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Full-Text Articles in Agronomy and Crop Sciences

Genetic Dissection Of Alkalinity Tolerance In Rice (Oryza Sativa L.), Lovepreet Singh Jul 2023

Genetic Dissection Of Alkalinity Tolerance In Rice (Oryza Sativa L.), Lovepreet Singh

LSU Doctoral Dissertations

Alkaline stress is a major threat to rice production globally. The resources for genetic improvement of alkalinity tolerance in rice are limited. We performed genome-wide association study (GWAS) and QTL mapping integrated with whole genome sequencing and expression analysis to identify and confirm QTLs and candidate genes. We developed a near-isogenic line (NIL) population to fine map the two important QTLs. In GWAS experiment, we genotyped and phenotyped a panel of indica and japonica genotypes for alkalinity tolerance and identified genomic regions and candidate genes conferring alkalinity tolerance. Principal component analysis revealed that alkalinity tolerance score, shoot dry weight, and …


Identification Of Quantitative Trait Loci (Qtls) For Resistance To Bacterial Leaf Streak: Xanthomonas Translucens Using Qtl And Association Mapping In Three Populations Of Soft Red Winter Wheat, Benjamin Tyler Meritt Nov 2022

Identification Of Quantitative Trait Loci (Qtls) For Resistance To Bacterial Leaf Streak: Xanthomonas Translucens Using Qtl And Association Mapping In Three Populations Of Soft Red Winter Wheat, Benjamin Tyler Meritt

LSU Doctoral Dissertations

Bacterial leaf streak (BLS) and black chaff, caused by Xanthomonas translucens pv. undulosa (Xtu), can be a very destructive disease of wheat, especially in the warmer, wetter areas of the Southeastern U.S. Yield losses of up to 40 percent have been recorded in some cases in southern wheat growing regions. With no effective agronomic or chemical method of disease control, identification of genetic resistance is seen as a promising solution. Three soft red winter wheat populations (GAWN, ARK-SNP, and AGS 2060- AGS 2035 DH) representative of soft red winter wheat germplasm in the southeastern U.S. developed by …


Marker-Trait Association Mapping Of Sorghum Mosaic Virus Resistance In Sugarcane, Chenie Zamora Apr 2022

Marker-Trait Association Mapping Of Sorghum Mosaic Virus Resistance In Sugarcane, Chenie Zamora

LSU Master's Theses

Mosaic is a potentially devastating disease of sugarcane that had severe economic impact on Louisiana’s sugarcane industry in the 1920’s and has caused periodic problems ever since. The disease is vectored by migrating aphids that transmit Sugarcane mosaic virus (SCMV) and Sorghum mosaic virus (SrMV) in a non-persistent manner. Mosaic in Louisiana is currently caused by strains of SrMV. Mosaic has been controlled primarily by developing resistant cultivars. Recently, mosaic was detected in some near-commercial clones in the cultivar selection program. This prompted extensive screening of breeding program parent populations that detected infiltration of susceptibility and revealed the need for …


Multi-Year Data Analysis And Genomic Selection To Improve The Efficiency Of A Rice Breeding Program, Tommaso Cerioli Mar 2022

Multi-Year Data Analysis And Genomic Selection To Improve The Efficiency Of A Rice Breeding Program, Tommaso Cerioli

LSU Doctoral Dissertations

Plant breeding dramatically improved crops performances during human history and will play a pivotal role in shaping the future of agriculture. However, this activity requires large amount of time and resources. The availability of multi-year datasets and abundant DNA information enables new analyses and breeding approaches that can increase the productivity and efficiency of a breeding program. In recent years, the LSU Rice Breeding Program has implemented marker assisted selection (MAS) and genomic selection (GS) to predict performance of rice genotypes before field testing. The goal of this project was to conduct analyses and test molecular approaches to increase the …


Resistance To Aflatoxin Accumulation In Maize Mediated By Host-Induced Gene Silencing Of Aspergillus Flavus Alkaline Protease And O-Methyltransferase-A Genes, Olanike Omotola Omolehin Jan 2021

Resistance To Aflatoxin Accumulation In Maize Mediated By Host-Induced Gene Silencing Of Aspergillus Flavus Alkaline Protease And O-Methyltransferase-A Genes, Olanike Omotola Omolehin

LSU Doctoral Dissertations

Aspergillus flavus is a soil-borne fungal pathogen that infects maize and produces aflatoxins. In the current study, portions of the alkaline protease (alk) and the O-methyl transferase (omtA) genes, which are key in A. flavus virulence and aflatoxin biosynthesis, respectively, were targeted for suppression through an RNAi (RNA interference) approach known as Host-Induced Gene Silencing (HIGS). Separate RNAi vectors were designed to carry regions of the alk and omtA gene fragments (Alk-RNAi and OmtA-RNAi) and introduced into B104 maize zygotic embryos. Eight and six transformation events were positive for the alk and omtA transgene, respectively. …


Development Of Sheath Blight-Resistant Breeding Lines For Southern U.S. Environments And Morphological And Genetic Survey Of Giant Salvinia Populations In Louisiana And Texas, Dominique Clark Galam Mar 2019

Development Of Sheath Blight-Resistant Breeding Lines For Southern U.S. Environments And Morphological And Genetic Survey Of Giant Salvinia Populations In Louisiana And Texas, Dominique Clark Galam

LSU Doctoral Dissertations

The southern US environment is a very conducive environment for agriculture and fisheries. Rice farming, shrimping and water related activities help drive the local economy. However, there are several factors that impede the success of these activities. Sheath blight (SB) disease caused by Rhizoctonia solani is one of the major biotic constraints to high grain yield and quality for most commercial U.S. rice varieties. Although different breeding lines with high levels of "partial resistance" have been developed none has been used directly as a commercial variety. The first research objective of this research was to identify and develop advanced breeding …


Genome Wide Association Studies For Identification Of Markers Linked To Sucrose Traits In Sugarcane, Nathanael Darrell Fickett Oct 2018

Genome Wide Association Studies For Identification Of Markers Linked To Sucrose Traits In Sugarcane, Nathanael Darrell Fickett

LSU Doctoral Dissertations

Sugarcane, being a complex aneu-polyploid, poses unique challenges to fine mapping of quantitative trait loci (QTL) controlling agronomic traits of interest. Genome-wide association studies (GWAS) could be a better alternative to identify molecular markers associated with specific traits due to high linkage disequilibrium in sugarcane. In the first study, marker-trait associations (MTAs) were evaluated for three sucrose traits, Brix, total recoverable sugar (TRS), and percent sucrose on 48 elite and historic Louisiana breeding clones using 1,062 alleles. These sucrose traits were highly correlated (P-value < 0.0001) at >0.96. TASSEL 5.1 and JMP Genomics 8.0 were compared with eight models run in each program. …


Identification Of Quantitative Trait Loci (Qtl) For Tolerance To Metribuzin In Soft Red Winter Wheat (Triticum Aestivum L.), Hugo Alfonso Anzueto Ponciano Aug 2018

Identification Of Quantitative Trait Loci (Qtl) For Tolerance To Metribuzin In Soft Red Winter Wheat (Triticum Aestivum L.), Hugo Alfonso Anzueto Ponciano

LSU Master's Theses

Wheat is one of the world’s most important food crops and provides nearly 20% of the calories consumed. Wheat is the third most important crop after corn and rice on a global production scale. In Louisiana wheat harvest was about 6000 hectares in 2017. Wheat production is negatively affected by several biotic and abiotic factors including weather, diseases, and weeds. Metribuzin is a broad-spectrum herbicide commonly used in wheat because it is inexpensive and controls most of the common weeds in wheat fields. Metribuzin has benefits for the grower controlling weeds that might cause yield loss in varieties or lines …


The Determinants Of Nucleosome Patterns And The Impact Of Phosphate Starvation On Nucleosome Patterns And Gene Expression In Rice, Qi Zhang Mar 2018

The Determinants Of Nucleosome Patterns And The Impact Of Phosphate Starvation On Nucleosome Patterns And Gene Expression In Rice, Qi Zhang

LSU Doctoral Dissertations

In eukaryotic cells, DNA is a large molecule that must be greatly condensed to fit within the nucleus. DNA is wrapped around histone proteins to form nucleosomes, which facilitate DNA condensation, but on the other hand, may limit DNA processes. Organisms must respond to environmental stress in order to survive, and one strategy is by remodeling nucleosomes to promote changes in DNA accessibility to alter gene expression. Studies have demonstrated a clear correlation between nucleosome dynamics and transcriptional change in some eukaryotes, however factors that affect nucleosome positioning in plants are largely unknown, and the correlation between nucleosome dynamics and …