Intraspecific variations in activities of four classes of fine root phosphatases in <italic>Quercus serrata</italic>, a dominant deciduous oak, occurring across a wide soil phosphorus gradient in Japan.

Background and aims: Phosphatase secretion by roots is an important phosphorus (P) acquisition strategy for plants growing under soil P deficiency. Four different classes of phosphatases degrade specific fractions of soil organic P (phosphomonoesterase, PME degrading labile monoester P; pyrophosphatase, PyP for pyrophosphate; phytase, PhT for phytate; and phosphodiesterase, PDE for diester P). We investigated how plants depend on these phosphatases and how their activities are regulated.Activities of four phosphatases were measured in roots of <italic>Quercus serrata,</italic> which is a dominant deciduous oak in Japan. Root samples were collected from 14 sites that formed a wide soil P gradient. Activities of four phosphatases were analyzed as releasing rate of product under a common laboratory condition.Activities of the three phosphatases that produced phosphate as their end product (i.e. PME, PyP and PhT) showed significant inter-site variations, while PDE activity was invariant. PME activity was higher by one to two-order(s) of magnitude than the others in all sites. In structural equation modeling, PME activity was negatively related to the concentration of labile inorganic P in soils, implying that PME was regulated by its product but not by substrate.PME appears to be the main phosphatase for <italic>Quercus serrata</italic> to acquire phosphate from organic P. PyP and PhT are assumed to play supplementary roles to PME<italic>.</italic> The variations patterns of activities among sites probably reflect cost–benefit balance of acquiring phosphate in <italic>Q. serrata</italic>. This regulatory mechanism may allow <italic>Q. serrata</italic> to grow across a wide soil P gradient.Methods: Phosphatase secretion by roots is an important phosphorus (P) acquisition strategy for plants growing under soil P deficiency. Four different classes of phosphatases degrade specific fractions of soil organic P (phosphomonoesterase, PME degrading labile monoester P; pyrophosphatase, PyP for pyrophosphate; phytase, PhT for phytate; and phosphodiesterase, PDE for diester P). We investigated how plants depend on these phosphatases and how their activities are regulated.Activities of four phosphatases were measured in roots of <italic>Quercus serrata,</italic> which is a dominant deciduous oak in Japan. Root samples were collected from 14 sites that formed a wide soil P gradient. Activities of four phosphatases were analyzed as releasing rate of product under a common laboratory condition.Activities of the three phosphatases that produced phosphate as their end product (i.e. PME, PyP and PhT) showed significant inter-site variations, while PDE activity was invariant. PME activity was higher by one to two-order(s) of magnitude than the others in all sites. In structural equation modeling, PME activity was negatively related to the concentration of labile inorganic P in soils, implying that PME was regulated by its product but not by substrate.PME appears to be the main phosphatase for <italic>Quercus serrata</italic> to acquire phosphate from organic P. PyP and PhT are assumed to play supplementary roles to PME<italic>.</italic> The variations patterns of activities among sites probably reflect cost–benefit balance of acquiring phosphate in <italic>Q. serrata</italic>. This regulatory mechanism may allow <italic>Q. serrata</italic> to grow across a wide soil P gradient.Results: Phosphatase secretion by roots is an important phosphorus (P) acquisition strategy for plants growing under soil P deficiency. Four different classes of phosphatases degrade specific fractions of soil organic P (phosphomonoesterase, PME degrading labile monoester P; pyrophosphatase, PyP for pyrophosphate; phytase, PhT for phytate; and phosphodiesterase, PDE for diester P). We investigated how plants depend on these phosphatases and how their activities are regulated.Activities of four phosphatases were measured in roots of <italic>Quercus serrata,</italic> which is a dominant deciduous oak in Japan. Root samples were collected from 14 sites that formed a wide soil P gradient. Activities of four phosphatases were analyzed as releasing rate of product under a common laboratory condition.Activities of the three phosphatases that produced phosphate as their end product (i.e. PME, PyP and PhT) showed significant inter-site variations, while PDE activity was invariant. PME activity was higher by one to two-order(s) of magnitude than the others in all sites. In structural equation modeling, PME activity was negatively related to the concentration of labile inorganic P in soils, implying that PME was regulated by its product but not by substrate.PME appears to be the main phosphatase for <italic>Quercus serrata</italic> to acquire phosphate from organic P. PyP and PhT are assumed to play supplementary roles to PME<italic>.</italic> The variations patterns of activities among sites probably reflect cost–benefit balance of acquiring phosphate in <italic>Q. serrata</italic>. This regulatory mechanism may allow <italic>Q. serrata</italic> to grow across a wide soil P gradient.Conclusion: Phosphatase secretion by roots is an important phosphorus (P) acquisition strategy for plants growing under soil P deficiency. Four different classes of phosphatases degrade specific fractions of soil organic P (phosphomonoesterase, PME degrading labile monoester P; pyrophosphatase, PyP for pyrophosphate; phytase, PhT for phytate; and phosphodiesterase, PDE for diester P). We investigated how plants depend on these phosphatases and how their activities are regulated.Activities of four phosphatases were measured in roots of <italic>Quercus serrata,</italic> which is a dominant deciduous oak in Japan. Root samples were collected from 14 sites that formed a wide soil P gradient. Activities of four phosphatases were analyzed as releasing rate of product under a common laboratory condition.Activities of the three phosphatases that produced phosphate as their end product (i.e. PME, PyP and PhT) showed significant inter-site variations, while PDE activity was invariant. PME activity was higher by one to two-order(s) of magnitude than the others in all sites. In structural equation modeling, PME activity was negatively related to the concentration of labile inorganic P in soils, implying that PME was regulated by its product but not by substrate.PME appears to be the main phosphatase for <italic>Quercus serrata</italic> to acquire phosphate from organic P. PyP and PhT are assumed to play supplementary roles to PME<italic>.</italic> The variations patterns of activities among sites probably reflect cost–benefit balance of acquiring phosphate in <italic>Q. serrata</italic>. This regulatory mechanism may allow <italic>Q. serrata</italic> to grow across a wide soil P gradient. [ABSTRACT FROM AUTHOR]