Effects of Azospirillum brasilense with genetically modified auxin biosynthesis gene ipdC upon the diversity of the indigenous microbiota of the wheat rhizosphere.
The phytostimulatory properties of Azospirillum inoculants, which entail production of the phytohormone indole-3-acetic acid (IAA), can be enhanced by genetic means. However, it is not known whether this could affect their interactions with indigenous soil microbes. Here, wheat seeds were inoculated with the wild-type strain Azospirillum brasilense Sp245 or one of three genetically modified (GM) derivatives and grown for one month. The GM derivatives contained a plasmid vector harboring the indole-3-pyruvate/phenylpyruvate decarboxylase gene ipdC (IAA production) controlled either by the constitutive promoter PnptII or the root exudate-responsive promoter PsbpA, or by an empty vector (GM control). All inoculants displayed equal rhizosphere population densities. Only inoculation with either ipdC construct increased shoot biomass compared with the non-inoculated control. At one month after inoculation, automated ribosomal intergenic spacer analysis (ARISA) revealed that the effect of the PsbpA construct on bacterial community structure differed from that of the GM control, which was confirmed by 16S rDNA-based denaturing gradient gel electrophoresis (DGGE). The fungal community was sensitive to inoculation with the PsbpA construct and especially the GM control, based on ARISA data. Overall, fungal and bacterial communities displayed distinct responses to inoculation of GM A. brasilense phytostimulators, whose effects could differ from those of the wild-type.
Université de Lyon, F-69622 Lyon, France; Université Lyon 1, Villeurbanne, France.
Ezékiel
E
Baudoin
Anat
A
Lerner
M Sajjad
MS
Mirza
Hamdy
H
El Zemrany
Claire
C
Prigent-Combaret
Edouard
E
Jurkevich
Stijn
S
Spaepen
Jos
J
Vanderleyden
Sylvie
S
Nazaret
Yaacov
Y
Okon
Yvan
Y
Moënne-Loccoz
D015806:Azospirillum brasilense / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics; D044822:Biodiversity; D018533:Biomass; D053898:Biosynthetic Pathways / Q000235:genetics; D002262:Carboxy-Lyases / Q000235:genetics; D016172:DNA Fingerprinting / Q000379:methods; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D018628:Gene Dosage; D005818:Genetic Engineering; D007210:Indoleacetic Acids / Q000378:metabolism*; D054892:Metagenome; D009691:Nucleic Acid Denaturation; D030781:Organisms, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D018517:Plant Roots / Q000382:microbiology*; D018520:Plant Shoots / Q000254:growth & development; D010957:Plasmids; D012988:Soil Microbiology; D014908:Triticum / Q000382:microbiology*
D001426:Bacterial Proteins; D021903:DNA, Ribosomal Spacer; D007210:Indoleacetic Acids; D002262:Carboxy-Lyases; C109058:phenylpyruvate decarboxylase