Download or read book Identification of Quantitative Trait Loci for Gray Leaf Spot Resistance Maturity and Grain Yield in a Semi tropical Recombinant Inbred Population of Maize written by Michael Phillip Jines and published by . This book was released on 2004 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: Keywords: qtl, maturity, gls resistance.
Download or read book Identification of Quantitative Trait Loci QTL for Gray Leaf Spot Resistance Maturity and Grain Yield in a Semi tropical Recombinant Inbred Population of Maize written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Identification of QTL can aide in future breeding objectives by allowing breeders either to improve a line through targeted introgressions or assist in forward breeding strategies. Such analyses may be particularly helpful in integrating exotic germplasm into a breeding program. The percentage of tropical maize germplasm grown in U.S. farmers' fields is almost nonexistent. Tropical germplasm in maize (Zea mays L.) is a valuable resource to decrease the dependence upon a limited genetic base currently used to produce commercial hybrids, extend selection limits for grain yield, and to provide an insurance function against emerging biotic and abiotic stresses. Results of research presented in this dissertation support these recommendations. Experiments were conducted to evaluate 143 S4:5 recombinant inbred lines (RILs) resulting from a cross between NC300, an all-tropical, temperate adapted line, and B104, a stiff stalk line. The 143 RILs were topcrossed to the Lancaster tester FR615xFR697 and randomly subdivided into two sets. The two sets were evaluated for resistance to GLS disease and yielding ability in three and eight North Carolina environments, respectively. Spatial trends were examined in the GLS trials. Significant (P d".01) trend effects were fitted in five of the six set-by-environment combinations, which led to improved analyses within and across environments for both sets. Ninety-three and eighty-two percent of the RILs in topcrosses (RILT) were significantly (P = 0.05) more resistant to GLS when compared to the mean of the commercial checks for set 1 and 2, respectively. Twenty-one RILs from both sets did not differ significantly (P = 0.05) for grain yield when compared to the mean of the commercial checks. RIL 2070 yielded significantly (P = 0.05) higher when compared to one commercial check, HC33. TR7322. RIL 1991 was rated the most resistant entry in set 1 and also did not differ from the mean of the commercial checks for grain yield. The RILs we.
Download or read book Quantitative Trait Loci Identification of Gray Leaf Spot Resistance in Maize written by Matthew L. Ramage and published by . This book was released on 2000 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Identification of Major Quantitative Trait Loci for Grain Quality Traits in Tropical Maize Recombinant Inbred Lines written by Haci-Murat Arpat and published by . This book was released on 1996 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Quantitative Trait Loci Associated with Resistance to Gray Leaf Spot of Corn written by Michael Joe Clements and published by . This book was released on 1999 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Resistance to Gray Leaf Spot of Maize written by Jacqueline Marie Benson and published by . This book was released on 2013 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gray leaf spot (GLS) is a foliar disease of maize caused by Cercospora zeae-maydis and Cercospora zeina and quantitative resistance to GLS is important for maize production. A nested association mapping (NAM) maize population, consisting of 25 populations of 150 recombinant inbred lines, was used to identify quantitative trait loci (QTL) for GLS resistance. Trials were conducted in Blacksburg, VA, in a field with high natural incidence of GLS. A multivariate mixed model was used in ASReml3 to give the best linear unbiased predictions of disease severity ratings. QTL were selected using a general linear model selection procedure in SAS 9.2. Sixteen QTL, distributed across the maize genome, were identified using a likelihood of odds (LOD) selection threshold>4. Seven of these 16 QTL displayed allelic series with significantly higher and lower effects than the common parent allele. Near-isogenic lines (NILs) extracted from heterogeneous inbred families were developed to confirm and further finemap select QTL, targeting the loci with the greatest LOD scores from the model selection QTL analysis. Phenotypic characterization of the NILs confirmed that the loci in bins 1.04, 2.09 and 4.05 likely contribute significantly to disease resistance, with bins 1.04 and 2.09 conferring reductions in disease of 12% and 23%, respectively. In contrast, the susceptible allele in bin 4.05, which was associated with the distance between major veins, conferred an increase of 8.4%. This disease-related venation trait was confirmed using the 4.05 NILs. Genome-wide association studies revealed candidate genes related to the production of carotenoids, anthocyanins and antioxidant compounds that may play a role in cercosporin detoxification. Expression analysis of 1.05 NILs treated with cercosporin implicated a flavin-monooxygenase gene in cercosporin detoxification. Furthermore, significant associations between NAM parental allelic effects and parental phenotypes at the microscopic level for the 1.02 and 1.06 loci implicated callose plug and phenolic accumulation, respectively, in host defense. Elucidating the genetics of quantitative disease resistance loci provides breeders with valuable information that may enhance their ability to use molecular markers as a means to rapidly introgress loci that provide quantitative disease resistance.
Download or read book Molecular Markers for Quantitative Trait Loci QTLs in Maize Gray Leaf Spot GLS Resistance written by Anke Lehmensiek and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Genetic Analysis of Quantitative Trait Loci with Inbred and Hybrid Progeny of Maize written by David Frederick Austin and published by . This book was released on 1997 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first objective of this study was to compare quantitative trait loci (QTL) detection in two climatically diverse environments in a population of F6:-- lines of an elite maize (Zea mays L.) single-cross. The second objective was to detect QTL for general (GCA) and specific (SCA) combining ability effects in hybrid progeny of F2:3 and F6: lines from the same population. Evaluations of both inbred per se and hybrid progeny from the same population enabled comparisons between QTL controlling the two progeny types. The results from the F6:-- inbred progeny evaluations suggest that QTL detection can be greatly affected by environmental conditions with only 17% (grain yield traits) and 35% (morphological traits) of the QTL detected among the stress and nonstress environments being detected in both environments. The mean environment was effective in detecting 68% (morphological traits) and 54% (grain yield traits) of the QTL detected in either of the individual environments.
Download or read book Identification of Alleles from Exotic Maize for Maize Improvement Using Advanced Backcross QTL Analysis written by Huver Posada-Suarez and published by . This book was released on 2000 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2008 with total page 906 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Identification of Quantitative Trait Loci in Crosses of Elite Inbred Lines of Maize Using Isozyme Loci written by Brenda Sue Bateman and published by . This book was released on 1988 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Enhancing Genetic Gain in Maize with Tropical Germplasm QTL Mapping and Spatial Methodologies written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Advance-cycle breeding is restricting the germplasm base for U.S. maize (Zea Mays L.). Many breeding programs devote efforts to adapt diverse germplasm to U.S. growing conditions, but few are participating in continual enhancement. Incorporating tropical germplasm into U.S. breeding pools could broaden the maize germplasm base, while concomitantly providing favorable alleles for yield and disease resistance. Knowing the genomic regions, or quantitative trait loci (QTL), for disease resistance can enhance gain by permitting selection on marker genotypes in the absence of disease expression. In addition, accounting for spatial variability can improve the precision of experiments and aid breeders in line advancement decisions and QTL mapping. Recombinant inbred (RI) lines were derived from a cross between NC300, a temperate-adapted, all-tropical line, and B104, a Stiff-Stalk-synthetic line. The RI lines were topcrossed to the tester FR615. FR697 (a C103 sister line cross). Resistance QTL for Southern Rust (rust) (Puccinia polysora) were mapped in the topcrosses, while Gray Leaf Spot (GLS) (Cercospora zeae-maydis) QTL were mapped in both the RI lines and topcross populations. A major resistance gene for rust was identified on the short-arm of chromosome 10, while ten GLS QTL mapped to chromosomes 1, 2, 3, 4, 8, and 10. Similar markers on chromosome 1 and 8 flanked three GLS and flowering time QTL pairs, and the resistance alleles were associated with increased flowering time. No flowering time regions co-localized with rust-resistance loci. The major rust-resistance gene and three GLS QTL corresponded to regions mapped in prior populations. The tropical parental allele, NC300, increased resistance at three of these four loci. Extensively haplotyping germplasm at these four consensus regions could aid in forward breeding strategies to efficiently integrate resistance packages into U.S. maize breeding populations. Spatial analyses, such as trend and trend analysis with cor.
Download or read book Combined Population Analyses for Mapping Loci Conditioning Resistance to Southern Corn Leaf Blight written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Southern leaf blight (SLB) is a fungal disease that attacks the leaves of maize plants, forming tan elliptical lesions. The causal agent is Cochliobolus heterostrophus, a necrotrophic ascomycete, which is endemic to hot, humid maize-growing regions. Most maize hybrids have at least a moderate level of quantitative resistance to SLB, which is the primary method of control for the disease. Quantitative resistance is conditioned by small effects of many genes; thus, to make most efficient use of the genetic variation present for SLB resistance, the number of genes involved, the effects they have singly and in combinations, and their potential interactions with the environment must be elucidated. Because the maize-SLB pathosystem is an excellent model for host-necrotroph genetics, the identification of genes underlying the disease response will not only accelerate breeding progress for SLB resistance, but also for necrotrophic resistance in other crop species. Several attempts have been made to map quantitative trait loci (QTL) responsible for conditioning resistance to SLB in biparental segregating populations; however, the precision of the positional estimates of the resultant loci does not allow for identification of genes underlying the response. In addition, the limited germplasm studied only offers the potential of examining two alleles per locus. Many more alleles exist in breeding germplasm, and for this reason, usefulness of results are limited. The objective of the two studies presented here is to address these limitations by combining data across distinct populations. The first study jointly analyzed data from four independently derived B73 x Mo17 populations to validate the existence of and fine map an SLB resistance QTL in bin 3.04, the most significant QTL detected in a study of the IBM population (a set of advanced intercross lines derived from a B73 x Mo17 cross). The four populations used consisted of the IBM population, a set of recombinant inbred line.
Download or read book Identification of Quantitative Trait Loci Associated with Flowering Vegetative Traits and Photoperiod Response in Maize Zea Mays L written by Rkia Moutiq and published by . This book was released on 2002 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: In general, maize, especially germplasm from the tropics and subtropics, is sensitive to photoperiod. This sensitivity hindered the exchange of germplasm between latitudes. To identify quantitative trait loci (QTL) associated with the response to photoperiod, a population of 236 F3 lines produced from a cross between a photoperiod-sensitive line CML9 and insensitive inbred A632Ht was used. These F3 lines were evaluated in three long and three short-day environments, in adjacent fields using artificial light, and in fields located in different latitudes, Mexico and Iowa. Days from sowing to anthesis (DTA), final leaf number (FLN) and plant height (PH) were measured. For each of these traits, photoperiod response (PPR) was estimated as the difference between the trait in long- and short-days divided by the trait in short-days. Composite interval mapping was used to detect QTL for each trait and comparison of locations of QTL detected in different daylengths for the same trait and for different traits were examined. A unique set of QTL was detected for each photoperiod and for each trait. One QTL for DTA, three QTL for FLN and four QTL for PH were detected in the same genetic regions in both daylengths. Five QTL for DTA, four QTL for FLN and three QTL for PH were detected only in long-day environments. Nine QTL for DTA, five QTL for FLN and three QTL for PH were detected only in short-day environments. QTL for photoperiod response were detected on four chromosomes for PPR[Subscript DTA], on three chromosomes for PPR[Subscript FLN] and on three chromosomes for PPR[Subscript PH]. Chromosomes 2, 3, 4, 5, 6, 8, 9, and 10 had a cluster of QTL for different traits. This might suggest a common initial mechanism with subsequent specific pathways that regulate different traits.
Download or read book Bibliography of Agriculture written by and published by . This book was released on 1996 with total page 2376 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Identification of Quantitative Trait Loci Im Maize written by Michael Richard Kerns and published by . This book was released on 1998 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Genetic Analysis of Leaf Angle and Tassel Traits in Maize written by Suzanne M. Mueller and published by . This book was released on 2000 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt:
