The Inhibition Of Small Molecular Weight Substances Extracted From Plants On TMV Or On Four Plant Pathological Fungi

The inhibiting effect of the ethanol extractive of the 38 species of plants on tobacco mosaic virus (TMV) in vitro was determined separately. Infectivity of TMV in Nicotiana glutinosa was strongly inhibited (more than 80%) by concentration at 0.05 g-mL"1 of the ethanol extractives of 18 species plants. The ethanol extractives of the 18 species of plants have been extracted by water and chloroform. The water phase showed strong anti-TMV activity while chloroform phase showed little inhibiting activity in most plant species. The two phase ofPolygonum cuspidatum or chloroform phase of Paeonia suffruticoss showed strong anti-TMV activity. The inhibition and inhibiting mechanisms of tannins, paeonol, emodin and anthraquinones on TMV in vitro have been studied.The water phase of 11 species of plant has lost most inhibiting ffect by discarding tannins using gelatin. It showed that tannins might play roles in reducing infectivity. The anti-TMV activities of tannins extracted from the 11 species of plants on TMV in different concentration or in different time incubated with TMV were determined separately. The results have showed that tannins have strong inhibition on TMV in low concentration incubated immediately with TMV. The tannins did not inhibited multiplication of TMV in infected leaf discs. The infectivity of TMV recovered by dialysis from incubation in vitro with tannins. The results show that the virus regained infectivity, and the tannins did not direct viricidal effect. Tannins extracted from Polygonum perfoliatum or Archontophoenix alexandrae seeds showed strongly anti-TMV activities separately. TMV virions seems to be aggregated when TMV incubated with the tannins by electron microscope. It seems that TMV coat protein (CP) bind to the tannins based on PAGE. Tannins did. not reduce infectivity when applied either before or after TMV inoculation. It is proposed that tannins extracted from the 11 species inhibited TMV by binding with TMV coat protein to interfere with recognition site essential for viral coat protein. Tannins extracted from Euphorbia hirta, P. perfoliatum , P.cuspidatum reduce infectivity when applied immediately in N. glutinosa before TMV inoculation. It also retarded symptoms expressed later in first leaves of N. tobacum cv Ks26 when applied immediately before TMV inoculation.The paeonol extracted from Paeonia suflruticoss can inhibit TMV infectivity, Infectivity of TMV in N. glutinosa was strongly inhibited (more than 80%) by concentration at 0.6 mg-mL"1 of paeonol incubated with TMV 10 min in vitro. The paeonol inhibited multiplication of TMV in infected leaf discs. The morphology of virions seems to not be change after incubated with the paeonol by electron microscope. The regained infectivity of TMV recovered by dialysis from incubation with paeonol in vitro showed that the paeonol have not direct viricidal effect. The paeonol did not reduce infectivity when applied before TMV inoculation. The paeonol in low concentration can restrain the polymerization of TMV coat protein in vitro. The paeonol did not reduced infectivity of TMV-RNA in vitro. It is proposed that the paeonol inhibited TMV by binding with TMV coat protein to interfere with recognition of a host receptor essential for infection or by interfering TMV-CP polymerization in plants.The anti-TMV activity of low molecular weight chemicals extracted from Polygonum cuspidatum were determined. The emodin and anthraquinones can inhibit infectivity of TMV in vitro. The morphology of TMV seems to not be changed after incubated with emodin and anthraquinone glycosides. The emodin did not inhibited multiplication of TMV in infected leaf discs or infectivity of TMV-RNA in vitro. The infectivity of TMV recovered by dialysis from incubations with emodin in vitro has regained showed that the emodin did not direct viricidal effect. The emodin did not reduce infectivity of TMV when applied before TMV inoculation. It is proposed that the emodin inhibited TMV by binding to TMV virions to interfere with recognition of a host, recepto...