Environmental monitoring of the biocontrol agent Pantoea agglomerans CPA-2 applied to citrus fruit at preharvest

摘要

The aim of this study was to evaluate the environmental fate and behaviour of the biocontrol product based on Pantoea agglomeransCPA-2 cells after its release into the field. Three different methods, dilution plating, quantitative real-time PCR (qPCR) and propidium monoazide combined with qPCR (PMA-qPCR) were used to track the CPA-2 population. Populations quantified by qPCR were statistically different compared with those by the PMA-qPCR and dilution plating methods. In addition, the spray dispersion of the CPA-2 treatment was evaluated using water-sensitive papers. A lack of dispersion of the CPA-2 treatment was observed at distances of 2.5 +/- 0.5 m. The presence and persistence of CPA-2 in the environment were monitored in different areas, by dilution plating and confirmed by conventional PCR. The results showed that CPA-2 can survive but not proliferate on weed and leaves. The persistence on inert surfaces, such as motorised backpack sprayer, gloves and working clothes, was less than 7 days. In conclusion, PMA-qPCR was a potential tool for fast and specific monitoring of viable populations of CPA-2 and it gave valuable information on population behaviour. Moreover, the results demonstrate that CPA-2 would not present a risk for the environment because of its low establishment, survival and dispersion.