EFFECT OF RIBOSOME-INACTIVATING PROTEIN FROM CASTOR BEAN ON TOBACCO MOSAIC TOBAMOVIRUS

Abstract

Ribosome-inactivating proteins (RIPs) are homogenous family of plant proteins. It
is of special interest due to its unique activity. All RIPs possess a highly specific rRNA Nglycosidase
activity and capable of catalytically inactivating ribosome and so inhibit the
protein biosynthesis. The ricin, a RIP, was extracted and purified from castor bean (Ricinus
communis) seeds and its effect on tobacco mosaic virus (TMV) infectivity was studied. The
tobacco plant cells inoculated with ricin-TMV, under light microscope, a reduced number of
both of crystalline and amorphous inclusions induced by TMV was observed in the
cytoplasm of inoculated cells. Electron micrographs of inoculated leaves showed the
induction of apoptotic body formation in the ricin treated cells, which is the indication of
apoptosis.