Role of PGP arsenic-resistant bacteria in As mobilization and translocation in Helianthus annuus L

This study investigated the effect of arsenic-resistant Alcaligenes sp. strain DhalL with potential plant growth promoting characteristics on growth and arsenic uptake by sunflower ( Helianthus annuus L.). Pot experiments were prepared using an agricultural As-contaminated soil sown with seeds of sunflower uninoculated and inoculated with the strain. A Real Time PCR method, based on the quantification of ACR3( 2) gene carried by DhalL, was set up in order to monitor presence and colonisation of the soil by the strain. The arsenic content was significantly higher in inoculated than in the uninoculated aboveground part of the plants (1.63 mg kg d.w. -1 vs. 0.77), highlighting the effect of the strain on arsenic uptake by sunflower. ACR3( 2) gene copy number was one hundred times higher in inoculated than in uninoculated pots, especially in the rhizospheric soil, indicating that colonisation occurred. The results suggest that the presence of arsenic resistant strain such as Alcaligenes sp. DhalL in the rhizosphere of sunflower could influence As mobilization and uptake by plant.