Genetic Characterization Of Partial Resistance And Comparative Strategies For Improvement Of Host Resistance To Multiple Foliar Pathogens Of Maize

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Genetic Characterization of Partial Resistance and Comparative Strategies for Improvement of Host-resistance to Multiple Foliar Pathogens of Maize

Author : Godfrey Rox Asea
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (698 download)

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Book Synopsis Genetic Characterization of Partial Resistance and Comparative Strategies for Improvement of Host-resistance to Multiple Foliar Pathogens of Maize by : Godfrey Rox Asea

Download or read book Genetic Characterization of Partial Resistance and Comparative Strategies for Improvement of Host-resistance to Multiple Foliar Pathogens of Maize written by Godfrey Rox Asea and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Foliar diseases are important biotic constraints limiting maize production globally. Northern corn leaf blight (NCLB) incited by Exserohilum turcicum, gray leaf spot (GLS) incited by Cercospora zeae-maydis and maize streak incited by maize streak virus (MSV), are among the most destructive. Most of the maize foliar diseases are managed by means of quantitative partial resistance. Quantitative trait loci (QTL) conditioning partial-resistance to these pathogens have been identified. Validation of candidate QTL conferring partial resistance would present marker-assisted selection as a potentially viable strategy to improve host resistance. We were interested in determining the usefulness of molecular markers linked to consensus QTL controlling partial-resistance systems for improving the overall resistance level. We examined QTL for NCLB in chromosomal bins 3.06, 5.04 and 8.06; GLS QTL in bins 2.09 and 4.08; and a consensus MSV QTL in bin 1.04 as potential targets for selection in improving host resistance. We also examined the effectiveness of different selection strategies for the purpose of pyramiding resistance loci to these diseases. Field evaluations and subsequent selections were conducted independently for each disease in a population of 410 F2:3 lines derived from hybridization between inbred line CML202 with known resistance to NCLB and MSV, and VP31 a breeding line with known resistance to GLS. Maize streak evaluations were conducted in Zimbabwe, GLS tests were performed in Ohio, and NCLB evaluations were conducted in Uganda and Ohio. Genetic gains were calculated for simultaneous improvement of partial resistance following phenotype-based, marker-based, combined phenotype- and marker-based selection (MAS index), and random selection. Narrow-sense heritability estimates were 0.22, 0.25 and 0.39 for MSV, NCLB and GLS, respectively. Analysis of gene action using orthogonal contrasts showed mostly dominant gene action for NCLB, GLS and MSV. For NCLB, resistance due to presence of alleles from QTL in bins 3.06 and 5.04 was detected across two seasons. The chromosomal region in bin 4.08 for GLS resistance was significant (0.0001

Dissertation Abstracts International

Author :
Publisher :
ISBN 13 :
Total Pages : 860 pages
Book Rating : 4.F/5 ( download)

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Book Synopsis Dissertation Abstracts International by :

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2006 with total page 860 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Plant Functional Genomics

Author : Jose M. Alonso
Publisher : Humana
ISBN 13 : 9781493949137
Total Pages : 0 pages
Book Rating : 4.9/5 (491 download)

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Book Synopsis Plant Functional Genomics by : Jose M. Alonso

Download or read book Plant Functional Genomics written by Jose M. Alonso and published by Humana. This book was released on 2016-10-05 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This second edition volume discusses the revolutionary development of faster and less expensive DNA sequencing technologies from the past 10 years and focuses on general technologies that can be utilized by a wide array of plant biologists to address specific questions in their favorite model systems. This book is organized into five parts. Part I examines the tools and methods required for identifying epigenetic and conformational changes at the whole-genome level. Part II presents approaches used to determine key aspects of a gene’s function, such as techniques used to identify and characterize gene regulatory networks. This is followed by a discussion of tools used to analyze the levels of mRNA, mRNA translation rates and metabolites. Part III features a compilation of forward and reverse genetic approaches that include recent implementation of high-throughput sequencing in classical methodologies such as QTL mapping. The final two parts explore strategies to facilitate and accelerate the generation and testing of functional DNA elements and basic computational tools used to facilitate the use of systems biology approached by a broad spectrum of plant researchers. Written in the highly successful Methods of Molecular Biology series format, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols and key tips on troubleshooting and avoiding known pitfalls. Practical and timely, Plant Functional Genomics: Methods and Protocols, Second Edition highlights the latest developments in DNA sequencing technologies that are likely to continue shaping the future of functional genomics.

Maize Germplasm

Author : Mohamed A. El-Esawi
Publisher : BoD – Books on Demand
ISBN 13 : 1789230381
Total Pages : 102 pages
Book Rating : 4.7/5 (892 download)

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Book Synopsis Maize Germplasm by : Mohamed A. El-Esawi

Download or read book Maize Germplasm written by Mohamed A. El-Esawi and published by BoD – Books on Demand. This book was released on 2018-05-09 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: Maize is an important staple food crop worldwide. It is the third most important cereal crop after wheat and rice and is economically used for both livestock feeds and human consumption. The latest maize research has opened up new opportunities for crop improvement. This book brings together recent work and advances that have recently been made in the dynamic fields of genetic characterization, molecular breeding, genetic engineering technologies, and mapping of agronomic traits of global maize germplasm. It also provides new insights into and sheds new light regarding the current research trends and future research directions in maize. This book will provoke interest in many readers, researchers, and scientists, who can find this information useful for the advancement of their research works toward maize improvement.

Genetic Dissection of Maize Regeneration and Wheat Disease Resistance

Author : Guifang Lin
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (135 download)

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Book Synopsis Genetic Dissection of Maize Regeneration and Wheat Disease Resistance by : Guifang Lin

Download or read book Genetic Dissection of Maize Regeneration and Wheat Disease Resistance written by Guifang Lin and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The growing human population worldwide and the changing growth environments require significant crop improvement, which can be accelerated by plant genome engineering. Developing plant cultivars amenable to transformation and improving understanding of the genetic bases of important phenotypic traits can facilitate the use of advanced genome engineering technologies. This dissertation is focused on the genetic analysis of maize transformation and wheat resistance to the disease of leaf rust. The results will provide knowledge to improve crop transformation and wheat disease resistance. Plant transformation is a powerful tool for crop improvement and gene function validation. However, the transformation efficiency of maize is highly dependent on the tissue types and the genotypes. The maize inbred line A188 is amenable to transformation. A188 also exhibits many contrasting traits to the inbred line B73, which is recalcitrant to transformation. B73 was used to generate the first maize reference genome. The lack of genome sequences of A188 limits the use of A188 as a model for functional studies. Here, a chromosome-level genome assembly of A188 was constructed using long reads and optical physical maps. Genome comparison of A188 with B73 based on both whole genome alignments and sequencing read depths identified approximately 1.1 Gb syntenic sequences as well as extensive structural variation. Further, transcriptome and epigenome analyses with the A188 reference genome revealed enhanced gene expression of defense pathways and altered DNA methylation patterns of embryonic callus. The A188 genome assembly provides a foundational resource for analyses of genome variation and gene function in maize. In maize, morphologic types of calli induced from immature embryos are associated with the regeneration capability, which is a major factor determining the transformation efficiency. Here, two contrasting callus types, slow-growth type I calli and fast-growth type II calli, from the selected B73xA188 F2 population were sequenced using Genotyping-By-Sequencing (GBS) and RNA-Seq. With both approaches, the genomic loci associated with the callus type were mapped to chromosomes 2, 5, 6, 8, and 9. From F2 RNA-Seq, differentially expressed genes were identified from the comparison of type II and I calli. In addition, RNA-Seq analysis was performed using fast- and slow-growth calli identified for the A188 calli. Gene ontology (GO) enrichment analysis showed that the down-regulated genes in type II F2 calli and fast-growth A188 calli, as respectively compared to type I calli and slow-growth A188 calli, are overrepresented in the pathway related to cell wall organization, suggesting the role of cell wall formation in the callus development. Besides maize genetic and genomic studies, the dissertation includes the cloning of a leaf rust resistance gene in wheat. Wheat leaf rust disease is caused by a fungal pathogen, Puccinia triticina. The Lr42 gene from the wheat wild relative Aegilops tauschii confers resistance to all leaf rust races tested to date. Through bulked segregant RNA-Seq (BSR-Seq) mapping and further fine mapping, we identified an Lr42 candidate gene, which encodes a nucleotide-binding site leucine-rich repeat (NLR) protein. Transformation of the candidate gene to a leaf rust-susceptible wheat cultivar markedly enhanced the disease resistance, confirming the candidate NLR gene is the Lr42 gene. Cloning of Lr42 expands the repertoire of cloned rust resistance genes, as well as provides precise diagnostic gene markers for wheat improvement.

ASA News

Author :
Publisher : African Studies Association
ISBN 13 :
Total Pages : 130 pages
Book Rating : 4.3/5 ( download)

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Book Synopsis ASA News by :

Download or read book ASA News written by and published by African Studies Association. This book was released on 2006 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Wheat Blast

Author : Sudheer Kumar
Publisher : CRC Press
ISBN 13 : 0429894074
Total Pages : 157 pages
Book Rating : 4.4/5 (298 download)

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Book Synopsis Wheat Blast by : Sudheer Kumar

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.

The Genetic Architecture of Quantitative Disease Resistance in Maize

Author : Jesse Abner Poland
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (613 download)

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Book Synopsis The Genetic Architecture of Quantitative Disease Resistance in Maize by : Jesse Abner Poland

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.

Phenotypic and Genotypic Investigation of Multiple Disease Resistance in Maize

Author : Junyun Yang
Publisher :
ISBN 13 :
Total Pages : 310 pages
Book Rating : 4.E/5 ( download)

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Book Synopsis Phenotypic and Genotypic Investigation of Multiple Disease Resistance in Maize by : Junyun Yang

Download or read book Phenotypic and Genotypic Investigation of Multiple Disease Resistance in Maize written by Junyun Yang and published by . This book was released on 2007 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Genetics of Multiple Disease Resistance in Maize Inbred NY22613 and Science Communication of Quantitative Genetics

Author : Dhyaneswaran Palanichamy
Publisher :
ISBN 13 :
Total Pages : 159 pages
Book Rating : 4.:/5 (115 download)

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Book Synopsis Genetics of Multiple Disease Resistance in Maize Inbred NY22613 and Science Communication of Quantitative Genetics by : Dhyaneswaran Palanichamy

Download or read book Genetics of Multiple Disease Resistance in Maize Inbred NY22613 and Science Communication of Quantitative Genetics written by Dhyaneswaran Palanichamy and published by . This book was released on 2019 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt: Given unpredictable pathogen pressures caused by changing climatic patterns, plant breeders aim to breed crop varieties with durable resistance to multiple plant pathogens. Understanding the genetic basis of multiple disease resistance will aid in this endeavor. Maize inbred NY22613, developed at Cornell University, have shown resistance to northern leaf blight (NLB), gray leaf spot (GLS), common rust, and Stewart's wilt (SW). A BC3S3 bi-parental mapping population (resistant inbred NY22613 and susceptible inbred Oh7B) was used to map the QTLs responsible for disease resistance. The analysis revealed that 16 quantitative trait loci (QTL) were associated with NLB resistance, 17 QTL with GLS resistance and 16 QTL with SW resistance. No QTL were colocalized for all three diseases. Three QTL were shared for NLB and GLS and one QTL was shared for GLS and SW. To select individuals with multiple disease resistance, we demonstrated a selection method that uses phenotypic data, QTL data and high density marker information in a cluster analysis, designated the high density marker phenotype (HEMP) QTL selection strategy. A differential expression study was conducted using susceptible inbred Oh7B and resistant inbred NY22613 in both field and greenhouse conditions, to identify genes that are differentially expressed when inoculated with Setosphaeria turcica (NLB). The Zm00001d024772 gene (unknown function in maize) was differentially expressed between the uninoculated and inoculated Oh7B in field and greenhouse conditions. Zm00001d027691, Zm00001d011152, Zm00001d008951, Zm00001d033623, Zm00001d021770 and Zm00001d034421 were differentially expressed in response to NLB inoculation in NY22613 in field and greenhouse conditions. None have a previously known function in maize, but Zm00001d033623 plays a major role in rice disease immunity. QTL analyses implicates liguleless1 to be associated with disease resistance to GLS and SW and the differential expression study implicates liguleless1 gene to be associated with disease resistance for NLB. This suggests that liguleless1 is an important candidate gene for multiple disease resistance. Direct-to-consumer genetic testing companies conduct low cost genotyping and genome sequencing for humans. This has led to the public having access to their genomic data more than ever before. Quantitative genetics is essential to understand genomic data. Science communication of quantitative genetics to the public is an under-explored strategy to address this issue. The story of quantitative genetics in humans is ugly due to its eugenic origins, however, the story of quantitative genetics in agriculture is inspiring. Using the achievements of quantitative genetics in agriculture, key concepts can be communicated to a diverse audience. Further, the quantitative genetics methods used in plant and animal breeding are being used in human genomic data. This necessitates plant and animal breeders/geneticists to participate in the communication of quantitative genetic methods to the public, so that the public can make informed decisions with their genomic data.

Durability of Disease Resistance

Author : Th. Jacobs
Publisher : Springer Science & Business Media
ISBN 13 : 9401120048
Total Pages : 370 pages
Book Rating : 4.4/5 (11 download)

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Book Synopsis Durability of Disease Resistance by : Th. Jacobs

Download or read book Durability of Disease Resistance written by Th. Jacobs and published by Springer Science & Business Media. This book was released on 2012-02-02 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: From February 24 -28, 1992 an international symposium on Durability of Disease Resistance was held at the International Agricultural Centre in Wageningen, the Netherlands. The symposium, organized by the Department of Plant Breeding of Wageningen Agricultural University and the Centre for Plant Breeding and Repro duction Research, CPRO-DLO, was part of the DGIS funded programme Durable Resistance in Developing Countries. Without any form of prevention or protection nearly all crops will be seriously or even severely damaged by a range of pathogens. In modern agriculture man has been able to control many if not most pathogens using i) pesticides, ii) phyto sanitary methods such as control of seed and plant material in order to start a crop disease free, iii) agronomic measures such as crop rotation, iv) disease resis tance or combinations of these measures. Over the years the use of pesticides has increased enormously and so did the pro blems associated with pesticide use, such as environmental pollution and building of resistance and tolerance to these pesticides in the pathogens. The use of resis tance too increased strongly over the years and here too problems arose.

Advances in Plant Breeding Strategies: Agronomic, Abiotic and Biotic Stress Traits

Author : Jameel M. Al-Khayri
Publisher : Springer
ISBN 13 : 3319225189
Total Pages : 707 pages
Book Rating : 4.3/5 (192 download)

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Book Synopsis Advances in Plant Breeding Strategies: Agronomic, Abiotic and Biotic Stress Traits by : Jameel M. Al-Khayri

Download or read book Advances in Plant Breeding Strategies: Agronomic, Abiotic and Biotic Stress Traits written by Jameel M. Al-Khayri and published by Springer. This book was released on 2016-03-29 with total page 707 pages. Available in PDF, EPUB and Kindle. Book excerpt: The basic concept of this book is to examine the use of innovative methods augmenting traditional plant breeding towards the development of new crop varieties under different environmental conditions to achieve sustainable food production. This book consists of two volumes: Volume 1 subtitled Breeding, Biotechnology and Molecular Tools and Volume 2 subtitled Agronomic, Abiotic and Biotic Stress Traits. This is volume 2 which contains 18 chapters highlighting breeding strategies for specific plant traits including improved nutritional and pharmaceutical properties as well as enhanced tolerance to insects, diseases, drought, salinity and temperature extremes expected under predicted global climate change.

Population Genetics of the Maize Foliar Pathogen Cercospora Zeina Crous & U. Braun in Five Countries of Sub-Saharan Africa

Author : David Livingstone Nsibo
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (131 download)

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Book Synopsis Population Genetics of the Maize Foliar Pathogen Cercospora Zeina Crous & U. Braun in Five Countries of Sub-Saharan Africa by : David Livingstone Nsibo

Download or read book Population Genetics of the Maize Foliar Pathogen Cercospora Zeina Crous & U. Braun in Five Countries of Sub-Saharan Africa written by David Livingstone Nsibo and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Cercospora zeina, a causal pathogen of gray leaf spot (GLS) of maize, is responsible for up to 1 % of global yield losses. Previous small-scale population genetics studies have revealed that C. zeina is a highly diverse pathogen. Using microsatellite markers, we set out to determine the genetic diversity and population structure of 835 C. zeina isolates from five countries in Sub-Saharan Africa: Kenya, South Africa, Uganda, Zambia, and Zimbabwe, and to establish their evolutionary potential. Our findings revealed that populations from different farming systems exhibited partial, but significant population differentiation. Also, smallholder populations had a higher genetic diversity, number of private alleles and lower clonality than commercial populations. Country-level populations were highly diverse and structured, with migration occurring among populations. Interestingly, Zambia came out as a distinct population, with a lower genetic diversity, higher clonality and private alleles, indicative of a more recently introduced population. Our findings rejected the existing hypothesis of Durban harbor being the entry point of C. zeina into Africa, thus suggesting that the pathogen has other point(s) of entry. Additionally, signatures of cryptic sexual recombination were observed even though an attempt to induce the sexual stage in laboratory conditions was unsuccessful. We found no evidence for C. zeae-maydis, C. zeinaaÌ22́Ơ4́Øs sibling species in more than 1000 isolates collected from around Africa, thus confirming that C. zeina is the predominant species in Africa. Overall, this pathogen is a genetically well-established pathogen in Africa with its population structure being influenced by sexual recombination, migration and human activities. This study, therefore, provides a basis for effective monitoring of C. zeinaaÌ22́Ơ4́Øs dispersal and is a tool for designing more effective regional-specific management strategies to reduce the acquisition and movement of highly virulent strains that overcome host resistance or fungicide control.

Viruses and Virus Diseases of Poaceae (Gramineae)

Author : Hervé Lapierre
Publisher : Editions Quae
ISBN 13 : 9782738010889
Total Pages : 904 pages
Book Rating : 4.0/5 (18 download)

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Book Synopsis Viruses and Virus Diseases of Poaceae (Gramineae) by : Hervé Lapierre

Download or read book Viruses and Virus Diseases of Poaceae (Gramineae) written by Hervé Lapierre and published by Editions Quae. This book was released on 2004 with total page 904 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many well-known specialists have contributed to this book which presents for the first time an in-depth look at the viruses, their satellites and the retrotransposons infecting (or occuring in) one plant family: the Poaceae (Gramineae). After molecular and biological descriptions of the viruses to species level, virus diseases are presented by crop: barley, maize, rice, rye, sorghum, sugarcane, triticales, wheats, forage, ornamental and lawn. A detailed index of the viruses and taxonomic lists will help readers in the search for information.

Resistance to Gray Leaf Spot of Maize

Author : Jacqueline Marie Benson
Publisher :
ISBN 13 :
Total Pages : 254 pages
Book Rating : 4.:/5 (913 download)

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Book Synopsis Resistance to Gray Leaf Spot of Maize by : Jacqueline Marie Benson

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.

The Physiology and Host Genetics of Quantitative Resistance in Maize to the Fungal Pathogen Cochliobolus Heterostrophus

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (656 download)

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Book Synopsis The Physiology and Host Genetics of Quantitative Resistance in Maize to the Fungal Pathogen Cochliobolus Heterostrophus by :

Download or read book The Physiology and Host Genetics of Quantitative Resistance in Maize to the Fungal Pathogen Cochliobolus Heterostrophus written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantitative disease resistance, despite widespread use, remains poorly understood. A previous project in the NCSU Maize Disease Resistance Genetics lab has generated 253 near-isogenic lines (NILs) in the background of the historically important maize inbred line B73. B73, although of excellent overall agronomic quality, is highly resistant to a number of common maize diseases. Each NIL is genetically differentiated by its combination of 1-5 of 12 total introgressed regions from the multiple disease-resistant parent NC250P. These 12 NC250P introgressions were selected for study as, following an initial B73 x NC250P cross, they had been retained by a program of recurrent backcrossing to B73 and selection for resistance to the fungal maize pathogen Cochliobolus heterostrophus, causal agent of southern corn leaf blight (SLB). Prior research also evaluated the effect of each NC250P introgression in conferring quantitative resistance or susceptibility against SLB. Introgressions having an effect can be designated as disease resistance quantitative trait loci, or ÃØâ'ƠÅ"dQTLsÃØâ'ƠÂ . Presented here is a 2-phase study with the ultimate aim of characterizing the physiological basis for the effect on disease severity of these NC250P-derived SLB dQTLs. The first phase attempts to determine more precisely how infection is altered by the two largest-effect introgressions, termed dQTL 3.04 and dQTL 6.01 (or 3B and 6A). To do so, it uses growth chamber juvenile plant trials to compare the interactions between C. heterostrophus and 6 select lines - B73, the major-gene resistant line B73rhm (also a B73-background NIL), and four NILs with varying combinations of dQTLs 3.04 and 6.01 - by quantifying spore germination and penetration efficiency, hyphal growth, and host expression of the pathogenesis related genes PR1 and PR5. The second phase investigates dQTL disease specificity by field testing 236 NILs for adult plant resistance to 5 fungal maize pathogens. Based on the results of.

Insights Into Disease Resistance

Author : Tiffany Marie Jamann
Publisher :
ISBN 13 :
Total Pages : 197 pages
Book Rating : 4.:/5 (892 download)

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Book Synopsis Insights Into Disease Resistance by : Tiffany Marie Jamann

Download or read book Insights Into Disease Resistance written by Tiffany Marie Jamann and published by . This book was released on 2014 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: The genes and mechanisms underlying quantitative disease resistance remain largely elusive. The objective of this dissertation was to resolve the structure of multiple disease resistance loci, explore the dynamics that shape the genome at those loci, and identify genes associated with plant defense. In order to do this, both locus-specific and genome-wide approaches were taken, as each resistance locus has a unique resistance profile and mechanism(s) of resistance. Bins 1.02 and 1.06 of the maize genome carry loci of interest conditioning multiple disease resistance. The two loci differ in allelic diversity, pathogen specificity, and mechanism of resistance. The locus in bin 1.06 is particularly interesting, as it has been characterized as yield-stabilizing and exhibits signs of genome plasticity. I have used fine-mapping, association mapping, expression evidence, and mutant analysis to dissect these loci, identify candidate genes, and demonstrate the role of candidate genes in plant defense. Each locus was unique, although common themes arose. Both loci may have multiple underlying genes, demonstrating that the genetic architecture of disease resistance is complex. Resistance to multiple diseases appears to be due to linkage, although there may be a role for pleiotropy at both loci. Fine-mapping narrowed the intervals, and was complemented by association mapping and expression analysis to evaluate candidate genes. A putative remorin was implicated by fine-mapping and expression analysis; roughsheath2-interacting KH domain protein (rik) and pangloss1 (pan1) were identified through fine-mapping and association mapping. rik was later eliminated as a candidate for the QTL of interest through fine-mapping and association mapping. Mutants were used to confirm the role of candidate genes in plant defense, including for pan1 and the putative remorin. Based on these results, pan1 was inferred to be a susceptibility gene for NLB and Stewart's wilt, and increased resistance was correlated with decreased expression. Susceptibility conditioned by wild-type pan1 could be due to a passive mechanism, such as altered anatomical structures, or an active process, such as actin re-organization during pathogen attack. To test genome-wide association mapping candidate genes, mutants were identified and evaluated for NLB phenotype. Approximately 37% of the 123 families tested differed in disease phenotype from the background line. One of these was the putative remorin gene, which was inferred to contribute to resistance. Overall, I have examined candidate genes, explored genomic structure at these loci, and demonstrated a role for pan1 in resistance to multiple diseases.