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Genetic Variability For Resistance To Leaf Blight And Diversity Among Selected Maize Inbred Lines
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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.
Book Synopsis Handbook of Maize: Its Biology by : Jeff L. Bennetzen
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.
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.
Book Synopsis Managing Global Genetic Resources by : National Research Council
Download or read book Managing Global Genetic Resources written by National Research Council and published by National Academies Press. This book was released on 1993-02-01 with total page 476 pages. Available in PDF, EPUB and Kindle. Book excerpt: This anchor volume to the series Managing Global Genetic Resources examines the structure that underlies efforts to preserve genetic material, including the worldwide network of genetic collections; the role of biotechnology; and a host of issues that surround management and use. Among the topics explored are in situ versus ex situ conservation, management of very large collections of genetic material, problems of quarantine, the controversy over ownership or copyright of genetic material, and more.
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.
Book Synopsis Genetic Studies of Resistance to Cochliobolus Carbonum Race 3 Among Elite Lines of Maize (Zea Mays) by : Javier Gonzalez-Ramos
Download or read book Genetic Studies of Resistance to Cochliobolus Carbonum Race 3 Among Elite Lines of Maize (Zea Mays) written by Javier Gonzalez-Ramos and published by . This book was released on 1987 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Studies of Resistance to Northern Leaf Blight in Maize by : Alice Elaine Johnson
Download or read book Studies of Resistance to Northern Leaf Blight in Maize written by Alice Elaine Johnson and published by . This book was released on 1985 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: Several forms of resistance to northern leaf blight were exomined in the previously described studies with the following results: 1. The degree of polygenic resistance varied between inbred lines. RD6501, LB-31 and RD5502 are the most resistant lines tested. The resistance of RD5502 is either additive or partially recessive since the resistance is not expressed in F1 hybrids. The resistance of RD6501 appears to involve either a major partially dominant factor with modifiers or a block of closely linked resistance genes. A generation means study of this inbred almost fits a one gene model, but the F2, BC2 and F3 data exhibit either crossovers between resistant and susceptible factors or modifier effects over different environements. F1's do not show completedominance. RD6501 exhibits reduction of sporulation on developing lesions, a trait generally associated with single gene ressitance, and RD6501, LB-31 and RD5502 show reduction of rate of lesion development typical of polygenic resistance. So, some form of polygenic resistance was detected, but it doesn't appear to involve a large of genes. Yield studies of hybrids with various degrees of polygenic resistance indicate this form of resistance is effective in reducing yield loss due to northern leaf blight. 2. Studies with the Ht2 gene, which is reported to be a single dominant gene for resistance to H. turcicum race 2, gave some interesting results. Expression of the chlorotic-lesion symptoms reported to be typical of HT2 resistance varied in lines with (...).
Book Synopsis Breeding Potential of Maize Inbred Lines for Resistance to Northern Leaf Blight by : Geoffrey Ronald Hughes
Download or read book Breeding Potential of Maize Inbred Lines for Resistance to Northern Leaf Blight written by Geoffrey Ronald Hughes and published by . This book was released on 1967 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A Genetic Study of Nuclear Controlled Resistance to Southern and Yellow Leaf Blights in Maize (Zea Mays L.) by : Ivor Gerard Caunter
Download or read book A Genetic Study of Nuclear Controlled Resistance to Southern and Yellow Leaf Blights in Maize (Zea Mays L.) written by Ivor Gerard Caunter and published by . This book was released on 1977 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Genetic Analysis of Southern Leaf Blight, Gray Leaf Spot, and Northern Leaf Blight Resistance Using Near-isogenic Lines and Mapping Populations in Maize by : John Charles Zwonitzer
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.
Book Synopsis Mechanisms of Resistance to Plant Diseases by : R.S. Fraser
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.
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.
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.
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
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.
Book Synopsis Combined Population Analyses for Mapping Loci Conditioning Resistance to Southern Corn Leaf Blight by :
Download or read book Combined Population Analyses for Mapping Loci Conditioning Resistance to Southern Corn Leaf Blight written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Southern leaf blight (SLB) is a fungal disease that attacks the leaves of maize plants, forming tan elliptical lesions. The causal agent is Cochliobolus heterostrophus, a necrotrophic ascomycete, which is endemic to hot, humid maize-growing regions. Most maize hybrids have at least a moderate level of quantitative resistance to SLB, which is the primary method of control for the disease. Quantitative resistance is conditioned by small effects of many genes; thus, to make most efficient use of the genetic variation present for SLB resistance, the number of genes involved, the effects they have singly and in combinations, and their potential interactions with the environment must be elucidated. Because the maize-SLB pathosystem is an excellent model for host-necrotroph genetics, the identification of genes underlying the disease response will not only accelerate breeding progress for SLB resistance, but also for necrotrophic resistance in other crop species. Several attempts have been made to map quantitative trait loci (QTL) responsible for conditioning resistance to SLB in biparental segregating populations; however, the precision of the positional estimates of the resultant loci does not allow for identification of genes underlying the response. In addition, the limited germplasm studied only offers the potential of examining two alleles per locus. Many more alleles exist in breeding germplasm, and for this reason, usefulness of results are limited. The objective of the two studies presented here is to address these limitations by combining data across distinct populations. The first study jointly analyzed data from four independently derived B73 x Mo17 populations to validate the existence of and fine map an SLB resistance QTL in bin 3.04, the most significant QTL detected in a study of the IBM population (a set of advanced intercross lines derived from a B73 x Mo17 cross). The four populations used consisted of the IBM population, a set of recombinant inbred line.
Book Synopsis Quantitative Genetics in Maize Breeding by : Arnel R. Hallauer
Download or read book Quantitative Genetics in Maize Breeding written by Arnel R. Hallauer and published by Springer Science & Business Media. This book was released on 2010-09-28 with total page 669 pages. Available in PDF, EPUB and Kindle. Book excerpt: Maize is used in an endless list of products that are directly or indirectly related to human nutrition and food security. Maize is grown in producer farms, farmers depend on genetically improved cultivars, and maize breeders develop improved maize cultivars for farmers. Nikolai I. Vavilov defined plant breeding as plant evolution directed by man. Among crops, maize is one of the most successful examples for breeder-directed evolution. Maize is a cross-pollinated species with unique and separate male and female organs allowing techniques from both self and cross-pollinated crops to be utilized. As a consequence, a diverse set of breeding methods can be utilized for the development of various maize cultivar types for all economic conditions (e.g., improved populations, inbred lines, and their hybrids for different types of markets). Maize breeding is the science of maize cultivar development. Public investment in maize breeding from 1865 to 1996 was $3 billion (Crosbie et al., 2004) and the return on investment was $260 billion as a consequence of applied maize breeding, even without full understanding of the genetic basis of heterosis. The principles of quantitative genetics have been successfully applied by maize breeders worldwide to adapt and improve germplasm sources of cultivars for very simple traits (e.g. maize flowering) and very complex ones (e.g., grain yield). For instance, genomic efforts have isolated early-maturing genes and QTL for potential MAS but very simple and low cost phenotypic efforts have caused significant and fast genetic progress across genotypes moving elite tropical and late temperate maize northward with minimal investment. Quantitative genetics has allowed the integration of pre-breeding with cultivar development by characterizing populations genetically, adapting them to places never thought of (e.g., tropical to short-seasons), improving them by all sorts of intra- and inter-population recurrent selection methods, extracting lines with more probability of success, and exploiting inbreeding and heterosis. Quantitative genetics in maize breeding has improved the odds of developing outstanding maize cultivars from genetically broad based improved populations such as B73. The inbred-hybrid concept in maize was a public sector invention 100 years ago and it is still considered one of the greatest achievements in plant breeding. Maize hybrids grown by farmers today are still produced following this methodology and there is still no limit to genetic improvement when most genes are targeted in the breeding process. Heterotic effects are unique for each hybrid and exotic genetic materials (e.g., tropical, early maturing) carry useful alleles for complex traits not present in the B73 genome just sequenced while increasing the genetic diversity of U.S. hybrids. Breeding programs based on classical quantitative genetics and selection methods will be the basis for proving theoretical approaches on breeding plans based on molecular markers. Mating designs still offer large sample sizes when compared to QTL approaches and there is still a need to successful integration of these methods. There is a need to increase the genetic diversity of maize hybrids available in the market (e.g., there is a need to increase the number of early maturing testers in the northern U.S.). Public programs can still develop new and genetically diverse products not available in industry. However, public U.S. maize breeding programs have either been discontinued or are eroding because of decreasing state and federal funding toward basic science. Future significant genetic gains in maize are dependent on the incorporation of useful and unique genetic diversity not available in industry (e.g., NDSU EarlyGEM lines). The integration of pre-breeding methods with cultivar development should enhance future breeding efforts to maintain active public breeding programs not only adapting and improving genetically broad-based germplasm but also developing unique products and training the next generation of maize breeders producing research dissertations directly linked to breeding programs. This is especially important in areas where commercial hybrids are not locally bred. More than ever public and private institutions are encouraged to cooperate in order to share breeding rights, research goals, winter nurseries, managed stress environments, and latest technology for the benefit of producing the best possible hybrids for farmers with the least cost. We have the opportunity to link both classical and modern technology for the benefit of breeding in close cooperation with industry without the need for investing in academic labs and time (e.g., industry labs take a week vs months/years in academic labs for the same work). This volume, as part of the Handbook of Plant Breeding series, aims to increase awareness of the relative value and impact of maize breeding for food, feed, and fuel security. Without breeding programs continuously developing improved germplasm, no technology can develop improved cultivars. Quantitative Genetics in Maize Breeding presents principles and data that can be applied to maximize genetic improvement of germplasm and develop superior genotypes in different crops. The topics included should be of interest of graduate students and breeders conducting research not only on breeding and selection methods but also developing pure lines and hybrid cultivars in crop species. This volume is a unique and permanent contribution to breeders, geneticists, students, policy makers, and land-grant institutions still promoting quality research in applied plant breeding as opposed to promoting grant monies and indirect costs at any short-term cost. The book is dedicated to those who envision the development of the next generation of cultivars with less need of water and inputs, with better nutrition; and with higher percentages of exotic germplasm as well as those that pursue independent research goals before searching for funding. Scientists are encouraged to use all possible breeding methodologies available (e.g., transgenics, classical breeding, MAS, and all possible combinations could be used with specific sound long and short-term goals on mind) once germplasm is chosen making wise decisions with proven and scientifically sound technologies for assisting current breeding efforts depending on the particular trait under selection. Arnel R. Hallauer is C. F. Curtiss Distinguished Professor in Agriculture (Emeritus) at Iowa State University (ISU). Dr. Hallauer has led maize-breeding research for mid-season maturity at ISU since 1958. His work has had a worldwide impact on plant-breeding programs, industry, and students and was named a member of the National Academy of Sciences. Hallauer is a native of Kansas, USA. José B. Miranda Filho is full-professor in the Department of Genetics, Escola Superior de Agricultura Luiz de Queiroz - University of São Paulo located at Piracicaba, Brazil. His research interests have emphasized development of quantitative genetic theory and its application to maize breeding. Miranda Filho is native of Pirassununga, São Paulo, Brazil. M.J. Carena is professor of plant sciences at North Dakota State University (NDSU). Dr. Carena has led maize-breeding research for short-season maturity at NDSU since 1999. This program is currently one the of the few public U.S. programs left integrating pre-breeding with cultivar development and training in applied maize breeding. He teaches Quantitative Genetics and Crop Breeding Techniques at NDSU. Carena is a native of Buenos Aires, Argentina. http://www.ag.ndsu.nodak.edu/plantsci/faculty/Carena.htm
