Stimulation of Biosynthesis of Tobacco Mosaic Virus by Antimetabolites

Abstract

Tobacco leaf discs wcrc treated with different concentrations of actinomycin C, DL-parafluorphenylalanine, 8-azaguaninc, chloramphenicol and puromycin-dihydrochloride before, simultaneously and after inoculation with tobacco mosaic virus. The treatment with low concentrations of antimetabolite simultaneously with tobacco mosaic virus inoculation stimulated the tobacco mosiac virus biosynthesis up to ninefold, whereas higher concentrations caused a ten-to iooo-fold inhibition. The stimulatory effect of pretreatment suggests the presence of a factor or factors with antiviral propcrties present in plant tissue becoming activated upon virus infcction. The lack of an effect of treatment with antimetabolites ½ to 3o hr after inoculation indicates that activation of such factor(s) must occur within the first 3o rain. after infection of tobacco leaf cells with tobacco mosaic virus.

Action of Antimetabolites on the Biosynthesis of Tobacco necrosis virus in Locally‐infected Cells of Chenopodium amaranticolor1)

“…and Pur. is not surprising, since similar results were obtained for several other plant viruses: Bean pod mottle virus (BANCROFT andKEY 1964, LOCKHART andSEMANCIK 1969), Tobacco mosaic virus (PROZOROVSKAYA, BALANDIN and ToNGUR 1966, SANDER 1969, LOEBENSTEIN et al 1969), Cucumber mosaic virus (NACHMAN et al 1971), Potato virus X (REUNOVA, REUNOV and REIFMAN 1973) ect. Our findings that such antimetabolites are much more effective when applied close to the inoculation time, generally agree with the previous reports as well.…”

“…The pattern of AMD action with respect to time of application was similar for the higher antibiotic concentrations, but an inverse correlation between the increase in AMD concentration and the increase in virus replicaton was experienced ( Fig. 1), probably because high AMD concentration depressed the whole cell metabolism (SANDER 1969), partially impairing stimulation of viral replication. Chloramphenicol in the range of the concentrations used (10 to 250//g/ml) at any time of application stimulated SRNV biosynthesis even more than AMD.…”

“…Knowing that in animal cells an antiviral factor (interferon) prevents virus multiplication (ISAAC 1963, MARCUS andSALB 1966), and that its action is prevented by AMD and Pur. treatments (LEVINE 1964), SANDER (1969) hypothesized the presence of an antiviral factor(s), in order to explain the effect of the above mentioned antimetabolites on TMV biosynthesis.…”

“…To compare the results of all experiments of the same type, the number of lesions caused by antimetabolirc treated half-leaves or discs was divided by the number of lesions caused by non treated ones. The resulting quotient, called the efficiency index according to SANDER (1969), indicated stimulation when greater than 1 and inhibition when less than 1. In eadi experiment 10 efficiency indexes were calculated (one for each pair of inoculated opposite half-leaves).…”

Incorporation of Uridine‐H3 into Healthy and Tobacco Necrosis Virus‐infected Mesophyll Cells of Chenopodium amaranticolor1)

“…It is also known that AMD used in high doses could cause "side effects" in addition to the inhibition of DNA-dependent RNA synthesis (SEMAL 1967). In fact it has been experienced that the antibiotic could increase or decrease the synthesis of RNA viruses in plant cells (see review by SEMAL 1967, LOCKHART and SEMANCIK 1969, LOEBENSTEIN, SELA and VAN PRAAGH 1969, SANDER 1969.…”