Molecular basis for differential uptake and sensitivity to arsenic among clones of shrub willow (Salix spp.)

Arsenic (As) uptake and translocation in two shrub willow (Salix spp.) clones with differential As tolerance were investigated in hydroponic culture, As-spiked potting mix, and contaminated field soil in relation to phosphorus (P) availability. In hydroponics and potting mix, the addition of P to solution or substrate resulted in increased plant vigor and increased As uptake. The As tolerant clone (S. viminalis L. x S. miyabeana; clone ID 99202-011) required 2.5-fold more substrate As than the sensitive clone (S. eriocephala Michx.; clone ID 00X-026-082) for equal biomass reductions. In the field soil experiment, As was not detected in leaf and stem tissue, suggesting that strong soil amendments will need to be investigated to release soil bound As and increase the plant available As pool. Additionally, DNA fragments of three genes (high-affinity phosphate transporters, gamma-glutamylcysteine synthetase, and phytochelatin synthase) were cloned and sequenced. These genes can be further characterizated to elucidate differential As tolerance between willow species.;Key words: gamma-glutamylcysteine synthetase, metal transport, phosphate, phosphate transporters, phytochelatin synthase, phytoremediation, stress tolerance...