Metabolic changes in washed, isolated steles.

Steles isolated from maize roots grown under non-sterile conditions showed an increase in ion absorption capacity and in the rate of oxygen uptake when washed for 24 h, although the levels of protein and of several hydrolytic and respiratory tnzymes fell over the same period. Fresh isolated cortex showed higher activity than fresh steles in relation to both ion absorption and respiration. The large increase with washing in the ion absorption capacity of the steles was not observed when the tissue was isolated from roots grown under sterile conditions. These results are discussed in relation to proposed mechanisms for the radial transport of ions across the root and to the effect of micro-organisms on ion absorption studies in higher plant cells.