-12p40 und IL-10 heraus, um einschätzen zu können, ob die Immunantwort eher humoral oder zellvermittelt abläuft. Zur möglichen Bestimmung der Sensitivität und Genauigkeit, wurden die crossing points der Standardverdünnungsreihen jeweils einmal in einem Lauf dreifach, ausserdem jeweils in drei unabhängigen Läufen von einander einfach eingesetzt, und miteinander verglichen. Unsere Ergebnisse decken sich mit den Ergebnissen aktueller Literatur und Etablierungen anderer Zytokine. Die Etablierung des ELISAs sollte dem Vergleich zwischen mRNA-Ebene und Proteinebene dienen. Zur richtigen Einordnung unserer Arbeiten mit dem Immunoassay müssen die Limitierungen der Ergebnisse beachtet werden. Die Versuche zur Quantifizierung der mRNA murinen TNF&#945;s aus den Versuchsserien misslang. Auch die erzielten Ergebnisse mit Protein-basierten Nachweisverfahren konnten letztendlich nicht suffizient beurteilt werden. Die großen Schwankungen in der Konzentration und die Widersprüchlichkeit im Vergleich der Ergebnisse aktueller Literatur, machen eine Verfälschung durch Kontamination mit Proteinen aus lysierten Zellen sehr wahrscheinlich. Die erzielten Ergebnisse der RT-PCR anhand der Inter- und Intra-Assay- Vergleiche jedoch können nachfolgenden Projekten dazu dienen, hauptsächlich das Instrument LightCycler in seiner Sensitivität und Genauigkeit einschätzen zu können, und so die ermittelten Daten besser verarbeiten zu können. / In this study we analysed the accuracy of PCR for identification of murine cytokine levels. Using blood samples of with A. Fumigatus infected mice, we wanted to reach a conclusion concerning the immune reaction. We picked TNF&#945;, IL-12p40 and IL-10 to decide if the immune reaction is humoral or cell mediated. For determination of sensitivity and accuracy we compared the crossing points of the dilution standard series. We used the standard series once three times in one run and on the other hand in three independent runs. Our results correspond with the results in current literature. The establishment of the ELISA should have served for comparing the mRNA level with the protein level. But the tests failed. We couldn´t find mRNA of murine TNF&#945;, and there was big variability in the concentration of protein. Probably the falsification happend because of the contamination with proteins from lysis of cells. But the conclusions from the RT-PCR inter- and intra-assay comparison could be helpful to assess the LightCycler instrument in its sensitivity and its accuracy and so facilitate the assessment of the results.

The main objective of this study was to investigate promoter sequences of putative HSR genes for the presence of unique regulatory elements and modules that might be involved in the regulation of HSR. In order to achieve this objective, an in silico promoter analysis strategy was devised, which focused on the identification of promoter sequences and regulatory elements, and modelling of promoter modules by using Genomatix software tools such as MatInspector and ModelInspector. Results showed that two modules (EGRF_SP1F_01 and SP1F_CEBP_01) were conserved in the promoter sequences of three well-known Hsp-genes (Hsp90, Hsp105β and αβ-crystallin). Screening the 60 target gene promoters for the presence of the two modules revealed that 12 genes (20 %) contained both modules. These included Moesin, Proline-4 hydroxylase, Poly(A) binding protein and Formin-binding protein. None of these genes had been previously associated with heat shock response.

Traditionally, response to treatment in hematological malignancies is evaluated by light microscopy of bone marrow (BM) smears, but due to more effective therapies more sensitive methods are needed. Today, detection of minimal residual disease (MRD) using immunological and molecular techniques can be 100 times more sensitive than morphology. The main aim of this thesis was to compare and evaluate three currently available MRD methods in childhood acute lymphoblastic leukemia (ALL): (i) real-time quantitative PCR (RQ-PCR) of rearranged antigen receptor genes, (ii) multicolor flow cytometry (FCM) of leukemia-associated immunophenotypes and (iii) real-time quantitative PCR of fusion gene transcripts (RT-PCR). In paper I, we assessed the applicability of RQ-PCR in a population-based cohort of childhood ALL diagnosed in Sweden between 2002-2006. Clonal IG/TCR rearrangements were identified in the 96% of the 279 ALL cases. Using RQ-PCR, the quantitative range of 10-3 was reached in 93% of B-cell precursor (BCP) ALL and 86% of T-cell ALL (T-ALL) by at least one target gene. In paper II, we compared MRD detection using both RQ-PCR and FCM in the context of NOPHO ALL-2000 protocol. By applying the stratification threshold of ≥0.1% MRD late during induction therapy (day 29), we could demonstrate that both methods can predict the risk of BM relapse but not extramedullary relapse. However, the threshold of ≥0.2% MRD appears to be more optimal using RQ-PCR in BCP ALL, whilst in T-ALL, the results indicate that RQ-PCR is preferable for MRD assessment. The stability of RNA in vitro is a critical factor when using sensitive molecular techniques such as MRD detection. In paper III, we evaluated the influence on MRD detection when blood is collected in tubes with RNA stabilization reagents (PAX gene Vacutatiner®) compared to collection in EDTA-tubes (non-stabilized). We analyzed 68 matched samples from chronic myeloid leukemia patients and the results indicated that non-stabilized blood processed within 30 hours is preferable for MRD detection. In paper IV, follow-up samples from eight children with Philadelphia positive (Ph+) ALL were evaluated with the three available MRD methods. MRD measured by the fusion gene transcripts (BCR-ABL1) appeared to be the most sensitive method, however, precise quantification can be difficult and the other methods are thus complementary. In conclusion, all three applied MRD methods are useful and correlate to each other, although not necessary exchangeable in individual patients. We also conclude that MRD assessment by RQ-PCR, based on rearranged IG/TCR genes and multicolor FCM are predictive for identification of high risk childhood ALL patients.

The main objective of this study was to investigate promoter sequences of putative HSR genes for the presence of unique regulatory elements and modules that might be involved in the regulation of HSR. In order to achieve this objective, an in silico promoter analysis strategy was devised, which focused on the identification of promoter sequences and regulatory elements, and modelling of promoter modules by using Genomatix software tools such as MatInspector and ModelInspector. Results showed that two modules (EGRF_SP1F_01 and SP1F_CEBP_01) were conserved in the promoter sequences of three well-known Hsp-genes (Hsp90, Hsp105β and αβ-crystallin). Screening the 60 target gene promoters for the presence of the two modules revealed that 12 genes (20 %) contained both modules. These included Moesin, Proline-4 hydroxylase, Poly(A) binding protein and Formin-binding protein. None of these genes had been previously associated with heat shock response.

結核病是目前全球傳染病中死亡率最高的疾病，由於抗藥菌株的產生以及與愛滋病的共同感染而使得結核病的控制面臨更嚴厲的挑戰。目前，結核病的預防主要是施打卡介苗，卡介苗是世界上使用最廣泛的疫苗之一，其優點是沒有施打時間的限制、便宜、副作用小、穩定性高。卡介苗目前仍然是採用培養後統計可培養之菌落數來判定疫苗之效價。但由於卡介苗菌的生長十分緩慢，培養時間有時甚至長達二個月，製程監控不易達到效果。本研究的目的即是利用同步定量聚合酶連鎖反應技術檢測BCG 16S ribosomal RNA及IS6110基因，並分別比較檢測BCG菌之DNA及RNA檢體的敏感度及專一性，以建立一個快速、靈敏度高且專一性高的BCG效價檢測方法。在研究中已成功建立檢測之標準曲線，並能在8天培養後檢測出BCG菌的生長，可以有效率的減少BCG疫苗菌數的檢測時間。因此，期望未來能夠將此技術應用做為BCG疫苗生產製程中管控的工具，以取代曠日費時的傳統檢測方式，並期望將來可以將此檢測系統應用於結核病之臨床檢測。 / Tuberculosis is one of the important infectious diseases with the highest mortality rate worldwide. The control of tuberculosis infection is facing an even more strict challenge because of the evolving of drug-resistant clones and the co-infection of AIDS. Currently, the prevention of tuberculosis is mainly done by BCG vaccination, which is one of the most widely used vaccines. The advantages of BCG vaccine are its low cost, low side effects, and high stability. At present, the BCG potency is analyzed by calculating the growth of colonies after culture. However, the growth of BCG is pretty slow, sometimes it can take as long as two months and has made the in process control very difficult. The aim of this study was to establish a rapid, sensitive, and specific real-time quantitative PCR (Q-PCR) method for the detection of BCG potency and separately compares BCG DNA and RNA samples for BCG 16S ribosomal RNA and IS6110 genes for Q-PCR detection system. We have successfully set up the standard curves for the detection of BCG using Q-PCR, and the method could detect the growth of BCG after 8 day of cultivation. Using Q-PCR system, the detection of BCG vaccine is more efficient and the detection time can be largely reduced. We hope we will be able to apply this method as a tool for the in process control during the BCG vaccine production and to replace the time-consuming traditional culture method. / 目錄 誌謝 ------------------------------------------------------------------------ i 中文摘要 ------------------------------------------------------------------------ ii 英文摘要 ------------------------------------------------------------------------ iii 目錄 ------------------------------------------------------------------------ iv 表目錄 ------------------------------------------------------------------------ vi 圖目錄 ------------------------------------------------------------------------ viii 第一章 緒論------------------------------------------------------------------ 1 第二章 文獻回顧------------------------------------------------------------ 4 第一節 結核病 (Tuberculosis)-------------------------------------------- 4 第二節 分歧桿菌 (Mycobacteria)---------------------------------------- 6 第三節 卡介苗 (Bacille Calmette-Guérin vaccine ; BCG vaccine) 的發展--------------------------------------------------------------- 8 第四節 聚合酶連鎖反應 (Polymerase chain reaction；PCR) 及其應用------------------------------------------------------------------ 9 第五節 同步定量聚合酶連鎖反應 (Real-time quantitative polymerase chain reaction; 定量PCR)------------------------- 10 第三章 材料與方法--------------------------------------------------------- 13 一 BCG菌製備與培養----------------------------------------------- 13 二 定量PCR的primer與probe設計----------------------------- 13 三 定量PCR的primer與probe最適化-------------------------- 14 四 BCG DNA檢體萃取---------------------------------------------- 14 五 BCG RNA萃取與反轉錄---------------------------------------- 15 六 定量PCR反應條件----------------------------------------------- 16 七 傳統PCR反應條件----------------------------------------------- 16 八 洋菜膠體 (agarose gel) 電泳分析----------------------------- 16 九 BCG定量標準曲線製作與製圖-------------------------------- 17 第四章 結果與討論--------------------------------------------------------- 18 一 定量PCR primer 與 probe的設計----------------------------- 18 二 16S rRNA及IS6110 定量PCR中primers與 probes 之最適化--------------------------------------------------------------- 19 三 建立BCG疫苗之定量PCR檢測標準曲線------------------- 20 四 以16S rRNA primer進行BCG疫苗培養分析--------------- 22 五 以定量PCR檢測BCG疫苗菌株之最佳檢測濃度--------- 23 六 依16S rRNA及IS6110定量PCR建立BCG疫苗效價之檢測------------------------------------------------------------------ 25 第五章 結論與建議--------------------------------------------------------- 27 參考文獻 ------------------------------------------------------------------------ 30 附錄一 16S ribosomal RNA 基因序列---------------------------------- 81 附錄二 IS6110基因序列--------------------------------------------------- 83 表目錄 表一 臨床中重要的分歧桿菌------------------------------------------ 37 表二 分歧桿菌之致病力------------------------------------------------ 38 表三 Primer Express軟體設計之16S rRNA及IS6110 primers與probes------------------------------------------------------------ 39 表四 定量PCR primer與probe最適化測試濃度組合------------ 40 表五 反轉錄反應藥品配方--------------------------------------------- 41 表六 定量PCR試劑配方------------------------------------------------ 42 表七 定量PCR反應條件------------------------------------------------ 43 表八 傳統PCR試劑配方------------------------------------------------ 44 表九 16S rRNA定量PCR之primer與probe最適化結果------- 45 表十 IS6110定量PCR之primer與probe最適化結果------------- 46 表十一 以16S rRNA及IS6110定量PCR檢測DNA檢體結果---- 47 表十二 以16S rRNA及IS6110定量PCR檢測RNA檢體結果---- 48 表十三 16S rRNA及IS6110定量PCR標準曲線之有效檢測範團及靈敏度比較------------------------------------------------------ 49 表十四 16S rRNA定量PCR檢測BCG疫苗在不同培養條件下之生長情形------------------------------------------------------------ 50 表十五 以16S rRNA定量PCR檢測BCG疫苗之最佳檢測濃度--- 51 表十六 以IS6110定量PCR檢測BCG疫苗之最佳檢測濃度-------- 52 表十七 16S rRNA定量PCR檢測BCG疫苗之效價------------------ 53 表十八 IS6110定量PCR檢測BCG疫苗之效價---------------------- 55 圖目錄 圖一 TaqMan Probe之定量PCR的作用原理反應流程--------- 57 圖二 ABI 7700 Sequence Detection System之同步偵測光學路徑原理--------------------------------------------------------------- 58 圖三 定量PCR偵測螢光後之Threshold cycle圖---------------- 59 圖四 PCR過程及定量PCR偵測原理------------------------------- 60 圖五 Primer Express軟體中，設計primer與probe的 Preferences操作界面---------------------------------------------- 61 圖六 以傳統PCR測試16S rRNA primer之PCR產物agarose gel電泳分析-------------------------------------------------------- 62 圖七 以傳統PCR測試IS6110 primer之PCR產物agarose gel電泳分析------------------------------------------------------------ 63 圖八 16S rRNA定量PCR primer與probe 最適化結果----------- 64 圖九 IS6110定量PCR primer與probe 最適化結果--------------- 65 圖十 16S rRNA定量PCR primer與probe最適化結果產物agarose gel 電泳分析--------------------------------------------- 66 圖十一 16S rRNA定量PCR以DNA建立檢測標準曲線之結果--- 67 圖十二 16S rRNA定量PCR以DNA檢體所建立之標準曲線----- 68 圖十三 16S rRNA定量PCR以RNA檢體建立標準曲線之結果-- 69 圖十四 16S rRNA 定量PCR以RNA檢體所建立之標準曲線---- 70 圖十五 IS6110定量PCR以DNA檢體建立標準曲線之結果------ 71 圖十六 IS6110 定量PCR以DNA檢體所建立之標準--------------- 72 圖十七 IS6110定量PCR以RNA檢體建立標準曲線之結果------ 73 圖十八 IS6110定量PCR於RNA檢體所建立之標準曲線---------- 74 圖十九 以16S rRNA 定量PCR檢測BCG疫苗DNA檢體之生長------------------------------------------------------------------------ 75 圖二十 以16S rRNA 定量PCR檢測BCG疫苗RNA檢體之生長------------------------------------------------------------------------ 76 圖二十一 建立16S rRNA 定量PCR之BCG菌最佳檢測濃度-------- 77 圖二十二 建立IS6110定量PCR之BCG菌最佳檢測濃度------------ 78 圖二十三 以16S rRNA定量PCR檢測BCG疫苗效價----------------- 79 圖二十四 以IS6110定量PCR檢測BCG疫苗效價---------------------- 80

Highbush blueberry (Vaccinium corymbosum L.) has one of the highest antioxidant capacities and flavonoid concentrations of any fruit or vegetable, and regular consumption of blueberries has been connected to a wide range of health benefits. A diversity of flavonoids (flavonols, anthocyanins, proanthocyanidins) are likely responsible for many of the health benefits, and these compounds also significantly contribute to the organoleptic properties of ripe blueberries. Despite the potential importance of these flavonoids in diet, there has been little investigation into the molecular genetics of blueberry flavonoid biosynthesis. Therefore, I developed a real-time quantitative PCR protocol to monitor expression of flavonoid genes throughout development and ripening. Following evaluation of five reference genes, expression profiling of biosynthetic genes revealed that flavonoid synthesis is tightly controlled at the transcriptional level in a biphasic developmental pattern. These results are discussed in relation to flavonoid metabolite accumulation profiles, which were produced as part of a collaboration. Finally, in conjunction with a second group of collaborating scientists, some promising preliminary evidence is provided suggesting that the hormone abscisic acid might have a role in regulating ripening initiation in blueberry. / Graduate

Masters of Science / The main objective of this study was to investigate promoter sequences of putative HSR genes for the presence of unique regulatory elements and modules that might be involved in the regulation of HSR. In order to achieve this objective, an in silico promoter analysis strategy was devised, which focused on the identification of promoter sequences and regulatory elements, and modelling of promoter modules by using Genomatix software tools such as MatInspector and ModelInspector. Results showed that two modules (EGRF_SP1F_01 and SP1F_CEBP_01) were conserved in the promoter sequences of three well-known Hsp-genes (Hsp90, Hsp105β and αβ-crystallin). Screening the 60 target gene promoters for the presence of the two modules revealed that 12 genes (20 %) contained both modules. These included Moesin, Proline-4 hydroxylase, Poly(A) binding protein and Formin-binding protein. None of these genes had been previously associated with heat shock response. / South Africa

Les bactéries rhizosphériques qualifiées de PGPR (Plant Growth-Promoting Rhizobacteria) forment des symbioses associatives avec les plantes, stimulant la croissance de ces dernières. Les PGPR présentent différents mécanismes phytobénéfiques (production de phytohormones, fixation non symbiotique de l’azote, etc.). Plusieurs PGPR sont susceptibles d’interagir avec la même plante hôte, et il est possible que leurs effets phytobénéfiques soient influencés par les interactions qu’elles auront les unes avec les autres. L’objectif de cette thèse était de caractériser la compatibilité des PGPR dans la rhizosphère d’une même plante hôte, dans le cas de modèles bactériens appartenant aux genres Azospirillum et Pseudomonas. Certains Pseudomonas phytobénéfiques produisant des métabolites antimicrobiens, comme le 2,4-diacétylphloroglucinol (DAPG), nous avons tout d’abord examiné si la capacité à produire du DAPG pouvait inhiber Azospirillum. Les expériences de confrontation réalisées in vivo avec P. fluorescens F113 et un mutant DAPG-négatif, en système gnotobiotique, ont montré que la colonisation racinaire et l’activité phytostimulatrice de certaines PGPR Azospirillum pouvaient effectivement être diminuées en présence de Pseudomonas producteurs de DAPG. Pour évaluer la colonisation racinaire par Azospirillum en sol non stérile, des outils de PCR quantitative en temps réel ont été développés et validés pour trois souches de premier plan (A. lipoferum CRT1, A. brasilense UAP-154 et CFN-535). L’utilisation de ces outils a permis la comparaison de ces trois souches d’Azospirillum, chacune co-inoculée avec la souche P. fluorescens F113 productrice de DAPG, sur du maïs cultivé en sol non stérile. Les niveaux de colonisation racinaire différaient selon la souche d’Azospirillum, et la combinaison de microorganismes phytobénéfiques conduisait à une meilleure croissance du maïs par comparaison avec des plantes non inoculées. Les résultats suggèrent que des PGPR des genres Pseudomonas et Azospirillum peuvent être compatibles dans la rhizosphère d’une même plante, même si les premiers ont le potentiel d’inhiber certains des seconds par la production de métabolites secondaires antimicrobiens / Plant Growth-Promoting Rhizobacteria (PGPR) can form an associative symbiosis with plants, which results in stimulation of plant growth. PGPR harbour different phytobeneficial mechanisms (non-symbiotic nitrogen fixation, phytohormone synthesis, etc.). Various PGPR can interact with the same host plant, and it is possible that their phytobeneficial effects will be influenced by the interactions between these PGPR. The objective of this doctoral work was to characterize PGPR compatibility in the rhizosphere of the same host plant, in the case of model bacteria belonging to the genera Azospirillum and Pseudomonas. Because certain phytobeneficial Pseudomonas produce antimicrobial metabolites, such as 2,4-diacetylphloroglucinol (DAPG), we have first examined if DAPG production capacity could be involved in Azospirillum inhibition. In vivo experiments, performed with P. fluorescens F113 and a DAPG-negative mutant in gnotobiotic systems, showed that root colonization and phytostimulation activity of certain Azospirillum PGPR was indeed affected in the presence of DAPG-producing Pseudomonas. In order to evaluate Azospirillum root colonization in non-sterile soil, real-time quantitative PCR tools were developed and validated for three prominent Azospirillum strains (A. lipoferum CRT1, A. brasilense UAP-154 and CFN-535). The use of these real-time PCR tools enabled the comparison of the three Azospirillum strains, each co-inoculated with the DAPG-producing strain P. fluorescens F113, in the rhizosphere of maize grown in non-sterile soil. Root colonization levels differed according to the Azospirillum strain, and the combination of phytobeneficial microorganisms led to enhanced maize growth in comparison with non-inoculated plants. These results suggest that PGPR belonging to the genera Pseudomonas and Azospirillum may be compatible in the rhizosphere of a same plant, even if the former have the potential to inhibit some of the latter by producing antimicrobial secondary metabolites