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Articles 1 - 28 of 28

Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

Molecular Genetic Analyses Of Oilseed Brassica Germplasm: Determination Of Life Forms And Germplasm Management Strategies By Using Microsatellite Markers And Flowering Locus-C (Flc1 And Flc3) Gene Sequences , Von Mark V. Cruz Jan 2006

Molecular Genetic Analyses Of Oilseed Brassica Germplasm: Determination Of Life Forms And Germplasm Management Strategies By Using Microsatellite Markers And Flowering Locus-C (Flc1 And Flc3) Gene Sequences , Von Mark V. Cruz

Retrospective Theses and Dissertations

Molecular markers were utilized in conjunction with phenological and morphological information, and statistical methods for diversity analyses to address plant genetic resource conservation issues. The objectives of this study have been categorized into two sets. The first set pertains to exploratory surveys of genetic variation using molecular markers and DNA sequences to determine if microsatellite markers or variation in two copies of the FLOWERING LOCUS C gene (FLC1 and FLC3) can be used in determining life forms of fifty representative accessions of Brassica napus. The second set of objectives addresses good genebank practices and includes: characterization of flowering time of ...


Phenotypic, Biochemical, And Molecular Diversity In Coriander (Coriandrum Sativum L) Germplasm, Pedro Antonio López Jan 2006

Phenotypic, Biochemical, And Molecular Diversity In Coriander (Coriandrum Sativum L) Germplasm, Pedro Antonio López

Retrospective Theses and Dissertations

A study was conducted to assess phenotypic, biochemical, and molecular diversity in coriander accessions from the North Central Regional Plant Introduction Station, in Ames, IA; initially, 139 accessions were characterized for phenological and morphological traits and for fatty-acid composition. A second year of data was collected on those traits from 60 accessions. Fruit essential-oil content and composition were determined, along with a headspace analysis from leaves and an analysis of amplified fragment length polymorphisms (AFLPs). Basic statistics and Pearson correlations were estimated. Matrices of geographical distances (GD), modified Rogers' (MD) distances for molecular data, and Euclidean distances for phenotypic (PD ...


Recognition And Signal Transduction In The Expression Of Phytophthora Resistance In Soybean [Glycine Max (L) Merr] , Hongyu Gao Jan 2006

Recognition And Signal Transduction In The Expression Of Phytophthora Resistance In Soybean [Glycine Max (L) Merr] , Hongyu Gao

Retrospective Theses and Dissertations

Phytophthora sojae, a hemibiotrophic oomycete, is the causal pathogen of stem and root rot disease of soybean (Glycine max [L.] Merr). The annual soybean yield loss suffered from this disease is valued at about 300 million dollars. A series of single Rps genes protect soybean from the root and stem rot disease. In the last two decades Rps1-k has been the most stable and widely used Phytophthora resistance gene in the major soybean-producing regions of the United States;Two classes of CC-NB-LRR-type Rps1-k genes were isolated from the Rps1-k locus. Representative members from each gene class were expressed in transgenic ...


Cell Envelope Constituents Of Pseudomonas Putida Contributing To Growth And Survival In Low-Water-Content Habitats , Martinus Franciscus Maria Van De Mortel Jan 2005

Cell Envelope Constituents Of Pseudomonas Putida Contributing To Growth And Survival In Low-Water-Content Habitats , Martinus Franciscus Maria Van De Mortel

Retrospective Theses and Dissertations

The ability of bacteria to respond to the ever changing environmental conditions they encounter requires the utilization of a broad range of colonization and survival strategies. One of the most important and probably least understood factors determining bacterial activity in terrestrial habitats is water availability. The goal of this dissertation research was to identify traits that contribute to maintaining a functional cell envelope when cells are dehydrated, which will help us to assess the scope of physiological changes necessary for growth in low-water-content habitats. The primary objective was to identify genes that are specifically regulated by dehydration (matric stress), and ...


Expression Analysis Of Maize Opaque2 Mutants And Glu-1dx5 Transgenic Corn , Hongwu Jia Jan 2004

Expression Analysis Of Maize Opaque2 Mutants And Glu-1dx5 Transgenic Corn , Hongwu Jia

Retrospective Theses and Dissertations

The maize (Zea mays L.) opaque2 (o2) mutant has high lysine content, but soft and starchy kernels. We confirm that Lys content, kernel density, and reduction of zein proteins in o2 mutants are genetic-background dependent. Microarray analysis was carried out by pooling the same amount of mRNA from eight o2 lines to probe the maize Unigene cDNA chip to understand the o2 main effects. 202 genes identified as differentially expressed fit our definition of main effect genes. Comparative analysis of the expression profiles of two additional inbred lines shows that B46WT/B46 o2 with the most extreme phenotype has the ...


Investigation Of Iron-Deficiency Chlorosis In Soybean , Dirk Victor Charlson Jan 2003

Investigation Of Iron-Deficiency Chlorosis In Soybean , Dirk Victor Charlson

Retrospective Theses and Dissertations

Iron-Deficiency Chlorosis (IDC) causes yield losses in soybean and other crop species as a result of the plant's inability to efficiently acquire iron from calcareous soils. Although plants differ in their response to iron deficiency and IDC resistance has been improved in soybean, the biology of IDC is not well understood. We undertook an interdisciplinary approach towards increasing our knowledge of IDC resistance and iron acquisition strategies in higher plants. Firstly, we examined the usefulness of molecular markers to improve breeding efficiency for IDC resistance in soybean. After examining Simple Sequence Repeats (SSR) markers genetically linked to previously identified ...


Molecular Marker Analysis Of Population Genetic Structure And Progress From Reciprocal Recurrent Selection In Two Iowa Maize (Zea Mays L) Populations , Lori Lynn Hinze Jan 2003

Molecular Marker Analysis Of Population Genetic Structure And Progress From Reciprocal Recurrent Selection In Two Iowa Maize (Zea Mays L) Populations , Lori Lynn Hinze

Retrospective Theses and Dissertations

Studies of the genetic structure of the Iowa Corn Borer Synthetic #1 (CB) and Iowa Stiff Stalk Synthetic (SS) maize populations are of particular significance because they serve as the model on which development of modern commercial hybrids are based. These populations are part of a reciprocal recurrent selection breeding strategy. With this strategy, plants from one population are crossed to plants from the opposite population (i.e. forming hybrids). These hybrids are tested, and the best ones are chosen. The plants crossed to form the chosen hybrids are identified and used to form the next generation in each population ...


Genetic Basis Of Autumn Growth And Winter Hardiness In Alfalfa , Baldomero Alarcón Zúñiga Jan 2003

Genetic Basis Of Autumn Growth And Winter Hardiness In Alfalfa , Baldomero Alarcón Zúñiga

Retrospective Theses and Dissertations

Alfalfa (Medicago sativa L.) has a broad geographic distribution, with populations adapted to both cold and warm climates. Despite considerable research on winter hardiness, the mechanisms and genetic control of winter survival are poorly understood. We conducted two experiments designed to identify and quantify morphological, physiological, and biochemical traits associated with winter hardiness and to estimate the genetic relationship of these traits with winter hardiness. In Experiment 1, ten alfalfa genotypes were planted in June 2000 and in May 2001 at Ames, IA, and traits were measured in August, November, and the following April in each year. Concentrations of palmitate ...


Molecular And Genetic Characterization Of The Inheritance And Expression Of The Synthetic Porcine Alpha-Lactalbumin Transgene In Maize (Zea Mays L) , Earl H. Bicar Jan 2003

Molecular And Genetic Characterization Of The Inheritance And Expression Of The Synthetic Porcine Alpha-Lactalbumin Transgene In Maize (Zea Mays L) , Earl H. Bicar

Retrospective Theses and Dissertations

A codon-adjusted version of a gene encoding the porcine milk protein alpha-lactalbumin was synthesized to create maize with improved nutritional quality. Three expression vectors (P64, P45, P57) containing the synthetic gene were constructed and transformed into maize callus by particle bombardment. The constructs differed in their promoters and subcellular targeting domains. PCR analysis showed that the alpha-La transgene was integrated into the maize genome and transmitted to the F1 generation. Western blot analysis indicated that the transgenes were functional and the alpha-La protein accumulated in the target endosperm. Genomic Southern blot analysis detected no new rearrangements demonstrating stable transgene integration ...


Enzyme Activities In Soils As Affected By Management Practices , Mine Ekenler Jan 2002

Enzyme Activities In Soils As Affected By Management Practices , Mine Ekenler

Retrospective Theses and Dissertations

Studies were undertaken to investigate the long-term effects of lime application and tillage systems (no-till, ridge-till, and chisel plow) on soil microbial biomass C (Cmic) and N (Nmic) and the activities of glycosidases (alpha- and beta-glucosidases, alpha- and beta-galactosidases and beta-glucosaminidase); phosphatases (acid and alkaline phosphatases and phosphodiesterase); amidohydrolases (L-asparaginase, L-glutaminase, amidase, urease, and L-aspartase); and arylamidase at their optimal pH values. With the exception of acid phosphatase, which was significantly but negatively correlated, all other enzyme activities were significantly and positively correlated with soil pH values at four sites in Iowa. Delta activity/Delta pH values showed that among ...


Molecular Marker Analysis Of Seed Size In Soybean , Joseph Andrew Hoeck Jan 2002

Molecular Marker Analysis Of Seed Size In Soybean , Joseph Andrew Hoeck

Retrospective Theses and Dissertations

Seed size is an important attribute of soybean [Glycine max (L.) Merr.] for some food uses. The objectives of this study were to identify markers associated with quantitative trait loci for seed size (SSQTL), determine the influence of the environment on expression of the marker-SSQTL associations, and compare the efficiency of phenotypic selection and marker-assisted selection for the trait. Three small-seeded lines were crossed to a line or cultivar with normal seed size to form three two-parent populations. The parents of the populations were screened with 178 simple sequence repeat (SSR) markers to identify polymorphism. Population 1 (Pop 1) had ...


Backcross Introgression And Two-Stage Testing For Conversion Of Improved Tropical Germplasm To Temperate Environments , Freeman Callaway Whitehead Jan 2002

Backcross Introgression And Two-Stage Testing For Conversion Of Improved Tropical Germplasm To Temperate Environments , Freeman Callaway Whitehead

Retrospective Theses and Dissertations

The use of exotic maize (Zea mays L.) germplasm, particularly of tropical and subtropical adaptation, has been suggested to increase genetic variability and grain yield of maize breeding material in temperate environments. Lack of adaptation to temperate areas and photoperiod sensitivity may mask desirable traits and reduce breeding progress. The objectives of this study included two-stage evaluation and selection of segregating families in the central U.S. Corn Belt derived from the backcross introgression of previously improved tropical CIMMYT germplasm into adapted, elite U.S. Corn Belt germplasm. The U.S. Corn Belt heterotic patterns of Stiff Stalk and non-Stiff ...


Genetic Analysis Of Reproductive Traits In Soybean [Glycine Max (L) Merr] , I. Made Tasma Jan 2001

Genetic Analysis Of Reproductive Traits In Soybean [Glycine Max (L) Merr] , I. Made Tasma

Retrospective Theses and Dissertations

The objectives of this study were to: (1) estimate the number of genes controlling photoperiod insensitivity in soybean; (2) map quantitative trait loci controlling flowering time, maturity, and photoperiod insensitivity in soybean; (3) map homologous and cloned flowering time gene sequences in soybean; (4) correlate these sequences with maturity (E) loci by means of near isogenic lines (NILs). Three populations, two F 6:7 recombinant inbred lines of 101 and 100 progeny and an F2:4 G. max x G. soja population (60 progeny), were used. Forty-one NILs were also included. At least three genes were proposed to control photoperiod ...


Response To S1 Recurrent Selection And Estimation Of Genetic Parameters In Effective Population Sizes Of The Bs11 Maize Population , Kebede Mulatu Ponta Jan 2001

Response To S1 Recurrent Selection And Estimation Of Genetic Parameters In Effective Population Sizes Of The Bs11 Maize Population , Kebede Mulatu Ponta

Retrospective Theses and Dissertations

Recurrent selection is a cyclical breeding technique that has become popular in comprehensive maize improvement strategies. The magnitude of response in recurrent selection depends upon the modes of gene action and their frequencies in effective population sizes. We studied four effective population sizes with the objectives: (1) to estimate response to selection and inbreeding effects, (2) to partition the response to selection into that due to additive and dominance genetic components, and (3) to examine changes in the correlated traits. Four effective population sizes 5, 10, 20, and 30 were developed by S1-progeny selection in the BS11 maize population using ...


The 1dx5 High Molecular Weight Subunit Gene From Wheat In Transgenic Maize , Varaporn Sangtong Jan 2001

The 1dx5 High Molecular Weight Subunit Gene From Wheat In Transgenic Maize , Varaporn Sangtong

Retrospective Theses and Dissertations

We have developed a method for detecting a transgene and its protein product in maize endosperm that allows the kernel to be germinated after analysis. Our method involves first sampling the endosperm with a hand-held rotary grinder. This tissue is then serially extracted for phenotypic analysis by SDS-PAGE with visualization by total protein staining or immuno-blot detection and genotypic analysis by PCR reactions to detect the transgene. This method is useful for screening transgenic kernels in breeding experiments. We have produced transgenic maize plants containing a wheat Glu-1Dx5 gene encoding the high molecular weight glutenin subunit 1Dx5. Analysis by SDS-PAGE ...


Evaluation Of Recurrent Selection In Leaming And Midland Maize Populations , Marcelo Javier Carena Jan 1999

Evaluation Of Recurrent Selection In Leaming And Midland Maize Populations , Marcelo Javier Carena

Retrospective Theses and Dissertations

Rates of maize (Zea mays L.) yield improvement in the United States has been reduced during the 1990's. Double-cycle breeding in a few old inbred lines and limited germplasm evaluation and utilization are possible explanations. Only one heterotic pattern (Iowa Stiff Stalk Synthetic x Lancaster Sure Crop) is being widely exploited in U.S. dent maize breeding programs. Alternative U.S. heterotic patterns have been suggested, but they received limited attention and improvement. The objectives of this research were to evaluate inbred-progeny recurrent selection in Leaming (originated in Ohio), the oldest known U.S. open-pollinated variety, and Midland Yellow ...


Assessment Of Plant Introductions For Increasing The Genetic Variability Of Soybean Populations , James Mark Narvel Jan 1999

Assessment Of Plant Introductions For Increasing The Genetic Variability Of Soybean Populations , James Mark Narvel

Retrospective Theses and Dissertations

Plant introductions (PIs) may increase the genetic variability of soybean populations and lead to greater genetic gains from selection. Five soybean populations containing different percentages of PI parentage were developed at Iowa State University to evaluate the use of PIs for increasing genetic variability for seed yield in a recurrent selection program. The objective of this study was to evaluate the performance and genetic variability of the Cycle 4 (C4) populations of AP 10 (100 % PI), AP 11 (75 % PI), AP12 (50 % PI), AP13 (25 % PI), and AP14 (0 % PI) for agronomic traits and seed composition. Multiplexing technology for simple ...


Selection For Soybean Seed Yield With Molecular Markers , Joseph Richard Byrum Jan 1999

Selection For Soybean Seed Yield With Molecular Markers , Joseph Richard Byrum

Retrospective Theses and Dissertations

Molecular markers may facilitate the identification of and selection for quantitative trait loci (QTL) that control economically important traits. The objective of the study was to compare the efficiency of selection among soybean [Glycine max (L.) Merrill] lines for seed yield based on single replication progeny-row-yield tests (PRYT), molecular marker loci selected by pedigree analysis, and a combination of PRYT and molecular marker data. A total of 380 random F3-derived lines from three populations were evaluated in the PRYT at Ames, IA, in 1997 and were genotyped for simple sequence repeats (SSRs) that had been chosen by pedigree analysis for ...


Genetic Analysis Of Quantitative Trait Loci With The Early Generations Of An Elite, Single-Cross Maize Population , Dwi Asmono Jan 1998

Genetic Analysis Of Quantitative Trait Loci With The Early Generations Of An Elite, Single-Cross Maize Population , Dwi Asmono

Retrospective Theses and Dissertations

The first objective of this study was to detect QTLs affecting agronomically important traits in the F2 plants of an elite, single-cross of maize (Zea mays L.). The second objective was to compare QTL detection in the F2 and F2:3 generations. The third objective was to compare QTL detection in two samples of F2:3 lines derived from the same F2 population;Thirty-eight QTLs affecting five traits were identified in the F2 plants. The QTLs were associated with 6 to 43% of the phenotypic variation. QTLs explaining more than 40% of the variation were observed for plant height and ...


Genetic Analysis Of Quantitative Trait Loci With Inbred And Hybrid Progeny Of Maize , David Frederick Austin Jan 1997

Genetic Analysis Of Quantitative Trait Loci With Inbred And Hybrid Progeny Of Maize , David Frederick Austin

Retrospective Theses and Dissertations

The first objective of this study was to compare quantitative trait loci (QTL) detection in two climatically diverse environments in a population of F6:7 lines of an elite maize (Zea mays L.) single-cross. The second objective was to detect QTL for general (GCA) and specific (SCA) combining ability effects in hybrid progeny of F2:3 and F6:8 lines from the same population. Evaluations of both inbred per se and hybrid progeny from the same population enabled comparisons between QTL controlling the two progeny types;The results from the F6:7 inbred progeny evaluations suggest that QTL detection can ...


Molecular Marker Analysis Of Iron Efficiency In Soybean (Glycine Max (L.) Merr.) , Shun-Fu Lin Jan 1996

Molecular Marker Analysis Of Iron Efficiency In Soybean (Glycine Max (L.) Merr.) , Shun-Fu Lin

Retrospective Theses and Dissertations

The objectives of the studies were to map genes affecting iron deficiency chlorosis in soybean, to test the hypothesis that two genetic mechanisms control iron deficiency chlorosis in soybean, and to determine the effectiveness of nutrient solution evaluation for iron deficiency chlorosis in soybean. Chlorosis symptoms of one hundred and twenty F2:4 lines from a Pride B216 x A15 population, and 92 F2:4 lines from an Anoka x A7 population grown in a field of calcareous soil in 1993 and 1994 were evaluated by visual scores and spectrometric chlorophyll determinations. Each population also was evaluated separately with two ...


Rflp Mapping Of Quantitative Trait Loci For Reproductive, Morphological, And Seed Traits Of Soybean (Glycine Max L.) Across Environments , Heike Kross Jan 1995

Rflp Mapping Of Quantitative Trait Loci For Reproductive, Morphological, And Seed Traits Of Soybean (Glycine Max L.) Across Environments , Heike Kross

Retrospective Theses and Dissertations

Quantitative trait loci (QTL) and QTL x environment interaction were identified for 11 agronomic traits in soybean, when measured at two locations in each of two years in Iowa. The segregating population consisted of 76 F[subscript]2:5/F[subscript]2:6 families derived from the cross between the two soybean (Glycine max (L.) Merr.) cultivars 'Minsoy' (PI27.890) and 'Noir 1' (PI 290.136). A genetic linkage map consisting of 81 markers in 25 linkage groups was used to locate QTL by interval mapping. Analyses of variance was performed on 72 linked and unlinked markers to test for ...


Restriction Fragment Length Polymorphism In Sorghum (Sorghum Bicolor (L.) Moench): Characterization Of Genetic Diversity And Quantitative Trait Loci , Dario Ahnert Jan 1995

Restriction Fragment Length Polymorphism In Sorghum (Sorghum Bicolor (L.) Moench): Characterization Of Genetic Diversity And Quantitative Trait Loci , Dario Ahnert

Retrospective Theses and Dissertations

Restriction fragment length polymorphisms (RFLPs) were employed to investigate genetic diversity and quantitative trait loci (QTL) for morphological characters on sorghum (Sorghum bicolor (L.) Moench). The objectives of this research were accomplished by studying two different sets of genotypes. One set was composed of 105 elite inbred lines (47 B- and 58 R-lines) and the other of 152 F[subscript]2:3 lines. In the R- and B-lines set, the objectives were to define the level of genetic similarity (GS) and relationships within these lines. In the 152 F[subscript]2:3 lines set, the objectives were to characterize QTL ...


Parent Selection To Maximize Heterosis Expression In Soybean (Glycine Max L. [Merr.]) , Francisco Jonathan Cerna Jan 1992

Parent Selection To Maximize Heterosis Expression In Soybean (Glycine Max L. [Merr.]) , Francisco Jonathan Cerna

Retrospective Theses and Dissertations

Utilization of heterosis effects in breeding soybean (Glycine max (L.) Merr) cultivars for commercial production is still a possibility. One objective of this research was to determine heterosis expression in soybean germplasms obtained from the crossing of parents selected on the basis of restriction fragment length polymorphism (RFLP) diversity and isozyme loci (ISO) constitution compared to parents selected for high-yielding (HY) ability and differences in geographic origin (GO). The second objective was to compare mean heterotic performance of F[subscript]1 hybrids and F[subscript]2 bulks evaluated in hill- and row-plots;Twenty-one genotypes of each of Maturity Groups (MG ...


Cell-Wall Components And Lignin Biosynthesis In Forages , James Enderby Bidlack Jan 1990

Cell-Wall Components And Lignin Biosynthesis In Forages , James Enderby Bidlack

Retrospective Theses and Dissertations

Lignin is the major cell-wall (CW) component that lowers forage digestibility. Negative relationships between lignin and forage quality are caused by interactions and variability of lignin with other CW components. This study was conducted to better understand how lignin content, concentration, deposition, and change in concentration vary with other CW components in maturing stems and to provide preliminary information about phenylpropanoid metabolism in relation to lignification;Regrowth from basal stem tissue was sampled weekly or biweekly from greenhouse-grown forage grass and legume species. Samples were collected for a period of about 8 weeks and analyzed for fiber concentration and content ...


Studies On Nitrogen Accumulation, Fiber Chemistry, And In Vitro Digestibility Of Alfalfa , Kenneth Adrian Albrecht Jan 1983

Studies On Nitrogen Accumulation, Fiber Chemistry, And In Vitro Digestibility Of Alfalfa , Kenneth Adrian Albrecht

Retrospective Theses and Dissertations

Alfalfa is a high quality forage and also provides a nitrogen (N) benefit to following nonlegume crops. This study examined growth habit and harvest schedule effects on in vitro digestibility of forage; yield and N accumulation of forage, stubble, crowns, and roots; and structural polysaccharide composition and in vitro digestibility of leaves and stems;Six cultivars varying in growth habit were harvested each time they reached the bud, first-flower, mid-flower, or early-pod stage of development. With winter-dormant cultivars, greatest 2-year forage, root, crown, and in vitro digestible dry matter yields were obtained by using the mid-flower cutting schedule. Greatest 2-year ...


Photoinactivation Of Catalase And Some Other Porphyrins In An Albino Mutant Of Corn (W3) And Sarcina Lutea , Roger Lowry Mitchell Jan 1961

Photoinactivation Of Catalase And Some Other Porphyrins In An Albino Mutant Of Corn (W3) And Sarcina Lutea , Roger Lowry Mitchell

Retrospective Theses and Dissertations

No abstract provided.


Some Effects Of Limestone And Hydrated Lime On Bio-Chemical Activities In Acid Soils , Henry Dorsey Jan 1926

Some Effects Of Limestone And Hydrated Lime On Bio-Chemical Activities In Acid Soils , Henry Dorsey

Retrospective Theses and Dissertations

No abstract provided.