Download or read book Inheritance of Resistance to Gray Leaf Spot in Maize written by Nguyen Quoc Manh and published by . This book was released on 1977 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Inheritance of Gray Leaf Spot Resistance in Corn written by Jason Michael David Cromley and published by . This book was released on 1999 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: The range of AUDPC values among the parents were 11.4 to 42.9 for B98 and MS 1334, respectively. Generation mean analyses showed significant additive genetic effects, except for B79 x B98, and dominance genetic effects were expressed by all populations. Nonsignificant residuals indicate that epistatic effects were not as important in these populations. A high broad sense heritability estimate of .78 indicates that selection per se within the B79 x B98 population for gray leaf spot resistance should be effective. Resistance to gray leaf spot in the maize genotypes evaluated was conditioned by both additive and dominance effects with the cross B79 x B98 being highly heritable for gray leaf spot resistance.

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 Genetic Mapping of Gray Leaf Spot Resistance Genes in Maize written by Anke Lehmensiek and published by . This book was released on 2000 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Inheritance of Reactions to Gray Leaf Spot and Maize Dwarf Mosaic Virus in Maize and Their Associations with Physiological Traits written by Patrick J. Donahue and published by . This book was released on 1989 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Screening Teosinte Maize Introgression Lines for Resistance to Northern Leaf Blight and Gray Leaf Spot Resistance Inheritance and Yield Effects written by Oliver Otis Ott and published by . This book was released on 2013 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Genetic Analysis of Southern Leaf Blight Gray Leaf Spot and Northern Leaf Blight Resistance Using Near isogenic Lines and Mapping Populations in Maize written by John Charles Zwonitzer and published by . This book was released on 2008 with total page 177 pages. Available in PDF, EPUB and Kindle. Book excerpt: Keywords: southern leaf blight, gray leaf spot, northern leaf blight, quantitative disease resistance, multiple disease resistance, disease resistance quantitative trail loci, near-isogenic lines, maize, recombinant inbred lines.

Download or read book Handbook of Maize Its Biology written by Jeff L. Bennetzen and published by Springer Science & Business Media. This book was released on 2008-12-25 with total page 593 pages. Available in PDF, EPUB and Kindle. Book excerpt: Handbook of Maize: Its Biology centers on the past, present and future of maize as a model for plant science research and crop improvement. The book includes brief, focused chapters from the foremost maize experts and features a succinct collection of informative images representing the maize germplasm collection.

Download or read book Genetic Studies of Phaeosphaeria Leaf Spot Resistance in Maize written by Oliver Mhembere and published by LAP Lambert Academic Publishing. This book was released on 2013 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: Genetic studies and technological edge on maize are increasingly advancing since the turn of the decade. This has come as a result of the increasing threat of pests and diseases in maize producing regions of the world. This book provides a new metric to the fungal disease, Phaeosphaeria leaf spot that has seen increased incidence and severity of epidemics in these growing areas. The author explores the inheritance of the disease and the combining ability of other secondary traits like early maturity in germplasm adaptable to Southern Africa. Thus the book confirms that phaeosphaeria leaf is a highly heritable disease combined with additive gene action and earliness is a moderately heritable trait. Hence, scientists, maize breeding houses and students will be able to fix resistance in their line breeding programs using novel methodologies and technologies that include marker assisted selection and recurrent selection, to generate resistant commercial hybrids. Finally, the general and specific combining abilities of phaeosphaeria leaf spot and other secondary maize traits are further discussed.

Download or read book Increasing Line Combining Ability and Gray Leaf Spot Resistance in Maize by Integrating Conventional with DNA Marker Technology written by Barnabas Anthony Kiula and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Maize is the staple food for the majority of Tanzanians. However, maize production in the Southern highlands of Tanzania (SHT) is highly reduced by gray leaf spot disease (GLS) caused by the fungus Cercospora zea maydis. GLS reduces grain yield, kernel and silage quality. The most common GLS control methods in Tanzania include amongst others: fungicides, crop rotation, field sanitation, host resistance. These methods except host resistance are, however, either expensive or less effective or unsafe to the environment. Furthermore, conventional breeding strategies are not very effective for traits, which are lowly inherited such as GLS resistance. Lastly, to date there are few GLS resistant commercial hybrids in SHT. Thus, this study aimed to produce more commercial GLS resistant hybrids, increase farmers' hybrid choices of growing genetically different GLS insensitive hybrids, which will also provide a constant supply of GLS resistant maize cultivars in case of GLS resistance breakdown due to new GLS pathotypes. This research combined conventional breeding with molecular technologies to increase the efficacy of selecting GLS resistant hybrids and assist breeders in predicting best inbred combinations for commercial hybrid production. Studies conducted to meet the main aims were on: the prediction of best line combiners and heterosis in Tanzanian maize breeding lines through the use of amplified fragment length polymorphism, (AFLP), an association of AFLPs and the performance of phenotypic traits in maize, evaluation of maize hybrids for gray leaf spot resistance in multienvironments and finally a preliminary study on gray leaf spot PCR-based marker development with the long term objective of implementing cleaved amplified polymorphic markers (CAPS) in a marker assisted selection (MAS) strategy in the SHT maize breeding programme. Results from the study revealed that pairwise GD (genetic distance) of the lines varied from a GD of 0.13 to 0.5. High coancentry coefficients were exhibited by these lines. Joint data analyses showed that there were tighter associations between line GD and F1 traits or MPH in the intergroup than in the intragroup crosses. Combined analyses revealed that hybrids 48, 90 and 45 recorded higher stable yields and consistently low GLS scores in multienvironments. Fifteen CAPS marker bands were identified that are putatively linked to the GLS resistant genes. In summary, it was noted that strong selection during inbreeding programs should be avoided as it reduces germplasm variability. Local landraces/varieties can be improved by introgressing desirable genes into them. AFLP marker system could be effectively used for inbred genetic diversity studies in Tanzania. Intergroup crosses with high GD-MPH should be the main target for commercial hybrid production but field testing of them is inevitable to confirm their yielding potentials. Intergroups and intragroup crosses with low GD-MPH should be discarded to avoid field costs. Better F1 hybrid performance predictions can be achieved by integrating inbred GD and F1 phenotypic data. Hybrids with low GLS/high GLS resistance could be used to produce other breeding populations. Hybrids 45, 48 and 90 can be commercially preleased. Lastly a study to characterize the GLS fungus in the SHT is imperative since information on virulence of isolates is needed for long term breeding strategies against the fungus. Finally, the SHT maize germplasm has potential GLS resistant inbred lines which could be used in the deployment of genes to susceptible lines and in the development of commercial GLS resistant hybrids/open pollinated varieties/doubled haploid hybrids.

Download or read book Genetic Mapping and Components of Resistance to Cercospora Zeae maydis in Maize written by Stuart G. Gordon and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Gray leaf spot of maize (Zea mays L.), caused by Cercospora zeae-maydis (Tehon & Daniels), can greatly reduce grain yield worldwide. This study evaluated a novel source of resistance to C. zeae-maydis in the US Corn Belt and the Republic of South Africa (RSA), linked molecular markers to resistance loci using selective genotyping, and examined the components of resistance, sporulation, lesion length and number of lesions. The resistant maize inbred, VO613Y, was crossed to the susceptible inbred, Pa405, to obtain a population of 144 F2:3 progeny lines. These lines were evaluated at Wooster, Ohio, USA, and Cedara, RSA, for resistance to C. zeae-maydis based on percent leaf area affected (PLAA). A selected F3:4 population, derived by self-pollination of resistant and susceptible F2:3 lines, was evaluated at two Ohio locations over two seasons and at Cedara. Simple sequence repeat, restriction fragment length polymorphisms and resistance gene analog molecular marker data were obtained and analyzed based on F2:3 and F3:4 PLAA means across all environments by Kruskal-Wallis and ANOVA single factor analyses and composite interval mapping. Lesion length measurement, lesion counts and lesion sporulation data were taken on 4 resistant F3:4 progeny lines, 4 susceptible F3:4 progeny lines, and the parents. Quantitative trait loci located on two chromosome arms, 2L and 4L, together explained 47% of the variance in the F2:3 generation and 55% in the F3:4 generation across environments. Spearman rank correlations demonstrated that genotypes retained their relative ranks across environments. VO613Y-derived resistance extended the incubation period, resulted in the presence of fewer lesions and shortened the length of lesions. Taken together, this resulted in a lower percent leaf area affected by gray leaf spot. VO613Y and its resistant progeny did not inhibit spore production compared to Pa405 and its susceptible progeny, but resistant maize genotypes should contain fewer lesions capable of producing spores. The total number of spores produced on resistant maize genotypes should therefore be less than that produced on susceptible ones. These results indicate that VO613Y possesses QTL that may be introgressed into elite maize lines and deployed effectively in both southern Africa and the US Corn Belt.

Download or read book The Genetic Architecture of Quantitative Disease Resistance in Maize written by Jesse Abner Poland and published by . This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Several large scale quantitative genetic studies were conducted to better understand the genetic basis for quantitative disease resistance (QDR) in plants. The focus of these studies was the economically important disease of maize (Zea mays L. ssp. mays), northern leaf blight (NLB, caused by Setosphaeria turcica L. anamorph Exserohilum turcicum). The maize nested association mapping (NAM) population, a reference design population consisting of 4,630 recombinant inbred lines, was evaluated over three environments for quantitative resistance to NLB, giving highly heritable resistance phenotypes. Over 200 resistance alleles at 30 different quantitative trait loci (QTL) for disease resistance were identified. Genome-wide nested association mapping for NLB resistance identified genes at six of the QTL that have been associated with disease resistance including three receptor-like kinases, two ethylene response factors, and one Mlo-like gene. Further insight on QDR, with a focus on multiple disease resistance (MDR), was gained by jointly analyzing independent data on NAM for resistance to southern leaf blight (SLB), gray leaf spot (GLS) and NLB. To examine the possibility of MDR genes, the estimated allele effects from each founder inbred were compared at loci were QTL for two or more diseases co-localized. At seven loci, positively correlated allele effects provided evidence for MDR genes. Analysis of the NAM population suggested that resistance to the three diseases studied here is largely due to the accumulation of disease-specific genes and, to a limited extent, pleiotropic genes that condition MDR. A final study was conducted to determine the effect of variability in visual disease rating on mapping disease QTL by assessing the effects of scorer variability and rating scales on mapping QTL for NLB in a single recombinant inbred line population from NAM. Stepwise general linear model selection (GLM) and inclusive composite interval mapping (ICIM) were used for QTL mapping. For both GLM and ICIM the same QTL were largely found across scorers, though some QTL were only identified by some scorers. Strikingly, the magnitudes of estimated allele effects from different scorers at identified QRL were drastically different, sometime by as much as three fold. The studies conducted here advance the understanding of QDR in plants and lay groundwork for identifying the genes responsible for resistance to NLB in maize. A greater understanding of QDR will assist in the development of durable resistant crop cultivars, improving food security and safety.

Download or read book Wheat Blast written by Sudheer Kumar and published by CRC Press. This book was released on 2020-04-09 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wheat Blast provides systematic and practical information on wheat blast pathology, summarises research progress and discusses future perspectives based on current understanding of the existing issues. The book explores advance technologies that may help in deciding the path for future research and development for better strategies and techniques to manage the wheat blast disease. It equips readers with basic and applied understanding on the identification of disease, its distribution and chances of further spread in new areas, its potential to cause yield losses to wheat, the conditions that favour disease development, disease prediction modelling, resistance breeding methods and management strategies against wheat blast. Features: Provides comprehensive information on wheat blast pathogen and its management under a single umbrella Covers disease identification and diagnostics which will be helpful to check introduction in new areas Discusses methods and protocol to study the different aspects of the disease such as diagnostics, variability, resistance screening, epiphytotic creation etc. Gives deep insight on the past, present and future outlook of wheat blast research progress This book’s chapters are contributed by experts and pioneers in their respective fields and it provides comprehensive insight with updated findings on wheat blast research. It serves as a valuable reference for researchers, policy makers, students, teachers, farmers, seed growers, traders, and other stakeholders dealing with wheat.

Download or read book Mechanisms of Resistance to Plant Diseases written by R.S. Fraser and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 473 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plant resistance to pathogens is one of the most important strategies of disease control. Knowledge of resistance mechanisms, and of how to exploit them, has made a significant contribution to agricultural productivity. However, the continuous evolution of new variants of pathogen, ana additional control problems posed by new crops and agricultural methods, creates a need for a corresponding increase in our understanding of resistance and ability to utilize it. The study of resistance mechanisms also has attractions from a purely academic point of view. First there is the breadth of the problem, which can be approached at the genetical, molecular, cellular, whole plant or population lev~ls. Often there is the possibility of productive exchange of ideas between different disciplines. Then there is the fact that despite recent advances, many of the mechanisms involved have still to be fully elucidated. Finally, and compared with workers in other areas of biology, the student of resistance is twice blessed in having as his subject the interaction of two or more organisms, with the intriguing problems of recognition, specificity and co-evolution which this raises.

Download or read book A Greenhouse Screening Method for Resistance to Gray Leaf Spot in Maize written by Min Du and published by . This book was released on 1993 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Increasing Line Combining Ability and Gray Leaf Spot Resistance in Maize by Integrating Conventional Breeding with DNA Marker Technology written by Barnabas Anthony Kiula and published by . This book was released on 2007 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dissection of Gray Leaf Spot of Maize Through Functional Genomics written by Robert Louis Hirsch and published by . This book was released on 2014 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gray leaf spot, caused by Cercospora zeae-maydis, is a devastating disease of maize that reduces yields and increases management costs. C. zeae-maydis penetrates maize leaves through stomata, but the biological and molecular bases of this process are poorly understood. The goal of this research was to elucidate the biological parameters of stomatal infection in C. zeae-maydis, and to identify and characterize novel genetic pathways involved in stomatal sensing and pathogenesis. Histopathological observations of a GFP-expressing strain of C. zeae-maydis during infection of maize indicated that the fungus responded to host-derived stomatal cues during the infection process. C. zeae-maydis was observed exhibiting tropism toward non-host stomata, which ultimately implicated molecular oxygen as a possible stomatal chemoattractant. To explore the role of circadian rhythmicity in gray leaf spot, the putative central circadian oscillator gene FRQ in C. zeae-maydis was functionally disrupted and characterized. Interestingly, FRQ deletion strains were non-pathogenic when inoculated on maize leaves. Histological observations suggested that FRQ deletion strains failed to form appressoria in association with maize stomata. In order to identify other novel genes involved in pathogenesis, a collection of 1228 insertional mutants was created and assayed for infectious development. Ten mutants were identified, including one that was disrupted in RJP1, a putative epigenetic regulator of gene expression. In a related study, thirty-one genes were selected for functional disruption based on sequence similarity to known fungal regulatory genes. Analysis of these mutants indicated that GPA2, which encodes a putative G protein alpha subunit, was required for pathogenesis. Lastly, gene expression analysis during pre-penetration infectious development revealed widespread transcriptional reprogramming. Key findings from this research include the discovery of novel pathogenesis-related genes and potential roles for oxygen sensing and the fungal circadian clock in foliar pathogenesis. Furthermore, this research illuminated a previously unrecognized level of complexity underlying the regulation of stomatal infection during gray leaf spot of maize and established a foundation for future molecular investigations.