In the present study the role of the plasma membrane H(+) -ATPase for growth and development of roots as response to nitrogen starvation is studied. It is known that root development differs dependent on the availability of different mineral nutrients. These include processes such as initiation of lateral root primordia, root elongation and increase the root biomass. However, the signal transduction mechanisms, which enable roots to sense changes in different mineral environments and match their growth and development patterns to actual conditions in the soil, are still unknown. Most recent comments have focused on one of the essential macroelements, namely nitrogen, and its role in the modification of the root architecture of Arabidopsis thaliana. As yet, not all elements of the signal transduction pathway leading to the perception of the nitrate stimulus, and hence to anatomical changes of the root, which allow for adaptation to variable ion concentrations in the soil, are known. Our data demonstrate that primary and lateral root length were shorter lower in aha2 mutant lines compared to wild-type plants in response to a variable nitrogen source. This suggests that the plasma membrane proton pump AHA2 is important for root growth and development during different nitrogen regimes. This is possible by controlling the pH homeostasis in the root during growth and development as shown by pH biosensors.