Analysis of the Acetylene Reducing Ability of Root Nodule Protoplasts Isolated from Glycine max

Using microaerobic conditions, stable preparations of soybean (Glycine max var. Bragg) root nodule protoplasts were isolated. The enzyme mixture consisted of 2% Cellulase R10, 1% Macerozyme R10 in a 0.6 M mannitol osmoticum.

The protoplasts showed acetylene reduction activity of up to 50nmol ethylene g^-1 nodule FWh^-1 for at least 12 hours. This activity occurred immediately after isolation, and no lag period was observed. The observed specific activities were considerably (up to 40 fold) higher than those previously reported (e.g. Schetter and Hess 1977). However, in view of the overall reduction of activity which is observed between the whole plant stage and the isolated protoplasts (about a 1000 fold decrease), one has to question the general applicability of the isolated protoplast system for the study of physiological parameters affecting symbiotic nitrogen fixation.