Degree
Doctor of Philosophy (PhD)
Department
School of Plant, Environmental, and Soil Sciences
Document Type
Dissertation
Abstract
Salinity stress significantly challenges agricultural productivity, particularly affecting major crops like rice and soybean. This research investigates the genetic basis of salt tolerance in both crops through high-resolution genetic mapping, genome-wide association studies (GWAS), and RNA-Seq analysis. In rice, we examined quantitative trait loci (QTLs) associated with salt tolerance at the seedling and flowering stages using a population of advanced backcrossed introgression lines (ILs). A genetic map, constructed with 14,230 polymorphic SNP markers, identified distinct QTLs and candidate genes for salt tolerance at both stages, suggesting differential genetic controls. Notable genes such as OsHAK13 and OsCYP21-4 were upregulated under salt stress at the flowering stage, while OsHAK20 and STRK1 showed similar expression patterns at the seedling stage. In soybean, a diverse panel of 269 accessions was screened under saline conditions, revealing a strong positive correlation between leaf scorching score and sodium and chloride accumulation. GWAS identified 32 significant marker-trait associations, explaining 14% to 52% of the total variation in the trait. Key candidate genes such as GmKUP6 and GmWRKY33, involved in ion transport and stress response, were differentially expressed between salt-tolerant and susceptible genotypes. Based on the screening, the extreme genotypes PI561363 and PI601984 were selected for physiological and transcriptomic analysis at various time points (0 h, 6 h, 24 h, 48 h) under salt stress conditions. Physiological responses highlighted differences in malondialdehyde production, peroxidase activity, and potassium uptake between salt-tolerant and salt-susceptible soybean genotypes. Gene Ontology (GO) enrichment analysis underscored crucial processes such as lipid metabolism and ion homeostasis for salt tolerance. Additionally, several gene families, including CHX, KUP, and HKT, were upregulated, playing vital roles in salt exclusion, and maintaining ionic balance. These findings highlight the complexity of salt tolerance mechanisms and the potential of marker-assisted selection to enhance salinity tolerance in rice and soybean. Integrating QTL stacking and genomic selection could facilitate the development of varieties adapted to saline conditions improving crop resilience and productivity in salt-affected areas.
Date
7-15-2024
Recommended Citation
Pruthi, Rajat, "Leveraging the Genomic Tools to Explore the Molecular Basis of Salinity Tolerance in Rice and Soybean" (2024). LSU Doctoral Dissertations. 6548.
https://repository.lsu.edu/gradschool_dissertations/6548
Committee Chair
Subudhi, Prasanta
Included in
Genetics Commons, Genomics Commons, Molecular Genetics Commons, Plant Breeding and Genetics Commons