Einfluss eines gentechnisch veränderten, Auxin produzierenden Rhizobienstammes auf die bakterielle Bodengemeinschaft

At present, legumes cover one third of the total protein intake of the human diet. Therefore any improvement of forage and grain legume yields achieved without using potentially harmful chemical fertilizers are of extreme importance, in particular to the developing countries. One promising approach is the inoculation with a genetically modified Rhizobium strain releasing the plant hormone indole-3-acetic acid (IAA) to the rhizosphere of their host plant. For this purpose I used Rhizobium leguminosarum bv. viciae VF39, which was modified by inserting the iaaM (tryptophane monooxygenase) and tms2 (indole-3-acetamide hydrolase) genes for IAA-synthesis into two separate plasmids pRD20 and pBBRIAA, each derived from the same origin. The expression of these two genes in pRD20 is under control of the strong constitutive cat promotor, whereas in pBBRIAA the rolA promotor is stationary-phase and acid inducible. Within the framework of this thesis I analysed the stability and spreading of the plasmids from the genetically modified rhizobia to the present soil bacteria with a cultivation independent detection system. Simultaneously I analysed, whether the inoculation with the genetically modified Rhizobium strain had any impact on the composition and diversity of the bacterial community in the rhizosphere and rhizoplane of Pisum sativum by DGGE analysis and GC-MS. I could investigate a horizontal gene transfer of the used plasmids to the majority of the tested soil bacteria (gram - and gram +). The expression of the eGFP I used to detect the transferred plasmid in the recipient cells was disturbed by metabolic inactivity and the attachment of the bacteria to fluorescent soil particles. Therefore it was not possible to transfer the cultivation independent detection system, developed for aquatic systems, to the soil system. The investigation of an effect of the genetically modified rhizobia indicated that time alone is the core issue that affected the diversity and activity of the soil bacteria. There was no influence of the genetically modified rhizobia strains on the amount of IAA in the rhizosphere of the plants. Finally, no significant effect of genetically modified rhizobia, producing high amounts of IAA, could be observed on the composition and diversity of the present and active part of the soil bacteria.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2008

Author dc:creator

• Lantin, Corinna

Contributors dc:contributor

• Priefer, Ursula B.

• info:eu-repo/classification/ddc/570
• Rhizobium leguminosarum
• Gentransfer
• Detektion
• Denaturierende Gradienten-Gelelektrophorese
• GC-MS
• Indolessigsäure
• GFP
• Biowissenschaften, Biologie
• Horizontaler Gentransfer
• VF39
• rolA
• Mantel Test
• MDS
• IAA
• horizontal gene transfer
• cultivation independent detection system

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-112431%22

OAI record oai:identifier

https://publications.rwth-aachen.de/oai2d?verb=GetRecord&metadataPrefix=oai_dc&identifier=oai%3Apublications.rwth-aachen.de%3A49863