bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification of Soybean Genotypes Resistant to Fusarium graminearum and Genetic Mapping of Resistance Quantitative Trait Loci in the Cultivar Conrad
Authors: Ellis Margaret L. , Wang Hehe , Paul Pierce A. , St. Martin Steven K. , McHale Leah K. , Dorrance Anne E. 
Published: August 2012

ABSTRACTFusarium graminearum, a necrotroph, has emerged as an important soybean [Glycine max (L.) Merr.] seedling pathogen in Ohio. An effective management strategy for seedling pathogens is host resistance; thus, the objectives of this research were to identify and characterize sources of resistance to F. graminearum. Twenty‐four soybean genotypes were screened for resistance using a rolled‐towel assay; seeds were inoculated with 2.5 × 104 macroconidia mL−1. A disease severity index (DSI) was calculated on the basis of the ratio of lesion length to total plant length at 7 days after inoculation. Five genotypes had high levels of resistance to F. graminearum, with DSIs ranging from 24 to 41.5%. These included the cultivar Conrad, which has high levels of partial resistance to the hemibiotroph, Phytophthora sojae. A population of 262 F6:8 recombinant inbred lines derived from a cross of Conrad × Sloan (susceptible) was then evaluated for resistance. The same rolled towel method was used, and resistance to F. graminearum segregated as a quantitative trait. The DSI ranged from 22 to 100% and the broad‐sense heritability estimate was 0.72. Four putative quantitative trait loci (QTLs) were identified from Conrad on chromosomes 8, 13, 15, and 16, and one putative QTL from Sloan mapped to chromosome 19. The putative QTLs identified in this population were not the same as those that confer resistance to P. sojae, which suggests that different loci are required for resistance to these two different types of seedling pathogens.
Assessment of Reliability of Secondary Traits in Selecting for Improved Grain Yield in Drought and Low‐Nitrogen Environments
Authors: Badu‐Apraku B. , Akinwale R.O. , Franco J. , Oyekunle M. 
Published: August 2012

ABSTRACTGrain yield of maize (Zea mays L.) has low heritability under low soil nitrogen (low N) and drought, necessitating the use of secondary traits with strong associations with yield for selection. A base index involving anthesis–silking interval, plant and ear aspects, ears per plant, and stay green characteristic is used for selection for yield under drought and low‐N stresses. Reports are contradictory on the reliability of stay green characteristic for selecting for yield under drought stress and of ears per plant and anthesis–silking interval in selecting for low‐N tolerance. Ninety extra‐early inbreds were evaluated for 2 yr at three locations in Nigeria under low N and drought to confirm reliability of stay green characteristic for selecting for drought tolerance and of ears per plant and anthesis–silking interval for low N. Plant aspect and plant and ear heights were identified as the most reliable traits for simultaneous selection for yield under low N and drought in the extra‐early inbreds. Stay green characteristic was unreliable for selecting drought tolerant genotypes while ears per plant and anthesis–silking interval were not among the reliable traits for selecting low‐N tolerant genotypes. Ear height, plant and ear aspects, and stay green characteristic were identified by both path–coefficient and genotype main effect plus genotype × environment interaction (GGE) biplot analyses as reliable for selecting for low N and ear aspect, plant height, and anthesis–silking interval for drought tolerance.
A Stable dw3 Allele in Sorghum and a Molecular Marker to Facilitate Selection
Authors: Barrero Farfan Ivan D. , Bergsma Benjamin R. , Johal Gurmukh , Tuinstra Mitchell R. 
Published: August 2012

ABSTRACTDwarfism plays a key role in adapting crops to high‐input production systems by contributing to improved lodging resistance and fertilizer efficiency. In sorghum [Sorghum bicolor (L.) Moench], four dwarfing mutations have been found that profoundly reduce the stalk height. Notable among these mutations is dwarf‐3 (dw3), even though the phenotype it confers is unstable. The objectives of this research were to identify and characterize a stable mutant allele of the dw3 locus. Polymerase chain reaction (PCR) was used to amplify a region of dw3 containing the 882 bp tandem duplication that is diagnostic for the unstable allele. Analyses of PCR fragments from dwarf sorghum accessions that lacked the duplicated region led to the identification of Tx2737 as a possible carrier of a novel mutant dw3 allele. Sequence analysis confirmed and revealed the presence of a 6 bp deletion in exon 5 of dw3 that eliminates two highly conserved amino acids, Q1275 and R1276, from the enzyme. The frequency of this allele in sorghum germplasm appears to be very low with only 1% of the accessions in the diversity panel exhibiting this deletion. Field trials demonstrated that this allele of dw3 produces a stable dwarf phenotype with no height mutants found in Tx2737 and KS19. The new allele has been coined dw3‐sd2. The discovery of dw3‐sd2 and a DNA marker assay to facilitate selection will provide an opportunity to replace the unstable dw3 allele currently used in most commercial sorghum hybrids through introgression of dw3‐sd2 into elite parent lines.
Genetic Diversity and Host Specificity of Fungal Endophyte Taxa in Fescue Pasture Grasses
Authors: Ekanayake Piyumi N. , Hand Melanie L. , Spangenberg German C. , Forster John W. , Guthridge Kathryn M. 
Published: August 2012

ABSTRACTA number of pasture and turf grass species form mutually beneficial symbiotic associations with endophytic fungal species. Within the fescue grasses, diploid meadow fescue (Festuca pratensis Huds.) interacts with Neotyphodium uncinatum while allohexaploid tall fescue (Festuca arundinacea Schreb.) has been reported to associate with Neotyphodium coenophialum and two other morphologically distinct taxa (Festuca arundinacea taxonomic groups 2 and 3 [FaTG‐2 and FaTG‐3]). The evolutionary history of hexaploid tall fescue is complex, as part of a species group with varying ploidy levels and exhibiting distinct ecogeographical morphotypes. To evaluate both naturally occurring variation and host grass taxon specificity, diversity was determined in collections representing multiple meadow fescue and tall fescue accessions. Initial screening with a minimal set of endophyte‐specific simple sequence repeat (SSR) genetic markers detected endophyte incidence in 33% of 701 tested accessions. Subsequent analysis identified N. coenophialum genotypes within Continental and rhizomatous hexaploid and octoploid tall fescue [F. arundinacea subsp. atlantigena (St.‐Yves) Auquier] accessions. Festuca arundinacea taxonomic group 2 and FaTG‐3 endophytes appeared to be restricted to Mediterranean hexaploid and decaploid tall fescue [F. arundinacea cirtensis (St.‐Yves) Gamisans] hosts. Endophytes of meadow fescue were confirmed as belonging to N. uncinatum. This study has elucidated host specificity of fescue endophyte taxa and supported models for host–symbiont coevolution. A substantial number of candidate novel endophytes have been identified that are suitable for metabolic characterization and deployment by inoculation in fescue breeding programs.
Perspective on Forage Legume Systems for the Tallgrass and Mixed‐Grass Prairies of the Southern Great Plains of Texas and Oklahoma
Authors: Butler T. J. , Muir J. P. 
Published: August 2012

ABSTRACTLegumes have potential to transfer fixed N to nonlegume crops via grazing or decomposition as well as improve production, seasonal distribution, nutritive value, soil structure, and fertility in forage systems. This article summarizes the legume establishment, management, and grazing production experiments conducted in the southern Great Plains. It attempts to give perspective on the current state of producer adoption and the potential for future research to improve legume adoption. Several medics (Medicago spp.) and clovers (Trifolium spp.) are compatible and can be established with tall fescue [Schedonorus arundinaceus (Schreb.) Dumort]; however, due to limited precipitation, these have not reliably regenerated. Hairy vetch (Vicia villosa Roth) required annual establishment and was not as economical as N fertilizer in the perennial grass systems, but it was profitable and comparable to the annual system with 112 kg N ha−1 by conventional fertilizer. Alfalfa (Medicago sativa L.) may have the greatest potential in the southern Great Plains with cool‐season perennial grass systems like tall fescue when planted in a checkerboard orientation. An alternative approach for utilizing legumes may be to limit grazing access in pure stands similar to a supplementation program during periods of limited forage production or quality. There is a need for greater research including germplasm and rhizobia evaluations, improved seed production, weed control, and grazing before producer adoption becomes widespread. Future research should address constraints including legume establishment, management practices that extend the life of legumes in forage systems, and appropriate economic analysis of proposed novel systems.
Quantitative Trait Loci for Waterlogging Tolerance in a Barley Cross of Franklin × YuYaoXiangTian Erleng and the Relationship Between Waterlogging and Salinity Tolerance
Authors: Zhou Meixue , Johnson Peter , Zhou Gaofeng , Li Chengdao , Lance Reg 
Published: August 2012

ABSTRACTBreeding for waterlogging tolerance is an important and challenging objective in high rainfall areas across many countries in the world, as evaluation of the tolerance in the field is difficult and not reliable. Molecular markers can be effectively used in a breeding program to indirectly select waterlogging tolerance. In this study, 172 doubled haploid (DH) lines originating from a cross of YuYaoXiangTian Erleng (YYXT) and ‘Franklin’ were used to identify the quantitative trait loci (QTL) controlling waterlogging tolerance. For the purpose of comparing QTL from different DH populations, a consensus map was constructed using six different populations. A total of four QTL were identified, which controlled 6.2 to 30.1% of the phenotypic variation. Among these QTL, one located on chromosome 6H was not identified in previous studies. Two of the QTL were located at similar positions to QTL for salinity tolerance that had been reported earlier. Further analysis showed some relationships between waterlogging and salinity tolerance. Therefore, waterlogging and salinity tolerance can be improved simultaneously by marker‐assisted selection.
Extra Long Staple Upland Cotton for the Production of Superior Yarns
Authors: Joy Kolbyn , Smith C. Wayne , Hequet Eric , Ed Hughs S. , Hague Steve 
Published: August 2012

ABSTRACTCotton (Gossypium spp.) fibers are produced primarily by G. hirsutum L., upland, and G. barbadense L., pima, or Extra Long Staple (ELS). Two ELS upland lines, developed by Texas AgriLife Research, along with ‘FiberMax 832LL’ (FM 832) and ‘DPL Pima HTO’ (Pima HTO), were grown in a randomized complete block design at College Station, TX, during 2007 and 2008. Subplots of spindle‐harvested seedcotton were ginned on a saw gin or roller gin with appropriate lint cleaning. High‐volume instrument (HVI) and Advanced Fiber Information System (AFIS) fiber parameters were determined. Combed 50‐Ne (English yarn count) and 80‐Ne yarns were produced. Upland ELS lines exhibited longer (p < 0.01) fibers than FM 832, but only TAM B182‐33 ELS produced fibers longer or equal (p < 0.01) to Pima HTO. Upland ELS lines produced stronger 50‐Ne ring‐spun yarns than FM 832 but not Pima HTO, which also produced stronger 80‐Ne ring‐spun yarn than the upland ELS lines. While roller ginning resulted in significantly higher micronaire, longer upper half mean length, more uniform fiber lengths, and longer upper‐quartile length than saw ginning among these genotypes, yarn parameters reported were not affected. All genotypes responded the same to ginning platform, suggesting that further development of the upland ELS trait will not dictate a change in ginning equipment for upland cotton. The upland ELS trait contributes to significantly improved upland yarn quality.
Grazing Management of Flaccidgrass Pastures in Autumn
Authors: Burns J.C. , Fisher D.S. 
Published: August 2012

ABSTRACT‘Carostan’ flaccidgrass (Pennisetum flaccidum Griseb.) is a perennial warm‐season grass with potential for pasture, but appropriate autumn (September to November) management is needed to maintain forage mass (FM) production and prevent declines in plant density. We evaluated 10 treatments over 3 yr consisting of an ungrazed control, four treatments with multiple grazing events (MG), four treatments with a single grazing event (SG), and one treatment grazed after frost. The winter residues after the treatments were greatest (P < 0.01) when ungrazed compared with the grazed treatments (3347 vs. 2265 kg ha−1) and differed (P ≤ 0.01) among and between (P < 0.01) the MG and SG treatments. Plant density decreased from 13 to 27% with 8 to 10 wk of regrowth before frost. Greater plant density decline (60%) occurred when plots were grazed three times and only allowed 4 wk of regrowth before frost. Total nonstructural carbohydrates (TNC) of ungrazed basal stems, crowns, and roots sampled in December were 158, 193, and 250 g kg−1, respectively, and when grazed were 124, 183, and 253 g kg−1, respectively. By April TNC had declined 56, 35, and 25%, respectively. Plant density was not related to autumn total FM, FM regrowth, or overwintering residue but was related (P ≤ 0.02) to TNC of December roots (r = 0.59) and TNC of April basal stems (r = 0.42), crowns (r = 0.61), and roots (r = 0.66). Allowing 6 wk of regrowth before frost minimized plant density losses for flaccidgrass.
Harvest Impacts on Alfalfa Stem Neutral Detergent Fiber Concentration and Digestibility and Cell Wall Concentration and Composition
Authors: Lamb JoAnn F. S. , Hans‐Joachim G. Jung , Riday Heathcliffe 
Published: August 2012

ABSTRACTAlfalfa (Medicago sativa L.) stem fiber concentration and digestibility, lignin, and polysaccharide composition impact energy availability for livestock and biofuel conversion. We evaluated stem neutral detergent fiber (NDF) concentration, 16‐ and 96‐h in vitro neutral detergent fiber digestibility (IVNDFD), total cell wall (CW) concentration, and proportions of Klason lignin (KL), cellulose (CEL), pectin (PEC), and hemicellulose (HC) in the cell wall for eight germplasms at two plant densities at two locations harvested at early bud (four cuts) and late flower (three cuts) for 2 yr. Growth environment influences at each harvest had the greatest impact on stem quality traits while plant density had no effect. Stem NDF, CW, and CEL were greater at late flower while 16‐ and 96‐h IVNDFD and PEC were greater at early bud. Stem KL and HC were variable but comparable at the two maturity stages. Correlations indicated that as NDF or CW increased, CEL increased, KL remained relatively constant, and 16‐ and 96‐h IVNDFD and PEC decreased. The large variability in response for stem quality traits suggested that to modify stem fiber and cell wall composition, alfalfa will need to be screened over several harvests to identify plants with consistent differences in stem quality.
Inheritance and Molecular Mapping of an Allele Providing Resistance to a Cowpea Mild Mottle‐Like Virus in Soybean
Authors: Brace Ryan C. , Fehr Walter R. , Graham Michelle A. 
Published: August 2012

ABSTRACTDamage to soybean [Glycine max (L.) Merr.] from a Cowpea mild mottle‐like virus (CPMMLV) (family Betaflexiviridae and genus Carlavirus) has been of increasing concern in Argentina, Brazil, Mexico, and Puerto Rico. Soybean cultivars and lines differing in their reaction to the virus have been identified. The first objective of our study was to determine the genetic basis of resistance and susceptibility of F1 plants and 100 F2–derived lines from the cross of ‘IA3023’ (resistant) × ‘IA3024’ (susceptible) using natural field infection in Puerto Rico and Mexico during 2011. All of the F1 plants were susceptible, and the segregation of F2–derived lines satisfactorily fit a ratio of 3 susceptible:1 resistant, which indicated that resistance was controlled by a recessive allele at a single locus. The second objective of our study was to determine the genetic location of the locus by genotyping 93 of the F2–derived lines. The molecular analysis identified a locus on chromosome 18 (linkage group G) at the same estimated genetic position as the marker BARCSOYSSR_18_0443 (89.8 cM). The locus was flanked by BARCSOYSSR_18_0456 (88.6 cM) and BARCSOYSSR_18_0458 (91.0 cM). The locus was designated Rbc1 and the resistance allele in IA3023 was identified as rbc1. Markers tightly linked to the Rbc1 locus can be used to select resistant progeny in segregating populations from crosses between resistant and susceptible parents.
Growth Regulators Improve the Intercrossing Rate of Cucumber Families for Recurrent Selection
Authors: Kumar Rakesh , Wehner Todd C. 
Published: August 2012

ABSTRACTCucumber (Cucumis sativus L.) populations for recurrent selection often are intercrossed after each cycle using bees (Apis mellifera) in isolation blocks to save the expense of hand labor. This experiment was conducted to determine whether the rate of natural outcrossing could be increased using growth regulators, plot size management, and node of fruit position for seed harvest. The experiment was a factorial in a randomized complete block design with 2 yr (1997 and 1998), two growth regulators (treated and none), two plot sizes (single plant hills and small plots), two nodes of harvest (crown and top), and four replications (six in 1998). Plots or hills were planted to white‐spined ‘Sumter’ and were surrounded by rows of black‐spined ‘Wisconsin SMR 18’ pollenizer. Plots or hills of Sumter were treated with ethrel to induce gynoecy, and pollenizer rows were treated with silver nitrate to induce androecy. Untreated isolation blocks remained monoecious. Progeny of the harvested white‐spined plants were planted the following year to evaluate spine color, with black‐spined plants indicating an outcross. Results showed that node of harvest had no effect on outcrossing rate. However, growth regulators and plot size had a significant effect. Treated small plots, treated hills, and untreated hills had high outcrossing rates (54%) relative to untreated plots (30%). Therefore, if families are to be intercrossed in isolation blocks, they should be treated with growth regulators for maximum outcrossing.
Diversity and Genetic Structure of a Collection of Spanish Durum Wheat Landraces
Authors: Ruiz Magdalena , Giraldo Patricia , Royo Conxita , Villegas Dolors , Aranzana M. Jose , Carrillo Jose M. 
Published: August 2012

ABSTRACTKnowledge of the genetic structure of germplasm collections is crucial for conservation and efficient use of genetic resources. This study assessed the diversity and genetic structure of a collection of landraces of Spanish durum wheat (Triticum turgidum L.) using several marker systems and correlated the diversity and agromorphological traits with geographic and climatic features. Analyzed genotypes were separated into nine populations, with moderate to great genetic divergence among them. The three subspecies dicoccon, turgidum, and durum present in the collection largely determined the clustering of the populations. Genotype variation was lower in dicoccon and turgidum than in durum. Genetic differentiation by the agroecological zone of origin was greater in dicoccon and turgidum than in durum. Diversity arrays technology markers revealed two geographic substructures, east–west for dicoccon and northeast–southwest for turgidum. The ssp. durum had a more complex structure, consisting of seven populations with high intrapopulation variation. Diversity arrays technology markers allowed the detection of subgroups within some populations, with agromorphological and gliadin differences, and distinct agroecological zones of origin. Two different phylogenetic groups were detected, revealing that some durum accessions were more related to ssp. turgidum from northern Spain while others seem to be more related to durum wheats from North Africa.
Computing Integrated Ratings from Heterogeneous Phenotypic Assessments: A Case Study of Lettuce Postharvest Quality and Downy Mildew Resistance
Authors: Simko Ivan , Hayes Ryan J. , Kramer Matthew 
Published: August 2012

ABSTRACTComparing performance of a large number of accessions simultaneously is not always possible. Frequently, only subsets of all accessions are tested in separate trials with only some (or none) of the accessions overlapping between subsets. Using standard statistical approaches to combine data from such a sparsely populated accession × trial matrix is precluded if different rating scales are used to evaluate accessions in those trials. Here we compare two approaches that can compute an overall linear rating for the performance of all accessions across a set of trials, even for accessions that were never tested together and were rated on dissimilar scales. We use data from lettuce (Lactuca sativa L.) postharvest quality collected on 178 accessions in 18 trials and assessment of lettuce resistance to downy mildew (Bremia lactucae Regel) performed on 583 accessions in 53 trials. The projected values (PV) approach uses a combination of principal component analysis and resampling to merge trial results and calculates an overall rating from real values. In contrast, the rank‐aggregation (RA) approach uses an extension of the Rasch model to combine rank‐ordered data from individual trials. We found high correlation between ratings produced by the two approaches for the postharvest quality (r= 0.803) and the resistance to downy mildew (r = 0.748). Combining data from multiple experiments identified lettuce accessions with a high level of resistance to the disease and a slow rate of deterioration when processed for salad. The PV and RA approaches also allow combining data from different laboratories or databases.
Genetic Variation for Morphology and Maturity Among the Half‐Sib Progeny of Nine Orchardgrass Germplasm Populations
Authors: Robins Joseph G. , Shaun Bushman B. , Jensen Kevin B. , Blaser Greg 
Published: August 2012

ABSTRACTOrchardgrass (Dactylis glomerata L.) acreage has declined compared to perennial ryegrass (Lolium perenne L.) and tall fescue (Festuca arundinacea Schreb.). With the intent of developing new sources of orchardgrass germplasm, 162 half‐sib families from six orchardgrass germplasm populations and three orchardgrass cultivars were evaluated during 2008 for maturity and plant morphology at locations in Idaho and Utah. Genetic similarity of the populations was also characterized using simple sequence repeat markers. Genetic variation between families differed from zero for seven of the nine traits evaluated, with broad‐sense heritability estimates ranging from 0.26 (flag leaf width) to 0.74 (maturity). For each trait that exhibited genetic variation, half‐sib families were identified that possessed trait values similar to or more extreme than the values corresponding to the included commercial orchardgrass cultivars. Through principle component analysis, potential groupings of half‐sib families with similar phenotypic characteristics were identified; for example, taller plants with earlier maturity. Therefore, germplasm could be targeted for development of improved orchardgrass with maturity and morphology suitable to specific management practices, such as short stature, narrow leaves, and late maturity for mixture with legumes.