Plant Pathology Commons^™

Intermediates In The Biosynthesis Of Double-Stranded Ribonucleic Acids Of Bacteriophage Φ6, D. L. Coplin, James L. Van Etten, James A. Koski, A. K. Vidaver

Department of Plant Pathology: Faculty Publications

Pseudomonas phaseolicola infected with bacteriophage φ6 synthesized all three viral double-stranded RNA segments, three single-stranded RNAs, and three replicative intermediate-like RNAs in the presence of rifampin. The single-stranded RNA intermediates sedimented and electrophoresed along with melted viral double-stranded RNA, annealed with melted viral double-stranded RNA, and were transient in nature. The relative amounts of the single-stranded RNA intermediates varied during the infection cycle and were altered in the presence of chloramphenicol. The replicative intermediate-like RNAs sedimented faster than double-stranded RNA, failed to enter 2.5% polyacrylamide gels, eluted with double-stranded RNA from a CF-11 cellulose column, were precipitated with single-stranded RNA …

Influence Of Molecular Weights Of Bacteriophage Φ6 Double-Stranded Ribonucleic Acids On Interferon Induction, W.J. Kleinschmidt, James L. Van Etten, A. K. Vidaver

Department of Plant Pathology: Faculty Publications

The interferon-inducing capabilities of the three molecular segments of bacteriophage φ6 double-stranded ribonucleic acid increased with increasing molecular weight.

Purification And Characterization Of Syringacin 4-A, A Bacteriocin From Pseudomonas Syringae 4-A, William L. Haag, Anne K. Vidaver

Department of Plant Pathology: Faculty Publications

Syringacin 4-A, a bacteriocin produced by Pseudomonas syrinagae 4-A, was obtained by induction with ultraviolet irradiation or mitomycin C. Approximately 1,000-fold purification of the bacteriocin was achieved by manganous chloride precipitation, differential centrifugation, and chromatography on hydroxyapatite columns. The purified syngacin was homogeneous on hydroxyapatite columns and sucrose density gradients; it also sedimented as a single entity in the analytical ultracentrifuge. The buoyant density of purified syringacin in cesium chloride was 1.294 g/ml. The sedimentation coefficient was calculated as 120S, and the diffusion coefficient was 6.49 x 10^-8 cm²/s. The molecular weight was calculated as …

Base Composition And Hybridization Studies Of The Three Double-Stranded Rna Segments Of Bacteriophage Φ6, James L. Van Etten, A. K. Vidaver, R. K. Koski, J. P. Burnett

Department of Plant Pathology: Faculty Publications

The three double-stranded ribonucleic acid (dsRNA) segments of the bacteriophage φ6 were isolated and shown to have similar melting temperatures and base compositions. RNA: RNA hybridization experiments with the isolated segments eliminate the possibility that the two smaller dsRNA segments arise from a cleavage of the large dsRNA segment. The two smaller RNA segments reanneal rapidly even at low temperatures; in contrast, the large dsRNA reannealed only at higher temperatures. Evidence is also presented which suggests that the dsRNAs may contain a short single-stranded RNA tail.

Physiological And Morphological Correlation Of Rhizopus Stolonifer Spore Germination, James L. Van Etten, Lee Bulla Jr., Grant St. Julian

Department of Plant Pathology: Faculty Publications

Sporangiospores of Rhizopus stolonifer were examined at various stages of germination by scanning electron and phase-contrast microscopy. These observations were correlated with changes in spore dry weight, spore volume, respiration, and syntheses of ribonucleic acid, deoxyribonucleic acid, and protein during germination.

Corynebacterium Nebraskense, A New, Orange-Pigmented Phytopathogenic Species, Anne K. Vidaver, Manley Mandel

Department of Plant Pathology: Faculty Publications

A new species of Corynebacterium isolated from field corn is described. The isolates form a homogeneous group that is recognized as a new species, Corynebacterium nebraskense. The organism is characterized by orange-pig-mented colonies, inability to grow on 0.005% triphenyltetrazolium chloride agar, specific bacteriophage sensitivity, and a guanine plus cytosine content of 73.5 mol%. These and other characters differentiate this organism from other described phytopathogenic corynebacteria. The type strain of C. nebraskense is Fur-1 (= ATCC 27822 = NCPPB 2578).

Survival Mechanisms Of Phytopathogenic Bacteria, M. L. Schuster, D. P. Coyne

Department of Plant Pathology: Faculty Publications

Natural habitats usually do not provide bacteria the continuity of agricultural crops. With continuous culture. perpetuation of pathogen is no problem. Although agricul­ tural practices provide some discontinuity between crops. it is less than that in nature. Uniformity of crop germ plasm also favors inoculum buildup and perhaps perpetuation of the pathogens.

Rna Polymerase Activity Associated With Bacteriophage Φ6, James L. Van Etten, A. K. Vidaver, R. K. Koski, J. S. Semancik

Department of Plant Pathology: Faculty Publications

The Pseudomonas phaseolicola bacteriophage φ6 incorporated labeled UTP into an acid-insoluble precipitate. Incorporation was dependent on the presence of manganese acetate, ATP, GTP, CTP, and a short heat treatment of the phage; the reaction was stimulated by NH,Cl. The substitution of ¹⁴C-ATP, -CTP or -GTP for UTP, together with the appropriate unlabeled ribonucleoside triphosphates, disclosed that CMP was incorporated to the greatest extent followed by GMP, UMP, and AMP. Radioactive RNAs formed by the reaction were resistant to RNases A and T₁ in high salt but susceptible to these nucleases in low salt. The labeled RNA co-sedimented and …

Characteristics Of Deoxyribonucleic Acid Polymerase Isolated From Spores Of Rhizopus Stolonifer , Cheng-Shung Gong, Larry Dunkle, James L. Van Etten

Department of Plant Pathology: Faculty Publications

Deoxyribonucleic acid (DNA)-dependent DNA polymerase was purified several hundredfold from germinated and ungerminated spores of the fungus Rhizopus stolonifer. The partially purified enzymes from both spore stages exhibited identical characteristics; incorporation of [³H] deoxythymidine monophosphate into DNA required Mg²⁺, DNA, a reducing agent, and the simultaneous presence of deoxyguanosine triphosphate, deoxycytidine triphosphate, and deoxyadenosine triphosphate. Heat-denatured and activated DNAs were better templates than were native DNAs. The buoyant density of the radioactive product of the reaction was similar to that of the template DNA. The enzyme is probably composed of a single polypeptide chain with …

Bacteriophage Φ6: A Lipid-Containing Virus Of Pseudomonas Phaseolicola, Anne K. Vidaver, R. K. Koski, James L. Van Etten

Department of Plant Pathology: Faculty Publications

The purification and properties of a lipid-containing bacteriophage, φ 6, are described. The phage contains a lipid envelope which is probably essential for infection. Infectivity of φ 6 was lost in the presence of organic solvents, sodium deoxycholate, and phospholipase A. The fatty acid composition of the phage lipid was similar to that of the Pseudomonas phaseolicola host cells. The phage was composed of about 25% lipid, 13% RNA, and 62% protein. The buoyant density of φ6 was 1.27 g/ml in cesium chloride. The morphology of φ6 was unusual; it had a polyhedral head of about 60 nm surrounded by …

Protein Synthesis During Fungal Spore Germination: Differential Protein Synthesis During Germination Of Botryodiplodia Theobromae Spores, James L. Van Etten, Henry Roker, Eric Davies

Department of Plant Pathology: Faculty Publications

The preformed messenger ribonucleic acid in Botryodiplodia theobromae spores directs the synthesis of several relatively stable polypeptides.

Preparation Of Biologically Active Ribosomal Subunits From Fungal Spores, James L. Van Etten

Department of Plant Pathology: Faculty Publications

Ribosomal subunits were prepared from fungal spore ribosomes and reassociated to yield biologically active ribosomes.

Systematic Infections For The Assay Of Plant Viruses, Myron K. Brakke

Department of Plant Pathology: Faculty Publications

The first infectivity assays of plant viruses relied on the percentage of inoculated plants becoming systemically infected. The use of systemic infections for assays became unfashionable, however, after the discovery of local lesions and the demonstration that their numbers depended on virus concentration. Continued emphasis on local lesions over the years led to the widely held belief that systemic infections could not be used for a reliable and accurate assay of plant viruses. There was never any good statistical evidence for this viewpoint. In fact, no thorough investigation has been published of the accuracy of "systemic assays" of plant viruses, …

Protein Synthesis During Fungal Spore Germination. Iv. Transfer Ribonucleic Acid From Germinated And Ungerminated Spores, James L. Van Etten, R. Kent Koski, Mahmoud El-Olemy

Department of Plant Pathology: Faculty Publications

Transfer ribonucleic acid (tRNA) fractions isolated from germinated and ungerminated spores of Botryodiplodia theobromae and Rhizopus stolonifer had acceptor activity for all 20 amino acids commonly found in protein, when tested with an enzyme fraction from germinated spores. Accordingly, it is unlikely that the absence of tRNA for a particular amino acid limits protein synthesis in fungal spores.

Characterization Of Xanthomonas Phaseoli Bacteriophages, Anne K. Vidaver, Max L. Schuster

Department of Plant Pathology: Faculty Publications

Ten bacteriophages for Xanthomonas phaseoli were characterized. On the basis of adsorption rates, latent period and burst size, plaque morphology, host range, efficiency of plating, ultrastructure, sensitivity to osmotic shock, streptomycin sensitivity, temperature effects on plating efficiency, and serology, the phages were separated into at least three groups. Some of the phages were infectious for Pseudomonas phaseolicola (four strains) and P. syringae (one strain) in a narrow temperature range. The taxonomic and ecological significance of this finding is discussed.

Protein Synthesis During Fungal Spore Germination Ii. Aminoacyl-Soluble Ribonucleic Acid Synthetase Activities During Germination Of Botryodiplodia Theobromae Spores, James L. Van Etten, Robert Brambl

Department of Plant Pathology: Faculty Publications

The specific activities of 13 aminoacyl-soluble ribonucleic acid (sRNA) synthetases were measured at various time intervals during the germination of Botryodiplodia theobromae conidiospores. The enzyme activities were low or absent in ungerminated spores, and they increased rapidly as germination proceeded. When extracts of the ungerminated spores were prepared with mortar and pestle, very little or no enzyme activity was detected. When the extracts were prepared with a mechanical homogenizer, however, they exhibited some enzyme activity, although less than did the extracts from germinated spores. Enzyme activities from germinated spores were approximately the same, regardless of the method of preparation. The …

Synthetic And Complex Media For The Rapid Detection Of Fluorescence Of Phytopathogenic Pseudomonads: Effect Of The Carbon Source, Anne K. Vidaver

Department of Plant Pathology: Faculty Publications

Fluorescence is of diagnostic value for differentiating among species of aerobic pseudomonads (R. Y. Stanier, N. J. Palleroni, and M. Doudoroff, J. Gen. Microbiol. 43:159, 1966). The standard medium for detecting fluorescence is Medium B (E. 0. King, M. K. Ward, and D. E. Raney, J. Lab. Clin. Med. 44:301, 1954), which supports fluorescent pigment production of most pseudomonads tested (0. Jessen, Pseudomonas aeruginosa and other green fluorescent pseudomonads, A taxonomic study, Munksgaard, Copenhagen, 1965; R. Y. Stanier et al., J. Gen. Microbiol. 43:159, 1966). Minerals (J. V. King, J. J. R. Campbell, and B. A. Eagles, Can. J. …

Changes In Fungi With Age I. Chemical Composition Of Rhizoctonia Solani And Sclerotium Bataticola , David Gottlieb, James L. Van Etten

Department of Plant Pathology: Faculty Publications

The chemical composition of the mycelium of Rhizoctonia solani and Sclerotium bataticola was determined in cells of various ages. The percentage, per unit of dry weight, of soluble amino nitrogen, deoxyribonucleic acid (DNA), ribonucleic acid (RNA), ergosterol, and protein decreased with age in both fungi. Total lipids and fatty acids increased with age in S. bataticola but remained constant in R. solani. Total carbohydrate increased with age in R. solani and decreased in S. bataticola. Fewer changes with age were observed when the results were calculated in ratio to DNA. There was no change in the ratios of protein, …

Changes In Fungi With Age Ii. Respiration And Respiratory Enzymes Of Rhizoctonia Solani And Sclerotium Bataticola, James L. Van Etten, H. Peter Molitoris, David Gottlieb

Department of Plant Pathology: Faculty Publications

The rate of respiration of Rhizoctonia solani and Sclerotium bataticola decreased with age. This decrease in respiratory rate might be produced by a decrease in the specific activity of one or more enzymes involved in carbohydrate metabolism. Specific activities in cell-free extracts were measured for most of the enzymes in the hexose monophosphate shunt, Embden-Meyerhof-Parnas pathway, tricarboxylic acid cycle, and terminal electron-transport system. In addition, glucose oxidase, isocitritase, and malic enzyme were measured. In R. solani, increases in activity with age occurred for hexokinase, α-glycerolphosphate dehydrogenase, malic dehydrogenase, and cytochrome oxidase. Decreases occurred for phosphohexokinase, aconitase, nicotinamide adenine dinucleotide-specific …

Biochemical Changes During The Growth Of Fungi: Ii. Ergosterol And Fatty Acids In Penicillium Atrovenetum, David Gottlieb, James L. Van Etten

Department of Plant Pathology: Faculty Publications

Changes in the lipid constituents of Penicillium atrovenetum were studied during the growth and development of this fungus. The stages in development, as measured by the dry weight, were divided into four phases: lag, log, stationary, and death. The total fatty acids on a dry-weight basis increased from a minimum in the spores to a maximum near the end of the log phase of growth. The major fatty acids were palmitic, stearic, oleic, and linoleic. Myristic, pentadecanoic, palmitoleic, heptadecanoic, linolenic, arachidic, and heptadecenoic acids, together with two unidentified components, were also present in the fatty acid fraction. Compared to ungerminated …

Density-Gradient Centrifugation: Non-Ideal Sedimentation And The Interaction Of Major And Minor Components, Myron K. Brakke, J. M. Daly

Department of Plant Pathology: Faculty Publications

A small amount of southern bean mosaic virus was contained in a narrow zone after density-gradient centrifugation, but in a much wider zone after centrifugation with a large amount of a second virus. Zone-spreading of a major component by non-ideal sedimentation in density-gradient centrifugation can cause zone spreading of a minor component that the major component overlaps.

Biochemical Changes During The Growth Of Fungi: I. Nitrogen Compounds And Carbohydrate Changes In Penicillium Atrovenetum, David Gottlieb, James L. Van Etten

Department of Plant Pathology: Faculty Publications

Changes in the biochemical constituents of cells were studied during the growth and development of Penicillium atrovenetum. Growth of the fungus, as measured by the dry weight, could be divided into four phases: lag, log, stationary, and death. The percentages of total nitrogen, cold trichloroacetic acid-soluble nitrogen, ribonucleic acid (RNA), and protein increased to a maximum during the lag phase, and subsequently decreased as the fungus aged. The percentage of deoxyribonucleic acid (DNA) was always slightly higher in the spores than in the mycelium. The DNA in the mycelium decreased in the lag phase, and then increased slightly to …

Hyperparasitism, Michael G. Boosalis

Department of Plant Pathology: Faculty Publications

Much of the research on hyperparasitism has been of a descriptive nature, based primarily on studies with dual cultures in synthetic media. The main contributions from these investigations concern the host range of the parasite, the mode of penetration and infection, and the morphological changes of the host and the parasite resulting from parasitism.

More recent studies on hyperparasitism emphasize the effect of environmental factors, especially nutrition, on the susceptibility of the host. Research on the physiology of hyperparasitism has been limited. Nevertheless, this important aspect of the problem should continue to receive increased attention as hyperparasitism is extremely amenable …

Secretion Of Amylase By Rumex Virus Tumors In Vitro, L. G. Nickell, M. K. Brakke

Department of Plant Pathology: Faculty Publications

The secretion of extracellular enzymes by intact cells of higher plants apparently is a rare occurrence. One example of it is the secretion of an extra, cellular amylase by the tissue of a virus-induced tumor from the root of Rumex wetosa L. An amylase is secreted in sufficient quantities by this tissue to enable it to grow as well in vitro on a starch-containing medium as on one containing sucrose.

Lack Of Effect Of Plant Growth-Regulators On The Action Of Alpha-Amylase Secreted By Virus Tumor Tissue, M. K. Brakke, L. G. Nickell

Department of Plant Pathology: Faculty Publications

This report deals with the effect of certain synthetic plant growth-regulators on the activity of alpha-amylase (1) secreted by virus tumor tissue grown in vitro. Previous studies have lacked adequately controlled conditions and have been carried out with enzyme preparations obtained through the usual methods of destruction of cells. In this particular study (a) the assay employed to measure enzyme activity includes control of pH and temperature and (b) this enzyme, being secreted, is not subject to the drastic preparative procedures involving destruction of cellular structure usually necessary to obtain enzymes.

The Sedimentation Rate Of Potato Yellow-Dwarf Virus, M. K. Brakke, L. M. Black, Ralph W. G. Wyckoff

Department of Plant Pathology: Faculty Publications

BLACK et al. (1948) have published electron micrographs of bodies believed to represent the New York variety of potato yellow-dwarf virus (Aureogenus vastans (H) Black) (Holmes 1948). The photographs showed bodies in several different extracts of infected plants of Nicotiana rustica L., but not in corresponding preparations from healthy plants. Similar bodies were found in concentrates from plants infected with the New Jersey variety of the virus (var. agalliae Black). These bodies were larger than, and of a different character from, those of plant viruses hitherto examined in the electron microscope. The present study was undertaken to obtain evidence …

Mechanical Transmission Of A Plant Tumor Virus To An Insect Vector, Karl Maramorosch, Myron K. Brakke, L. M. Black

Department of Plant Pathology: Faculty Publications

Most plant viruses transmitted by leafhoppers have not been demonstrated to be infective in extracts. The virus dealt with in this paper causes tumors in certain susceptible plants, is carried by leafhoppers, and like others in that group has proven difficult to detect in extracts. It is our purpose to recount briefly the variety of methods that failed to transmit the virus and to report on the success of insect-to-insect transmission by injection.

Controlling The Ph Of Cultures Of Penicillium Notatum Through Its Carbon And Nitrogen Nutrition, Albert E. Dimond, George L. Peltier

Department of Plant Pathology: Faculty Publications

A survey of published material reveals relatively little information concerning the nutritional physiology of Penicillium notatum Westl. on synthetic media. Metabolism studies of P. notatum on various media have appeared to be incidental to the more pressing problem of producing penicillin quickly and in quantity. Fleming (1929) originally used a nutrient broth non-synthetic in nature. The Oxford group (Abraham et al., 1941) then adopted a modification of the so-called Czapek-Dox synthetic medium which supplies nitrogen as sodium nitrate and glucose as carbohydrate. Hobby, Meyer, and Chaffee (1942) suggested that brown sugar be substituted for glucose in this nutrient, with …

A Research Delusion, George L. Peltier

Department of Plant Pathology: Faculty Publications

With the administrative heads of many of our educational institutions demanding a doctorate of every member of the permanent staff, as it is supposed to be a prerogative for research, and the issuing of a list of titles published each year by their staff, the urge for so-called research, namely, a list of titles, goes madly on. In fact publication sometimes becomes a sort of self-defense, for the absence of any titles over a brief period of years stamps one either as lacking the ability of doing research or inefficient. Likewise, such a policy has permeated the staff, so that …

A Consideration Of The Physiology And Life History Of A Parasitic Botrytis On Pepper And Lettuce, George L. Peltier

Department of Plant Pathology: Faculty Publications

During the autumn of 1911, while gathering the peppers (Capsicum) in the vegetable plat of the Missouri Botanical Garden, the writer observed a fungus which was appearing as a parasite on the fruits. The peduncles were covered with a dark brown mass of conidia and mycelium, which so weakened the tissues that the fruit soon fell to the ground. On opening the peppers a number of large, flat, crust-like sclerotia, 1 cm. long and .5 cm. wide, were found to fill the interior. In most cases the seeds were also covered with the crust-like masses. The conidial stage …