(2007). Plants were cultivated in a growth chamber under controlled conditions (8 h at TSA HDAC 22 °C/16 h at 25 °C) with a light intensity of 33 μEm−2 s−1,

watered every day. Once a week, water was replaced by a 500-fold dilution of a commercial nutrient stock solution (Hydrokani AO, HydroAgri, Nanterre, France). The experiment was duplicated in similar conditions. Soil infestation was performed by adding 1 mL of conidial suspension per well containing the expected inoculum densities. In the heat-treated soil, Fo47 was introduced alone at 1 × 103, 1 × 104, 1 × 105 microconidia mL−1 of soil or in combination with the pathogenic strain Fol8 at 1 × 103 mL−1 of soil. In the nontreated soil, Fo47 was introduced alone at the same concentrations as in the heat-treated soil. In the noninfested control, the fungal inoculum was replaced by 1 mL of distilled water. There were 24 plants per treatment. Plants were harvested 10, 20 and 30 days after soil infestation. For analysis performed 10 and 20 days after soil

infestation, sampling consisted of root systems of three plants; for analysis performed 30 days after inoculation, only one root system was taken. Roots were washed GKT137831 concentration with sterile-distilled water, dried, weighed and frozen at −80 °C in liquid nitrogen. Frozen roots (100 mg) were ground in liquid nitrogen and DNA was extracted and purified using DNeasy Plant Mini Kit (Qiagen GmbH, Hilden, Germany). The DNA samples were stored at 4 °C. Fo47 DNA was quantified within the root DNA by real-time PCR, as described above. The quantification was performed on each of the three replicate samples and the real-time PCR reactions were duplicated. The levels of root colonization by Fo47, expressed as number of SCAR marker copies g−1 root

tissues (fresh weight), were compared by anova followed by Newman and Keuls’ test at P=0.05. ERIC-PCR fingerprinting generated various patterns among the Fusarium strains analyzed, PAK5 including multiple distinct DNA fragments ranging in size from approximately 100 to 4000 bp. The comparison of ERIC patterns revealed a 440-bp fragment specific for the strain Fo47 (Fig. 1). This fragment, called FC8, was sequenced and primers P47A (CTGGTGCTCGCAGAAATGCT) and P47B (GCATGCATCGAGCGAACAAC) were designed from the sequence of FC8 to amplify a 400-bp fragment. The primer set P47A/P47B was nonspecific for the strain Fo47, as it generated a PCR fragment for all six fungal strains tested. PCR products obtained for the six strains, including Fo47 with primers P47A and P47B, were compared. Two mismatches were found between the sequence of Fo47 and the five other sequences (Fig. 2). Two oligonucleotides including these mismatches at their 3′ ends were designed: P47C (CCTCAACTTCTGATTTAAATATGA) and P47D (GAGCGAACAACTACAATAAAAG). The expected size of the PCR product with this second primer set was 211 bp. The specificity of the P47C/P47D primer pair was tested in conventional PCR (Fig.