Comparison of prominent Azospirillum strains in Azospirillum–Pseudomonas–Glomus consortia for promotion of maize growth

• Published in: Applied microbiology and biotechnology Vol. 97; no. 10; pp. 4639 - 4649
• Main Authors: Couillerot, Olivier, Ramírez-Trujillo, Augusto, Walker, Vincent, von Felten, Andreas, Jansa, Jan, Maurhofer, Monika, Défago, Geneviève, Prigent-Combaret, Claire, Comte, Gilles, Caballero-Mellado, Jesus, Moënne-Loccoz, Yvan
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.05.2013; Springer; Springer Nature B.V; Springer Verlag
• Subjects: Analysis; Auxins; Azospirillum; Azospirillum - isolation & purification; Azospirillum - physiology; Bacteria; Biomedical and Life Sciences; Biotechnology; Consortia; Corn; Environmental Biotechnology; Genetic aspects; Genetic transcription; Glomeromycota - physiology; Health aspects; Life Sciences; Metabolism; Microbial Genetics and Genomics; Microbiology; Microorganisms; Plant growth; Pseudomonas - physiology; Real-Time Polymerase Chain Reaction; Studies; Zea mays - growth & development; Zea mays - microbiology; Mexico; Maize; PGPR; Inoculum survival; Microbial consortia; Chemistry and Materials Science
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-012-4249-z

Azospirillum are prominent plant growth-promoting rhizobacteria (PGPR) extensively used as phytostimulatory crop inoculants, but only few studies are dealing with Azospirillum -containing mixed inocula involving more than two microorganisms. We compared here three prominent Azospirillum strains as part of three-component consortia including also the PGPR Pseudomonas fluorescens F113 and a mycorrhizal inoculant mix composed of three Glomus strains. Inoculant colonization of maize was assessed by quantitative PCR, transcription of auxin synthesis gene ipdC (involved in phytostimulation) in Azospirillum by RT-PCR, and effects on maize by secondary metabolic profiling and shoot biomass measurements. Results showed that phytostimulation by all the three-component consortia was comparable, despite contrasted survival of the Azospirillum strains and different secondary metabolic responses of maize to inoculation. Unexpectedly, the presence of Azospirillum in the inoculum resulted in lower phytostimulation in comparison with the Pseudomonas – Glomus two-component consortium, but this effect was transient. Azospirillum 's ipdC gene was transcribed in all treatments, especially with three-component consortia, but not with all plants and samplings. Inoculation had no negative impact on the prevalence of mycorrhizal taxa in roots. In conclusion, this study brought new insights in the functioning of microbial consortia and showed that Azospirillum – Pseudomonas – Glomus three-component inoculants may be useful in environmental biotechnology for maize growth promotion.