Download or read book Genetic Variation Within Populations Used in Maize Zea Mays L Breeding written by Myron Ossie Fountain and published by . This book was released on 1993 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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

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

Download or read book Leveraging Genetic Diversity in Maize Breeding written by Alden Perkins and published by . This book was released on 2024 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Maize (Zea mays L.) cultivars grown in the United States are not closely related to cultivars found in many other parts of the world, and pedigree records suggest that there has been little use of germplasm from other countries in US maize breeding. Exotic germplasm could be a useful source of alleles for improving traits such as grain quality, disease resistance, and abiotic stress tolerance in US populations. Exotic cultivars may also contain alleles that confer adaptation to different climate conditions and management practices, however, which could be detrimental in US growing environments. This dissertation contains a review article about the importance of genetic diversity in breeding and three research projects that involve the incorporation of exotic diversity into US maize germplasm. In the first research project, we investigated the effects of introgressions from open-pollinated populations that originated in Latin America on the performance of maize hybrids in US environments. We compared the phenotypic stability of exotic-derived hybrids and US-adapted hybrids, and we found that the two groups had significantly different stability values for grain yield and flowering time. In the second project, we estimated the effects of exotic introgressions contained in maize populations created by a public-private partnership on grain protein content, kernel vitreousness, and other agronomic traits. One introgression was estimated to increase grain protein content by 0.78%, although it was also associated with detrimental changes in the time of flowering and plant height. Finally, we compared models that could be used to predict the phenotypes of untested hybrids in diverse populations, which could make the process of incorporating new diversity into US germplasm more efficient. We found that models using near-infrared absorbance data collected on inbred seeds as predictors were inferior to models based on genotypic data in most cases, although the difference between the methods was small for traits such as grain moisture and test weight. An alternative to the standard genomic best linear unbiased prediction (GBLUP) method that included additional regularization, called the sparse selection index method, was superior to GBLUP models when large training populations were available. Collectively, the results from these projects provide new insights into how exotic germplasm can be used in US maize breeding most effectively.

Download or read book Maize Genetics and Breeding in the 20th Century written by Peter A. Peterson and published by World Scientific. This book was released on 1999 with total page 398 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides the biographies, and a related summary, of geneticists and breeders of maize who have contributed to the major discoveries in the 20th century. Their relationships to one another, as well as the general developments in maize genetics and breeding growth, are included. Photographs of events and related personnel, all part of the biographic presentation, portray the maize community and its growth. Most of the geneticists and breeders have a common origin in their training, and their sucessors are among the current contributors to maize development.

Download or read book An Analysis of Genetic Variation in Complex Traits of Maize written by Jason Andrew Peiffer and published by . This book was released on 2012 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: Maize (Zea mays L.) is a complex crop. Governed by the universal processes of evolution that dictate the differential reproduction of all life, maize germplasm has been gradually adapted to better suit societal needs through domestication and breeding. However, these modifications were largely accomplished with little knowledge of the genetic architecture or molecular mechanics of its traits. Investigating the reaches of the rhizosphere to the top of the tassel, the following studies analyze the natural variation of complex maize traits to better understand both their means and degree of inheritance. First, the heritability and environmental specificity of maize-microbe interactions were estimated by pyrosequence profiling 16s rRNA gene amplicons from rhizosphere bacterial populations of diverse inbreds grown in multiple maize field environments. We found substantial variation in bacterial diversity was attributable to environment. Nonetheless, a small but significant proportion of variation was heritable. While kinship inferred from a simple additive model assuming contributions from all polymorphisms did not explain this heritable variation, its discovery is a step toward identifying those genes responsible for novel plantmicrobe interactions in natural environments. Second, maize stalk strength variation was analyzed to delineate the accuracy of genomic prediction in a low heritability trait. While few robust loci were associated with stalk strength, a significant proportion of heritable variation was captured by kinship among the inbreds. This revealed the efficacy of genomic prediction and suggested the potential to accurately predict other low heritability phenotypes such as yield. These and similar efforts to facilitate the selection of genotyped seed with desirable qualities before planting will enhance breeding efficiency. Finally, variation in the most classic and heritable of complex traits, maize height was partitioned to reveal its genetic architecture and pleiotropy with other traits such as flowering time and node counts. As anticipated height was highly polygenic and well captured by kinship; however, an interesting finding was the lacking concordance between mapped loci and those established through previous cloning efforts. Equally intriguing was the paucity of pleiotropic loci identified for height and flowering time. These findings reveal the potential for independent evolvability of these traits during maize breeding.

Download or read book Molecular Marker Analysis of Population Genetic Structure and Progress from Reciprocal Recurrent Selection in Two Iowa Maize Zea Mays L Populations written by Lori Lynn Hinze and published by . This book was released on 2003 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: Studies of the genetic structure of the Iowa Corn Borer Synthetic #1 (CB) and Iowa Stiff Stalk Synthetic (SS) maize populations are of particular significance because they serve as the model on which development of modern commercial hybrids are based. These populations are part of a reciprocal recurrent selection breeding strategy. With this strategy, plants from one population are crossed to plants from the opposite population (i.e. forming hybrids). These hybrids are tested, and the best ones are chosen. The plants crossed to form the chosen hybrids are identified and used to form the next generation in each population. The goal of each successive generation is to improve on the previous generation while maintaining variability within the populations. We measured the progress of this program by testing for between- and within-population level genetic differentiation by analyzing the variation at 86 SSR loci among plants sampled from eight groups (progenitors, Cycle 0, Cycle 1, Cycle 3, Cycle 6, Cycle 9, Cycle 12, and Cycle 15) in each population. The progenitors used to form these populations are highly polymorphic (3.8 alleles/locus and 0.56 expected heterozygosity). This polymorphism decreases through Cycle 15 (1.9 alleles/locus and 0.25 expected heterozygosity). Individual plants within groups have a larger amount of genetic variation (66%) than groups within each population (13%) or between populations (21%). Consistent with theoretical expectations is the repartitioning of variation from within populations (96% in progenitors) to between populations (58% in Cycle 15) over time. When testing for deviations from natural processes, we identified approximately 26 of the 86 SSR loci affected by a non-random process over time. These results implicate genetic drift with a more profound effect than artificial selection in small populations. Through the use of smaller sample sizes, we were able to analyze more intermediate groups than any previous work in these populations. These intermediate time points represent a comprehensive genetic look within CB and SS to evaluate the applied effectiveness of the reciprocal recurrent selection program in relationship to its theoretical framework.

Download or read book Trait Variation and QTL Mapping in Early Season Maize Populations written by Raja Khanal and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Maize Genome written by Jeffrey Bennetzen and published by Springer. This book was released on 2018-11-24 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses advances in our understanding of the structure and function of the maize genome since publication of the original B73 reference genome in 2009, and the progress in translating this knowledge into basic biology and trait improvement. Maize is an extremely important crop, providing a large proportion of the world’s human caloric intake and animal feed, and serving as a model species for basic and applied research. The exceptionally high level of genetic diversity within maize presents opportunities and challenges in all aspects of maize genetics, from sequencing and genotyping to linking genotypes to phenotypes. Topics covered in this timely book range from (i) genome sequencing and genotyping techniques, (ii) genome features such as centromeres and epigenetic regulation, (iii) tools and resources available for trait genomics, to (iv) applications of allele mining and genomics-assisted breeding. This book is a valuable resource for researchers and students interested in maize genetics and genomics.

Download or read book Advances in Genetic Enhancement of Early and Extra Early Maize for Sub Saharan Africa written by Baffour Badu-Apraku and published by Springer. This book was released on 2017-11-10 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book focuses on the principles and practices of tropical maize improvement with special emphasis on early and extra-early maize to feed the increasing population in Sub-Saharan Africa. It highlights the similarities and differences between results obtained in temperate regions of the world and WCA in terms of corroboration or refutation of genetic principles and theory of maize breeding. The book is expected to be of great interest to maize breeders, advanced undergraduates, graduate students, professors and research scientists in the national and international research institutes all over the world, particularly Sub-Saharan Africa. It will also serve as a useful reference for agricultural extension and technology transfer systems, Non-governmental Organizations (NGOs) and Community-Based Organizations (CBOs), seed companies and community-based seed enterprises, policy makers, and all those who are interested in generating wealth from agriculture and alleviating hunger and poverty in Sub-Saharan Africa.

Download or read book Genetic Dissection of Yield Component Traits in Zea Mays Using Multiparent Advanced Generation Intercross Populations written by Kathryn Michel and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Maize (Zea mays L.) yield is a highly quantitative trait controlled by many loci of small effect, the environment, and genotype by environment interactions, which make it a difficult trait to study at the gene level. However, yield may be broken into components such as ear and kernel size and shape, which are more heritable than yield measured in small plots. Multiparent advanced generation intercross (MAGIC) populations and diversity panels are two types of populations that are useful for identifying quantitative trait loci (QTL) that influence phenotypes. This dissertation contains three research projects designed to investigate the control of quantitative traits impacting maize yield. First, we present the genomes of five founders of a Stiff Stalk MAGIC population. Between the reference inbred B73 and the other five inbreds, we found substantial genetic and genomic variation in addition to conservation of haplotypes from the base population from which the inbreds were selected. Second, we describe the Wisconsin-Stiff Stalk-MAGIC population, its associated resources, and demonstrate QTL mapping and genomic prediction for flowering time and plant height. Flowering time and plant height are important characteristics in hybrid maize breeding, so we measured them in both the per se population and two test-crossed hybrid populations. We found that QTL detection depended on the tester used, which was consistent with lower genomic predictive ability when training models with per se data to predict hybrid phenotypes. Third, we used a high throughput image analysis pipeline to measure yield components on four MAGIC populations and a diversity panel. We performed genetic mapping to identify candidate genes underlying ear and kernel size and shape. We found substantial overlap of our results across traits within and between populations and overlap with known metaQTL identified through previous studies. The results from these projects provide new insight into the genetic control of traits including flowering time, plant height, and the size and shape of ears and kernels, all of which impact overall maize yield.

Download or read book Maize Breeding and Genetics written by David B. Walden and published by John Wiley & Sons. This book was released on 1978 with total page 824 pages. Available in PDF, EPUB and Kindle. Book excerpt: History; Evolution; Breeding; Diseases and insects; Endosperm; Tissue; Gene action; Cytogenetics.

Download or read book Estimates of Genetic Variability and Gene Action in Two Maize Zea Mays L Populations written by Geng-Chen Han and published by . This book was released on 1987 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Introgression of Exotic Germplasm for Improving Maize Zea Mays L Breeding Populations written by Jose L. Crossa-Hiriart and published by . This book was released on 1984 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ninety S1 families from three populations representing three levels (0%, 25% and 50%) of introgression of exotic maize germplasm into an adapted population were developed and evaluated at two locations. A theoretical approach to the problem of finding an intensity os selection and effective population size which maximizes the final chance of fixation of favorable alleles in different foundation stocks was examined. The S1 families from the cross yielded significantly less than those from adapted and backcross populations. Adapted and backcross populations yielded similarly. This suggests that major genes for lack of adaptation are acting in the crosses population. A significant quadratic relationships between S1 family means and proportion of adapted materialin the foundation stock for grain yield indicate that a second backcross to the adapted population would not produce a significant increase in grain yield. Greater genetic variance and predicted gain from selection in the population cross compared to the adapted and backcross population indicate possible benefits from the use of exotic germplasm in long-term selection programs. The choice of using one or two generations of backcrossing to the adapted population does not seem to be useful when, for a given locus, Ps (frequency of favorable allele in adapted population) is low and P2 (frequency of favorabel allele in exotic population) takes values larger than .5.5 While the N (effective population size) in cross population, that makes the final (...).

Download or read book Farmers Gene Banks and Crop Breeding Economic Analyses of Diversity in Wheat Maize and Rice written by Melinda Smale and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 275 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Evaluation of Genetic Variability Using Full sib Families Within and Between the BS10 and BS11 Synthetic Maize Zea Mays L Populations for the Original and Tenth Cycle of Selection written by Todd Eugene Frank and published by . This book was released on 1997 with total page 418 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Quantitative Genetics of a Non stiff stalk Maize Zea Mays L Population written by Brandon M. Wardyn and published by . This book was released on 2006 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: The genetic relationship among individuals is at the core of nearly all quantitative genetic theory. Dominant gene action has long been either ignored or disregarded as insignificant in many previous genetic models. For grain yield in maize (Zea mays L.), dominance has consistently accounted for a large proportion of genetic variance. We have used previously developed genetic theory that accounts for dominance variance during inbreeding and applied it to a unique breeding design. Our breeding design allowed us to estimate five genetic covariance parameters for six traits. In addition, we developed genetic gain equations that accounted for both dominance and inbreeding. We found that the genetic covariance parameters introduced via inbreeding were significant for five traits. Our estimates of the genetic covariance parameters allowed us to predict genetic gain over a range of selection units and response units. Half-sib selection proved superior to inbred progeny selection when the response was measured in the outbred progeny. In addition, the relative proportions of additive and dominance variance influenced the effectiveness of inbred progeny selection. We also showed that even when dominance constitutes a larger proportion of the total genetic variance than additive variance, the loss of additive effects has a greater influence on the decline associated with inbreeding than the addition of homozygous dominance deviations. Our results also indicated that the reason realized gain often falls short of predicted gain is due to the negative covariance between additive effects and homozygous dominance effects. The effect of a negative covariance is that positive gain via additive effects is offset by negative gain via homozygous dominance deviations.