Genome Wide Association and Forward Genetic Studies to Identify Genes Involved in Salt Tolerance

Salinity tolerance varies considerably between natural accessions of rice. In this project, the main aims were to identify well-known genes and novel determinant candidate genes for salinity tolerance using genome wide association study (GWAS) and forward genetic screening. To assess salinity tolerance in rice and Arabidopsis, relative growth rate of plants and cations in roots and shoots were analysed. This research has found that relative growth rate, root K+, and shoot Na+ traits are parameters for salinity tolerance in both species. Moreover, the growth parameter is correlated with the root K+ and shoot Na+. Regarding the identification of determinant genes for saline conditions, the GWAS approach has revealed 120 association signals and several of them were not revealed before using genomic mapping. The association signals contained ~1500 novel candidate genes across the rice genome and 32 well-known published candidate genes that play roles in saline conditions. One of the relevant outcomes was that the genomic region of the well-known qSaltol QTL correlated with a SNP position identified by this approach. The qSaltol has already been introgressed into elite rice cultivars and assessed for its effectiveness in saline field conditions. Concerning forward genetic screening, this approach has identified two candidate genes that have molecular functions which correlate with the candidate genes identified by GWAS. These findings may contribute to our understanding of the complex and dynamic mechanisms of plants and the roles of genes to achieve salinity tolerance in plants.