A trade-off may exist between the capacity of plants to downregulate their phosphorus (P) uptake capacity and their efficiency of P resorption from senescent leaves in species from severely P-impoverished environments. de Campos et al. grow four Australian native species (Banksia attenuata, B. menziesii, Acacia truncata and A. xanthina) in nutrient solutions at a range of P concentrations and determine rates of uptake, leaf concentrations, and resorption proficiency values. The results support the hypothesis that the ability to resorb P from senescing leaves is inversely related to the capacity to downregulate net P uptake. Constitutive synthesis of P transporters may be a prerequisite for proficient P remobilization from senescing tissues.
