Life Sciences Commons^™

Saving The Sagebrush Sea: An Ecosystem Conservation Plan For Big Sagebrush Plant Communities, Kirk W. Davies, Chad S. Boyd, Jeffrey L. Beck, Jon D. Bates, Tony J. Svejcar, Michael A. Gregg

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Vegetation change and anthropogenic development are altering ecosystems and decreasing biodiversity. Successful management of ecosystems threatened by multiple stressors requires development of ecosystem conservation plans rather than single species plans. We selected the big sagebrush (Artemisia tridentata Nutt.) ecosystem to demonstrate this approach. The area occupied by the sagebrush ecosystem is declining and becoming increasingly fragmented at an alarming rate because of conifer encroachment, exotic annual grass invasion, and anthropogenic development. This is causing rangewide declines and localized extirpations of sagebrush associated fauna and flora. To develop an ecosystem conservation plan, a synthesis of existing knowledge is …

Forage Nutritional Quality Evaluation Of Bahiagrass Selections During Autumn In Florida, Robert Myer, Ann Blount, Samuel Coleman, Jeffery Carter

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Bahiagrass (Paspalum notatum Flugge) is the major pasture forage in the southern Gulf Coast, USA. A bahiagrass selection breeding program has been ongoing since 1960 at the Coastal Plain Experiment Station at Tifton, Georgia, USA, to increase forage yield in Pensacola (P. notatum var. sanese) bahiagrass. However, the impact of selecting for forage yield on forage nutritional quality is unknown. Forage quality was evaluated on four Pensacola derived selection cycles (C) of bahiagrass [C0 (Pensacola), C4, C9 (Tifton 9), and C23]. A total of 175 plants per cycle were grown. Forage from individual 1-year-old plants was harvested by …

Effect Of Coal Combustion By-Products On Phosphorus Runoff From A Coastal Plain Soil, Keisha N. Johnson, Arthur L. Allen, Peter J. A. Kleinman, Fawzy M. Hashem, Andrew N. Sharpley, William L. Stout

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Coal combustion by-products can lower soil phosphorus (P) solubility, but few studies have assessed their effect on runoff P. A soil with elevated P content was amended with fluidized bed combustion ash, flue gas desulfurization gypsum, and anthracite refuse ash at rates of 0–40 g kg⁻¹ soil, and runoff from small plots was monitored over 3 years. In the first year, by-products lowered dissolved P in runoff by up to 47% below the untreated control; however, effects did not persist into the remaining years of the study. Total P losses were not significantly affected by coal combustion by-products, likely …

Dehydration Of Pollock Skin Prior To Gelatin Production, Cindy K. Bower, Roberto J. Avena-Bustillos, Katie A. Hietala, Cristina Bilbao-Sainz, Carl W. Olsen, Tara H. Mchugh

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Alaska pollock (Theragra chalcogramma) is the U.S.A.’s largest commercial fishery, with an annual catch of over 1 million tons. During pollock processing, the skins are discarded ormade into fish meal, despite their value for gelatin production. The absence of gelatin-processing facilities in Alaska necessitates drying of the skins before transport to decrease the moisture content, but conventional hot-air drying is expensive. This study evaluated a less energy-intensive technology, the use of desiccants for reducing water weight in pollock skins prior to shipment. To ensure that the functional properties of gelatin obtained from dried pollock skins were not affected …

Past And Projected Future Changes In Snowpack And Soil Frost At The Hubbard Brook Experimental Forest, New Hampshire, Usa, John L. Campbell, Scott V. Ollinger, Gerald N. Flerchinger, Haley Wicklein, Katharine Hayhoe, Amey S. Bailey

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Long-term data from the Hubbard Brook Experimental Forest in New Hampshire show that air temperature has increased by about 1°C over the last half century. The warmer climate has caused significant declines in snow depth, snow water equivalent and snow cover duration. Paradoxically, it has been suggested that warmer air temperatures may result in colder soils and more soil frost, as warming leads to a reduction in snow cover insulating soils during winter. Hubbard Brook has one of the longest records of direct field measurements of soil frost in the United States. Historical records show no long-term trends in maximum …

Uncertainty In Modelling Of Faecal Coliform Overland Transport Associated With Manure Application In Maryland, A. K. Guber, Y. A. Pachepsky, A. M. Yakirevich, D. R. Shelton, A. M. Sadeghi, D. C. Goodrich, C. L. Unkrich

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Concerns for microbial safety of surface water facilitate development of predictive models that estimate concentrations and total numbers of pathogen and indicator organisms leaving manure-fertilized fields in overland flow during runoff events. Spatial variability of bacterial concentrations in applied manure introduces high uncertainty in the model predictions. The objective of this work was to evaluate the uncertainty in model predictions of the manure-borne bacteria overland transport caused by limited information on the spatial distribution of bacteria in surface-applied manure. Experiments were carried out at the ARS Beltsville experimental watershed site (OPE3) in Maryland. Dairy bovine manure was applied at a …

Identification Of Wild Apple Germplasm (Malus Spp.) Accessions With Resistance To The Postharvest Decay Pathogens Penicillium Expansum And Colletotrichum Acutatum, W. M. Jurick Ii, W. J. Janisiewicz, R. A. Saftner, I. Vico, V. L. Gaskins, E. Park, P. L. Forsline, G. Fazio, W. S. Conway

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Penicillium expansum and Colletotrichum acutatum cause blue mould and bitter rot of apples during storage which results in significant economic losses. Resistance to these pathogens in commercial apple cultivars has not been documented in the literature. An apple germplasm collection, from the centre of origin in Kazakhstan, is maintained in Geneva, New York. This collection represents a more diverse apple gene pool than commercial cultivars and was evaluated for resistance to the pathogens that cause blue mould and bitter rot. Resistance reactions were skewed towards susceptibility for both fungi and comprised the majority of accessions examined. However, resistance to P. …

Pathogenicity And Molecular Characterization Of Emerging Porcine Reproductive And Respiratory Syndrome Virus In Vietnam In 2007, S. Metwally, F. Mohamed, K. Faaberg, T. Burrage, M. Prarat, K. Moran, A. Bracht, G. Mayr, M. Berninger, L. Koster, T. L. To, V. L. Nguyen, M. Reising, J. Landgraf, L. Cox, J. Lubroth, C. Carrillo

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

In 2007, Vietnam experienced swine disease outbreaks causing clinical signs similar to the ‘porcine high fever disease’ that occurred in China during 2006. Analysis of diagnostic samples from the disease outbreaks in Vietnam identified porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV-2). Additionally, Escherichia coli and Streptococcus equi subspecies zooepidemicus were cultured from lung and spleen, and Streptococcus suis from one spleen sample. Genetic characterization of the Vietnamese PRRSV isolates revealed that this virus belongs to the North American genotype (type 2) with a high nucleotide identity to the recently reported Chinese strains. Amino acid …

Regulatory Control Of High Levels Of Carotenoid Accumulation In Potato Tubers, Xiangjun Zhou, Ryan Mcquinn, Zhangjun Fei, Anne-Marie A. Wolters, Joyce Van Eck, Charles Brown, James J. Giovannoni, Li Li

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Potato (Solanum tuberosum L.) tubers contain a wide range of carotenoid contents. To decipher the key factors controlling carotenoid levels in tubers, four potato lines (Atlantic, Désirée, 91E22 and POR03) were examined by a combination of biochemical, molecular and genomics approaches. These lines contained incremental levels of carotenoids, which were found to be associated with enhanced capacity of carotenoid biosynthesis as evident from norflurazon treatment. Microarray analysis of high and low carotenoid lines (POR03 versus Atlantic) revealed 381 genes that showed significantly differential expression. The carotenoid metabolic pathway genes b-carotene hydroxylase 2 (BCH2) and b-carotene hydroxylase 1 (BCH1), along …

Invited Commentary: Dietary Pattern Analysis, Fumiaki Imamura, Paul F. Jaques

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The analytic approaches used in nutritional epidemiology for dietary pattern analyses share common characteristics with those of genetic epidemiology. In this issue of the Journal, Gorst-Rasmussen et al. (Am J Epidemiol. 2011;173(10):1097–1104) discuss one such approach. Application of methods used in genetic pattern analyses to nutritional epidemiology could prove valuable but raises important issues that need to be considered because dietary and genetic studies often address different types of questions in analyzing interrelated variables. These different aims require statistical methods that assume different characteristics of the underlying patterns. The authors briefly describe such differences to facilitate interpretation and …

Physiology And Endocrinology Symposium: Role Of The Oviduct In Maintaining Sustained Fertility In Hens, M. R. Bakst

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

In poultry, sperm transferred by natural mating or AI into the distal end of the vagina immediately begin their ascent to the uterovaginal junction (UVJ) at the anterior end of the vagina. However, due to an intense selection process in the vagina, less than 1% of the sperm transferred actually reach the UVJ. Those sperm that do reach the UVJ enter numerous tubular invaginations of the surface epithelium of the vagina located in the UVJ mucosa, collectively referred to as the sperm-storage tubules (SST). Sperm residing in the SST lumen are capable of surviving up to several weeks while retaining …

Use Of Gis-Based Site-Specific Nitrogen Management For Improving Energy Efficiency, Kevin F. Bronson, Peter C. Scharf, Newell R. Kitchen

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

To our knowledge, geographical information system (GIS)-based site-specific nitrogen management (SSNM) techniques have not been used to assess agricultural energy costs and efficiency. This chapter uses SSNM case studies for corn (Zea mays L.) grown in Missouri and cotton (Gossypium hirsutum L.) grown in Texas. In five case studies, the impact of SSNM will be compared with blanket N fertilizer recommendations. The five case studies are investigating (I) the impact N on energy produced in cotton production, (2) the impact of variable-rate N for cotton production based on soil nitrate and crop reflectance, (3) the feasibility of variable-rate …

Antibody Recognition Of Porcine Circovirus Type 2 Capsid Protein Epitopes After Vaccination, Infection, And Disease, Benjamin R. Trible, Maureen Kerrigan, Nicholas Crossland, Megan Potter, Kay Faaberg, Richard Hesse, Raymond R. R. Rowland

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Open reading frame 2 (ORF2) of porcine circovirus type 2 (PCV2) codes for the 233-amino-acid capsid protein (CP). Baculovirus-based vaccines that express only ORF2 are protective against clinical disease following experimental challenge or natural infection. The goal of this study was to identify regions in CP preferentially recognized by sera from experimentally infected and vaccinated pigs and to compare these responses to those of pigs diagnosed with porcine circovirus-associated disease (PCVAD), including porcine multisystemic wasting syndrome (PMWS) and porcine dermatitis and nephropathy syndrome (PDNS). The approach was to react porcine sera with CP polypeptide fragments followed by finer mapping studies …

Conservation Reserve Enhancement Program Nebraska Platte-Republican Resources Area

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Overview

Benefits

Goals

Program Cost

Eligible Areas and Eligibility Requirements

Approved Conservation Practices

Acreage Limitations

Sign-up and Contract Duration

CREP Payments

CREP and CRP

For More Information

Patterns Of Widespread Decline In North American Bumble Bees, Sidney A. Cameron, Jeffrey D. Lozier, James P. Strange, Jonathan B. Koch, Nils Cordes, Leellen F. Solter, Terry L. Griswold

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Bumble bees (Bombus) are vitally important pollinators of wild plants and agricultural crops worldwide. Fragmentary observations, however, have suggested population declines in several North American species. Despite rising concern over these observations in the United States, highlighted in a recent National Academy of Sciences report, a national assessment of the geographic scope and possible causal factors of bumble bee decline is lacking. Here, we report results of a 3-y interdisciplinary study of changing distributions, population genetic structure, and levels of pathogen infection in bumble bee populations across the United States. We compare current and historical distributions of eight species, compiling …

Long-Term Water Balance And Conceptual Model Of A Semi-Arid Mountainous Catchment, G.M. Chauvin, G.N. Flerchinger, T.E. Link, Danny Marks, A.H. Winstral, M.S. Seyfried

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Long-term water balance investigations are needed to better understand hydrologic systems, especially semi-arid mountainous catchments. These systems exhibit considerable interannual variability in precipitation as well as spatial variation in snow accumulation, soils, and vegetation. This study extended a previous 10-year water balance based on measurements and model simulations to 24 years for the Upper Sheep Creek (USC) catchment, a 26 ha, snow-fed, semi-arid rangeland headwater drainage within the Reynolds Creek Experimental Watershed in southwestern Idaho, USA. Additional analyses afforded by the additional years of data demonstrated that the variability between streamflow and annual precipitation (r² = 0.54) could be …

Landform, Soil, And Plant Relationships To Nitrate Accumulation, Central Nevada, W.D. Nettleton, F.F. Peterson

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Nitrate (NO₃ ⁻¹) accumulates in Haplocambids and Torrifluvents in inset fan and fan skirt positions in central Nevada. The soils store as much as 17,600 kg of NO3 −1 N ha−1 within the upper 208 cm. This paper provides an explanation. These Holocene soils receive NO₃ ⁻¹ N from mineralization of organic matter and other NO₃ ⁻¹ N sources including snowmelt. The NO₃ ⁻¹ is delivered to soils in the first part of snowmelt in run-off from the higher surfaces. The last part of the melt and the run-off, when sufficient, serve to move the …

Forage Soybean Yield And Quality Response To Water Use, David C. Nielsen

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Forages could be used to diversify reduced and no-till dryland cropping systems from the traditional wheat (Triticum aestivum L.)-fallow system in the semiarid central Great Plains. Forages present an attractive alternative to grain and seed crops because of greater water use efficiency and less susceptibility to potentially devastating yield reductions due to severe water stress during critical growth stages. However, farmers need a simple tool to evaluate forage productivity under widely varying precipitation conditions. The objectives of this study were to (1) quantify the relationship between crop water use and dry matter (DM) yield for soybean (Glycine max …

Methodologies For Simulating Impacts Of Climate Change On Crop Production, Jeffrey W. White, Gerrit Hoogenboom, Bruce A. Kimball, Gerard W. Wall

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Ecophysiological models are widely used to forecast potential impacts of climate change on future agricultural productivity and to examine options for adaptation by local stakeholders and policy makers. However, protocols followed in such assessments vary to such an extent that they constrain cross-study syntheses and increase the potential for bias in projected impacts. We reviewed 221 peer-reviewed papers that used crop simulation models to examine diverse aspects of how climate change might affect agricultural systems. Six subject areas were examined: target crops and regions; the crop model(s) used and their characteristics; sources and application of data on [CO₂] …

Evaluation Of Hha And Hha Sepb Mutant Strains Of Escherichia Coli O157:H7 As Bacterins For Reducing E. Coli O157:H7 Shedding In Cattle, Vijay K. Sharma, Evelyn A. Dean-Nystrom, Thomas A. Casey

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Escherichia coli O157:H7 colonizes cattle intestines by using the locus of enterocyte effacement (LEE)- encoded proteins. The induction of systemic immune response against LEE-encoded proteins, therefore, will prove effective in reducing E. coli O157:H7 colonization in cattle. The previous studies have demonstrated that a hha (encodes for a hemolysin expression modulating protein) deletion enhances expression of LEE-encoded proteins and a sepB (encodes an ATPase required for the secretion of LEE-encoded proteins) deletion results in intracellular accumulation of LEE proteins. In this study, we demonstrate the efficacy of the hha and hha sepB deletion mutants as bacterins for …

Evaluation Of Waxy Grain Sorghum For Ethanol Production, Shuping Yan, Xiaorong Wu, Scott R. Bean, Jeffery F. Pedersen, Tesfaye Tesso, Yuanhong Chen, Donghai Wang

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The objective of this research was to investigate the fermentation performance of waxy grain sorghum for ethanol production. Twenty-five waxy grain sorghum varieties were evaluated with a laboratory dry-grind procedure. Total starch and amylose contents were measured following colorimetric procedures. Total starch and amylose contents ranged from 65.4 to 76.3% and from 5.5 to 7.3%, respectively. Fermentation efficiencies were in the range of 86.0-92.2%, corresponding to ethanol yields of 2.61-3.03 gallons/bushel. The advantages of using waxy sorghums for ethanol production include easier gelatinization and low viscosity during liquefaction, higher starch and protein digestibility, higher free amino nitrogen (FAN) content, and …

Evaluation Of Propane Combustion Traps For The Collection Of Phlebotomus Papatasi (Scopoli) In Southern Israel, Daniel Kline, Gunter Miller, Jerome Hogsette

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

In this study, we evaluated the efficacy of eleven commercial models of propane combustion traps for catching male and female Phlebotomus papatasi. The traps differed in physical appearance, amount of carbon dioxide produced and released, type and location of capturing device, and the method by which the trap suction fans were powered. The traps tested were the Mosquito Magnet^™(MM)-Pro, MM-Liberty, MM-Liberty Plus, MM-Defender, SkeeterVac^®(SV)-35, SV-27, Mosquito Deleto™(MD)-2200, MD-2500, MT150-Power Trap, and two models of The Guardian Mosquito Traps (MK-01 and MK-12). All trap models except the SV-35, the SV-27, the MD-2500, and the MK-12 attracted …

Nitrous Oxide Emissions From Several Nitrogen Sources Applied To A Strip-Tilled Corn Field, Ardell Halvorson, Stephen J. Del Grosso, Claudia Pozzi Jantalia

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

We evaluated the effects of nitrogen (N) source on nitrous oxide (N₂O) emissions from a clay loam soil that was in strip-tilled (ST), irrigated continuous corn production in 2010 near Fort Collins, CO. Emissions were monitored from six different inorganic N fertilizer sources (urea, ESN¹, SuperU, UAN, UAN+AgrotainPlus, UAN+Nfusion). Each N source was applied at a rate of 202 kg N/ha, surface band applied near the corn row and watered into the soil the day after application including a subsurface band application of ESN (ESNssb). A check treatment (no N applied since 2000) located in separate …

The Ability Of Selected Pupal Parasitoids (Hymenoptera: Pteromalidae) To Locate Stable Fly Hosts In A Soiled Equine Bedding Substrate, Jimmy B. Pitzer, Phillip E. Kaufman, Christopher Geden, Jerome A. Hogsette

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The ability of Spalangia cameroni Perkins, Spalangia endius Walker, and Muscidifurax raptorellus Kogan and Legner to locate and attack stable fly hosts was evaluated under laboratory conditions. Postfeeding third-instar stable fly larvae were released and allowed to pupate in two arena types: large 4.8 liter chambers containing a field-collected, soiled equine bedding substrate; or 120-ml plastic cups containing wood chips. At the time of fly pupariation, parasitoids were released and permitted 72 h to locate and attack hosts. On average, parasitism rates of freely accessible stable fly pupae in cups were not significantly different between parasitoid species. However, parasitism rates …

Field-Scale Soil Property Changes Under Switchgrass Managed For Bioenergy, Marty R. Schmer, M. A. Liebig, K. P. Vogel, Robert B. Mitchell

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

The capacity of perennial grasses to affect change in soil properties is well documented but information on switchgrass (Panicum virgatum L.) managed for bioenergy is limited. An on-farm study (10 fields) in North Dakota, South Dakota, and Nebraska was sampled before switchgrass establishment and after 5 years to determine changes in soil bulk density (SBD), pH, soil phosphorus (P), and equivalent mass soil organic carbon (SOC). Changes in SBD were largely constrained to near-surface depths (0–0.05 m). SBD increased (0–0.05 m) at the Nebraska locations (mean=0.16 Mgm^-3), while most South Dakota and North Dakota locations showed declines …

The Composition And Origins Of Genomic Variation Among Individuals Of The Soybean Reference Cultivar Williams 82, William J. Haun, D. L. Hyten, Wayne W. Xu, Daniel J. Gerhardt, Thomas J. Albert, Todd Richmond, Jeffrey A. Jeddeloh, Gaofeng Jia, Nathan M. Springer, Carroll P. Vance, Robert M. Stupar

Department of Agronomy and Horticulture: Faculty Publications

Soybean (Glycine max) is a self-pollinating species that has relatively low nucleotide polymorphism rates compared with other crop species. Despite the low rate of nucleotide polymorphisms, a wide range of heritable phenotypic variation exists. There is even evidence for heritable phenotypic variation among individuals within some cultivars. Williams 82, the soybean cultivar used to produce the reference genome sequence, was derived from backcrossing a Phytophthora root rot resistance locus from the donor parent Kingwa into the recurrent parent Williams. To explore the genetic basis of intracultivar variation, we investigated the nucleotide, structural, and gene content variation of different …

Soil Fertility And Crop Yields In Long-Term Organic And Conventional Cropping Systems In Eastern Nebraska, Samuel E. Wortman, Tomie D. Galusha, Stephen C. Mason, Charles A. Francis

Department of Agronomy and Horticulture: Faculty Publications

Organic agriculture aims to build soil quality and provide long-term benefits to people and the environment; however, organic practices may reduce crop yields. This long-term study near Mead, NE was conducted to determine differences in soil fertility and crop yields among conventional and organic cropping systems between 1996 and 2007. The conventional system (CR) consisted of corn (Zea mays L.) or sorghum (Sorghum bicolor (L.) Moench)–soybean (Glycine max (L.) Merr.)–sorghum or corn–soybean, whereas the diversified conventional system (DIR) consisted of corn or sorghum– sorghum or corn–soybean–winter wheat (wheat, Triticum aestivum L.). The animal manure-based organic system (OAM) …

Stacking Resistance Alleles From Wild And Domestic Soybean Sources Improves Soybean Cyst Nematode Resistance, Myungsik Kim, D. L. Hyten, Terry L. Niblack, Brian W. Diers

Department of Agronomy and Horticulture: Faculty Publications

The soybean cyst nematode (SCN; Heterodera glycines Ichinohe) is the most economically important soybean [Glycine max (L.) Merr.] pathogen in the United States. Field SCN populations are adapting to the narrowly based SCN resistance currently deployed in soybean cultivars. The objective of our research was to measure the effects of combinations of SCN resistance genes or quantitative trait loci (QTL) from the wild soybean (Glycine soja Siebold & Zucc.) PI 468916 and the domesticated soybean accessions PI 88788 and PI 437654. Two populations were developed to test the combinations of QTL and genes. Both populations segregated for the …

Identification Of A Second Asian Soybean Rust Resistance Gene In Hyuuga Soybean, Mandy D. Kendrick, Donna K. Harris, Bo-Keun Ha, D. L. Hyten, P. B. Cregan, Reid D. Frederick, H. Roger Boerma, Kerry F. Pedley

Department of Agronomy and Horticulture: Faculty Publications

Asian soybean rust (ASR) is an economically significant disease caused by the fungus Phakopsora pachyrhizi. The soybean genes Rpp3 and Rpp?(Hyuuga) confer resistance to specific isolates of the pathogen. Both genes map to chromosome 6 (Gm06) (linkage group [LG] C2). We recently identified 12 additional soybean accessions that harbor ASR resistance mapping to Gm06, within 5 centimorgans of Rpp3 and Rpp?(Hyuuga). To further characterize genotypes with resistance on Gm06, we used a set of eight P. pachyrhizi isolates collected from geographically diverse areas to inoculate plants and evaluate them for differential phenotypic responses. …

Cytokinin-Mediated Source ⁄Sink Modifications Improve Drought Tolerance And Increase Grain Yield In Rice Under Water-Stress, Zvi Peleg, Maria Reguera, Ellen Tumimbang, Harkamal Walia, Eduardo Blumwald

Department of Agronomy and Horticulture: Faculty Publications

Drought is the major environmental factor limiting crop productivity worldwide. We hypothesized that it is possible to enhance drought tolerance by delaying stress-induced senescence through the stress-induced synthesis of cytokinins in crop-plants. We generated transgenic rice (Oryza sativa) plants expressing an isopentenyltransferase (IPT) gene driven by PSARK, a stress- and maturation-induced promoter. Plants were tested for drought tolerance at two yield-sensitive developmental stages: pre- and post-anthesis. Under both treatments, the transgenic rice plants exhibited delayed response to stress with significantly higher grain yield (GY) when compared to wild-type plants. Gene expression analysis revealed a significant shift in expression of hormone-associated …