The effect of sugars on the respiratory response of beech mycorrhizas to salts

Publisher Website
Google Scholar
Abstract
Beech mycorrhizas are shown to be capable of absorbing sugar from solutions of glucose, fructose or sucrose. The rate of absorption of hexoses is shown to be dependent upon the concentration applied, upon the pH of the medium, and to be sensitive to the presence of 2:4-dinitrophenol and silver nitrate. Glucose is preferentially absorbed from mixtures of glucose and fructose. Mycorrhizas immersed in sucrose solution cause a rapid release of hexoses into the medium, fructose being released in greater quantity than glucose. From a study of the factors affecting sugar absorption from sucrose solutions it is concluded that sucrose itself is not absorbed, but that the glucose moiety is preferentially selected for absorption. The release of hexoses is little affected by heat treatment of the plant tissue which abolishes its ability to absorb sugar. As hexoses are absorbed, sucrose and polysaccharides increase in the tissues, but the change in the internal concentration of hexoses is small. During sugar absorption a respiratory stimulation occurs which is similar to the respiratory rise occurring during the absorption of nutrient salts. It is suggested from a study of the combined effects of phosphate and sugars that these respiratory effects of sugars and salts may have a common explanation if it is assumed that consumption of high energy phosphate occurs in both processes. This hypothesis is discussed.