Sensitivity of induced localized acquired resistance to actinomycin D

doi:10.1016/0042-6822(68)90235-3

Virology

Volume 34, Issue 2, February 1968, Pages 264-268

https://doi.org/10.1016/0042-6822(68)90235-3 Get rights and content

Abstract

Development of localized acquired resistance to tobacco mosaic virus (TMV) in Nicotiana tabacum L. var. Samsun NN and Phaseolus vulgaris L. var. Pinto was partially or completely inhibited in the presence of actinomycin D. In tobacco plants challenged 5 days after the inducing inoculation, acquired resistance was almost completely abolished when actinomycin D had been injected intercellularly 3 days before the challenge. When tobacco plants were challenged 6 days after the inducing inoculation, acquired resistance was partially inhibited by actinomycin D which had been injected 3 days before the challenge. However, no inhibition resulted when actinomycin D was injected close in time to the challenges, inoculated 5 or 6 days after the inducing inoculation. In Pinto bean plants acquired resistance was also significantly reduced in the presence of actinomycin D.

These results suggest that development of localized acquired resistance depends on the transcription mechanism of the cell from DNA to RNA, thereby producing a resistance-inducing substance. Sensitivity of acquired resistance to actinomycin D negates the hypothesis that acquired resistance is caused by drainage of metabolites.

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Cited by (13)

Influence of actinomycin D, ethephon, cycloheximide and chloramphenicol on the infection of a resistant and a susceptible cucumber cultivar with cucumber mosaic virus (price's no. 6 strain)
1978, Physiological Plant Pathology
While China-K cucumber plants are resistant to CMV, their response to TMV and TRSV is closer to that of Ashley, which is susceptible to CMV. Resistance of China-K to strain P6 of CMV could be partially overcome by actinomycin D, which restricts transcription, but not by ethephon (2-chloroethyl-phosphonic acid), which, while inducing senescence, did not restrict transcription. Inhibition of chloroplast ribosome function with chloramphenicol and cytoplasmic ribosomes with cycloheximide indicated that cytoplasmic ribosomes were essential for virus replication. Neither treatment promoted enhanced virus accumulation.
The results are consistent with the view that an induced compound, whose synthesis depends on transcription of host DNA but not translation on chloroplast ribosomes, assists in limiting virus multiplication. It was not possible to conclude whether or not expression of resistance required active cytoplasmic ribosomes. Attempts to demonstrate the presence of such a compound by more direct approaches are referred to.
Effects of viral protein, viral RNA, and some other polyelectrolytes on infection of tobacco protoplasts by TMV
1976, Virology
Tobacco cv. Samsun protoplasts were inoculated with TMV in the presence of different polyelectrolytes. Retention of [¹⁴C]TMV was determined by radioactivity of the protoplasts or by infectivity in homogenates of samples frozen immediately after inoculation and washing. Virus yield was determined by infectivity in protoplasts following incubation for 48 hr in light at 28°.
Infectious TMV, noninfectious TMV, and TMV protein (100 μg/ml) enhanced virus retention. However, the virus yield for the first substance was essentially lower. When the substances were added to the incubation medium, they decreased virus yield. Bovine serum albumin and casein hydrolysate did not appreciably affect retention; yet, they also decreased virus yield.
Virus RNA, whether infective or not, strongly suppressed the virus yield when present in the inoculation medium at a concentration of 1 μg/ml or more. This effect was independent of the presence of actinomycin D in the medium. Experiments with labeled TMV revealed the low virus yield to be the result of a reduction of virus retention in inoculum containing a mixture of TMV and TMV RNA. Similar effects on virus retention and yield were produced by total RNA of animal origin and by dextran sulfate. The authors assume that the three above-mentioned polyelectrolytes block virus adsorption on the plasmalemma by binding with a virus-polyornithine complex.
Peroxidase activity in leaves of Nicotiana tabacum var. Xanthi nc. before and after infection with tobacco mosaic virus
1976, Physiological Plant Pathology
The possible rôle of peroxidase in the hypersensitive reaction of Nicotiana tabacum var. Xanthi nc. to tobacco mosaic virus was investigated. A comparison was made between leaves of different ages as regards lesion size and peroxidase activity. Peroxidase activity was measured in the leaf tissue of three successive zones (1 mm each) around the lesions, in the tissue between the lesions, and in healthy plants. The existenxe of a gradient of enhanced peroxidase activity from the lesion edge to the tissue between the lesions was found. Peroxidase activity around lesions was positively correlated with lesion size; a negative correlation existed between peroxidase activity at inoculation and lesion size. Although the functioning of peroxidase in inducing resistance seems likely, the enzyme does not seem to be involved in the resistance mechanism itself.
The influence of actinomycin D on cucumber mosaic virus (strain W) multiplication in cucumber cultivars
1974, Physiological Plant Pathology
Actinomycin D was demonstrated, by its effect on the incorporation of [³H]uridine into acid-precipitable material, to curtail RNA synthesis in cucumber cotyledons.
Treatment of China cucumber plants, normally resistant to infection by cucumber mosaic virus (CMV), with actinomycin D allowed an enhanced accumulation of virus infectivity, measured 4 days after infection, compared to that in control plants, the maximum observed increase occurring following injection of an actinomycin solution containing 10 μg/ml 1 h after infection. No significant influence on infectivity in susceptible Ashley plants was observed.
While not ruling out alternative possibilities, the results are consistent with the hypothesis that the China cultivar responds to CMV infection with the synthesis of one or more antiviral compounds, a process restricted by actinomycin treatment. Although a different virus and cultivar were employed, these observations agree in principle with those reported by Nachman et al.
Increased multiplication of cucumber mosaic virus in a resistant cucumber cultivar caused by actinomycin D
1971, Physiological Plant Pathology
Multiplication of cucumber mosaic virus in the cotyledons of a resistant cucumber (Cucumis sativus L.) cultivar (Elem) increased in the presence of actinomycin D. Compared with water-injected controls, infectivity increased 3·5 to 5·8 times when cotyledons were injected with 5 μg actinomycin D/ml from 1 day before until 1 day after inoculation. The effect decreased the longer the interval between the inoculation and the application of the antibiotic and was negligible when the antibiotic was injected 3 to 4 days after inoculation.
The number of virions, observed with an electron microscope, in extracts of cotyledons injected with actinomycin D 6 h after inoculation, was also significantly higher than in control extracts. No difference in infectivity titre was obtained when actinomycin D was injected into the cotyledons of a susceptible cucumber variety. Sensitivity of the resistance mechanism to actinomycin D suggests that it depends on the transcription of cellular DNA to RNA, thereby producing a susbstance(s) that is responsible for the resistance, and that this mechanism is activated by the virus.
Polyacrylamide disc electrophoresis of the soluble leaf proteins from Nicotiana tabacum var. 'Samsun' and 'Samsun NN'. II. Changes in protein constitution after infection with tobacco mosaic virus
1970, Virology
Electrophoresis in 5, 7.5, and 10% acrylamide gels revealed that characteristic changes appear in the protein constitution of N. tabacum var. ‘Samsun,’ ‘Samsun NN,’ and N. glutinosa after infection with tobacco mosaic virus (TMV). Apart from significant quantitative changes, one new band was present in Samsun plants 4 weeks after infection. This band was characterized as TMV coat protein by coelectrophoresis and serology. A change in the electrophoretic mobility of the major band was recorded.
In Samsun NN plants four new bands (I–IV) were present 1 week after infection. These bands are not related to TMV coat protein and are not new isozymes of peroxidase, polyphenoloxidase, acid phosphatase, glucose-6-phosphate dehydrogenase, or 6-phosphogluconate dehydrogenase. The bands first appear at the onset of necrosis and increase in intensity with time. Five days after infection band I ceases to increase, whereas bands II, III, and IV increase up to day 14. From day 7 onward, the four bands are also present in the noninoculated, young developing leaves, where they further increase with time. The amount of the four new protein components was related to lesion density and was reduced by treatment of the leaves with actinomycin D 2 days after infection.
In N. glutinosa one new band was induced and two bands increased markedly after infection, while one had disappeared from the protein pattern. These changes relate to other protein components than those found in infected Samsun NN, but are also apparent in the noninoculated parts of the plants from day 7 after infection.
The possible relation of the new protein components to the phenomenon of systemic acquired resistance is discussed.

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Contribution from The National and University Institute of Agriculture, Rehovoth, Israel. 1967 Series, No. 1220-E.

This work was partially supported by grant FG-Is-187 from the U.S. Department of Agriculture under P.L. 480

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Sensitivity of induced localized acquired resistance to actinomycin D☆

Abstract

Progr. Nucleic Acid Res.

Virology

Virology

Biochem. Biophys. Res. Commun.

Advan. Virus Res.

The role of deoxyribonucleic acid in ribonucleic acid synthesis. III. The inhibition of the enzymatic synthesis of ribonucleic acid and deoxyribonucleic acid by actinomycin D and proflavin