38 results
Search Results
Now showing 1 - 10 of 38
Item Association Mapping and Genetic Diversity Studies of Agronomic and Quality Traits in Durum Wheat [Triticum turgidum L. var. durum (Desf.)](North Dakota State University, 2017) Johnson, MarinaGenetic diversity studies in breeding programs are important to identify parental lines for hybridization and introgression of desirable alleles into elite germplasm. The genetic diversity analysis of 283 North Dakota State University (NDSU) advanced durum wheat breeding lines developed during the last 20 years indicated that the population was structured according to its breeding history. Total genetic diversity analysis (HT = 0.334) showed adequate level of genetic variation. The results will help in breeding efforts to broaden the genetic base and select lines for crossing as well as for genetic and genomic studies to facilitate the combination of desirable alleles. The quantitative nature of important target traits, combined with environmental effects, makes it difficult to bring the desirable improvement in durum wheat to meet the expectations of all the stakeholders involved in the durum wheat industry. With an objective to identify molecular markers for marker-assisted breeding (MAB), the present study attempted to identify marker-trait associations for six agronomic and 29 quality traits using a genome-wide association study (GWAS) mapping approach. The study used two types of phenotypic datasets, a historic unbalanced dataset belonging to a total of 80 environments collected over a period of 16 years and a balanced dataset collected from two environments, to identify the applicability of historic unbalanced phenotypic data for GWAS analysis. A total of 292 QTL were identified for agronomic and quality traits, with 10 QTL showing major effects (R2 >15%). Over 45% of QTL for agronomic and quality traits were present in both the unbalanced and balanced datasets, with about 50% of those present in both environments in the balanced dataset. Genome-wide association mapping studies identified several candidate markers for use in marker-assisted selection (MAS) for height, gluten strength, distribution of small kernels, polyphenol oxidase (PPO) activity, and yield.Item Identification of Molecular Markers for Marker-Assisted Selection of Malting Quality and Associated Traits in Barley(North Dakota State University, 2015) Jung, RenataBarley (Hordeum vulgare L.) is one of the most important cereal crops in North Dakota, which ranks second amongst all states for barley production in the United States. Barley is used for the production of malt, which is used for brewing beer. The malting and brewing industries set strict standards for malt quality; yet, determining malt quality of experimental barley lines is very expensive. For this reason, quality is typically determined at the latter stages of the breeding program, resulting in rejection of many genotypes after large investments for agronomic performance, disease resistance, and end-use quality evaluations have occurred. High quality malt cultivars must possess numerous genetically controlled characteristics. This limits the effectiveness of phenotypic selection for malt quality. The use of marker-assisted selection (MAS) may enable breeders to eliminate lines with undesirable traits earlier in the breeding process, reducing costs, and improving genetic gain. In spite of the large number of mapped QTLs, few examples exist in the literature in which QTL analysis and MAS have been applied to the genetic improvement of malting barley. This research was initiated to identify robust marker-trait associations for malting quality, disease resistance, and agronomic traits utilizing genome-wide association mapping of selected NDSU two-rowed lines. Our research successfully identified numerous marker-trait associations for the traits evaluated to be used for MAS to improve the North Dakota State University barley breeding program.Item Blizzard Watch : Plant Sciences : 2000-2001(North Dakota State University, 2001) North Dakota State University. Department of Plant SciencesNewsletter for the Department of Plant Sciences.Item Blizzard Watch : Plant Sciences : 1999-2000(North Dakota State University, 2000) North Dakota State University. Department of Plant SciencesNewsletter for the Department of Plant Sciences.Item Genetic Diversity and Genome-Wide Association Mapping of Agronomic, Disease Resistance, and Quality Traits in Barley Accessions from Ethiopia, Icarda, and the U.S.(North Dakota State University, 2015) Daba, Sintayehu DebebePlant breeding is a dynamic process that incorporates new germplasm to introduce genetic variation. Knowledge gained from genetic diversity studies and identification of potentially useful germplasm is critical for efficiently utilizing these new materials for breeding program. Linkage disequilibrium (LD), diversity, and association mapping analyses in barley (Hordeum vulgare L.) were done using a mapping panel that included Ethiopian landraces, and cultivars and breeding lines from the Ethiopian, ICARDA, and NDSU breeding programs. LD decayed within 10 to 20 cM in the mapping panel and large proportions of unlinked loci were found to have large LD estimates, indicating that factors other than linkage contributed to LD. Diversity analyses using phenotypic data and molecular markers indicated that the mapping panel was highly structured according to spike row-type, geographic origin, and breeding history; thus, accounting for population structure and familial relatedness was crucial for association analyses. Comparison of the four models (Naïve, P, K, and P+K) indicated that the P+K model is the best model for the current mapping panel. The genome-wide association study (GWAS) identified 94 QTL for 14 agronomic and disease resistance traits; and 145 QTL for 11 malt and grain quality traits. Association mapping of agronomic and disease resistance traits identified six photoperiod related loci (Ppd_H1, HvFT4, HvGI, HvFT2, HvCO2, and HvCO1) and one vernalization-related locus (VRN-H1) for days to heading, one semi-dwarf locus (sdw3) for plant height, and four resistance loci (Rrs1, Rrs15, rpt.k and rpt.r). The largest number of QTL for malt and grain quality traits was detected in chromosome 5H, followed by chromosome 7H. QTL for malt and grain quality traits were mapped near the Hor1, Hor2, Upg2, Dor4, Ltp1, Amy1, and Amy2 loci. Several unique QTL were identified in the ICARDA and NDSU accessions, with the NDSU materials having the favorable marker genotypes. These regions could be useful to the Ethiopian breeding program for improving malt quality. The current study indicated that association mapping provided useful tool to identify QTL for several traits simultaneously. Because the QTL had small effect and distributed across the genome, genome selection may be warranted for improving these traits.Item Development and Characterization of Wheat Germplasm for Resistance to Stem Rust UG99 in Wheat(North Dakota State University, 2013) Zhang, QijunWorld wheat production is currently threated by stem rust (caused by Puccinia graminis f. sp. tritici) Ug99 race (TTKSK). The ongoing global effort to combat Ug99 is focusing on the identification and deployment of Ug99-resistant genes (Sr) into commercial cultivars. The objectives of this study were to identify TTKSK-effective Sr genes in untapped durum and common wheat germplasm and introgression of TTKSK-effective Sr genes from tetraploid wheat (Triticum turgidium) and Aegilops tauschii into hexaploids through production of synthetic hexaploid wheat (SHW). For identification of TTKSK-effective Sr genes, 177 durum and common wheat cultivars and lines were first evaluated using three highly virulent races TTKSK, TRTTF, and TTTTF and 71 cultivars and lines with TTKSK resistance were identified. The TTKSK-resistant cultivars and lines were then evaluated using six local races and the molecular markers that are diagnostic or tightly linked to the known TTKSK-effective Sr genes. The race specification and marker analysis showed that several previously deployed TTKSK-effective Sr genes such as Sr2, Sr24 and Sr42 were present in some of the cultivars and lines. A number of resistant cultivars and lines derived from wheat relatives such as Thinopyrum ponticum, Th. elongatum, Th. intermedium, and Ae. speltoides may carry novel Sr genes. For SHW development, 200 new SHW lines were developed by crossing 181 tetraploid wheat accessions to 14 Ae. tauschii accessions. Sixty-six of the new SHW lines, 14 previously-developed SHW lines, and their parents were evaluated for resistance to TTKSK, TRTTF, TTTTF and six other races and genotyped using molecular markers linked to the known genes in T. dicoccum and Ae. tauschii. The evaluation data showed that 44 SHW lines were resistant to TTKSK. The race specification and marker analysis showed that Sr2 from T. dicoccum and Sr33 from Ae. tauschii were present in some of the SHW lines and a number of SHW lines have novel genes conferring TTKSK resistance. The durum and wheat cultivars and lines and SHW lines with known and novel Sr genes conferring resistance to TTKSK will be useful resources for improving wheat resistance to TTKSK and other emerging races of stem rust.Item Validation of Molecular Markers Associated with Grain Cadmium in Durum Wheat (Triticum turgidum L. var. durum Desf.)(North Dakota State University, 2016) Salsman, Evan LeeDurum wheat is capable of accumulating cadmium, a toxic heavy metal, in the grain at levels that have been deemed unsafe. Previous studies have identified genetic variation in durum wheat that can be exploited to create low Cd cultivars. In this study, six KASP markers were validated on 4,178 durum wheat samples from preliminary and advanced yield trials grown in 2013 and 2014 at Langdon, Minot, and Williston, North Dakota. One marker on chromosome 5B was polymorphic in all crosses between high and low Cd parents and had r² values ranging from 0.38-0.85. Two other markers on the same chromosome predicted similar levels of variation in many trials; however these were not polymorphic in all populations. Two markers linked to the grain Cd locus on chromosome 5B are suitable for marker assisted selection due to the more widely shared polymorphism of one and the closer linkage distance of the other.Item Blizzard Watch : Plant Sciences : 2009-2010(North Dakota State University, 2010) North Dakota State University. Department of Plant SciencesNewsletter for the Department of Plant Sciences.Item Blizzard Watch : Plant Sciences : 2014(North Dakota State University, 2015) North Dakota State University. Department of Plant SciencesNewsletter for the Department of Plant Sciences.Item Unraveling the Genetics of Seed Dormancy in Barley Using Genome-Wide Association and Biparental Mapping(North Dakota State University, 2013) Correa-Morales, Ana MariaSeed dormancy is the delay or inability of viable seeds to germinate under favorable conditions. The differential expression of dormancy levels in barley (Hordeum vulgare L.) seeds impacts malt quality. While dormant genotypes are required to avoid the incidence of preharvest-sprouting, genotypes with low dormancy are needed for uniform germination of seeds during malting. The objective of this study was to determine the genetic basis underlying seed dormancy in spring barley using genome-wide association mapping (AM) and linkage mapping. A panel of 3,072 elite U.S. spring barley breeding lines from eight breeding programs participating in the USDA-NIFA Barley Coordinated Agricultural Project and 193 F1-derived doubled-haploid lines from the cross `Stander'/ `Robust' were used to map QTL controlling seed dormancy. The AM panel and the doubled-haploid population were genotyped with SNP markers using the Illumina Golden Gate assay. Four mixed linear models that controlled population structure and kinship were used for the AM analyses, while composite interval mapping was used for the analysis of the biparental population. Our results confirmed the existence of marker-trait associations delineating two QTL regions in the long arm of chromosome 5H (5HL) using the AM panel, and a large effect QTL in the same region using the biparental population. The locations and effects of these marker-trait associations are congruent with previously mapped QTL for seed dormancy and demonstrate the two mapping methods effectively targeted the same genetic regions on the barley genome and provide insights about the genetics of seed dormancy.