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

Genetics, Genomics and Breeding of Maize

Author : Ramakrishna Wusirika
Publisher : CRC Press
ISBN 13 : 1482228130
Total Pages : 310 pages
Book Rating : 4.4/5 (822 download)

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Book Synopsis Genetics, Genomics and Breeding of Maize by : Ramakrishna Wusirika

Download or read book Genetics, Genomics and Breeding of Maize written by Ramakrishna Wusirika and published by CRC Press. This book was released on 2014-08-05 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sequencing of the maize genome has opened up new opportunities in maize breeding, genetics and genomics research. This book highlights modern trends in development of hybrids, analysis of genetic diversity, molecular breeding, comparative and functional genomics, epigenomicsand proteomics in maize. The use of maize in biofuels, phytoremediation and

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.

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:

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.

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.

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.

Genetic Variability for Resistance to Leaf Blight and Diversity Among Selected Maize Inbred Lines

Author : Abera Wende
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (115 download)

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Book Synopsis Genetic Variability for Resistance to Leaf Blight and Diversity Among Selected Maize Inbred Lines by : Abera Wende

Download or read book Genetic Variability for Resistance to Leaf Blight and Diversity Among Selected Maize Inbred Lines written by Abera Wende and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Maize (Zea mays L.) is an important staple food crop in sub-Saharan Africa (SSA). The productivity of the crop is limited partly by the leaf blight disease caused by Exserohilum turcicum. In breeding for resistance to leaf blight, the germplasm needs to be well-characterized in order to design efficient breeding programs. This study evaluated the (i) genetic variability among maize inbred lines and (ii) diversity of selected medium to late maturity tropical maize inbred lines for hybrid breeding. Plants of 50 maize inbred lines were artificially inoculated in the field during 2011 and 2012. Disease severity and incidence as well as grain yield were measured. A subset of 20 elite maize inbred lines was genotyped using 20 SSR markers. The germplasm showed significant differences in reaction to leaf blight and were classified as either resistant or intermediate or susceptible. Mean disease severity varied from 2.04 to 3.25. Seven inbred lines were identified as potential sources of resistance to leaf blight for the genetic improvement of maize. The genotyping detected 108 alleles and grouped the inbred lines into five clusters consistent with their pedigrees. The genetic grouping in the source population will be useful in the exploitation of tropical maize breeding programs.

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.

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.

Characterization and Genetic Analysis of Maize Germplasm for Resistance to Northern Corn Leaf Blight Disease in Tanzania

Author : Tulole Lugendo Bucheyeki
Publisher :
ISBN 13 :
Total Pages : 366 pages
Book Rating : 4.:/5 (83 download)

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Book Synopsis Characterization and Genetic Analysis of Maize Germplasm for Resistance to Northern Corn Leaf Blight Disease in Tanzania by : Tulole Lugendo Bucheyeki

Download or read book Characterization and Genetic Analysis of Maize Germplasm for Resistance to Northern Corn Leaf Blight Disease in Tanzania written by Tulole Lugendo Bucheyeki and published by . This book was released on 2012 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Genetic Characterization of Maize for Stenocarpella Maydis Ear Rot Resistance

Author : Lieketso Moremoholo
Publisher :
ISBN 13 :
Total Pages : 274 pages
Book Rating : 4.:/5 (89 download)

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Book Synopsis Genetic Characterization of Maize for Stenocarpella Maydis Ear Rot Resistance by : Lieketso Moremoholo

Download or read book Genetic Characterization of Maize for Stenocarpella Maydis Ear Rot Resistance written by Lieketso Moremoholo and published by . This book was released on 2008 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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.

Characterization of Stewart's Wilt Resistance in Juvenile Pan1 Mutants of Maize

Author : Kaiyue Deng
Publisher :
ISBN 13 :
Total Pages : 45 pages
Book Rating : 4.:/5 (11 download)

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Book Synopsis Characterization of Stewart's Wilt Resistance in Juvenile Pan1 Mutants of Maize by : Kaiyue Deng

Download or read book Characterization of Stewart's Wilt Resistance in Juvenile Pan1 Mutants of Maize written by Kaiyue Deng and published by . This book was released on 2017 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt: The bacterium Pantoea stewartii subsp. stewartii is the causal agent of Stewart's Wilt (SW), the most severe bacterial disease that affects sweet corn and maize in north-central and eastern USA. P. stewartii is a vascular pathogen that preferentially colonize the xylem, causing wilting symptoms. Overlapping regions within maize chromosomal bin 1.06 have been identified as multiple disease resistance QTL for both Northern Leaf Blight and Stewart's Wilt. However, the mechanisms behind the resistance QTL remains unknown. Fine mapping analysis reveals that the pan1 gene, that encodes a leucine-rich repeat receptor-like kinase (LRR-RLK) involved in stomatal complex formation, falls within the QTL. Field-grown adult pan1 mutant plants have been shown to have increased resistance to SW, which indicates that pan1 may underlie the resistance QTL. Our project examines how pan1 increases SW resistance in juvenile maize plants via evaluating SW resistance and quantifying PAN1 protein levels in different maize genotypes. We confirmed that juvenile pan1 mutant plants exhibits consistent resistance phenotype by comparing two independent null pan1 mutants to wild type B73. Our results showed that the stomatal defects in pan1 mutants does not cause the resistance phenotype. Unexpectedly, pan1 mutant allele acts in a dominant manner while PAN1 protein level is reduced by about half of the normal amount in leaf division zone of heterozygous pan1 plants. Our results also indicated that insufficient induction of Type III secretion system does not explain the increased SW resistant phenotype in pan1 mutants. These results will guide further investigation in our effort to elucidate the underlying mechanism of pan1 mutants increased SW resistance.

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.

Increasing Line Combining Ability and Gray Leaf Spot Resistance in Maize by Integrating Conventional with DNA Marker Technology

Author : Barnabas Anthony Kiula
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (956 download)

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Book Synopsis Increasing Line Combining Ability and Gray Leaf Spot Resistance in Maize by Integrating Conventional with DNA Marker Technology by : Barnabas Anthony Kiula

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.

Maize Germplasm - Characterization and Genetic Approaches for Crop Improvement

Author : Mohamed El-Esawi
Publisher :
ISBN 13 : 9781789230390
Total Pages : 100 pages
Book Rating : 4.2/5 (33 download)

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Book Synopsis Maize Germplasm - Characterization and Genetic Approaches for Crop Improvement by : Mohamed El-Esawi

Download or read book Maize Germplasm - Characterization and Genetic Approaches for Crop Improvement written by Mohamed El-Esawi and published by . This book was released on 2018 with total page 100 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.