THE BIOLOGY OF MYCORRHIZA IN THE ERICACEAE

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Abstract
Summary: The major soluble carbohydrates of mycorrhizal and non‐mycorrhizal roots of the cultivated cranberry, Vaccinium macrocarpon Ait., have been identified and quantitatively analysed. Mycorrhizal roots contained two sugars, mannitol and trehalose, not found in uninfected roots. As these sugars are abundant in extracts of endophyte mycelium grown in liquid culture, they appear to be of fungal origin. Analysis of neutral sugars derived by acid hydrolysis of insoluble residues showed an accumulation of a mannose‐containing polymer in mycorrhizal roots. Mannose was a principal component of insoluble polymers in the endophyte.All soluble carbohydrates in the root, including mannitol and trehalose, became labelled after feeding 14CO2 to the shoots. Sucrose was the most strongly labelled sugar in both types of root. Mannose present in hydrolysates of mycorrhizal roots was more heavily labelled than that derived from uninfected roots but most 14C in insoluble fractions was found in glucose polymers.The hypothesis that the endophyte derives a supply of carbohydrate from its host plant is discussed.