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International audience; Aims: To assess the applicability of the 16S–23S rDNA internal spacer regions (ISR) as targets for PCR detection of Azospirillum ssp. and the phytostimulatory plant growth-promoting rhizobacteria seed inoculant Azospirillum lipoferum CRT1 in soil. Methods and Results: Primer sets were designed after sequence analysis of the ISR of A. lipoferum CRT1 and Azospirillum brasilense Sp245. The primers fAZO ⁄ rAZO targeting the Azospirillum genus successfully yielded PCR amplicons (400–550 bp) from Azospirillum strains but also from certain non- Azospirillum strains in vitro, therefore they were not appropriate to monitor indigenous Azospirillum soil populations. The primers fCRT1 ⁄ rCRT1 targeting A. lipoferum CRT1 generated a single 249-bp PCR product but could also amplify other strains from the same species. However, with DNA extracts from the rhizosphere of field-grown maize, both fAZO ⁄ rAZO and fCRT1 ⁄ rCRT1 primer sets could be used to evidence strain CRT1 in inoculated plants by nested PCR, after a first ISR amplification with universal ribosomal primers. In soil, a 7-log dynamic range of detection (102–108 CFU g)1 soil) was obtained. Conclusions: The PCR primers targeting 16S–23S rDNA ISR sequences enabled detection of the inoculant A. lipoferum CRT1 in field soil. Significance and Impact of the Study: Convenient methods to monitor Azospirillum phytostimulators in the soil are lacking. The PCR protocols designed based on ISR sequences will be useful for detection of the crop inoculant A. lipoferum CRT1 under field conditions.

peer-reviewed Envionmental and consumer concerns have focused interest on the development of biological control as an alternative, environmentally-friendly strategy for the protection of agricultural and horticultural crops against phytopathogens. Biological control agents. producing a variety of secondary metabolites and hydrolytic enzymes, have been identified among fungi, actinomyceles and bacteria. Pseudomonas fluorescens FII3 and Stenotrophomonas maltophilia W81 inhibit growth of the phytopathogenic fungus Pythium ultimum in vitro and are capable of protecting sugar beet against the effects of damping-off under soil conditions. Transposon mutagenesis of strains FIl3 and W81 has demonstrated that the biocontrol abilities of these strains are mediated by 2,4-diacetylphloroglucinol (pm...) or lytic enzyme production, respectively. Globodera roslochiensis is a phytopathogenic cyst neml1.tode of major agronomic importance. Purified PHL, lytic enzymes, and chitinolytic or phloroglucinol-producing bacterial inoculants negatively influence hatch of G. rostochiensis eggs and decrease subsequent viability of juvenile cyst nematodes in vitro. Similar results were obtained under soil conditions.