Wounding of aged pea epicotyls enhances the reinitiating ability of isolated ribosomes

Abstract

Total ribosomes (monosomes plus polysomes) isolated from wounded pea epicotyls are more efficient at supporting protein synthesis in a wheat germ S30 system (containing wheat ribosomes) than are total ribosomes from aged (control) pea tissue. This increased efficiency is seen when enriched large polysomes, almost devoid of monosomes, are used to program a wheat germ S300 system, from which the wheat germ ribosomes have been removed. Reactions primed by enriched polysomes from wounded tissue, but not aged tissue, continue for at least 30 min, suggesting that reinitiation is occurring during the reaction, albeit in the initial absence of monosomes from wheat or pea. Wheat germ ribosomes, but not monosomes from either aged or wounded pea tissue, are able to translate pea poly(A) RNA and globin mRNA. Aurintricarboxylic acid reduces protein synthesis in a rather indiscriminate manner, whereas, pactamycin seems to have an inhibitory effect specific for initiation, and it is much more effective on wounded than on control tissue polysomes. We interpret these results to imply that polysomal ribosomes from wounded tissue are more efficient at initiation than are polysomal ribosomes from control tissue or than non-polysomal ribosomes (monosomes) from either tissue. © 1985 The Japanese Society of Plant Physiologists.