TRANSLOCATION OF SOLUTES IN ECTOMYCORRHIZAL AND SAPROTROPHIC RHIZOMORPHS

The principles governing translocation in rhizomorphs of ectomycorrhizal and saprotrophic basidiomycetes are similar. Translocation appears to be strongly polarized along concentration gradients towards sinks for various compounds, not only at the level of the rhizomorph system, but also within individual rhizomorphs. Bi-directional translocation must occur, for the most part, within spatially separated hyphal elements. It is suggested that rapid acropetal translocation of carbon occurs along part of the rhizomorph length by a turgor-driven mass flow of solution in the apoplast of empty 'vessel' hyphae. Basipetal nutrient translocation seems likely to be confined to the symplast of living hyphae, driven down concentration gradients towards sinks by mixing resulting from cytoplasmic streaming. Basipetal water movement may also occur by mass flow in the rhizomorph apoplast.