Early transcriptomic changes in cucumber and maize roots in response to FePO nanoparticles as a source of P and Fe.

The use of nanoparticles as an alternative to traditional fertilizers, aiming at a more efficient use of nutrients, is a recently developed concept that requires a thorough understanding of the processes occurring in the soil-plant system. A crucial aspect in this framework is to decipher the plant responses to the unique characteristics of these materials. In this work, we aim at decoding the transcriptional responses of cucumber and maize roots to FePO nanoparticles applied as P and Fe sources, respectively. The results demonstrate that P and Fe supplied as nanoscale salts support plant nutrition with an efficiency comparable to that of ionic forms of the nutrients. This supposition is confirmed by transcriptomic profiles that show no significant upregulation of transcripts typically induced by deficiencies in P and Fe in cucumber and maize plants in which these nutrients were provided by FePO nanoparticles. The analysis further revealed that nanoparticles alter the expression of genes involved in root development and stress responses, effect that appeared to be independent on the nutritional status of the plants. Our data further underline the challenge to identify generalizable elements of the impact of nanomaterials on plant species, as responses are intimately linked to the type of nanomaterials and differ among plant species.