Potato root and leaf phosphatase activity in response to P deprivation

Abstract

Background: Plants are not able to take up organically bound phosphorus (P) before it is hydrolyzed by extracellular phosphatases while intracellular phosphatases play a role in P remobilization. Aims: The aim of this study was to evaluate intra- and extracellular acid phosphatase activity as well as root and shoot growth of two modern starch potato cultivars at different levels of P deprivation. Methods: In vitro propagated potato plantlets (cultivars Kuba and Cardoso) were grown in sand and fertigated with five different P concentrations, ranging from 1 to 0.05 mM P. Growth parameters, plant P concentrations, and acid phosphatase activities were determined after 40 days. Results: Shoot and root biomass decreased gradually with decreasing P supply, while the root-to-shoot ratio increased. Shoot P concentration decreased steadily, but root P concentration remained constant at P levels below 0.5 mM. Root-associated and root intracellular acid phosphatase activity increased in both cultivars with rising levels of P deprivation. The activity of acid phosphatases in old but not in young leaves was increased with P deprivation. Intracellular acid phosphatase activity was genotype dependent, with higher activity in the cultivar Kuba than in Cardoso. Conclusions: Our results point to a tissue specific regulation of acid phosphatase activity depending on plant P status and potato genotype. Increasing root-associated acid phosphatase activities may help P starved potato plants to ensure a sufficient P nutrition. Further research is needed to unravel the roles of leaf intracellular acid phosphatases in potato.