Protease Activity in the Rhizosphere of Tomato Plants Is Independent from Nitrogen Status

Abstract

Rhizoboxes were developed in order to analyse root system and correspond- ing protease activity in the rhizosphere of young tomato plants (Solanum lycopersicum cv. Moneymaker). The activity of proteases exuded by tomato roots applying in situ zymography was detected along the entire root system. The corresponding root architecture as well as root and shoot biomasses was determined to correlate protease activity with plant growth parameters under varying nitrogen supplies. With higher nitrate fertilisation, the proteases in the rhizosphere were more active than nitrogen-deficient plants. This may indicate that exuded proteases were not solely a plant response to nitrogen deficiency with the aim to increase nitrogen availability. Instead, they may have different roles, e.g. in root development.