Detection of Pseudomonas savastanoi pv. savastanoi in olive plants by enrichment and PCR

The sequence of the gene iaaL of Pseudomonas savastanoi EW2009 was used to design primers for PCR amplification. The iaaL-derived primers directed the amplification of a 454-bp fragment from genomic DNA isolated from 70 strai ns of P. savastanoi, whereas genomic DNA from 93 non-P. savastanoi isolates did not yield this amplified product. A previous bacterial enrichment in t he semiselective liquid medium PVF-1 improved the PCR sensitivity level, al lowing detection of 10 to 100 CFU/ml of plant extract. P. savastanoi was de tected by the developed enrichment-PCR method in knots from different varie ties of inoculated and naturally infected olive trees. Moreover, P. savasta noi was detected in symptomless stem tissues from naturally infected olive plants. This enrichment-PCR method is more sensitive and less cumbersome th an the conventional isolation methods for detection of P. savastanoi.