NO 3 - , PO 4 3 - and SO 4 2 - deprivation reduced LKT1-mediated low-affinity K + uptake and SKOR-mediated K + translocation in tomato and Arabidopsis plants.

Regulation of essential macronutrients acquisition by plants in response to their availability is a key process for plant adaptation to changing environments. Here we show in tomato and Arabidopsis plants that when they are subjected to NO3 - , PO4 3 - and SO4 2 - deprivation, low-affinity K+ uptake and K+ translocation to the shoot are reduced. In parallel, these nutritional deficiencies produce reductions in the messenger levels of the genes encoding the main systems for low-affinity K+ uptake and K+ translocation, i.e. AKT1 and SKOR in Arabidopsis and LKT1 and the tomato homolog of SKOR, SlSKOR in tomato, respectively. The results suggest that the shortage of one nutrient produces a general downregulation of the acquisition of other nutrients. In the case of K+ nutrient, one of the mechanisms for such a response resides in the transcriptional repression of the genes encoding the systems for K+ uptake and translocation.