Life Sciences Commons^™

Effect Of Wheat Streak Mosaic Virus Infection On Total Dna And Chloroplast Ribosomal Rna In Wheat Leaves, Myron K. Brakke, J. L. White, R. G. Samson, J. Joshi

Department of Plant Pathology: Faculty Publications

The amount of chloroplast 23s rRNA relative to either DNA or to cytoplasmic 28s rRNA was reduced in young wheat leaves infected with wheat streak mosaic virus.
ChlorophyiJ was reduced in infected leaves. Fresh weight per leaf and DNA content per leaf were reduced in infected leaves, but DNA per g was increased.
Cytoplasmic ribosomal RN.A appeared to degrade more slowly during senescence in infected leaves than in uninfected. Virus was undetectable by density gradient centrifugation in systemicaliy infected leaves less than 6 cm long and reached its highest concentration when young leaves reached their maximum size. Mosaic developed in …

Chlorophyll, Chloroplast Ribosomal Rna, And Dna Are Reduced By Rarley Stripe Mosaic Virus Systemic Infection, Myron K. Brakke, J. L. White, R. G. Samson, Jay Joshi

Department of Plant Pathology: Faculty Publications

Barley stripe mosaic virus became systemic 3 days alter inoculation of barley plants in the two-leaf stage. The first leaf to show mosaic was leaf 3. which was 4.5 cm long at 3 days after inoculation when it was invaded by virus. Since all of Ieaf 3 showed mosaic, the events leading to mosaic occurred during cell expansion and after cell division. which is limited to the basal centimeter of young cereal leaves. Molecular changes associated with mosaic formation included a 509, reduction in chloroplast ribosomal RNA and chlorophyll, expressed as amount per unit DNA, in young leaves with an …

Comparisons Of Mitochondrial Dna From The Sibling Species Heterodera Glycines And H. Schachtii, A. D. Radice, Thomas O. Powers, Laurie J. Sandall, R. D. Riggs

Department of Plant Pathology: Faculty Publications

Restriction fragment patterns of mitochondrial DNA from sibling species of cyst nematodes Heterodera glycines and H. schachtii were examined. Fourteen restriction endonucleases recognizing four, five, and six base-pair sequences yielded a total of 90 scorable fragments of which 10% were shared by both species. Mitochondrial genome sizes for H. glycines and H. schachtii were estimated to be 22.5-23.5 kb and 23.0 kb, respectively. A single wild type mitochondrial genome was identified in all populations of H. glycines examined, although other mitochondrial genomes were present in some populations. The H. schachtii genome exhibited 57 scorable fragments, compared with 33 identified in …

Estimation Of Genetic Divergence In Meloidogyne Mitochondrial Dna, Thomas O. Powers, Laurie J. Sandall

Department of Plant Pathology: Faculty Publications

Restriction fragments from purified mitochondrial DNA can be readily detected following rapid end-labeling with [α-³²P] nucleoside triphosphates and separation by gel electropboresis. Mitochondrial DNA from 12 populations of Meloidogyne species was digested with 12 restriction enzymes producing more than 60 restriction fragments for each species. The mitochondrial genome of M. arenaria is the most genetically distinct of the four species compared. M. arenaria shows approximately 2.1-3.1% nucleotide sequence divergence from the mitochondrial genomes of M. javanica, M. incognita, and M. hapla. Among the latter three species, interspecific estimates of sequence divergence range from 0.7 to …

Diseases Of Native Flowers, Peter Mcr Wood

Journal of the Department of Agriculture, Western Australia, Series 4

The native flora of Australia has evolved in such a way as to render it resistant to many of the fungi and bacteria that commonly infect exotic cultivated flower crops. Many of our native plants have tough sclerophyllous foliage which makes it difficult for pathogenic organisms to gain access, particularly in their natural undisturbed habitats. Root tissue of these plants also tends to be woodier than that of exotic plants, thus making it less accessible as a food source for common rootattacking fungi such as Rhizoctonia and Pythium.

Effects Of Planting Date On Development Of Net Blotch Epidemics In Winter Barley In Pennsylvania, Leslie M. Delserone, H. Cole Jr.

University of Nebraska-Lincoln Libraries: Faculty Publications

The influence of planting date on fall and spring net blotch epidemics (caused by Pyrenophora teres) was evaluated with the winter barley cultivar Pennrad. Experiments were conducted in Centre County, Pennsylvania, in 1982 and 1983 and in Lancaster County, Pennsylvania, in 1983. The three planting dates evaluated corresponded to the recommended date as well as dates I wk earlier and later than recommended for each specific location. Planting date had a significant influence on fall net blotch epidemics, with the greatest and least disease severities observed in the earliest and latest plantings, respectively. When spring environmental conditions were warm …

Gray Mold Of Strawberry, John R. Hartman, Donald E. Hershman

Agriculture and Natural Resources Publications

Several fungi can cause developing and ripe strawberries to rot. In Kentucky the most common and economically important of these diseases is gray mold, caused by the fungus Botrytis cinerea. Also called Botrytis rot or ash mold, it is an ever-present threat to strawberries both in the field and after harvest. It can be particularly devastating because the disease strikes after investments in the crop have been made, but before returns have been fully realized.

Concentration Of Maize Chlorotic Mottle Virus Increased In Mixed Infections With Maize Dwarf Mosaic Virus, Strain B, Karen-Beth Goldberg, Myron K. Brakke

Department of Plant Pathology: Faculty Publications

The concentration of maize chlorotic mottle virus (MCMV) was up to 5.4 times higher in plants infected with both MCMV and maize dwarf mosaic virus. strain R (MDMV-BE. rhan in plants infected with MCMY only. The concentration of MDMV-B was the same in doubly and singly infected plants. Plants infected with both viruses had a reduced level of chlorophyIl and a lower than normal ratio of chloroplast to cytoplasmic rRNA. Purified MCMV had an extinction coefficient of 6.7 cm² mg^-1 at 260 nm, an absorption maximum at 258 nm, minimum at 240 nm, and 25% RNA.

Virus Disease Of Small Fruits, R. H. Converse

School of Biological Sciences: Faculty Publications

This illustrated handbook was compiled by international authorities on virus and viruslike diseases of small fruits. Crops covered are in the plant genera Fragaria (strawberry), Vaccinium (blueberry and cranberry), Ribes (currant and gooseberry), and Rubus (blackberry and raspberry). The history, geographic distribution, importance, symptoms, transmission, cause, detection, and control of virus and viruslike diseases attacking these crops are discussed.

Wheat Streak Mosaic Virus Cylindrical Inclusion Body Protein, M. K. Brakke, E. M. Ball, Y. H. Hsu, W. G. Langenberg

Department of Plant Pathology: Faculty Publications

A protein of apparent molecular weight 66000 was purified from wheat plants infected with wheat streak mosaic virus. Antiserum to this protein, labelled with gold, specifically stained cylindrical inclusions in ultrathin sections of virus-infected cells. Antiserum to the M_r 66000 protein did not react with capsid protein in Western blots, nor did antiserum to capsid protein react with the M_r 66000 protein. Both antiserum reacted with homologous antigens. The concentration of the M_r 66000 protein in extracts from infected leaves was about 100 µg per g of leaves, which is higher than the usual concentration of virions.

Potato Cyst Nematode, J M. Stanton

Journal of the Department of Agriculture, Western Australia, Series 4

For many years, Australia has been the only large land mass in the world in which potato cyst nematode has not been found. However, in 1986, potato cyst nematode was found on four properties at Munster 10km south of Perth, Western Australia.

Potato cyst nematode is a minute worm like organism which attacks the roots of several plant species including potatos, causing very high yield losses. It is a very serious pest of potatoes throughout the world and strict quarantine controls are enforced in countries and potato-growing areas froo of nematode.

Infection Rate Of Tall Fescue With Acremonium Coenephialum, B. J. Hankins, Terry Kirkpatrick

Journal of the Arkansas Academy of Science

No abstract provided.

Root Disease Of Cereals, G C. Macnish, Chang Sha Fang, Karen Mcroberts

Experimental Summaries - Plant Research

Effects of nitrogen source on take-all, 82N34, 77E4. Take-all, cultivar, fertilizer, fungicide interactions, 87MT47, 87MT48, 87MT49. Take –all decline, 86MT7. Rhizoctonia root rot. Rhizoctonia patch and soil compaction, 87E28. Rhizoctonia patch and short chemical fallow, 87E3, 87E38. Rhizoctonia strains and paddock history, 87E31. Rhizoctonia root rot - host effects on strains, 87BA4, 86E30. Fusarium crown rot. Fusarium crown rot and cultivars, 87ME2, 87ME4, 87ME3 ( abandoned ).

The Pollen Exostructure Of Striga (Scrophulariaceae), Mark A. Deleonardis

Biological Sciences Theses & Dissertations

In this survey, the pollen exostructure of 13 Striga species was examined using light microscopy and scanning electron microscopy. Two of the 13 species were also observed by transmission electron microscopy to assess major differences in exine composition. Striga pollen is consistently spherical to oblate, isopolar, tectate, and three or four colpate. Sculpturing may be psilate, psilate-perforate, finely rugulate, or coarsely rugulate. The equatorial width of the species surveyed ranged from 15 to 30 micrometers. It is concluded that variation in Striga pollen sculpturing, aperture structure, and size support the current taxonomy of the genus.

Differential Effects Of Lithium Chloride On In Vitro Growth Of Clavibacter Michiganense Subsp. Nebraskense Depending Upon Inoculum Source, Mary L. Smidt, Anne K. Vidaver

Department of Plant Pathology: Faculty Publications

The bacterium Clavibacter michiganense subsp. nebraskense (Corynebacterium michiganense subsp. nebraskense) was grown in broth cultures and inoculated into corn plants. The plating efficiency of cells from broth cultures was essentially the same on nutrient broth-yeast extract and the semiselective medium for this bacterium, CNS. However, when cells were isolated from Goss bacterial wilt- and blight-infected corn, very few were recovered on CNS compared with the amount recovered on nutrient broth-yeast extract agar. When lithium chloride was omitted from the CNS, recoveries from infected corn were nearly the same as on nutrient broth-yeast extract agar. No other ingredient of CNS …

Differential Effects Of Lithium Chloride On In Vitro Growth Of Clavibacter Michiganense Subsp. Nebraskense Depending Upon Inoculum Source, Mary L. Smidt, Anne K. Vidaver

Department of Plant Pathology: Faculty Publications

The bacterium Clavibacter michiganense subsp. nebraskense (Corynebacterium michiganense subsp. nebraskense) was grown in broth cultures and inoculated into corn plants. The plating efficiency of cells from broth cultures was essentially the same on nutrient broth-yeast extract and the semiselective medium for this bacterium, CNS. However, when cells were isolated from Goss bacterial wilt- and blight-infected corn, very few were recovered on CNS compared with the amount recovered on nutrient broth-yeast extract agar. When lithium chloride was omitted from the CNS, recoveries from infected corn were nearly the same as on nutrient broth-yeast extract agar. No other ingredient of …

Restriction Endonuclease Activity Induced By Pbcv-1 Virus Infection Of A Chlorella-Like Green Alga, Yuannan Xia, Dwight Burbank, Lothar Uher

Department of Plant Pathology: Faculty Publications

An enzyme was isolated from a eucaryotic, Chlorella-like green alga infected with the virus PBCV-1 which exhibits type I1 restriction endonuclease activity. The enzyme recognized the sequence GATC and cleaved DNA 5' to the G. Methylation of deoxyadenosine in the GATC sequence inhibited enzyme activity. In vitro the enzyme cleaved host Chlorella nuclear DNA but not viral DNA because host DNA contains GATC and PBCV-1 DNA contains GmATC sequences. PBCV-1 DNA is probably methylated in vivo by the PBCV-1-induced methyltransferase described elsewhere (Y. Xia and J. L. Van Etten, Mol. Cell. Biol. 6:144-1445). Restriction endonuclease activity was first detected …

Dna Methyltransferase Induced By Pbcv-1 Virus Infection Of A Chlorella-Like Green Alga, Yuannan Xia, James L. Van Etten

Department of Plant Pathology: Faculty Publications

A DNA methyltransferase was isolated from a eucaryotic, Chlorella-like green alga infected with the virus PBCV-1. The enzyme recognized the sequence GATC and methylated deoxyadenosine solely in GATC sequences. Host DNA, which contains GATC sequences, but not PBCV-1 DNA, which contains GmATC sequences, was a good substrate for the enzyme in vitro. The DNA methyltransferase activity was first detected about 1 h after viral infection; PBCV-1 DNA synthesis and host DNA degradation also began at about this time. The appearance of the DNA methyltransferase activity required de novo protein synthesis, and the enzyme was probably virus encoded. Methylation of …

Restriction Endonuclease Activity Induced By Pbcv-1 Virus Infection Of A Chlorella-Like Green Alga, Yuannan Xia, Dwight Burbank, Lothar Uher, Dietrmar Rabussay, James L. Van Etten

Department of Plant Pathology: Faculty Publications

An enzyme was isolated from a eucaryotic, Chlorella-lie green alga infected with the virus PBCV-1 which exhibits type II restriction endonuclease activity. The enzyme recognized the sequence GATC and cleaved DNA 5' to the G. Methylation of deoxyadenosine in the GATC sequence inhibited enzyme activity. In vitro the enzyme cleaved host Chlorella nuclear DNA but not viral DNA because host DNA contains GATC and PBCV-1 DNA contains G^mATC sequences. PBCV-1 DNA is probably methylated in vivo by the PBCV-1-induced methyltransferase described elsewhere (Y. Xia and J. L. Van Etten, Mol. Cell. Biol. 6:1440-1445). Restriction endonuclease activity was …

Black Root Rot In Tobacco, Jones H. Smiley, William C. Nesmith, Gary K. Palmer

Agriculture and Natural Resources Publications

Black root rot is an important disease of tobacco in Kentucky, causing estimated annual losses in excess of $6,000,000. It rarely causes spectacular damage in any one burley field since the recommended burley varieties have some degree of resistance to the causal fungus. However, in dark tobacco plantings damage may be extensive, especially where susceptible varieties are still planted. Still, the inability to see widespread damage from black root rot is misleading. A 5% yield reduction results in a high dollar loss because the acre value of the crop is great. In addition to the reduction in yield, a lower …

Research Into Lupin Root Diseases, M W. Sweetingham

Journal of the Department of Agriculture, Western Australia, Series 4

increased yield from wheat after lupins, obtained without the need for applied nitrogen, has led many farmers to adopt a 1:1 wheat-lupin rotation. One of the advantages of lupins is the cleaning effect they have by reducing wheat diseases such as septoria and yellow leaf spot and root diseases, in particular take-all.

Before the present research projext started, little was known about lupin root diseases, or what effect lupins grown in close rotation with wheat might have on the build-up of root disease of lupins.

Phomopsis-Resistanct Lupins : Breakthrough Towards The Control Of Lupinosis, W A. Cowling, J. G. Allen, P Mcr. Wood, J. Hamblin

Journal of the Department of Agriculture, Western Australia, Series 4

Attemots to control lupinosis in sheep have been thwarted by the unpredictable occurence of the disease in the field. The complex interaction of the toxin-producing fungus (Phomopsis leptostromiformis) with its host (the lupin plant), together with variable weather and paddock grazing conditions, have made it difficult to predict when stock are in danger of contracting the disease. The risk of lupinosis discourages many farmers from growing lupins, despite the many potential benefits of including them in crop rotations.

A team of Department of Agriculture plant breeders, plant pathologists, and animal scientists set out in the mid 1970s to find resistance …

Barley Breeding Update, P A. Portmann

Journal of the Department of Agriculture, Western Australia, Series 4

Barley production in Western Australia has increased over the past few years, peaking at 1.42 million tonnes in 1984. The European Economic Community, however, has flooded world markets for barley and over half of ourbarley was sold for feed to Saudi Arabia last year. Current prices therefore have declined as has the total area sown to barley in this State.

Despite this, the potential to increase barley yields is most promising. The Department of Agriculture has cross-bred lines in advanced stages of field testing which could increase yield by 10 per cent across the agricultural areas.

In the longer term, …

Phomopsis Infection Of Lupin Seed, D S. Petterson, P. Mcr. Wood

Journal of the Department of Agriculture, Western Australia, Series 4

Early reports of lupinosis in Western Australia implicated infected stems and leaves of the sandplain or W,A. blue lupin (Lupinus cosentinii) as the main source of toxicity.

After the introduction of low alkaloid varieties of L. augustifolius, lupinosis continued to oddur on stubbles but random testing of seeds showed only low levels of Phomopsis leptostromiformis infection.

However in 1976, scientists at the University of Western Australia who were evaluating the use of an all lupin seed ration for drought feeding sheep encounted lupinosis in one of their trials.Seven per cent of the seed used was found to be infected …

Rhizoctonia Patch Of Cereals, G C. Macnish

Journal of the Department of Agriculture, Western Australia, Series 4

Rhizoctonia patch is now widespread within Western Australia, having been recorded on all cereals and on a wide variety of other crops and pasture plants. Although the disease-as its name implies - looks spectacular in the field, the overall reduction in crop yield is probably small. However, its increasing frequency is causing considerable concern as the disease appears to be associated with minimum or reduced tillage systems.

Species-Specific Restriction Site Polymorphism In Root-Knot Nematode Mitochondrial Dna, Thomas O. Powers, E. G. Platzer, Bradley C. Hyman

Department of Plant Pathology: Faculty Publications

Research was initiated to physically characterize the mitochondrial genomes of several Meloidogyne spp. and host-races, to address questions regarding their systematics and dispersal, and to assess the possibility of developing molecular diagnostics for these nematodes. Techniques were developed for purification and rapid detection of mitochondrial DNA from root-knot nematodes. Mitochondrial DNAs among Meloidogyne spp. were demonstrated to exhibit extensive divergence. The potential for using the rapidly diverging mitochondrial genomes as a diagnostic assay for M. incognita, M. hapla, M. arenaria, and M. javanica is discussed.

Yellow Spot Of Wheat, R Loughman, J. M. Wilson, R. E. Wilson

Journal of the Department of Agriculture, Western Australia, Series 4

Yellow spot is a serious leaf disease of wheat in Western Australia. It also occurs in Queensland, New South Wales and South Australia. Yellow spot can appear as a severe leaf blight but generally the disease does not have the rapid epidemic development of wheat rust diseases. It builds up more slowly and is not as obvious in the crop, while caising appreciable yield loss.

Transposon Mutagenesis And Excision Of R' Plasmids By Conjugative, Chimeric Plasmid Puw942 In Extra-Slow-Growing Rhizobium Japonicum Strains, Alahari Arunakumari, Anne K. Vidaver

Department of Plant Pathology: Faculty Publications

Transposons Tn501 (specifying mercury resistance) and Tn7 (specifying resistance to trimethoprim and streptomycin) were introduced into extra-slow-growing Rhizobium japonicum by conjugal transfer of the 82 kilobase chimeric plasmid pUW942. Mercury-resistant transconjugants were obtained at a frequency of 10^-7 to 10^-9. The transfer frequency of streptomycin resistance was lower than that of mercury resistance, and Tn7 was relatively unstable. pUW942 was not maintained as an autonomously replicating plasmid in R. japonicum strains. However, some of the Hg^r transconjugants from the RJ19FY, RJ17W, and RJ12S strains acquired antibiotic markers of the vector plasmid pUW942. Southern hybridization of plasmid …

Bacterial Spot Of Pepper And Tomato, William C. Nesmith, John R. Hartman

Agriculture and Natural Resources Publications

Bacterial spot can result in severe damage to sweet pepper, tomato or pimento crops to the extent that it is a limiting factor to successful production. The bacterium (Xanthomonas vesicatoria) attacks leaves, fruits and stems causing blemishes on these plant parts. Outbreaks of leaf spotting have resulted in leaf drop and poor fruit set in the field. The defoliation from leaf spotting can increase the incidence of sun scald on the fruit. Badly spotted fruit is of little value. Injury from this disease allows secondary fruit rotting organisms to get into the fruits, causing further damage.

Blackleg And Soft Rot Disease Of Potato, John R. Hartman, William C. Nesmith

Agriculture and Natural Resources Publications

Blackleg and soft rot are bacterial diseases that, in some years, causes heavy losses in Kentucky potato patches. They may cause missing hills when it destroys the seed piece or the sprouts before they emerge from the ground. The bacteria can also cause serious rotting of tubers in the hill and in storage.