© 1988 Heron Publishing—Victoria, Canada
Cytokinins in the root pressure exudate of Citrus jambhiri Lush. colonized by vesicular-arbuscular mycorrhizae
R. K. Dixon (1), H. E. Garrett (2) and G. S. Cox (2)
1. School of Forestry, Auburn University, Auburn, AL 36849-5418, USA / 2. School of Forestry, Fisheries and Wildlife, University of Missouri, Columbia, MO 45211, USA / Received April 22, 1987
Summary
The influence of vesicular-arbuscular mycorrhizal (VAM) symbiosis on the transport of cytokinins from the root to the shoot
of Citrus jambhiri Lush. seedlings inoculated with cultures of Glomus etunicatum (Becker and Gerd.), G. fusciculatum (Thaxt.) Gerd. and Trappe, or G. mosseae (Nichol. and Gerd.) was investigated. Cytokinins collected from root exudates over a 90-day period were analyzed by high-performance
liquid chromatography, mass spectrometry and a bioassay. The flux of cytokinins was independent of root exudate flux. Seedlings
inoculated with G. fasciculatum or G. mosseae yielded a greater flux of zeatin, dihydrozeatin and zeatin riboside than non-inoculated seedlings. The flux of zeatin riboside
was significantly greater than the flux of zeatin in seedlings inoculated with VAM symbionts. Vesicular-arbuscular mycorrhizal
relationships apparently contributed to, or influenced, the export of cytokinins from the root. The elevated cytokinin flux
of inoculated seedlings was associated with improved tissue phosphorus nutrition and a significant increase in seedling biomass.
