Proteinase activity in mycorrhizal fungi

Abstract

SUMMARYThe ericoid mycorrhizal endophyte, Hymenoscyphus ericae (Read) Korf & Kernan, was grown in liquid media containing either ammonium, the amino acid alanine, peptide (di-, tri-, tetra-or hexa-alanine), or bovine serum albumin (BSA) as sole nitrogen (N) source. The effects of the various N sources upon production of extracellular acid proteinase, its specific activity and growth of the fungus were determined.While extracellular acid proteinase was induced in the presence of each N source, enzyme production was considerably enhanced in the culture grown with BSA. Total enzyme activity in the culture solutions declined in the order BSA ^ ammonium > peptides and alanine. Enzyme activity per mg dry weight of mycelium was greatest in the presence of BSA.Similar yields of fungal mycelium and rates of growth were observed regardless of N source. The results are discussed in relation to quantitative aspects of the N status of heathland soils.

Increases in nitrogen uptake rather than nitrogen-use efficiency support higher rates of temperate forest productivity under elevated CO 2

“…Mycorrhizal fungi play a crucial role in N cycling through the release of enzymes involved in the decomposition of SOM (39)(40)(41), the capture of organic and inorganic forms of N from the soil (42,43), and the transfer of N to host plants (44,45). Similarly, the addition of C substrates to the soil stimulates the decomposition of SOM, often as a result of an increase in microbial activity (reviewed in ref.…”

Intact amino acid uptake by northern hardwood and conifer trees

“…To date, much of the emphasis on the capture of organic N has focused on ectomycorrhizal (ECM) fungi because of their known proteolytic capability (Chalot and Brun 1998) and their transfer of N to host plants in culture studies (Abuzinadah and Read 1989;Leake and Read 1990). In contrast to many ECM fungi, arbuscular-mycorrhizal (AM) fungi lack proteolytic capacity, and they are thought to be more important in the capture and transfer of inorganic nutrients to host plants (Smith and Read 1997).…”

A comparison of the extracellular enzyme activities of two ectomycorrhizal and a leaf‐saprotrophic basidiomycete colonizing beech leaf litter

“…Additionally, extracellular proteases are also involved in the general phenomenon of autolysis displayed hy senescent fungi (Dosoretz et al, 1990). Extracellular protease activin-has been demonstrated in an ericoid and in a few ectomycorrhizal fungi (Leake & Read, 1990;Zhu et al, 1994). Indirect evidence of ectomycorrhizal protease production was also obtained in the experiments of Ahuzinadah, Finlay & Read (1986) and Ahuzinadah & Read (1986).…”

“…Usually ammoniuna is particularly effective in repressing protease production. However, several studies have shown that only partial repression occurs in the ericoid mycorrhizal fungus Hymenoscyphus ericae (Read) Korf & Kernan (Leake & Read, 1990, 1991, in the ectomycorrhizal fungus Hebeloma criistuliniforme (Bull. : St.-Amans) Quel.…”