Due to the arbitrary use of cupric fungicides in the last century, copper (Cu) has accumulated in agricultural soils worldwide. The concentrations of Cu exceed the safety limits of risk assessment for Cu in soil and this may cause toxicity in plants. Scientific knowledge about the interaction between Cu and other nutrients is still scarce, also the impact of Cu on the mechanisms underlying mineral nutrients uptake at root level. These aspects might be of paramount importance in the case of phosphorus (P), which is an essential macronutrient for all plants species.

In this work hydroponically grown cucumber plants were used to investigate the influence of different Cu concentrations (i.e. 0.2, 5, 25 and 50 µM) on i) the phenotypic traits of plants, particularly at root level, ii) the nutrient content in both root and shoot, iii) the P uptake activity at both biochemical and molecular levels.

The data display significances under elevated Cu concentrations: the growth of shoots and roots resulted stunted, and the net P uptake diminished. Furthermore, two P transporter genes were up-regulated at the highest concentration: CsPT1.4 showed a quick response, whereas CsPT1.9 seems to be involved in a long-term response to Cu toxicity. Overall, these results strengthen our hypothesis that high Cu concentrations in the growth medium can limit the uptake of P, most likely via a direct action on the uptake mechanisms (e.g. transporters) and/or by compromising the integrity of the root plasma membrane.