EFFECT OF NATURAL EXTRACTS OF SOME PLANTS ON THE ANTIVIRAL ACTIVITY OF TOMATO MOSAIC TOBAMOVIRUS

Abstract

The antagonistic activities of the extracts of black seed (N. sativa) and Neem
leaves were determined against TMV using N. glutinosa and D. metel as local lesion
hosts. The isolate of is study was first confirmed as it reacted with Ch. quinoa by
appearing necrotic local lesion (NLL), forming amorphous inclusion bodies in the
cytoplasm of TMV-infected tissue stained with 0.5% methyl green pyronin-Y and
electron microscopy of partial purified particles. The molecular confirmation by RTPCR
confirmed the presence of coat protein gene of TMV. Data showed that the
applied extracts were varied in their antiviral activities via the dilutions used. As
interestingly, their crude extracts completely inhibited the inducing of NLL on the
tested plants. By dilution of the extracts up to 1/2, 1/4, 1/8 and 1/16, and 1/32, the
NLL appeared on the inoculated leaves. This could be due to the decreasing of the
antiviral substance(s), which excreted out from the plant cells and released into the
supernatants. The results paid an attention to the possibilities of extraction,
purification and identification of such substances. Furthermore, this work also
encourages the idea for the use of such active extracts as a bio-control agent for
controlling plant pathogens, i.e, viruses. As a conclusion, the viral replication could
be inhibited due to the inhibition of protein synthesis, inhibition of ribosomal frame
shift, induction of viral nucleic acid hydrolysis and induction of apoptosis in the
infected cells. These criteria are involved in the inhibition of the viral infection and
decrease the viral propagation in plant.