bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic Diversity of a Maize Association Population with Restricted Phenology
Authors: Hansey Candice N. , Johnson James M. , Sekhon Rajandeep S. , Kaeppler Shawn M. , de Leon Natalia
Published: February 2011

Association analysis to identify genes and alleles underlying quantitative genetic variation is growing in value as the density of genotypic data increases. Association panels are often chosen to maximize molecular and phenotypic diversity, but traits measured at harvest require restricted phenology to obtain data on plants that mature within a comparable interval. The objective of this study was to characterize a set of inbred lines that will mature reliably in the upper midwestern United States for the purpose of assessing traits relevant to grain and stover yield as well as stover quality. A total of 1411 lines from the North Central Regional Plant Introduction Station, our program, and contributed by collaborators were grown in observation plots. A set of 627 lines were chosen based on flowering within the desired interval, production of viable seed, agronomic suitability, uniformity, and pedigree information. Flowering time ranged from 944 to 1645 growing degree days (GDD). Genotypic data for the 627 lines was obtained using a 1536 Illumina GoldenGate assay. The panel offers deep replication of most Midwest dent alleles. There is a lesser representation of tropical alleles relative to other association panels but includes some Germplasm Enhancement of Maize (GEM)‐derived lines and early flowering lines of tropical origin. The information described in this manuscript is anticipated to facilitate the use of this material for association genetic studies.
Strategies for the Development of Core Collections Based on Ecogeographical Data
Authors: Parra‐Quijano Mauricio , Iriondo José M. , de la Cruz Marcelino , Torres Elena
Published: February 2011

Ecogeographical data complement genotypic and phenotypic information on plant genetic resources and provide an alternative characterization when resources are scarce. Ecogeographical core collections can be created by directly characterizing georeferenced collecting sites or by assigning them categories from ecogeographical land characterization maps (CEM). Our objective was to determine the suitability of core collections based solely on ecogeographical data and the most appropriate combination of grouping and allocation methods in representativeness and simplicity. Using six Lupinus species as case studies and peninsular Spain and the Balearic Islands as workspace, we evaluated 16 ecogeographical core collections obtained by applying different grouping and allocation methods. Six core collection strategies met existing standard representativeness criteria and performed better than random selection of accessions. The Ward‐Modified Location Model (Ward‐MLM) and two‐step clustering (TSC) with proportional allocation strategy (P) produced the most representative core collections. Grouping according to CEM with P allocation also produced a highly representative core collection but through a simpler procedure. In conclusion, ecogeographical data can be used to create representative core collections with similar strategies to those used with genotypic or phenotypic data or simpler ones such as CEM, which is easy to apply and update.
Miniature Inverted‐Repeat Transposable Element Identification and Genetic Marker Development in Agrostis
Authors: Amundsen Keenan , Rotter David , Li Huaijun Michael , Messing Joachim , Jung Geunhwa , Belanger Faith , Warnke Scott
Published: February 2011

Creeping bentgrass (Agrostis stolonifera L.) is an important species to the turfgrass industry because of its adaptation for use in high quality turf stands such as golf course putting greens, tees, and fairways. Creeping bentgrass is a highly outcrossing allotetraploid, making genetic marker development difficult. Genetic markers anchored to miniature inverted‐repeat transposable elements (MITEs) were developed in Agrostis that could be used in genetic linkage mapping, quantitative trait loci studies, or diversity analyses. The FindMITE software program identified 495 candidate MITEs from 16,122 Agrostis DNA sequences. There was evidence of transposition in 79 of the candidate MITEs based on MITE insertional polymorphisms. Genetic markers were developed by MITE‐display, a modified amplified fragment length polymorphism technique that anchors amplified fragments to MITEs. Four MITE‐display primer combinations were tested on a creeping bentgrass experimental mapping population and 139 polymorphic markers were developed with a polymorphic information content of 0.33. Twenty‐eight of the polymorphic genetic markers segregated normally. MITE‐display genetic markers are a new class of genetic markers for studies of the Agrostis genome. These genetic markers target transposable elements and provide an easy method of identifying allelic variation between Agrostis accessions that may be used for diversity studies or genetic linkage map development.
Management‐Intensive Rotational Grazing Enhances Forage Production and Quality of Subhumid Cool‐Season Pastures
Authors: Oates Lawrence G. , Undersander Daniel J. , Gratton Claudio , Bell Michael M. , Jackson Randall D.
Published: February 2011

Management‐intensive rotational grazing is used by many farmers seeking to balance profitability, environmental stewardship, and quality of life. Productivity of pastures in much of the upper Midwest is limited to April through October, so promoting high quality forage production during the grazing season and for winter storage is critical to dairy and beef farm profitability. We conducted an experiment on pastures dominated by Kentucky bluegrass (Poa pratensisL.), orchardgrass (Dactylis glomerataL.), meadow fescue [Schedonorus pratensis(Huds.) P. Beauv.], perennial ryegrass (Lolium perenneL.), and white clover (Trifolium repensL.) to compare forage production, forage quality, and root production under management‐intensive rotational grazing, continuous grazing, haymaking, and land with no agronomic management. Rotational paddocks were grazed by cow‐calf pairs monthly for ∼2 d and then allowed to rest for ∼28 d. Plots designated for haymaking were harvested two times per growing season. Potential utilizable forage, quantified by incorporating the estimates of refused and nonutilized biomass, and relative forage quality were significantly greater under management‐intensive rotational grazing when compared to the other treatments. Root production in the surface 15 cm was significantly lower under both grazing treatments compared to the undefoliated control site. The perception of improved production has been used to advocate for rotationally grazed over continuously grazed systems in subhumid pasture, but experimental results have been equivocal. Our results point to managed grazing as a viable alternative to continuous grazing and haymaking in terms of both forage production and quality but not root production.
Effects of Nitrogen and 6‐Benzylaminopurine on Rice Tiller Bud Growth and Changes in Endogenous Hormones and Nitrogen
Authors: Liu Yang , Ding Yanfeng , Wang Qiangsheng , Meng Dexuan , Wang Shaohua
Published: February 2011

In the present study, 40 mg L−1 N (NH treatment) and 20 mg L−1 6‐benzylaminopurine (6‐BA; BA treatment) were used to stimulate tiller bud growth in rice (Oryza sativa L.). The hormone changes in the tiller nodes and tiller buds and the N levels in the leaf blades, leaf sheaths, and tiller nodes were measured. The results indicate that N and 6‐BA promoted tiller bud germination and increased the indole‐3‐acetic acid (IAA) and zeatin (Z) plus zeatin riboside (ZR) levels in tiller buds and tiller nodes but decreased the abscisic acid (ABA) levels in tiller buds. Before tiller bud germination, the IAA and Z plus ZR levels increased but the ABA did not change, suggesting that IAA and Z plus ZR but not ABA may be the key regulators of tiller bud growth. From 4 d posttreatment, the tiller bud growth of the BA‐treated plants markedly slowed but the buds of the NH‐treated plants continued to grow quickly. We also found that the N levels in the leaf blades, leaf sheaths, and tiller nodes of the NH‐treated plants increased significantly as compared to those of the control plants (the plants treated with 10 mg L−1 N). However, no significant differences in N levels were observed between the plants of BA and control treatments. This study suggests that N may regulate tiller bud growth in two ways: by regulating N metabolism and regulating endogenous hormones. External 6‐BA promoted tiller bud germination by regulating endogenous hormones, but tiller bud growth was not maintained because it could not increase the N levels in the plants.
Improving Birdsfoot Trefoil for Resistance to Fusarium Wilt
Authors: Miller‐Garvin J. E. , Hansen J. L. , Ehlke N. J. , Papadopoulos Y. A. , Smith R. R. , Bergstrom G. C. , Wunsch M. J. , Kalb D. W. , Tillapaugh B. P. , Crawford J. L. , Viands D. R.
Published: February 2011

Fusarium wilt (caused by Fusarium oxysporum f. sp. loti) is a serious disease of birdsfoot trefoil, Lotus corniculatus L., reducing yield of forage and seed. In the early 1990s a breeding program was begun to breed a Fusarium wilt‐resistant birdsfoot trefoil. Our objectives were to (i) determine progress from recurrent phenotypic selection for resistance to Fusarium wilt in six birdsfoot trefoil populations and (ii) compare forage yield and persistence of Fusarium wilt‐resistant populations to unselected populations in field trials. Recurrent phenotypic selection was effective in improving resistance in the greenhouse, with mean improvement of 35% across all populations after three cycles of selection. In a field with high natural disease pressure, a population developed after two cycles of selection for resistance had lower levels of disease incidence and yielded 1.33 Mg ha−1 more than the mean of nine cultivars in the seeding year. The Fusarium wilt‐resistant population had 52% higher plant stand than the mean of the other cultivars at the end of the first production year. In a trial inoculated with the Fusarium wilt organism, two cycle 3 populations averaged 28% more yield by June of the fourth production year and 22 more plants per m2 than the mean of the unselected populations. Birdsfoot trefoil with resistance to Fusarium wilt yielded more and persisted longer than other cultivars under Fusarium wilt‐infested field conditions.
Association Mapping for Enhancing Maize (Zea mays L.) Genetic Improvement
Authors: Yan Jianbing , Warburton Marilyn , Crouch Jonathan
Published: February 2011

Association mapping through linkage disequilibrium (LD) analysis is a powerful tool for the dissection of complex agronomic traits and for the identification of alleles that can contribute to the enhancement of a target trait. With the developments of high throughput genotyping techniques and advanced statistical approaches as well as the assembling and characterization of multiple association mapping panels, maize has become the model crop for association analysis. In this paper, we summarize progress in maize association mapping and the impacts of genetic diversity, rate of LD decay, population size, and population structure. We also review the use of candidate genes and gene‐based markers in maize association mapping studies that has generated particularly promising results. In addition, we examine recent developments in genome‐wide genotyping techniques that promise to improve the power of association mapping and significantly refine our understanding of the genetic architecture of complex quantitative traits. The new challenges and opportunities associated with genome‐wide analysis studies are discussed. In conclusion, we review the current and future impacts of association mapping on maize improvement along with the potential benefits for poor people in developing countries who are dependent on this crop for their food security and livelihoods.
Characterization of HMW Glutenin Subunits in Thinopyrum intermedium, Th. bessarabicum, Lophopyrum elongatum, Aegilops markgrafii, and Their Addition Lines in Wheat
Authors: Niu Z. X. , Klindworth D. L. , Wang R. R.‐C. , Jauhar P. P. , Larkin P. J. , Xu S. S.
Published: February 2011

High molecular weight (HMW) glutenin subunits (GSs) play an important role in determining end‐use quality in wheat (Triticum aestivum L.). They are also excellent protein markers for genotype identification. In this study, we analyzed the HMW‐GSs in Thinopyrum bessarabicum (Savul. and Rayss) Á. Löve, Th. intermedium (Host) Barkworth and D.R. Dewey, Lophopyrum elongatum (Host) Á. Löve, and A. markgrafii (Greuter) Hammer and genotyped eight sets of 44 disomic addition lines derived from these species in common wheat or durum wheat background using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) and urea/SDS‐PAGE. A total of 20 unique alleles for HMW‐GSs were identified from the alien species. Among the eight sets of addition lines, only four addition lines carried the HMW‐GSs derived from alien species. In the wheat–Th. intermedium chromosome 1Ai addition line TA3649, the HMW‐GSs encoded by Glu‐D1 were not expressed while the alien HMW‐GSs were present, indicating that the Glu‐D1 locus might be lost or the alien chromosomes might have silenced the expression of the Glu‐D1 alleles. The wheat–Th. intermedium chromosome 7Ai long arm ditelosomic addition line, TA3659, carried two sets of HMW‐GSs (1Dx4+1Dy12 and 1Dx5+1Dy10) encoded by the Glu‐D1 locus. The results in this study also provided information on the alien chromosome donors and wheat parents for some disomic addition lines. Such information is useful for the development of molecular markers that will facilitate the introgression of desirable genes from the alien chromosomes into wheat genomes. The identified novel HMW‐GS alleles may serve as new genetic resources for wheat quality improvement.
Evaluation of a Heterogeneous Population of Cotton (Gossypium hirsutum L.) Developed with Recurrent Mass Selection in an Ultradense Population
Authors: Hague S. , Smith C.W.
Published: February 2011

The pedigreed system is commonly used to develop improved genotypes of upland cotton (Gossypium hirsutum L.); however, this system can be resource intensive compared to mass selection methods. A project was initiated in 1995 to develop improved germplasm using recurrent mass selection in an ultradense plant population configuration. A composite population (CP) resulting from six cycles of selection was compared to two high‐performing cultivars at three plant population densities (203,858 plants ha−1, 101,929 plants ha−1, and 33, 975 plants ha−1). Traits of interest included lint yield, plant morphology, and fiber quality. Genotype had a significant effect on lint yield and fiber qualities. Population densities affected plant morphology. Lint yield potential of the CP was not competitive against cultivars at any of the three population densities. Fiber traits generally were unaffected by plant density. The CP was earlier maturing and plant height remained more constant across population densities in comparison to the two check cultivars. This type of recurrent mass selection system may be more effective if initial breeding lines with a high percentage of fixed alleles make up the initial population. The existing CP population may still have value as a source of individual plants with enhanced stress tolerance.
Shade and Traffic Tolerance Varies for Bermudagrass and Zoysiagrass Cultivars
Authors: Trappe Jon M. , Karcher Douglas E. , Richardson Michael D. , Patton Aaron J.
Published: February 2011

Bermudagrass (Cynodon spp.) and zoysiagrass [Zoysia spp. (Willd.)] are two of the most commonly used turfgrass species in the southern United States. Shade from trees is common on golf courses and limits turfgrass growth. Additionally, turfgrasses used on golf courses and sports fields are often subjected to traffic. The objective of this study was to evaluate shade and traffic effects on bermudagrass and zoysiagrass. Two shade treatments were imposed, full sun or 49% shade, using a light reducing fabric. A Cady Traffic Simulator was used to implement traffic stress. The cultivars with the highest coverage in shade without traffic were ‘Cavalier’, ‘Diamond’, ‘El Toro’, ‘Meyer’, ‘Palisades’, and ‘Zorro’ zoysiagrass, as well as ‘Princess 77’ and ‘Riviera’ bermudagrass. ‘Patriot’, ‘Tifsport’, and ‘Tifway’ bermudagrass and ‘Zenith’ zoysiagrass typically had the lowest coverage. Patriot bermudagrass and Zenith zoysiagrass consistently had the lowest coverage in shaded trafficked plots. El Toro, Palisades, and Zorro zoysiagrass as well as Princess 77, Riviera, Tifsport, and Tifway bermudagrass had the highest coverage (>72%) when trafficked under full sun for 4 wk. Coverage in shaded plots was decreased more from traffic than full‐sun plots. Riviera and Tifway bermudagrass had the most coverage after 6 wk of traffic in full sun. These studies identified cultivars of bermudagrass and zoysiagrass that perform better under reduced light and traffic stress.
Diallelic Nuclear Microsatellites for Diversity and Population Analyses of the Allotetraploid Creeping Bentgrass (Agrostis stolonifera)
Authors: Reichman Jay R. , Smith Bonnie M. , Londo Jason P. , Bollman Michael A. , Auer Carol A. , Watrud Lidia S.
Published: February 2011

Nine diallelic nuclear microsatellite loci were characterized and developed as markers for analyses of diversity and population biology in creeping bentgrass, Agrostis stolonifera L. (2n = 4x = 28, A2A2A3A3). They may also help with identification of bentgrass germplasm resources. Polymorphic loci were isolated from genomic libraries from A. stolonifera and from A. transcaspica Litv. (2n = 2x = 14, putative A3A3). Markers were characterized in 87 A. stolonifera individuals from six distinct population sources. Analysis of molecular variance indicated significant variation between crop and wild groups. Highly significant variation was observed among and within the six populations. Bayesian analyses with STRUCTURE resolved crop from wild genotypes and assigned individuals to clusters that corresponded to their sources, in agreement with principal coordinates analysis results. The markers also correctly identified intraspecific creeping bentgrass F1 hybrids. Cross‐species analyses were conducted on sexually compatible relatives A. gigantea R. (2n = 6x = 42, A1A1A2A2A3A3), A. capillaris L. (2n = 4x = 28, A1A1A2A2), and A. canina L. (2n = 2x = 14, A1A1 or possibly A2A2), plus A. transcaspica Seven markers were diallelic in A. gigantea Six of these markers were also diallelic in A. transcaspica, but not other species, suggesting that these loci are A3 genome specific. Results also support the hypothesis that A. transcaspica is the source of the A3 subgenome found in A. stolonifera and A. gigantea
A New Cheap and Efficient Single‐Grain Shatter Tester for Use in Rice Breeding
Authors: Lamo Jimmy , Tongoona Pangirayi , Okori Patrick , Derera John , Hendricks Roelof , Laing Mark
Published: February 2011

Grain shattering, also called grain shedding, is the relative ease with which rice (Oryza sativa L.) seed is dislodged from the pedicel at maturity. Several qualitative methods have been used to assess grain shattering and they tend to underestimate yield loss. Equipments available for quantitative assessment of grain shattering are mostly laboratory based. However, a recently developed prototype in Japan for fieldwork can be used, but the cost is prohibitive. An improved grain‐shattering tester that uses a hand‐held device has been developed and reported here. It is an improvement over the stationary laboratory device. It has the following modifications: a crocodile clip instead of a bench clamp and a helical spring for testing tensile material instead of tension gauge. The new device is affordable, handy for fieldwork, and effective for large experimental trials. This equipment was designed and developed at the University of KwaZulu‐Natal (UKZN) mechanical workshop (Pietmeritzburg, South Africa). Its efficiency was tested at the National Crops Resources Research Institute (NaCRRI) at Namulonge, Uganda. The efficiency was tested by first estimating yield loss in selected test plants using a method that involves shaking panicles. This finding was compared with the minimum force required to dislodge the grains using this new device and a high correspondence of R2 = 99.9% was found. This new equipment has therefore been recommended for field assessment of grain shattering.
Seed O2 Uptake and Germination of Cold‐Tolerant and Cold‐Intolerant Cultivars of Muskmelon
Authors: Edelstein Menahem , Welbaum Gregory E.
Published: February 2011

Muskmelon (Cucumis melo L.) is a warm‐season, frost‐sensitive crop that germinates poorly at low temperatures. The cold‐sensitive cultivar ‘Noy Yizre'el’ (NY) and the cold‐tolerant cultivar ‘Persia 202’ (P‐202) were compared at 15 and 25°C to determine how seed‐coat anatomy and O2 uptake affected low‐temperature germinability. A Clark‐type oxygen electrode was used to measure the O2 uptake of intact and decoated seeds through the gas phase. Scanning electron microscopy revealed pores on the surface and in the cross sections of seed coats of P‐202 but not NY. Both genotypes germinated at 25°C, but only intact P‐202 and decoated seeds of both genotypes germinated at 15°C. After 17 h of imbibition at 25°C, O2 uptake was 47% greater for intact seeds of P‐202 compared with those of NY. Removing the seed coat increased O2 uptake by 37 and 58% for P‐202 and NY, respectively, after 17 h of imbibition. At 15°C, the O2‐uptake rate of intact P‐202 seeds plateaued at a level 40% higher than that of NY after 80 h of imbibition. Removing the seed coat before imbibition at 15°C increased the O2 uptake of P‐202 and NY by 50 and 57%, respectively, compared with intact seeds. The seed coats of both cultivars restricted O2 uptake, but NY had a lower rate of uptake compared with P‐202 with or without the seed coat. The poor germination of NY at lower temperatures was related to lower O2 uptake by the embryo and to the restriction of O2 uptake by the seed coat.
Evaluation of USDA Soybean Germplasm Accessions for Resistance to Soybean Rust in the Southern United States
Authors: Walker D. R. , Boerma H. R. , Phillips D. V. , Schneider R. W. , Buckley J. B. , Shipe E. R. , Mueller J. D. , Weaver D. B. , Sikora E. J. , Moore S. H. , Hartman G. L. , Miles M. R. , Harris D. K. , Wright D. L. , Marois J. J. , Nelson R. L.
Published: February 2011

Soybean [Glycine max (L.) Merr.] resistance to soybean rust (SBR) caused by Phakopsora pachyrhizi could reduce reliance on fungicides to manage this disease. The objective of this study was to identify soybean germplasm with resistance to field populations of P. pachyrhizi in the United States. Field evaluations of 576 accessions from the USDA Soybean Germplasm Collection for resistance to SBR were conducted at seven locations in the southern United States between 2006 and 2008. Accessions from maturity groups (MG) 000 to X and North American susceptible check cultivars from each MG except X were rated for disease severity in all year–location environments, and for disease incidence, fungal sporulation, lesion type, and/or uredinia density in certain environments. While none of the accessions was immune in all environments, 64 were resistant in two or more locations each year that they were tested. Some accessions appeared to be more resistant in certain environments than in others. Of the original four Rpp genes described in the literature, Rpp1 provided the highest level of resistance, and among the accessions with uncharacterized Rpp genes, PI 567104B had the highest overall resistance across environments. The plant introductions confirmed to be resistant in these evaluations should be useful sources of genes for resistance to North American populations of P. pachyrhizi
Metabolic Changes During Cold Acclimation and Deacclimation in Five Bermudagrass Varieties. I. Proline, Total Amino Acid, Protein, and Dehydrin Expression
Authors: Zhang Xunzhong , Wang Kehua , Ervin E.H. , Waltz C. , Murphy T.
Published: February 2011

Bermudagrasses (Cynodon spp.) grown in the U.S. transition zone and other regions with a similar climate undergo cold acclimation in fall and deacclimation in spring. Physiological mechanisms of cold acclimation and deacclimation are not well documented or understood. This study investigated changes in quality, photochemical efficiency, N metabolite (proline, total amino acid [AA], and protein) content, and dehydrin expression during cold acclimation and deacclimation in five bermudagrass entries. One ecotype (GA‐851) and four cultivars (Patriot, Riviera, Tifway, and Princess‐77) were subjected to cold acclimation at 8/4°C (day/night; 10‐h photoperiod) for 28 d and then deacclimation at 10/5, 21/7, 23/8, and 26/14°C sequentially (11‐h photoperiod) for either 3 wk (standard deacclimation) or 1 wk (fast deacclimation treatment) at each temperature. In response to cold acclimation, turfgrass quality and photochemical efficiency declined, while proline, AA, protein, and abundance of 25 kDa dehydrin increased. Patriot and Riviera had higher levels of stolon proline, AA, protein, and abundance of 25 kDa dehydrin relative to Princess‐77 at the end of cold acclimation. Significant deacclimation occurred as temperature changed from 21/7 to 23/8°C. Patriot, GA‐851, and Tifway had greater turfgrass quality ratings and photochemical efficiency and also higher levels of N metabolites relative to Princess‐77 and Riviera during deacclimation. A similar response was observed with fast deacclimation treatment. The results suggest that selection and use of entries with higher levels of N metabolites during cold acclimation and deacclimation could improve bermudagrass persistence and spring green‐up in transition zone climates.
Metabolic Changes During Cold Acclimation and Deacclimation in Five Bermudagrass Varieties: II. Cytokinin and Abscisic Acid Metabolism
Authors: Zhang Xunzhong , Ervin E.H. , Waltz C. , Murphy T.
Published: February 2011

Bermudagrasses (Cynodon spp.) grown in the U.S. transition zone and other regions with a similar climate undergo cold acclimation in fall and deacclimation in spring. Physiological mechanisms of cold acclimation and deacclimation associated with freezing tolerance and spring green‐up are not well documented. This study investigated changes in cytokinin (t‐zeatin riboside [t‐ZR]) and abscisic acid (ABA) during cold acclimation and deacclimation in five bermudagrass entries in growth chambers. One ecotype (GA‐851) and four cultivars (Patriot, Riviera, Tifway, and Princess‐77) were subjected to cold acclimation at 8/4°C (day/night) for 28 d and then deacclimation at 10/5, 21/7, 23/8, and 26/14°C for either 3 wk (standard deacclimation) or 1 wk (fast deacclimation treatment). Stolon t‐ZR content declined while ABA content increased during cold acclimation. Patriot and Riviera had higher levels of stolon ABA relative to Princess‐77 at the end of cold acclimation. During deacclimation, t‐ZR increased as the temperature increased to 26/14°C, while ABA declined as the temperature increased from 10/5 to 21/7°C. Patriot, GA‐851, and Tifway had higher levels of t‐ZR relative to Riviera and Princess‐77. Abscisic acid level during cold acclimation may be associated with freezing tolerance, while cytokinin level during deacclimation may be associated with rate of spring green‐up of bermudagrass. The results suggest that selection and use of entries with higher levels of ABA during cold acclimation and cytokinin during deacclimation could improve bermudagrass winter survival and spring green‐up in transition zone climates.
DNA Profiling of Seed Parents and a Topcross Tester and its Application for Yield Improvement in Timothy (Phleum pratense L.)
Authors: Tanaka Tsuneki , Tamaki Hiroyuki , Cai Hong‐Wei , Ashikaga Kazunori , Fujii Hiroki , Yamada Toshihiko
Published: February 2011

Assessment of genetic diversity based on DNA profiling contributes to the selection of superior parents for heterosis. The objective of this study was to investigate how closely the yields of timothy (Phleum pratense L.) topcross progenies are related to the genetic diversity between their seed parents and the pollen tester parent ‘Aurora’, and to predict their yield potentials from the index based on simple sequence repeat (SSR) marker polymorphisms. Genetic diversity among 67 genotypes, which consisted of 16 plants of timothy cultivar Aurora, the pollen parent for topcross testers, and 51 clones derived from breeding populations was evaluated based on 28 SSR markers carrying 408 alleles. Genetic distance (GD) was estimated for all possible pairs of genotypes and then the mean of the GD estimates between each clone and Aurora (GDA) was also assessed to find the relationship between GDA estimates and yields of topcross progenies derived from all crosses between each clone and Aurora. The GDA estimates of the clones ranged from 0.653 to 0.756, and a correlation coefficient between the GDA estimates and yields of their topcross progenies was 0.675 (p < 0.001). These results strongly suggest that GD would provide reliable information on the yields of the assumed topcross progeny lines and that it will help breeders to accelerate yield improvements for a practical breeding program of timothy.
Mapping QTL for Agronomic Traits on Wheat Chromosome 3A and a Comparison of Recombinant Inbred Chromosome Line Populations
Authors: Ali M. Liakat , Baenziger P. Stephen , Ajlouni Zakaria Al , Campbell B. Todd , Gill K. S. , Eskridge K. M. , Mujeeb‐Kazi A. , Dweikat Ismail
Published: February 2011

Variation for wheat (Triticum aestivumL.) grain yield and agronomic traits was used to map quantitative trait loci (QTL) in a ‘Cheyenne’ (CNN) × [CNN (‘Wichita’ 3A)] recombinant inbred chromosome line (RICL) population consisting of 223 CNN(RICLs3A) and 7 check cultivars that were evaluated in six environments in Nebraska during 2005–2007. A chromosome 3A linkage map spanning 106 cM was constructed using 32 microsatellite markers. Composite interval mapping detected 19 QTL for seven agronomic traits that individually accounted for 4.6 to 16.8% of the phenotypic variation. Three small genomic segments, spanning 3.4, 5.3, and 5.3 cM, contained most of the QTL. Two yield QTL were detected in two environments and in data pooled over environments. For grain volume weight, a QTL was detected in five of the six environments while a plant height QTL was detected in all environments. Wichita (WI) alleles contributed to the increased trait values for yield, spikes per square meter, and grain volume weight, while CNN contributed alleles to the increased 1000‐kernel weight, plant height, and anthesis date. Both CNN and WI contained alleles for increased number of kernels per spike. The 223 CNN(RICLs3A) set had greater power to detect QTL than the two smaller subsets—128 CNN(RICLs3A) developed using doubled haploids and 95 CNN(RICLs3A) developed using recombinant monosomic lines. Neither of the subsets performed consistently better than the other in detecting QTL.
Changes in Yield and Yield Components of Single‐Cross Maize Hybrids Released in China between 1964 and 2001
Authors: Wang Tianyu , Ma Xinglin , Li Yu , Bai Dapeng , Liu Cheng , Liu Zhizhai , Tan Xianjie , Shi Yunsu , Song Yanchun , Carlone Mario , Bubeck David , Bhardwaj Hans , Jones Elizabeth , Wright Kevin , Smith Stephen
Published: February 2011

The objectives of this study were to (i) measure genetic gain using a set of maize (Zea mays L.) single‐cross hybrids that were widely used in Chinese maize production from 1964 to 2001, (ii) determine if there were changes in morphological characteristics, and (iii) examine the germplasm backgrounds of these hybrids. Yield trials were conducted for 3 yr, using a split‐plot design. Each hybrid was planted at three different densities in four locations, two locations each representing summer and spring corn areas. Mean rates of genetic gain were 52 kg ha−1 yr−1 when measured at the spring locations, 69 kg ha−1 yr−1 when measured at the summer locations, and 60 kg ha−1 yr−1 when measured across all locations. There was no significant effect of planting density on genetic gain. Genetic gain has been largely contributed by increased yield per plant and this strategy was reflected in changes in ear and plant morphology. Analyses of pedigree backgrounds showed continuing dependence on U.S. germplasm backgrounds, notably C103, Oh43, Mo17, and Iowa Stiff Stalk Synthetic (BSSS).
Searls Prairie Clover (Dalea searlsiae) for Rangeland Revegetation: Phenotypic and Genetic Evaluations
Authors: Bhattarai Kishor , Bushman B. Shaun , Johnson Douglas A. , Carman John G.
Published: February 2011

Few North American legumes are available for use in rangeland revegetation in the western USA, but Searls prairie clover [Dalea searlsiae (A. Gray) Barneby] is one that holds promise. Commercial‐scale seed production of this species could address the issues of unreliable seed availability and high seed costs associated with its wildland seed collection. To evaluate its utility for revegetation, we collected Searls prairie clover at 20 locations across Utah and Nevada. Amplified fragment length polymorphisms (AFLP) and morphological and phenotypic traits (measured in common‐garden plots) were used to clarify the role of evolutionary forces responsible for its genetic structure. Collections were evaluated for dry‐matter yield, inflorescence weight, number of inflorescences, plant height, foliage diameter, flowering date, acid‐detergent fiber, neutral‐detergent fiber, and crude protein at two common‐garden locations in northern Utah. Collections from southern Utah and eastern Nevada exhibited high phenotypic values, whereas collections from western Nevada and northwestern Utah had low phenotypic values. Collections from northwestern Utah were genetically differentiated from those of southern Utah and Nevada via AFLP markers. Strong isolation by distance between collections suggests that genetic drift and gene flow are important factors in determining population structure in Searls prairie clover.
High‐Throughput Sensing of Aerial Biomass and Above‐Ground Nitrogen Uptake in the Vegetative Stage of Well‐Watered and Drought Stressed Tropical Maize Hybrids
Authors: Winterhalter Loïc , Mistele Bodo , Jampatong Sansern , Schmidhalter Urs
Published: February 2011

The measurement of agronomical parameters of maize (Zea maysL.) indicating its biomass and nutritional status provides important information to understand its responses to the environment. The detection of significant differences among maize hybrids would be very useful in plant breeding programs screening for N uptake and drought tolerance. The aim of the study was to assess the efficacy of high‐throughput sensing measurements to determine the aerial biomass and N uptake of tropical maize hybrids grown in well‐watered (control) and drought stress treatments. Experiments were conducted at the National Corn and Sorghum Research Center in Thailand in the years 2007 through 2009. High‐throughput canopy reflectance measurements using spectral indices from the literature and newly developed for this study were performed regularly along with biomass samplings until flowering. The relationship of the spectral indices with each of aerial biomass and N uptake had coefficients of determination of up to 0.8 and were also able to distinguish between drought stress levels. Through most sampling dates and stress levels, varieties were similarly classified in their amount of aerial biomass and N uptake by destructive and noncontacting measurements. Our results support the possibility of incorporating these methods in the development of high‐throughput phenotyping techniques that could prove to be potentially useful for future plant breeding.
Drying of green bean and okra under solar energy
Authors: Doymaz İbrahim
Published: February 2011

In this study, sun drying behaviours of green bean and okra were
investigated. Drying experiments were conducted in Iskenderun-Hatay, Turkey.
The drying study showed that the times taken for drying of green bean and
okra from the initial moisture contents of 89.5% and 88.7% (w.b.) to final
moisture content of around 15?0.5% (w.b.) were 60 and 100 h in open sun
drying, respectively. The constant rate period is absent in drying curves.
The drying process took place in the falling rate period. The drying data
were fitted to thirteen thin-layer drying models. The performance of these
models was investigated by comparing the determination of coefficient (R2),
reduced chi-square (c2) and root mean square error (RMSE) between the
observed and predicted moisture ratios. Estimations by Approximation of
diffusion (for green bean) and Midilli et al. models (for okra) were in good
agreement with the experimental data obtained.
Antithyroid activity of some 6-(alkylsulfanyl)-9H-purines
Authors: Ismat Fatima , Munawar Munawar , Tasneem Affia , Jahan Sarwat , Khan Mibahul , Ahmed Shakeel
Published: February 2011

Some alkyl and aryl derivatives of 9H-purine-6-thiol were synthesized and
evaluated in vitro and in vivo for potential antithyroid effects.
Spectrophotometric studies demonstrated 1:1 charge transfer complexation
between iodine and these compounds with quite high values of the formation
constants. The blood assays of rats treated with these compounds revealed
significant antithyroid activity for almost all the compounds, which was
further supported by a histological study of the thyroid tissues of the
animals. These compounds are expected to provide less toxic alternative of
the existing medicines as the sulfa group, which is known to be a cause of
toxicity of many drugs, is blocked by alkyl/aryl substituents.
Interaction of Onset and Duration of Diabetes on the Percent of GAD and IA-2 Antibody–Positive Subjects in the Type 1 Diabetes Genetics Consortium Database
Authors: Tridgell David M. , Spiekerman Charles , Wang Richard S. , Greenbaum Carla J.
Published: February 2011

OBJECTIVE

GAD antibodies (GADA) are more common in type 1 diabetic subjects diagnosed at an older age, whereas insulinoma-antigen 2 antibodies (IA-2A) are more common in subjects with younger onset. The prevalence of both antibodies decreases with longer duration of type 1 diabetes. We evaluated the interaction between age of diagnosis (onset) and duration of diabetes on the percentage of GADA- and IA-2A–positive subjects.

RESEARCH DESIGN AND METHODS

Data were used from 5,020 individuals with type 1 diabetes obtained from the Type 1 Diabetes Genetics Consortium dataset. The percentages of GADA- and IA-2A–positive subjects were modeled with duration as the continuous independent variable using a modified spline.

RESULTS

Within the first 5 years from diagnosis, 19.4% of individuals (median age 13 years) had neither GADA nor IA-2A, and by 6 to 13 years after diagnosis (median age 18 years), 31.7% were antibody-negative. There was no significant interaction between onset of disease and duration of diabetes for IA-2A (P = 0.30). The interaction was significant for GADA (P = 0.0002), resulting from differences in subjects diagnosed at or older than age 14. For these individuals, there was no apparent effect of duration of disease on the percentage of GADA-positive subjects within the first 5 years of diagnosis.

CONCLUSIONS

Onset and duration of diabetes both have an important effect on antibody status. The interaction of onset and duration on GADA positivity, but not on IA-2A, suggests differences in biology. These data provide a context for clinicians to interpret results of autoantibody testing in clinical practice.
The Prevalence of Metabolic Syndrome and Determination of the Optimal Waist Circumference Cutoff Points in a Rural South African Community
Authors: Motala Ayesha A. , Esterhuizen Tonya , Pirie Fraser J. , Omar Mahomed A.K.
Published: February 2011

OBJECTIVE

To determine the prevalence of metabolic syndrome and to define optimal ethnic-specific waist-circumference cutoff points in a rural South African black community.

RESEARCH DESIGN AND METHODS

This was a cross-sectional survey conducted by random-cluster sampling of adults aged >15 years. Participants had demographic, anthropometric, and biochemical measurements taken, including a 75-g oral glucose tolerance test. Metabolic syndrome was defined using the 2009 Joint Interim Statement (JIS) definition.

RESULTS

Of 947 subjects (758 women) studied, the age-adjusted prevalence of metabolic syndrome was 22.1%, with a higher prevalence in women (25.0%) than in men (10.5%). Peak prevalence was in the oldest age-group (≥65 years) in women (44.2%) and in the 45- to 54-year age-group in men (25.0%). The optimal waist circumference cutoff point to predict the presence of at least two other components of the metabolic syndrome was 86 cm for men and 92 cm for women. The crude prevalence of metabolic syndrome was higher with the JIS definition (26.5%) than with the International Diabetes Federation (IDF) (23.3%) or the modified Third Report of the National Cholesterol Education Program Adult Treatment Panel (ATPIII) (18.5%) criteria; there was very good agreement with the IDF definition (κ = 0.90 [95% CI 0.87–0.94]) and good concordance with ATPIII criteria (0.77 [0.72–0.82]).

CONCLUSIONS

There is a high prevalence of metabolic syndrome, especially in women, suggesting that this community, unlike other rural communities in Africa, already has entered the epidemic of metabolic syndrome. Waist circumference cutoff points differ from those currently recommended for Africans.
On the extent of star countable spaces
Authors: Alas Ofelia , Junqueira Lucia , Mill Jan , Tkachuk Vladimir , Wilson Richard
Published: February 2011

For a topological property P, we say that a space X is star Pif for every open cover Uof the space X there exists Y ⊂ X such that St(Y,U) = X and Y has P. We consider star countable and star Lindelöf spaces establishing, among other things, that there exists first countable pseudocompact spaces which are not star Lindelöf. We also describe some classes of spaces in which star countability is equivalent to countable extent and show that a star countable space with a dense σ-compact subspace can have arbitrary extent. It is proved that for any ω
1-monolithic compact space X, if C
p(X)is star countable then it is Lindelöf.
Patching the Pipeline
Authors: Schultz P. Wesley , Hernandez Paul R. , Woodcock Anna , Estrada Mica , Chance Randie C. , Aguilar Maria , Serpe Richard T.
Published: February 2011

For more than 40 years, there has been a concerted national effort to promote diversity among the scientific research community. Yet given the persistent national-level disparity in educational achievements of students from various ethnic and racial groups, the efficacy of these programs has come into question. The current study reports results from a longitudinal study of students supported by a national National Institutes of Health–funded minority training program, and a propensity score matched control. Growth curve analyses using Hierarchical Linear Modeling show that students supported by Research Initiative for Science Excellence were more likely to persist in their intentions to pursue a scientific research career. In addition, growth curve analyses indicate that undergraduate research experience, but not having a mentor, predicted student persistence in science.
Who Benefits From Kindergarten? Evidence From the Introduction of State Subsidization
Authors: Dhuey Elizabeth
Published: February 2011

Over the past 70 years, all states in the United States began to publicly subsidize kindergarten using state revenue. The variation in adoption dates across states allows for a unique opportunity to measure the effectiveness of the largest early education program implemented in recent history. The significant, immediate increase in the availability of kindergarten within a state is used to identify the effect of enrollment in kindergarten. Hispanic children, non-English speakers, children from immigrant households, and children of low socioeconomic status benefit the most from the increased availability of kindergarten. Hispanic children with access to kindergarten are 17% less likely to be below grade for their age and earn wages 5% higher as adults.
Neurovascular structures adjacent to the lumbar intervertebral discs: an anatomical study of their morphometry and relationships
Authors: Arslan Mehmet , Cömert Ayhan , Açar Halil İbrahim , Özdemir Mevci , Elhan Alaittin , Tekdemir İbrahim , Tubbs R. Shane , Attar Ayhan , Uğur Hasan Çağlar
Published: February 2011

Object

Although infrequent, injury to adjacent neurovascular structures during posterior approaches to lumbar intervertebral discs can occur. A detailed anatomical knowledge of relationships may decrease surgical complications.

Methods

Ten formalin-fixed male cadavers were used for this study. Posterior exposure of the lumbar thecal sac, nerve roots, pedicles, and intervertebral discs was performed. To identify retroperitoneal structures at risk during posterior lumbar discectomy, a transabdominal retroperitoneal approach was performed, and observations were made. The distances between the posterior and anterior edges of the lumbar intervertebral discs were measured, and the relationships between the disc space, pedicle, and nerve root were evaluated.

Results

For right and left sides, the mean distance from the inferior pedicle to the disc gradually increased from L1–2 to L4–5 (range 2.7–3.8 mm and 2.9–4.5 mm for right and left side, respectively) and slightly decreased at L5–S1. For right and left sides, the mean distance from the superior pedicle to the disc was more or less the same for all disc spaces (range 9.3–11.6 mm and 8.2–10.5 mm for right and left, respectively). The right and left mean disc-to-root distance for the L3–4 to L5–S1 levels ranged from 8.3 to 22.1 mm and 7.2 to 20.6 mm, respectively. The root origin gradually increased from L-1 to L-5. The right and left nerve root–to-disc angle gradually decreased from L-3 to S-1 (range 105°–110.6° and 99°–108°). Disc heights gradually increased from L1–2 to L5–S1 (range 11.3–17.4 mm). The mean distance between the anterior and posterior borders of the intervertebral discs ranged from 39 to 46 mm for all levels.

Conclusions

To avoid neighboring neurovascular structures, instrumentation should not be inserted into the lumbar disc spaces more than 3 cm from their posterior edge. Accurate anatomical knowledge of the relationships of intervertebral discs to nerve roots is needed for spine surgeons.
Pedicle screw insertion in the thoracolumbar spine: comparison of 4 guidance techniques in the intact cadaveric spine
Authors: Alhabib Husam , Nataraj Andrew , Khashab Mohammed , Mahood James , Kortbeek Frank , Fox Richard
Published: February 2011

Object

Pedicle screw fixation is a mainstay of thoracolumbar stabilization. Screw insertion using anatomical landmarks and fluoroscopy is common but can be technically challenging and generally involves substantial exposure to ionizing radiation. Computerized navigation has been reported to improve accuracy but is expensive and complex. The authors undertook this study to evaluate these 3 methods in comparison with a fourth technique using standard cervical distractor screws to mark the entry point and trajectory.

Methods

Four cadaveric human spines were used for this study. After an initial CT scan, 34 pedicle screws were inserted in each intact spine from T-1 to L-5 using the following 4 screw insertion guidance techniques (1 technique per specimen): use of anatomical landmarks, use of cervical distractor screws and spot fluoroscopy, fluoroscopy-based navigation, and fluoroscopy- and CT-based navigation (using merged imaging data). Postprocedural CT and anatomical dissection were then performed to evaluate screw position for site and degree of breach.

Results

The cervical distractor screw method had a breach rate of 5.9% versus 29.4%, 32.4%, and 20.6% for use of anatomical landmarks, fluoroscopic navigation, and fluoroscopic-CT navigation, respectively (p < 0.05). There is also a significant association between degree of medial and distal breach and the method of screw insertion (p < 0.05).

Conclusions

Cervical distractor screws as pedicle markers offer favorable insertion accuracy and reduction of radiation exposure compared with the other 3 methods used in clinical practice.