Genomic Investigations Of Autumn Dormancy In Alfalfa Medicago Sativa
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| Author | : Gitanshu Munjal |
| Publisher | : |
| Total Pages | : |
| Release | : 2017 |
| Genre | : |
| ISBN | : 9780355764505 |
The primary goal of the research presented in the following chapters was to assess the genomic basis of the adaptive trait of autumn dormancy in alfalfa using high resolution genetic mapping approaches in diverse germplasm. Previous work in the field has developed protocols to generate vast amounts of sequence based marker data for this species using GBS. However, opportunity remains to extract more information from such data than had been previously possible. In chapter 1, we review some concepts relevant to the rest of this work including basic biology and improvement of alfalfa, the trait of autumn dormancy, and opportunities for molecular markers in alfalfa research. In chapter 2, we employ a recent SNP calling methodology and develop a framework for estimating allele frequencies from pooled sequencing. We use that framework to screen the non-dormant cultivar CUF 101 and populations developed by three cycles of selection for taller and shorter plants in autumn. We validated the robustness of our GBS-derived, population-specific allele frequency estimates using an analytic approach. In chapter 3, we analyze pre- and post-selection populations from an additional five backgrounds together with CUF 101 to seek evidence for loci under selection in germplasm expressing a range of dormancy levels. In chapter 4, we build on recent scientific reports to propose a method for conducting genome-wide association scans from low-coverage autotetraploid sequencing data that is able to account for uncertainty regarding genotypes. We apply this method to a panel of semi-dormant individuals from a commercial breeding program. Using simulations, we show this method to be more powerful than an existing method.
| Author | : Milton A. Sprague |
| Publisher | : |
| Total Pages | : 82 |
| Release | : 1938 |
| Genre | : |
| ISBN | : |
| Author | : Douglas James Brouwer |
| Publisher | : |
| Total Pages | : 364 |
| Release | : 1998 |
| Genre | : |
| ISBN | : |
| Author | : Baldomero Alarcón Zúñiga |
| Publisher | : |
| Total Pages | : 184 |
| Release | : 2003 |
| Genre | : |
| ISBN | : |
Alfalfa (Medicago sativa L.) has a broad geographic distribution, with populations adapted to both cold and warm climates. Despite considerable research on winter hardiness, the mechanisms and genetic control of winter survival are poorly understood. We conducted two experiments designed to identify and quantify morphological, physiological, and biochemical traits associated with winter hardiness and to estimate the genetic relationship of these traits with winter hardiness. In Experiment 1, ten alfalfa genotypes were planted in June 2000 and in May 2001 at Ames, IA, and traits were measured in August, November, and the following April in each year. Concentrations of palmitate, palmitoleate, linoleate, linolenate and total fatty acids increased in crowns and roots of all genotypes from August to November and declined by April. Winter injury showed a negative phenotypic correlation with concentrations of palmitate, linoleate, linolenate, total fatty acids in both roots and crowns. These data suggest an important role of fatty acids in winter hardiness. In Experiment 2, we established an F1 segregating population of 200 individuals in the field in successive years at Ames, IA and measured agronomic and physiological traits in August and November. Although differences among the individuals in the F1 population were present for all traits, and transgressive segregation present for many, the population mean tended to fall intermediate to the two parents. Broad sense heritabilities on an entry mean basis were 0.58 for winter injury, 0.60 for plant height in November, and ranged from 0.44 to 0.63 for shoot, crown, and root mass in August and November. Total fatty acid concentration had an H2 of 0.72 in August and 0.44 in November. Autumn plant height had weak positive genetic correlations with winter injury, in contrast to other research. Shoot, crown, and root biomass in both August and November showed strong negative genetic correlations with winter injury, suggesting that in this population, winter survival was related to plant vigor. Preliminary genetic mapping identified several chromosomal locations associated with most traits. These results suggest that the determinants of winter survival in this population formed from semidormant parents differ from those in populations with nondormant parental genotypes.
| Author | : Laxman Adhikari |
| Publisher | : |
| Total Pages | : 354 |
| Release | : 2018 |
| Genre | : |
| ISBN | : |
Fall dormancy (FD) and winter hardiness (WH) influence seasonal yield, stand persistence, and latitudinal adaptation of alfalfa (Medicago sativa L.). Selection of dormant alfalfa genotypes with higher WH has been a common practice. This research was carried out to dissect the genetic basis of FD and WH through quantitative trait loci (QTL) mapping and explore the potential of incorporating WH in non-dormant alfalfa. Other traits, including time of flowering (TOF), spring yield (SY), cumulative summer biomass (CSB), and leaf rust resistance were also evaluated. An F1 population was derived for linkage analysis and QTL mapping by crossing a dormant winter-hardy cultivar (3010) with a non-dormant cold-sensitive cultivar (CW 1010) Genotyping-by-sequencing was used for single nucleotide polymorphism (SNP) marker discovery. Dormancy and WH were evaluated according to NAAIC protocols. We mapped 45 FD and 35 WH QTLs on the genetic linkage maps of both parents. More than 70% of the FD QTLs did not share genomic locations with WH QTLs, suggesting that the two traits are inherited separately. This study also showed that using late autumn to early winter regrowth height is more reliable than early autumn in estimating alfalfa dormancy in southern environments with mild-winters. The QTL markers with higher phenotypic effects (R2) can be used in marker-assisted selection (MAS) of non-dormant alfalfa with improved WH. Incorporating WH in non-dormant alfalfa can ensure forage production in late autumn and early winter to minimize the forage gaps. In this research, we mapped a total of 25 QTLs for TOF, 17 QTLs for SY, six QTLs for CSB, and eight QTLs for leaf rust resistance in the same alfalfa population. Four TOF QTLs were detected in corresponding genomic positions of flowering QTLs of M. truncatula reported previously. The multiple QTLs detected for leaf rust resistance suggests that alfalfa resistance to the rust pathogen is polygenic. The QTL markers identified in this study constitute an important addition to alfalfa genomic resources and can be validated in populations with diverse genetic backgrounds and in multiple environments for potential use in MAS.
| Author | : Nina Christine Putzar |
| Publisher | : |
| Total Pages | : 208 |
| Release | : 1989 |
| Genre | : |
| ISBN | : |
| Author | : Deborah Y. Richardson |
| Publisher | : |
| Total Pages | : 62 |
| Release | : 1992 |
| Genre | : Plant breeding |
| ISBN | : |
| Author | : Long-Xi Yu |
| Publisher | : Springer Nature |
| Total Pages | : 296 |
| Release | : 2021-07-17 |
| Genre | : Science |
| ISBN | : 3030744663 |
This book is the first comprehensive compilation of deliberations on whole genome sequencing of the diploid and tetraploid alfalfa genomes including sequence assembly, gene annotation, and comparative genomics with the model legume genome, functional genomics, and genomics of important agronomic characters. Other chapters describe the genetic diversity and germplasm collections of alfalfa, as well as development of genetic markers and genome-wide association and genomic selection for economical important traits, genome editing, genomics, and breeding targets to address current and future needs. Altogether, the book contains about 300 pages over 16 chapters authored by globally reputed experts on the relevant field in this crop. This book is useful to the students, teachers, and scientists in the academia and relevant private companies interested in genetics, breeding, pathology, physiology, molecular genetics and breeding, biotechnology, and structural and functional genomics. The work is also useful to seed and forage industries.
| Author | : M. Humphreys |
| Publisher | : BRILL |
| Total Pages | : 286 |
| Release | : 2023-08-28 |
| Genre | : Nature |
| ISBN | : 9086865550 |
Grassland covers 26% of the world’s total land area. It produces feed for livestock; maintains soil fertility; protects and conserves soil and water resources; creates a habitat for wildlife; provides recreational space for sport and leisure and contributes to the general landscape. This book provides an up-to-date account of progress and potential in the genetic improvement of grassland to meet all needs. It encompasses work on a wide range of temperate and tropical grassland species (including grasses, clovers and other forage legumes) and will interest all those concerned with grassland use in livestock-based agriculture, recreation, environmental protection, bio-industry etc. Specifically, it demonstrates how recent advances in molecular techniques are being used to develop breeding objectives and strategies with key-note papers on: Objectives and benefits of molecular breeding, Linkage/physical mapping and map-based cloning, QTL analysis and trait dissection, Genomics, model species, gene discovery and functional analysis, Use of molecular markers and bioinformatics for breeding, Molecular genetics and breeding of endosymbiont and grass/legume associations, Transgenics, Genetic diversity, breeding systems and resources Future directions for research and breeding. State-of-the-art molecular techniques and resources are described that encompass a unique range of expertise in genetic mapping, trait dissection, comparative genomics, bioinformatics, gene discovery and risk assessment. Examples of work in progress or recently completed are provided from across the world. The book has broad educational value and will interest plant geneticists and breeders as well as grassland users and policy makers.
| Author | : Omena Bernard Ojuederie |
| Publisher | : Frontiers Media SA |
| Total Pages | : 151 |
| Release | : 2024-01-23 |
| Genre | : Science |
| ISBN | : 2832543324 |
Global demand for food is rising as a result of increases in the global population as well as dietary changes. Furthermore, climate change exerts additional pressure on the food supply, adversely affecting sustainable food production. Increased temperatures and drought stresses coupled with the migration of pests limit crop yields and affect their nutritional quality. Many staple crops are unable to adapt to these changing climatic conditions. To achieve the Sustainable Development Goals of the United Nation to end hunger and promote good health and well-being, concerted efforts need to be made to enhance food production while mitigating the effects of climate change through the promotion of climate-smart agricultural practices and the utilization of neglected and underutilized crop species. These species can be highly nutritious and well-adapted to different agroecologies and climatic conditions, meaning that they offer the possibility of improving food and nutritional security.
