Volume 10 Part 1 Article 33: The Role of Non-Structural Carbohydrates in the Life Cycle of Agaricus bisporus

Volume 10 Part 1 Article 33
Year 1979
Title: The Role of Non-Structural Carbohydrates in the Life Cycle of Agaricus bisporus
Author: J.B.W. Hammond

Abstract:

The life-cycle of Agaricus bisporus like that of other Agarics, involves the production of a self-supporting, fleshy fruiting body more complex than the mycelium which bears it. The chemical composition of the fruit body is well known. One of the most striking features is the large quantity of mannitol present ; values of between 8.6 and 50% of the dry weight have been reported (McConnell and Esselen, 1947; Rast, 1965; Hammond and Nichols, 1976a). The level increases in the stipe and pileus of the growing fruit body (Rast, 1965; Hammond and Nichols, 1976a). Mannitol is synthesised from fructose by an NADP1+-dependent mannitol dehydrogenase in A. bisporus (Edmundowicz and Wriston, 1963), but its function remains unknown. It has been suggested that fungal polyols are reserve materials, mediators in coenzyme regulation and osmoregulators (Lewis and Smith, 1967). Dutsch and Rast (1972a) suggested that in A. bisporus mannitol synthesis controls the rate of operation of the Hexose Monophosphate Pathway (HMP).

Trehalose and non-structural polysaccharide are present in lower quantities than mannitol (Rast, 1965; Hammond and Nichols, 1976a, b) but still constitute an important part of the total cell carbohydrate. Trehalose acts as an energy reserve in various spores (Horikoschi and Ikeda, 1966; Williams and Niederpruem, 1968) as it does, together with glycogen, in yeast cells (Trevelyan and Harrison, 1956). However there is little evidence for such a function in A. bisporus.

This paper reviews our work on carbohydrates in A. bisporus, and advances an hypothesis to account for the functions of the three non-structural carbohydrates mentioned above.

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