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.

Background Phosphorus (P) is an essential macronutrient required for plant metabolism and growth. Its acquisition by plants depends on the availability of dissolved P in the rhizosphere and on the characteristics of P uptake mechanisms such as root-system architecture (RSA). Compared to other crops, potato (Solanum tuberosum L.) has a relatively poor P acquisition efficiency. This is mainly due to its shallow and sparsely branched root system, resulting in a rather limited exploitable soil volume. Information about potato genotypes with RSA traits suitable to improve adaptation to nutrient scarcity is quite rare. Aim of this study is to assess phenotypic variation of RSA in a potato diversity set and its reactions to P deficiency. Results Only one out of 22 RSA-traits showed a significant increase under low-P conditions. This indicates an overall negative effect of P scarcity on potato root growth. Differences among genotypes, however, were statistically significant for 21 traits, revealing a high variability in potato RSA. Using a principal component analysis (PCA), we were able to classify genotypes into three groups with regard to their root-system size. Genotypes with both small and large root systems reacted to low-P conditions by in- or decreasing their relative root-system size to medium, whereas genotypes with an intermediate root system size showed little to no changes. Conclusions We observed a huge variation in both the potato root system itself and its adaptation to P deficiency. This may enable the selection of potato genotypes with an improved root-zone exploitation. Eventually, these could be utilized to develop new cultivars adapted to low-P environments with better resource-use efficiencies.

Background Phosphorus (P) is an essential macronutrient required for plant metabolism and growth. Its acquisition by plants depends on the availability of dissolved P in the rhizosphere and on the characteristics of P uptake mechanisms such as root-system architecture (RSA). Compared to other crops, potato (Solanum tuberosum L.) has a relatively poor P acquisition efficiency. This is mainly due to its shallow and sparsely branched root system, resulting in a rather limited exploitable soil volume. Aim of this study is to reveal phenotypic variability of RSA and its reactions to P deficiency.ResultsOnly one out of 22 RSA-traits showed a significant increase under low-P conditions. This indicates an overall negative effect of P scarcity on potato root growth. Differences among genotypes, however, were statistically significant for 21 traits, revealing a high variability in potato RSA. Using a principal component analysis (PCA), we were able to classify genotypes into three groups with regard to their root-system size. Genotypes with both small and large root systems reacted to low-P conditions by in- or decreasing their relative root-system size to medium, whereas genotypes with an intermediate root system size showed little to no changes. ConclusionsWe observed a huge variation in both the potato root system itself and its adaptation to P deficiency. This may enable the selection of potato genotypes with an improved root-zone exploitation. Eventually, these could be utilized in the development of new cultivars adapted to low-P environments with better resource-use efficiencies.