Variation of secondary metabolite levels in maize seedling roots induced by inoculation with Azospirillum, Pseudomonas and Glomus consortium under field conditions
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Background and aims
Many plant-beneficial microorganisms can influence secondary plant metabolism, but whether these effects add up when plants are co-inoculated is unclear. This issue was assessed, under field conditions, by comparing the early impacts of seed inoculation on secondary metabolite profiles of maize at current or reduced mineral fertilization levels.
Maize seeds were inoculated singly with selected strains from bacterial genera Pseudomonas and Azospirillum or mycorrhizal genus Glomus, or with these strains combined two by two or all three together. At 16 days, maize root methanolic extracts were analyzed by RP-HPLC and secondary metabolites (phenolics, flavonoids, xanthones, benzoxazionoids, etc.) identified by LC/MS.
Inoculation did not impact on plant biomass but resulted in enhanced total root surface, total root volume and/or root number in certain inoculated treatments, at reduced fertilization. Inoculation led to qualitative and quantitative modifications of root secondary metabolites, particularly benzoxazinoids and diethylphthalate. These modifications depended on fertilization level and microorganism(s) inoculated. The three selected strains gave distinct results when used alone, but unexpectedly all microbial consortia gave somewhat similar results.
The early effects on maize secondary metabolism were not additive, as combining strains gave effects similar to those of Glomus alone. This is the first study demonstrating and analyzing inoculation effects on crop secondary metabolites in the field.
KeywordsSecondary metabolites Benzoxazinoids Diethylphtalate Mineral fertilization Zea mays L.
This work was supported in part by the European Union (FW6 STREP project MicroMaize 036314). We are grateful to Pierre Castillon (Arvalis, Bazièges, France) and Arvalis staff at the Pouzol Etoile experimental station for implementation of the field trial. We thank Bachar Blal (Agrauxine, Quimper, France) and Aleš Látr (Symbio-M, Lanškroun, Czech Republic) for providing formulated microbial inoculants and MPN data, and Geneviève Défago (ETH Zürich) for discussions. This work made use of the platform DTAMB (IFR 41) in Université Lyon 1.
- Beauchamp CJ (1993) Mode of action of plant growth-promoting rhizobacteria and their potential use as biological control agent. Phytoprotection 74:19–28Google Scholar
- Combes-Meynet E, Pothier JF, Moënne-Loccoz Y, Prigent-Combaret C (2011) The Pseudomonas secondary metabolite 2,4-diacetylphloroglucinol is a signal inducing rhizoplane expression of Azospirillum genes involved in plant-growth promotion. Mol Plant-Microbe Interact 24:271–284PubMedCrossRefGoogle Scholar
- Couillerot O, Poirier MA, Prigent-Combaret C, Mavingui P, Caballero-Mellado J, Moënne-Loccoz Y (2010b) Assessment of SCAR markers to design real-time PCR primers for rhizosphere quantification of Azospirillum brasilense phytostimulatory inoculants of maize. J Appl Microbiol 109:528–538PubMedGoogle Scholar
- El Zemrany H, Cortet J, Lutz PM, Chabert A, Baudoin E, Haurat J, Maughan N, Felix D, Défago G, Bally R, Moënne-Loccoz Y (2006) Field survival of the phytostimulator Azospirillum lipoferum CRT1 and functional impact on maize crop, biodegradation of crop residues, and soil faunal indicators in a context of decreasing nitrogen fertilisation. Soil Biol Biochem 38:1712–1726CrossRefGoogle Scholar
- Hohnjec N, Vieweg MF, Pühler A, Becker A, Küster H (2005) Overlaps in the transcriptional profiles of Medicago truncatula roots inoculated with two different Glomus fungi provide insights into the genetic program activated during arbuscular mycorrhiza. Plant Physiol 137:1283–1301PubMedCrossRefGoogle Scholar
- Jacoud C, Job D, Wadoux P, Bally R (1999) Initiation of root growth stimulation by Azospirillum lipoferum CRT1 during maize seed germination. Can J Microbiol 45:339–342Google Scholar
- Karthikeyan B, Jaleel CA, Azooz MM (2009) Individual and combined effects of Azospirillum brasilense and Pseudomonas fluorescens on biomass yield and ajmalicine production in Catharanthus roseus. Acad J Plant Sci 2:69–73Google Scholar
- Mar Vázquez M, César S, Azcón R, Barea JM (2000) Interactions between arbuscular mycorrhizal fungi and other microbial inoculants (Azospirillum, Pseudomonas, Trichoderma) and their effects on microbial population and enzyme activities in the rhizosphere of maize plants. Appl Soil Ecol 15:261–272CrossRefGoogle Scholar
- Marimuthu S, Subbian P, Ramamoorthy V, Samiyappan R (2002) Synergistic effect of combined application of Azospirillum and Pseudomonas fluorescens with inorganic fertilizers on root rot incidence and yield of cotton. Z Pflanzenkr Pflanzenschutz 109:569–577Google Scholar
- Park J-W, Crowley DE (2005) Normalization of soil DNA extraction for accurate quantification of target genes by real-time PCR and DGGE. BioTechniques 38:579–586Google Scholar
- Prigent-Combaret C, Blaha D, Pothier JF, Vial L, Poirier M-A, Wisniewski-Dyé F, Moënne-Loccoz Y (2008) Physical organization and phylogenetic analysis of acdR as leucine-responsive regulator of the 1-aminocyclopropane-1-carboxylate deaminase gene acdS in phytobeneficial Azospirillum lipoferum 4B and other Proteobacteria. FEMS Microbiol Ecol 65:202–219Google Scholar
- Volpin H, Kapulnik Y (1994) Interaction of Azospirillum with beneficial soil microorganisms. In: Okon Y (ed) Azospirillum/Plant associations. CRC Press, Boca Raton, pp 111–118Google Scholar