bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of digital image analysis, viability stains, and germination assays to estimate conventional and glyphosate‐resistant cotton pollen viability
Authors: Pline Wendy A. , Edmisten Keith L. , Oliver Tim , Wilcut John W. , Wells Randy , Allen Nina S. 
Published: July 2010

AbstractBecause the success of labor‐intensive hand crosses by breeders is dependent upon pollen viability, quick, simple, and inexpensive methods for viability assessment are of interest. Four such cotton pollen viability assays were compared to determine differences in viability estimates, and relative accuracy by correlation to seed set. The methods compared were Brewbaker & Kwack (B & K) medium, B & K medium plus aniline blue, a fluorochromatic reaction method (FCR), and Alexander's stain. Additionally, digital images of germinated pollen grains were analyzed by means of morphometry software to quantify pollen tube area per pollen grain, as a proposed additional method of assessing viability. Pollen from conventional, nontreated glyphosate‐resistant (GR) and glyphosate‐treated GR cotton (Gossypium hirsutum L.) plants was tested by each method. Glyphosate treatments to GR cotton reduced pollen viability and corresponding seed set in all methods tested. Pollen germination measured by the B & K method was most closely related to seed set per boll, while Alexander's stain gave the highest estimates of viability. The FCR method indicated that many pollen grains from glyphosate‐treated GR cotton were irregularly shaped and only partially flourescein diacetate (FD) stained. All methods tested showed similar high correlation (0.7–0.8) of pollen viability to seed set. Morphometric analysis of digital images of germinated pollen found the greatest pollen tube area to pollen grain ratio with B & K medium + 30 mM sucrose. Because the B & K method most closely predicted the linear magnitude of seed set reduction to reduced pollen viability, allowed the use of morphometry software analysis, and was one of the simplest and least equipment‐demanding methods, it may provide broad utility for those assessing cotton pollen viability.
Nitrogen Uptake and Utilization in Contrasting Nitrogen Efficient Tropical Maize Hybrids
Authors: Worku Mosisa , Bänziger Marianne , Erley Gunda Schulte auf'm , Friesen Dennis , Diallo Alpha O. , Horst Walter J. 
Published: July 2010

ABSTRACTMaize cultivars with improved grain yields under nitrogen (N) stress are desirable for sub‐Saharan African maize growing environments. This study assesses N uptake, N utilization, and the genotype × environment (G × E) interaction of 16 tropical maize (Zea mays L.) hybrids differing in grain yield under low‐N conditions. Hybrids were evaluated under low‐N, medium‐N, and high‐N at Harare, Zimbabwe, in 2003 and 2004 and at Kiboko, Kenya, in 2003. At maturity, N accumulation in the aboveground biomass ranged from 47 to 278 kg N ha−1 in various experiments. Grain yields ranged from 1.5 to 4.3 Mg ha−1 and 10.6 to 14.9 Mg ha−1 for the same experiments, respectively. Significant G × E interactions were observed which became more pronounced as the difference in N stress intensity between two environments increased. High grain yield under low‐N was consistently associated with higher postanthesis N uptake, increased grain production per unit N accumulated, and an improved N harvest index. Additive main effect and multiplicative interaction analysis identified hybrids with specific adaptation to either low‐N or high‐N environments. Several hybrids produced high yields under both low‐N and high‐N conditions. More detailed studies with these hybrids are required to examine the underlying physiological mechanisms contributing to the N‐use efficiency.
Agronomic Performance of Striga Resistant Early‐Maturing Maize Varieties and Inbred Lines in the Savannas of West and Central Africa
Authors: Badu‐Apraku Baffour , Lum A. Fontem 
Published: July 2010

ABSTRACTThe potential maize (Zea mays L.) yield in the savannas of West and Central Africa (WCA) is constrained by Striga hermonthica (Del.) Benth. parasitism. Field trials at Ferkessedougou, Côte d'Ivoire; Abuja, Nigeria; and Mokwa, Nigeria, in 2002, and at Mokwa and Abuja in 2004, evaluated the performance of 11 early maturing maize varieties under artificial Striga infestation and Striga‐free conditions. Another trial at Mokwa and Abuja in 2004 evaluated 100 early maturing inbred lines under Striga infestation and Striga‐free conditions. The varieties differed significantly in grain yield under both conditions. Acr 94 TZE Comp 5‐W, Acr TZE Comp 5‐Y, and TZE‐W Pop × 1368 STR C1 were identified as promising varieties, based on grain yield, Striga damage ratings, and Striga emergence counts. The most promising variety, Acr 94 TZE Comp. 5‐W in terms of high grain yield, reduced Striga damage and low Striga emergence, outyielded the reference entry by 2% under Striga‐free conditions and 45% under Striga infestation. Ward cluster analysis of the varieties and inbred lines produced four major clusters each, under both Striga‐infested and Striga‐free conditions. In each case, the varieties and inbred lines assigned to each cluster under Striga infestation differed from those in the Striga‐free conditions. Several inbred lines with high grain yield, low Striga emergence and reduced Striga damage were identified as sources of Striga resistance for maize breeding programs in WCA.
Variation between Two Switchgrass Cultivars for Components of Vegetative and Seed Biomass
Authors: Boe Arvid 
Published: July 2010

ABSTRACTBiomass production potential in switchgrass (Panicum virgatum L.) populations is inversely related to latitude of origin. However, phenological adaptation limits the latitudinal range from which to select populations for breeding for biomass in the northern Great Plains. Objectives of this study were to compare patterns of biomass partitioning, determine importance of tiller density and size, and identify morphological traits as potential selection criteria for two cultivars, Summer (origin 40° 42′ N, 95° 52′ W) and Sunburst (origin 42° 42′ N, 96° 41′ W), of comparable phenology. Summer (12.6 Mg ha−1) produced 20% more vegetative biomass than Sunburst and had higher percent reproductive tillers (62% vs. 40%) and more phytomers tiller−1 (7.9 vs. 6.4). Sunburst had more tillers m−2 (677 vs. 530). Cultivars did not differ for seed biomass (311 kg ha−1), but seeds of Sunburst (1.8 mg seed−1) were 90% heavier than seeds of Summer. Vegetative biomass decreased acropetally among phytomers. Reproductive tillers per m2 and seed mass per panicle were accurate predictors of vegetative and seed biomass, respectively. Frequency of reproductive tillers, number of phytomers per tiller, and rate of phytomer development morphologically differentiated Summer and Sunburst and were potential selection criteria for improving biomass yield within a maturity class of switchgrass adapted to the northern Great Plains.
The Genetic Structure of a Maize Population: The Role of Dominance
Authors: Wardyn Brandon M. , Edwards Jode W. , Lamkey Kendall R. 
Published: July 2010

ABSTRACTThe combined effects of dominance and inbreeding on covariances between relatives are still poorly understood in maize (Zea mays L.) populations. Our objectives were to address the following questions: (i) What is the importance of dominance in a maize synthetic? (ii) How does inbreeding affect the genetic variance among individuals in a maize synthetic. (iii) How do the covariance parameters compare between populations? (iv) How does breeding design impact estimators? We estimated covariance components for inbred relatives in the maize synthetic BSCB1(R)C13. Previous estimates of covariance parameters have been used to explain the ineffectiveness of inbred progeny selection in the stiff‐stalk population BS13. We found that the dominance variance was larger than the additive variance for grain yield, whereas the additive variance was larger than the dominance variance for all other traits. Negative estimates of the covariance between additive and homozygous dominance deviations were found for all traits with the exception of traits associated with reproductive maturity, suggesting a negative relationship between inbred and outbred performance. The correlation between genotypic values and breeding values was lower for grain yield than for any other trait. Our results were similar to previous results found in the stiff‐stalk maize population BS13, suggesting similarity in structure among populations.
Application of Population Genetic Theory and Simulation Models to Efficiently Pyramid Multiple Genes via Marker‐Assisted Selection
Authors: Wang Jiankang , Chapman Scott C. , Bonnett David G. , Rebetzke Greg J. , Crouch Jonathan 
Published: July 2010

ABSTRACTBreeders face many complex choices in the design of efficient crossing and selection strategies aimed at combining desired alleles into a single target genotype. Both population genetic theory and a breeding simulation tool were used to study the effects of different strategies on population size and number of marker assays required to recover a target genotype in wheat (Triticum aestivum L.). Enriching the frequency of desirable alleles in the F2 of single‐cross and in the F1 of backcross and topcross populations greatly reduced the minimum required population size, but the gain from another enrichment selection is minor. General equations were developed to determine appropriate crossing strategies, and sequential culling was proposed to minimize total marker screening costs. For a topcross of three adapted lines from an existing breeding program, simulation of changes in allele frequencies at nine target genes (seven unlinked) showed that population size was minimized with a three‐stage selection strategy in the F1 generation of the topcross (TCF1), the F2 generation of the topcross (TCF2), and doubled haploid lines (DHs). Enrichment of allelic frequencies in TCF2 reduced the total number of lines screened from >3500 to <600. Eight of the genes were present at frequencies >0.97 after selection, while the tin reduced‐tillering allele was only at 0.77 in the final selected population due to its strong repulsion‐phase linkage to the grain quality gene Glu‐A3 in this cross and the incomplete linkage of the tin marker. Therefore, the presence of the tin gene needs to be further confirmed by other methods.
Effects of Solvent Retention Capacities, Pentosan Content, and Dough Rheological Properties on Sugar Snap Cookie Quality in Chinese Soft Wheat Genotypes
Authors: Zhang Qijun , Zhang Yong , Zhang Yan , He Zhonghu , Peña Roberto J. 
Published: July 2010

ABSTRACTDevelopment of soft wheat (Triticum aestivum L.) cultivars with excellent cookie quality is an important breeding objective in southern China. Seventeen Chinese soft wheat genotypes grown at three locations in the 2000–2001 and 2001–2002 seasons in the southern winter wheat region, were uniformly evaluated for their solvent retention capacities (SRC), pentosan content, dough rheology, and suitability for making sugar snap cookies, to identify the main parameters that could be used in wheat breeding programs for improving cookie quality. Significantly negative correlations were found between water SRC, sucrose SRC, and sugar snap cookie diameter, and between sodium carbonate SRC, alkaline water retention capacity (AWRC), and water soluble pentosan, while significantly positive correlations were obtained between water, sodium carbonate, lactic acid, and sucrose SRC and AWRC. Alveograph parameters were more closely associated with sugar snap cookie quality compared with parameters from farinograph and extensograph except for water absorption. Water SRC was highly and significantly associated with farinograph water absorption, extensograph extensibility, alveograph P (tenacity), and P/L (the ratio of tenacity and extensibility). Regression analyses showed that sucrose SRC and flour particle size could be used to predict the sugar snap cookie diameter. Cluster analysis based on sugar snap cookie diameter indicated that ‘Jianmai 1’, ‘Wanmai 19’, and ‘Wanmai 48’ were characterized by good cookie quality, with low water soluble and total pentosans, water and particularly sucrose SRC, water absorption, and P and P/L values. It also indicated that substantial progress for soft wheat sugar snap cookie quality improvement could be achieved through appropriate use of current elite germplasm.
Maize Kernel Moisture at Physiological Maturity as Affected by the Source–Sink Relationship during Grain Filling
Authors: Sala Rodrigo G. , Andrade Fernando H. , Westgate Mark E. 
Published: July 2010

ABSTRACTA wide range of values reported in the literature has precluded the use of grain moisture (GM) as an estimate of physiological maturity (PM) in maize (Zea mays L.). The reason for this variability in GM values remains unclear. Previous evidence suggests that the source–sink ratio could affect the dynamics of kernel water relations during grain filling and thus, GM at PM. To test this possibility, treatments were applied to manipulate the reproductive sink capacity or the assimilate availability during grain filling. Kernel dry weight, water content, and the dry weight to water content (D–W) ratio, were monitored throughout grain filling. A bilinear model relating dry weight and GM was used to estimate GM at PM for each treatment. Severely restricting source capacity during grain filling increased GM at PM. When the source capacity per kernel during grain filling was increased, however, GM at PM was not affected. A single model (r2 = 0.99, p < 0.001) described the relationship between relative dry weight and GM for all hybrids and treatments without source reduction during grain filling. The estimated value of GM at PM for this model was 34.9%. These results suggest that calculating GM late in grain filling can provide a reliable estimate of PM when the source capacity has not been severely restricted. A value of 35% moisture would be adequate in these situations. The D–W ratio of developing kernels was similar across all source–sink treatments until PM. Premature cessation of grain filling caused by defoliation increased the D–W ratio as the kernels continued to desiccate.
Genetic Effects of Thirteen Gossypium barbadense L. Chromosome Substitution Lines in Topcrosses with Upland Cotton Cultivars: II. Fiber Quality Traits
Authors: Jenkins Johnie N. , McCarty Jack C. , Wu Jixiang , Saha Sukumar , Gutierrez Osman , Hayes Russell , Stelly David M. 
Published: July 2010

ABSTRACTThirteen chromosome substitution lines (CS‐B) lines with individual 3‐79 Gossypium barbadense L. chromosome or arms substituted into TM‐1, G. hirsutum L., were crossed with five Upland cultivars and additive and dominance effects for fiber micronaire, elongation, length, and strength were measured over four environments. Additive genetic effects were considerably larger than dominance or environmental interaction effects. Fiber strength of 3‐79 and FM966 were 282 and 240 kN m kg−1, respectively. FM966 had greater additive effects for fiber length (1.13 mm) and strength (12.90 kN m kg−1) than any CS‐B line; however, CS‐B25 had the greatest additive effects (8.97 kN m kg−1) for strength among CS‐B lines. The greatest negative additive effect for fiber length was −1.29 mm (CS‐B22sh). Although several CS‐B lines had negative additive effects on strength, none was more negative than TM‐1 (−5.31 kN m kg−1). CS‐B02 and CS‐B25 had additive effects on strength of 2.36 and 8.97 kN m kg−1 SG747 had the greatest negative additive effect (−12.13 kN m kg−1) for strength among cultivars and CS‐B lines. CS‐B07 and CS‐B18 had negative additive effects for fiber strength but had significant and positive dominance effects with FM966. When individual CS‐B lines were crossed with elite cultivars beneficial alleles for fiber properties were uncovered on specific chromosomes or chromosome arms that should aid introgression of alleles from 3‐79 into Upland.
Development of a PCR‐Based Molecular Marker to Select for Nematode Resistance in Peanut
Authors: Chu Y. , Holbrook C. C. , Timper P. , Ozias‐Akins P. 
Published: July 2010

ABSTRACTThe peanut root‐knot nematode [Meloidogyne arenaria (Neal) Chitwood race 1] is a significant pathogen on peanut (Arachis hypogaea L.). Nematode resistant cultivars would reduce yield losses while reducing the use of nematicides in fields where these nematodes occur. Through years of breeding effort, nematode resistance gene(s) have been introgressed into peanut cultivars from their wild relatives, Arachis spp. Molecular markers RKN440 and Z3/265, linked to the resistance gene, previously were identified by random amplified polymorphic DNA (RAPD) analysis. Unfortunately, when these markers were applied to our breeding programs, neither could give a reproducible level of correlation with the phenotype data. In this study, we modified the marker RKN440 based on more complete sequencing data and established a new nematode resistance dominant marker 197/909. This marker is reproducible and shows a high correlation with the phenotype data. It amplifies fragments from both susceptible and resistant samples, but of different molecular weights, avoiding false negative judgment caused by failed reactions with dominant markers. When we applied this marker using a cost‐effective, high‐throughput DNA extraction method, it remained a robust assay. Plant breeders will be able to use this new marker to hasten efforts to combine nematode resistance with other important characteristics in peanuts.
Assessment of Different Legumes for the Control of Striga hermonthica in Maize and Sorghum
Authors: Khan Zeyaur R. , Midega Charles A. O. , Hassanali Ahmed , Pickett John A. , Wadhams Lester J. 
Published: July 2010

ABSTRACTThe witchweed, Striga hermonthica (Del.) Benth., is a major constraint to maize (Zea mays L.) and sorghum [Sorghum bicolor (L.) Moench] production in sub‐Saharan Africa. Intercropping maize and sorghum with desmodium (Desmodium spp.) effectively controls Striga and enhances grain yields. Studies were thus conducted to assess the potential role of intercropping maize and sorghum with different food legumes for control of Striga Seasonal Striga counts in the intercrops, other than greenleaf desmodium where the counts consistently remained close to zero, were generally not significantly different from those in the control in both crops. A pooled analysis across seasons, however, showed that intercropping sorghum with cowpea [Vigna unguiculata (L.) Walp.], greengram [Vigna radiata (L.) Wilczek], and crotalaria (Crotalaria ochroleuca G. Don), and maize with crotalaria significantly reduced Striga populations. Within‐season analysis showed that it was only the greenleaf desmodium intercrop that maintained significantly enhanced grain yields relative to the control. On the other hand, multiseason analysis showed that it was only the crotalaria, cowpea, and greenleaf desmodium intercrops in maize and greenleaf desmodium intercrop in sorghum that significantly enhanced grain yields. These results indicate that intercropping sorghum with cowpea, greengram, or crotalaria and maize with crotalaria could be combined with other cultural methods for a sustainable control of S. hermonthica.
Changing the Support of a Spatial Covariate: A Simulation Study
Authors: Hooks Tisha , Pedersen Jeffrey F. , Marx David B. , Gaussoin Roch E. 
Published: July 2010

ABSTRACTResearchers are increasingly able to capture spatially referenced data on both a response and a covariate more frequently and in more detail. A combination of geostatisical models and analysis of covariance methods may be used to analyze such data. However, very basic questions regarding the effects of using a covariate whose support differs from that of the response variable must be addressed to utilize these methods most efficiently. In this experiment, a simulation study was conducted to assess the following: (i) the gain in efficiency when geostatistical models are used, (ii) the gain in efficiency when analysis of covariance methods are used, and (iii) the effects of including a covariate whose support differs from that of the response variable in the analysis. This study suggests that analyses which both account for spatial structure and exploit information from a covariate are most powerful. Also, the results indicate that the support of the covariate should be as close as possible to the support of the response variable to obtain the most accurate experimental results.
A High‐Density Map and PCR Markers for Russian Wheat Aphid Resistance Gene Dn7 on Chromosome 1RS/1BL
Authors: Lapitan Nora L. V. , Peng Junhua , Sharma Vinod 
Published: July 2010

ABSTRACTThe Russian wheat aphid (RWA) [Diuraphis noxia (Kurdjumov)] is an economically significant insect pest of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) in the USA. Since 1986, only one biotype existed in the USA. In 2003, a new biotype appeared which was virulent to all known resistance genes in wheat, with the exception of Dn7. Dn7 is a rye gene transferred into a wheat background via 1RS/1BL translocation. It was previously mapped; however, no PCR‐based markers were developed for marker‐assisted selection (MAS) and the map was sparse. This study presents a higher density map of Dn7 containing 19 markers. The markers spanning Dn7 are XHor2 and Xscb241 at distances of 1.4 and 1 cM, respectively, from Dn7 PCR markers were developed and tested on 19 wheat cultivars. Two markers which amplified rye‐specific fragments proved to be useful for MAS. Xrems1303 amplified a 320‐bp band only in cultivars with high‐level resistance to biotype 2 and is effective for MAS of Dn7. Xib267 is linked to the susceptible locus and amplified a fragment specific for rye Petkus 1RS and would be a good marker for selecting against the susceptible locus. The value of Dn7 as a source of resistance has increased because of the broad spectrum resistance it provides against several biotypes. The markers developed in this study will be useful for facilitating the transfer of Dn7 into wheat cultivars with or without translocation chromosomes containing 1RS.
Induction of Human β-Cell Proliferation and Engraftment Using a Single G1/S Regulatory Molecule, cdk6
Authors: Fiaschi-Taesch Nathalie M. , Salim Fatimah , Kleinberger Jeffrey , Troxell Ronnie , Cozar-Castellano Irene , Selk Karen , Cherok Edward , Takane Karen K. , Scott Donald K. , Stewart Andrew F. 
Published: July 2010

OBJECTIVE
Most knowledge on human β-cell cycle control derives from immunoblots of whole human islets, mixtures of β-cells and non-β-cells. We explored the presence, subcellular localization, and function of five early G1/S phase molecules—cyclins D1–3 and cdk 4 and 6—in the adult human β-cell.

RESEARCH DESIGN AND METHODS
Immunocytochemistry for the five molecules and their relative abilities to drive human β-cell replication were examined. Human β-cell replication, cell death, and islet function in vivo were studied in the diabetic NOD-SCID mouse.

RESULTS
Human β-cells contain easily detectable cdks 4 and 6 and cyclin D3 but variable cyclin D1. Cyclin D2 was only marginally detectable. All five were principally cytoplasmic, not nuclear. Overexpression of the five, alone or in combination, led to variable increases in human β-cell replication, with the cdk6/cyclin D3 combination being the most robust (15% versus 0.3% in control β-cells). A single molecule, cdk6, proved to be capable of driving human β-cell replication in vitro and enhancing human islet engraftment/proliferation in vivo, superior to normal islets and as effectively as the combination of cdk6 plus a D-cyclin.

CONCLUSIONS
Human β-cells contain abundant cdk4, cdk6, and cyclin D3, but variable amounts of cyclin D1. In contrast to rodent β-cells, they contain little or no detectable cyclin D2. They are primarily cytoplasmic and likely ineffective in basal β-cell replication. Unexpectedly, cyclin D3 and cdk6 overexpression drives human β-cell replication most effectively. Most importantly, a single molecule, cdk6, supports robust human β-cell proliferation and function in vivo.