Wounding inhibits protein synthesis yet stimulates polysome formation in aged, excised pea epicotyls

Abstract

Wounding of aged, previously-excised pea epicotyl segments by removal of the basal 1-2 mm resulted in a rapid (beginning within 15 min) recruitment of monosomes on to polysomes and an even more rapid (maximal between 6-12 min) inhibition of protein synthesis in the remaining tissue. This inhibition of protein synthesis in vivo did not appear to be an artefact caused by the removal of highly active tissue (e.g., callus, contaminating bacteria), since wounds inflicted at a site distant from the region analyzed still elicited the response, and protein synthesis in the 1-2 mm slices (normally discarded) was inhibited even more strongly than it was in the remaining tissue. The proportion of radioactive methionine in nascent chains (bound to polysomes) increased, while the production of completed polypeptides decreased, after wounding. Cycloheximide, a known inhibitor of the ribosome translocation/release process mimicked some of the effects of wounding. We interpret the results to indicate that the initial effect of wounding is to inhibit translation by inhibiting the ribosome translocation/release process, whereas the subsequent recovery in protein synthesis is brought about partly by a recovery in ribosome translocation/release and partly by enhanced initiation. © 1986 The Japanese Society of Plant Physiologists.