Plant Biology Commons^™

The Pseudomonas Syringae Pv. Tomato Hrpw Protein Has Domains Similar To Harpins And Pectate Lyases And Can Elicit The Plant Hypersensitive Response And Bind To Pectate, Amy O. Charkowski, James R. Alfano, Gail Preston, Jing Yuan, Sheng Yang He, Alan Collmer

Center for Plant Science Innovation: Faculty Publications

The host-specific plant pathogen Pseudomonas syringae elicits the hypersensitive response (HR) in nonhost plants and secretes the HrpZ harpin in culture via the Hrp (type III) secretion system. Previous genetic evidence suggested the existence of another harpin gene in the P. syringae genome. hrpW was found in a region adjacent to the hrp cluster in P. syringae pv. tomato DC3000. hrpW encodes a 42.9-kDa protein with domains resembling harpins and pectate lyases (Pels), respectively. HrpW has key properties of harpins. It is heat stable and glycine rich, lacks cysteine, is secreted by the Hrp system, and is able to elicit …

A Sensitive Elisa For Pythium Ultimum Using Polyclonal And Species-Specific Monoclonal Antibodies, G. Y. Yuen, J. Q. Xia, C. L. Sutula

Department of Plant Pathology: Faculty Publications

A double-antibody sandwich indirect enzyme-linked immunosorbent assay (ELISA) was developed for the detection and quantification of Pythium ultimum. A polyclonal antibody produced to cell walls of P. ultimum was used as the capture antibody, while a P. ultimum-specific monoclonal antibody (MAb E5) was used for recognition of the fungus. In the ELISA, culture extracts of 7 isolates of P. ultimum exhibited strong positive reactions, whereas none of the 37 isolates of other Pythium spp. and fungal genera had positive reactions. P. ultimum was detected by ELISA in roots of bean, cabbage, and sugar beet seedlings grown in pathogen-infested …

A Partial Host Range Of The High Plains Virus Of Corn And Wheat, Dallas L. Seifers, Tom L. Harvey, T. J. Martin, Stanley G. Jensen

Department of Plant Pathology: Faculty Publications

Barley (Hordeum vulgare), cheat (Bromus secalinus), corn (Zea mays), oat (Avena sativa), rye (Secale cereale), and wheat (Triticum aestivum) were infected by a Kansas isolate of the High Plains virus (HPV) in greenhouse experiments, but several other grass species were not. Infection of a host was dependent upon wheat curl mite numbers. Although both green foxtail (Setaria viridis) and yellow foxtail (S. glauca) are found naturally infected by HPV, only yellow foxtail could be infected in greenhouse experiments. Field sampling (1994 to 1996) of …

Physiologic Specialization Of Puccinia Recondita F. Sp. Tritici In Nebraska During 1995 And 1996, J. E. Watkins, S. S. Rutledge, P. Stephen Baenziger, W. Youngquist

Department of Plant Pathology: Faculty Publications

Field samples of Puccinia recondita f. sp. tritici, collected from four wheat-growing regions in Nebraska in 1995 and from three in 1996, were characterized for virulence. Twenty virulence phenotypes were identified in 1995 and 18 in 1996. Virulence phenotypes MBR-10,18 (virulent on Lr genes, 1, 3, 3ka, 10, 11, 18, and 30) and MDR-10,18 (virulent on Lr genes 1, 3, 3ka, 10, 11, 18, 24, and 30) were the most prevalent, with each phenotype comprising 21.6% of the isolates characterized in 1995. Of the 1995 isolates, 24% were virulent on 10 or more host genes. No virulence to Lr16 and …

Polymerase Chain Reaction Detection And Phylogenetic Characterization Of An Agent Associated With Yellow Vine Disease Of Cucurbits, Francisco J. Avila, Benny D. Bruton, Jacqueline Fletcher, J. L. Sherwood, Sam D. Pair, Ulrich Melcher

Department of Plant Pathology: Faculty Publications

Diagnosis of yellow vine disease (YVD) in cucurbits, an important disease in the south-central United States, relies on external symptom appearance, phloem discoloration, and the presence of bacterium-like organisms (BLOs) in phloem. Polymerase chain reaction (PCR) amplification of BLO nucleotide sequences was explored as a means to improve diagnostic techniques. PCR, using a primer pair based on sequences of the citrus-greening BLO, amplified a 0.15-kilobase (kb) fragment from the DNA of symptomatic plants, but not from that of asymptomatic plants. Its nucleotide sequence suggested that the DNA amplified was of prokaryotic origin. A primer pair, designed to amplify nonspecific prokaryotic …

Population Biology Of Intraspecific Polyploidy In Grasses, Kathleen H. Keeler

School of Biological Sciences: Faculty Publications

Polyploidy is the duplication of an entire nuclear genome, whether diploid or higher level (Stebbins, 1971; Thompson and Lumaret, 1992) and a frequent occurrence in plants. Stebbins (1971) estimated that 30-35% of flowering plant species are polyploid, and that many more had a polyploid event in their evolutionary history, including all members of such important families as the Magnoliaceae, Salicaceae, and Ericaceae. Goldblatt (1980) estimated 55%, but probably up to 75%, of monocotyledons had at least one polyploid event in their history, using the criterion that if the species has a base number higher than n = 13 it is …

Characterization Of The Large (L) Rna Of Peanut Bud Necrosis Tospovirus, S. Gowda, Satyanarayana Tatineni, R. A. Naidu, A. Mushegian, W. O. Dawson, D. V. R. Reddy

Department of Plant Pathology: Faculty Publications

The nucleocapsids purified from peanut plants systemically infected with peanut bud necrosis virus (PBNV), a member of the genus Tospovirus, contained both viral(v) and viral complementary(vc) sense L RNAs. Defective forms of L RNA containing ‘core polymerase region’ were observed. The full length L RNA of PBNV was sequenced using overlapping cDNA clones. The 8911 nucleotide L RNA contains a single open reading frame (ORF) in the vc strand, and encodes a protein of 330 kDa. At the 50 and 30 termini of the v sense RNA there were 247 and 32 nt untranslated regions, respectively, containing an 18 …

Peanut Yellow Spot Virus Is A Member Of A New Serogroup Of Tospovirus Genus Based On Small (S) Rna Sequence And Organization, Satyanarayana Tatineni, S. Gowda, K. Lakshminarayana Reddy, S. E. Mitchell, W. O. Dawson, D. V. R. Reddy

Department of Plant Pathology: Faculty Publications

Peanut yellow spot virus (PYSV) represents a distinct tospovirus species based on serology and nucleic acid hybridization. The sequence of the S RNA was 2 970 nucleotides with 22 nucleotide long inverted repeats (with three mismatches) at the termini. The coding was ambisense with a long open reading frame (ORF) in each strand. The 5'-large ORF (1 440 nucleotides in the viral sense (v) strand) encoded a protein with a predicted size of 53.2 kDa that was identified as the nonstructural (NSs) protein based on 16–21% sequence identity and 42– 48% sequence similarity with other tospoviruses. A 3' ORF (741 …

Growth Traits Among Sorghum Genotypes In Response To Aluminum, J. H. Bernal, R. B. Clark

Department of Agronomy and Horticulture: Faculty Publications

Aluminum (Al) has many detrimental effects on plant growth, and shoots and roots are normally affected differently. A study was conducted to determine differences among sorghum [Sorghum bicolor (L.) Moench] genotypes with broad genetic backgrounds for growth traits of plants grown at 0,200,400,600, and 800 uM Al in nutrient solutions (pH 4.0). Genotypes were categorized into "Al-sensitive", "intermediate Al-tolerant", "Al-tolerant", and SC 283 (an Al-tolerant standard). As Al increased, shoot and root dry matter (DM), net main axis root length (NMARL), and total root length (TRL) became lower than controls (0 Al). Aluminum toxicity and/or nutrient deficiency symptoms become …

Identification Of The Wheat Curl Mite As The Vector Of The High Plains Virus Of Corn And Wheat, Dallas L. Seifers, Tom L. Harvey, T. J. Martin, Stanley G. Jensen

Department of Plant Pathology: Faculty Publications

Wheat with virus-like symptoms (extracts containing a 33-kDa protein in sodium dodecyl sulfate- polyacrylamide gel electrophoresis, negative in enzyme-linked immunosorbent assay to wheat streak mosaic virus, and not infectious in a backassay to other wheat) reacted positively to antiserum made against a protein purified from symptomatic corn infected with the High Plains virus (HPV), indicating a serological relationship between the corn and wheat pathogens. The wheat curl mite (WCM, Aceria tosichella Keifer) was identified as the vector of the virus and caused persistent infection of barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) in greenhouse experiments. The …

Comparison Of Avrd Alleles From Pseudomonas Syringae Pv. Glycinea, Lisa Wolfson Keith, Carol Boyd, Noel T. Keen, J. E. Patridge

Department of Plant Pathology: Faculty Publications

Avirulence gene D alleles resided on indigenous plasmids in races 0, 2, 3, 4, 5, and 6 of Pseudomonas syringae pv. glycinea (Psg), but the allele in race 1 appeared to be chromosomal. These were all nonfunctional avirulence genes because they neither induced the avirulence phenotype on Rpg4 soybean cultivars nor directed the production of syringolide elicitors when expressed in Escherichia coli cells. The predicted proteins encoded by the seven Psg avrD genes were very similar to that of a functional class II allele from P. syringae pv. phaseolicola G50 race 2, but contained mutations collectively …

Genetic Variability Among Maize Inbred Lines For Resistance To The High Plains Virus–Wheat Streak Mosaic Virus Complex, A. Marçon, S. M. Kaeppler, S. G. Jensen

Department of Plant Pathology: Faculty Publications

High plains virus (HPV) is a pathogen that causes a severe disease, especially in susceptible corn genotypes. The virus is transmitted by the eriophyid mite Aceria tosichella, which also transmits wheat streak mosaic virus (WSMV). This often results in a mixed infection by these two viruses. Genetic variability for resistance to the HPV exists among maize inbred lines but has not been characterized. The disease reaction of 30 maize inbred lines to the mixed infection and to WSMV alone was characterized in this study. Evaluation was based on symptom expression and virus titer (HPV and WSMV), as measured by …

Evolutionary Implications Of Meiotic Chromosome Behavior, Reproductive Biology, And Hybridization In 6x And 9x Cytotypes Of Andropogon Gerardii (Poaceae), Guillermo A. Norrmann, Camilo L. Quarín, Kathleen H. Keeler

School of Biological Sciences: Faculty Publications

Andropogon gerardii, big bluestem, has 60 and 90 chromosome cytotypes. Meiosis in the hexaploid was shown to be regular, although some secondary associations of bivalents form. Meiosis in the enneaploid (2n = 9x = 90) is irregular, leading to most gametes having unbalanced chromosome complements. Both cytotypes show considerable self-incompatibility. Cytotypes crossed freely, forming a variety of fertile euploids and aneuploids. Indistinguishable exomorphology, intermixing in natural populations, and compatibility suggest that A. gerardii is best understood as a cytotypically complex single species.

Soil Temperature And Fumigation Effects On Plant Phosphorus Uptake And Related Microbial Properties, Dennis L. Mccallister, L. A. Jawson, M. D. Jawson

Department of Agronomy and Horticulture: Faculty Publications

Early season problems with growth of corn (Zea mays L.) under cool, wet conditions prompted a study of the effects of soil and environmental conditions on mineralization and plant uptake of phosphorus (P). Our objective was to determine the effect of soil test P, temperature, and soil fumigation on soil P availability and uptake during early corn growth. Corn was grown in growth chambers at temperatures of 14°C or 25°C. Soils were a high-P Hastings silty clay loam (fine, montmorillonitic, mesic Udic Argiustoll) and a low-P Sharpsburg clay loam (fine, montmorillonitic, mesic Typic Argiudoll). Plants grew for up to …

Notes: Forage Yield, Quality, And Fertility Of Sorghum X Sudan Grass Hybrids In A1 And A3 Cytoplasm, Jeffrey F. Pedersen, J. J. Toy

Department of Agronomy and Horticulture: Faculty Publications

Currently, no information is available comparing the agronomic performance of A1 and A3 cytoplasms in sorghum x sudangrass [Sorghumbi color (L.) Moench] hybrids. The objectives of this study were to compare the effects of A1 and A3 cytoplasm on the maturity, fertility, height, forage yield, and forage quality of sorghum × sudangrass hybrids. In 1989, pollen from a bulk of eight sudangrass populations was used to pollinate four sorghum lines that had been male-sterilized in both A1 and A3 cytoplasm. Hybrids were grown at the Univ. of Nebraska Field Laboratory Ithaca, NE, in 1990 and 1991, in a split-plot …

Molecular And Functional Characterization Of A Novel Low-Affinity Cation Transporter (Lct1) In Higher Plants, Daniel P. Schachtman, Raman Kumar, Julian I. Schroeder, Ellen L. Marsh

Department of Agronomy and Horticulture: Faculty Publications

The transport of cations across membranes in higher plants plays an essential role in many physiological processes including mineral nutrition, cell expansion, and the transduction of environmental signals. In higher plants the coordinated expression of transport mechanisms is essential for specialized cellular processes and for adaptation to variable environmental conditions. To understand the molecular basis of cation transport in plant roots, a Triticum aestivum cDNA library was used to complement a yeast mutant deficient in potassium (K⁺) uptake. Two genes were cloned that complemented the mutant: HKT1 and a novel cDNA described in this report encoding a cation …

Cross-Polarized Magic-Angle Spinning 13c Nuclear Magnetic Resonance Spectroscopic Characterization Of Soil Organic Matter Relative To Culturable Bacterial Species Composition And Sustained Biological Control Of Pythium Root Rot, Michael J. Boehm, Tianyun Wu, Alex G. Stone, Bart Kraakman, Donna A. Iannotti, G. Edwin Wilson, Laurence V. Madden, Harry A.J. Hoitink

Department of Plant Pathology: Faculty Publications

We report the use of a model system that examines the dynamics of biological energy availability in organic matter in a sphagnum peat potting mix critical to sustenance of microorganism-mediated biological control of pythium root rot, a soilborne plant disease caused by Pythium ultimum. The concentration of readily degradable carbohydrate in the peat, mostly present as cellulose, was characterized by cross-polarized magic-angle spinning 13C nuclear magnetic resonance spectroscopy. A decrease in the carbohydrate concentration in the mix was observed during the initial 10 weeks after potting as the rate of hydrolysis of fluorescein diacetate declined below a critical threshold level …

Promoters From Chlorellavirus Genes Providing Expression Of Genes In Prokaryotic And Eukaryotic Hosts, Amitava Mitra, James L. Van Etten

Department of Plant Pathology: Faculty Publications

The invention is directed to novel promoters or mutants thereof from Chlorella virus DNA methyltransferase genes. A Chlorella virus gene promoter is operably linked to a first and/or second DNA sequence encoding a gene that is different from the Chlorella virus gene to form an expression cassette. An expression cassette can be introduced into prokaryotic and/or eukaryotic cells and can provide for a high level of expression of the gene encoded by the first and/or second DNA sequence. The invention also provides a method for screening other Chlorella virus genes for promoters that can function to express a heterologous gene …

Biotin Carboxyl Carrier Protein And Carboxyltransferase Subunits Of The Multi-Subunit Form Of Acetyl-Coa Carboxylase From Brassica Napus: Cloning And Analysis Of Expression During Oilseed Rape Embryogenesis, Kieran M. Elborough, Robert Winz, Ranjit K. Deka, Jennifer E. Markham, Andrew J. White, Stephen Rawsthorne, Antoni R. Slabas

Department of Biochemistry: Faculty Publications

In the oilseed rape Brassica napus there are two forms of acetyl- CoA carboxylase (ACCase). As in other dicotyledonous plants there is a type I ACCase, the single polypeptide 220 kDa form, and a type II multi-subunit complex analogous to that of Escherichia coli and Anabaena. This paper describes the cloning and characterization of a plant biotin carboxyl carrier protein (BCCP) from the type II ACCase complex that shows 61% identity/79% similarity with Anabaena BCCP at the amino acid level. Six classes of nuclear encoded oilseed rape BCCP cDNA were cloned, two of which contained the entire coding region. …

Movement Of Crop Transgenes Into Wild Plants, Kathleen H. Keeler, Charles E. Turner, Margaret R. Bolick

School of Biological Sciences: Faculty Publications

Despite the great potential and increasing importance of other weed control options (Turner et al. 1992) and unwanted environmental side effects of some herbicides, herbicides constitute a very important means of weed control. The escape of herbicide resistance genes to wild, weedy plants could cause more severe weed problems, and presents a very real threat to the efficacy of herbicides as a weed control option. Therefore, management strategies that prevent, or reduce the likelihood and frequency of HRG escape through containment methods are advisable, as are mitigation plans in the event of HRG escape to wild plants.

The Complete Nucleotide Sequence And Genome Organization Of The M Rna Segment Of Peanut Bud Necrosis Tospovirus And Comparison With Other Tospoviruses, Satyanarayana Tatineni, S. E. Mitchell, D. V. R. Reddy, S. Kresovich, R. Jarret, R. A. Naidu, S. Gowda, J. W. Demski

Department of Plant Pathology: Faculty Publications

The M RNA of peanut bud necrosis virus (PBNV; synonym groundnut bud necrosis virus) is 4801 nucleotides in length. It comprised two ORFs in an ambisense organization and terminal inverted repeats. The 3' large ORF (3363 nucleotides in the virus-complementary strand) encoded a protein with a predicted size of 127.2 kDa which was identified as the glycoprotein precursor (GP) of the G1 and G2 glycoproteins. A comparison of the deduced amino acid sequence of GP revealed 37 % identity and 58-59% similarity with that of tomato spotted wilt virus (TSWV, serogroup I) and impatiens necrotic spot virus (INSV, serogroup III), …

Peanut Bud Necrosis Virus: Purification Of Nucleocapsids And Sequence Homology Of Nucleocapsid Protein And Glycoprotein Precursor With Other Tospoviruses, Satyanarayana Tatineni, S. E. Mitchell, D. V. R. Reddy, S. Brown, S. Kresovich, R. Jarret, S. Gowda, R. A. Naidu, J. W. Demski

Department of Plant Pathology: Faculty Publications

A procedure for the purification of peanut bud necrosis virus (PBNV) nucleocapsids was developed. Virus particles were treated with nonionic detergent to disrupt the envelope membrane and free nucleocapsids were separated. into three lightscattering zones after sucrose gradient centrifogation. Nucleocapsids from the top zone contained S RNA and traces ofM RNA; whereas, nucleoplasids from the middle zone contained M RNA with detectable levels of S RNA and those from the bottom zone contained L RNA with traces of M and S RNAs. Clones from a cDNA library made from the purified PBNV Sand M RNAs were characterized and sequenced. Comparison …

Diagnosis And Resistance Breeding Of Peanut Bud Necrosis Virus, D. V. R. Reddy, Satyanarayana Tatineni, S. L. Dwivedi, A. S. Ratna, A. A. M. Buiel, G. V. Ranga Rao, S. N. Nigam, R. A. Naidu, H. T. Hsu, J. W. Demski

Department of Plant Pathology: Faculty Publications

The occu!fence of peanut bud necrosis (PBN) disease in India was first reported in 1968. The high incidence ofPBN disease during the 1960s coincided with largescale imports of the peanut cultivars Asiria Mwitundae and Spanish Improved, both of which are highly susceptible to PBN. Since then, a number of reports have been published in India describing bud necrosis under at least seven different names (Reddy 1988). Crop losses due to PBN have been estimated at USD89 million per year in India during 1976-1986. The disease is also currently recognized as economically important in Nepal (Sharma 1996), in Sri Lanka, and …

Molecular Diagnostics Of Three Diabrotica (Coleoptera: Chrysomelidae) Pest Species, Allen L. Szalanski, Thomas O. Powers

Department of Plant Pathology: Faculty Publications

A 257 bp region of the mitochondrial ND4 gene was analyzed for genetic variation in three species of corn rootworm, southern corn rootworm (Diabrotica undecim punctata howardi Barber, SCR), northern corn rootworm (D. barberi Smith and Lawrence, NCR), and western corn rootworm (D. virgifera virgifera LeConte, WCR). Nucleotide sequencing revealed 26 polymorphic sites. Genetic distances averaged 8% for all pair-wise comparisons among the three species. Restriction maps were constructed from sequence data and compared to potential species specific restriction sites. Polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) revealed three restriction enzymes (Alu I, Apo I …

Application Of The Single Kernel Wheat Characterization Technology To Sorghum Grain, Jeffrey F. Pedersen, C. R. Martin, F. C. Felker, J. L. Steele

Department of Agronomy and Horticulture: Faculty Publications

A single kernel wheat characterization system (SKWCS) was recently developed by the USDA, ARS Grain Marketing Research Laboratory and is currently being marketed by Perten Instruments North America, Inc. This device has been shown to accurately measure individual seed hardness, moisture, and size of wheat. The objective of this study was to determine if the SKWCS technology could be applied to the measurement of sorghum grain. Grains from 64 sorghum plots grown at Mead, NE in 1992 were characterized using a prototype SKWCS at the USDA, ARS Grain Marketing Research Laboratory. Problems encountered were primarily associated with the single kernel …

Annual Forages: New Approaches For C-4 Forages, Jeffrey F. Pedersen

Department of Agronomy and Horticulture: Faculty Publications

The current agricultural paradigm in the U.S. is heavily biased towards the production and marketing of crops as commodities. This paradigm is kept in place by grain handling and marketing infrastructure, as well as government farm programs, designed for crops as commodities. Sorghum (Sorghum bicolor L. Moench) and maize (Zea mays L.) grown for grain certainly fit into this current paradigm.

A new approach to agricultural production and marketing, identity preserved products, is gaining in importance. This is made possible through new technologies and markets demanding products designed specifically for their needs. Examples of investment in identity preserved …

Media Effects On Phenotype Of Callus Cultures Initiated From Photoperiod-Insensitive, Elite Inbred Sorghum Lines, H. F. Kaeppler, Jeffrey F. Pedersen

Department of Agronomy and Horticulture: Faculty Publications

Sorghum (Sorghum bicolor L. Moench) is a crop of worldwide agronomic importance. Routine production of high quality (friable, embryogenic, fast growing) callus cultures is fundamental to tissue culture based genetic study and improvement of sorghum. Genotype by culture medium interactions for sorghum callus growth and morphology have been previously reported. The objective of this study was to identify tissue culture media that would support high quality callus growth across photoperiod insensitive, relatively elite genotypes. Explants from immature inflorescences of 11 sorghum genotypes were cultured on 6 tissue culture media of differing composition. After 3 and 5 months in culture, calli …

Germplasm And Cultivar Development, M. D. Casler, Jeffrey F. Pedersen, G. C. Eizenga, S. D. Stratton

Department of Agronomy and Horticulture: Faculty Publications

Cool-season forage grasses have evolved, and continue to evolve, in natural ecosystems subject to environmental factors both in the presence and absence of human influences. The literature often lacks facts describing the evolution and domestication of forage grasses. Furthermore, the literature on this subject mainly deals with evolution of species in the broad scope, i.e., on a scale of hundreds of thousands or millions or years. Thus, some of our conclusions are necessarily speculative and are highly subject to the nature of the research that has been reported. We describe the forces of selection that act upon cool-season forage grasses …

Breeding Sorghum And Pearl Millet For Forage And Fuel, Jeffrey F. Pedersen

Department of Agronomy and Horticulture: Faculty Publications

Sorghum [Sorghum bicolor (L.) Moench] and pearl millet [Pennisetum glaucum (L.) R. Br.] are unique species in their ability to be used in many forage llivestock system roles. Such flexibility has made prioritizing breeding objectives difficult and has even contributed to contradictory opinions on appropriate forage breeding objectives. Few breeding projects identified in the USDA-ARS, USDA-CREES, or at ICRISAT had forage sorghum or forage pearl millet as their sole research assignment. In the United States, it can be argued that breeding resources committed to forage sorghum improvement are probably declining. A new forage sorghum and forage pearl millet …

Grasslands: An Introduction, Kathleen H. Keeler

Great Plains Quarterly (through 2013)

"Grasslands" was the subject of the seventeenth annual symposium of the Center for Great Plains Studies, held at the University of Nebraska-Lincoln, in April 1994. Grasslands are so basic to the Great Plains experience as to be invisible. If you stand here in eastern Nebraska, it is so far in any direction across grasslands to any other landscape (a cornfield is a planted grassland, after all) that the role of grasslands in our lives does not seem worth considering. Local variation is much more visible. You can't see the prairie for the grasses, to adapt the idiom. And yet, grasslands …