INCORPORATION OF C-14-LABELED SUBSTRATES BY UNINFECTED AND VA MYCORRHIZAL ROOTS OF ONION

VA mycorrhizal infection of onion roots with Glomus masseae increases their ability to incorporate carbon from external sources, such as sucrose, acetate and glycerol, as well as from photosynthetic assimilate. Within 20 min of photosynthesis in 14CO2, radioactivity was present in lipid and non‐lipid, soluble and insoluble compounds of roots. After a chase period of 18 h, c.30 % of the radioactivity in mycorrhizal and non‐mycorrhizal roots supplied with [2‐14C]‐acetate and [14C]glycerol and 12 to 20% of that from [14C]sucrose was in the lipid fraction, while c. 5% of the 14C‐labelled photosynthate received by the roots appeared in lipids. Mycorrhizal roots differed from uninfected roots in their significantly higher incorporation of carbon from photosynthate, sucrose and acetate into ethanol‐soluble compounds and insoluble materials, from sucrose into water‐soluble compounds and from acetate into lipids. Copyright © 1979, Wiley Blackwell. All rights reserved