Effects of Hebeloma arenosa and phosphorus fertility on root acid phosphatase activity of red pine (Pinus resinosa) seedlings

Abstract

The ectomycorrhizal fungus Hebeloma arenosa Burdsall, MacFall & Albers was assayed for surface-accessible acid phosphatase activity in vitro on roots of red pine (Pinus resinosa Ait.) seedlings. Hebeloma arenosa was grown in defined liquid media containing 0, 17, 34, 68, or 136 mg/L phosphorus for 4 weeks. When assayed for acid phosphatase activity with p-nitrophenyl phosphate, 7.3 μmol of orthophosphate were released per gram dry weight of fungal tissue. There was no effect of added P on enzyme activity, excluding the treatment with no added P in which there was negligible fungal growth. Red pine seedlings were grown in Sparta loamy fine sand amended with 0, 17, 34, 68, or 136 mg/kg P as superphosphate, with and without H. arenosa inoculum. Mycorrhizal roots had greater enzyme activity than nonmycorrhizal roots of seedlings grown in similarly P-amended soil. This was determined by the following three assays: orthophosphate release from two salts of myoinosital hexaphosphate (Na and KMg) and from p-nitrophenyl phosphate. It is suggested that greater acid phosphatase activity by roots mycorrhizal with H. arenosa is one mechanism for improved P nutrition through the formation of a pool of P released from sources unavailable for direct intake.

Heterogeneity of fungal and plant enzyme expression in intact Scots pine–Suillus bovinus and –Paxillus involutus mycorrhizospheres developed in natural forest humus

“…The acid phosphatase activity expressed in short roots and radicles was considerably lower than in corresponding S. bovinus mycorrhizal tissues. These data are in agreement with the earlier findings of MacFall & Slack (1991) and Pasqualini, Panara & Antonielli (1992) regarding acid phosphatase activities in mycorrhizal and non-mycorrhizal Pinus pinea and Pinus resinosa grown in pot cultures. The acid-phosphatase activity of P. involutus mycorrhizas was low in the current study, although higher than that detected in short roots.…”

In vivo demonstration of acid phosphatase activity in the rhizosphere of soil-grown plants

“…In many studies on ectomycorrhizae phosphatase activity is measured in in vitro cultures of the fungus or in excised mycorrhizal short roots (Alexander and Hardy, 1981;McFall et al, 1991). In contrast, the filter paper method allows determination of acid phosphatase activity in intact mycorrhizal root systems.…”

Influence of phosphorus limitations on the growth, nutrient partitioning and physiology of balsa (Ochroma pyramidale) seedlings

“…Plants can use organic P efficiently after the enzymatic hydrolysis to inorganic phosphate (Tarafdar & Claassen 1988) by phosphatase enzymes that are released by roots and microorganisms in the rhizosphere (Das et al 2014). There is little information concerning the effect of root phosphatase activity on the growth and physiology of tropical forest tree species (Kroehler & Linkins 1988, MacFall et al 1991, and data on balsa could not be found.…”