Phenotypic assessment of RILs of an interspecific biparental population (IR29/Oryza glaberrima Steud.) for seedling salinity tolerance and exploration QTL/haplotype in African rice (O. glaberrima S.) genome

Salinity is one of the most predominant abiotic stress factors affecting crop production across the planet earth. Rice is canonically a glycophytic species that becomes sensitive to salinity stress, especially at the seedling and early reproductive growth stage. Several studies have explored the potential of African rice (Oryza glaberrima Steud.) and its interspecific progenies to be salinity tolerant at the seedling stage of growth. In this context, we tested an interspecific biparental (IR29/O. glaberrima Steud.) recombinant inbred lines (RIL) population in the present study for seedling salinity tolerance and identified a few extreme tolerant and sensitive RILs in the population and assigned (SES = 3; highly tolerant) and (SES = 9; highly sensitive) scores to the contrasting RILs in salinity stress. A few relevant parameters had been scored and a majority had shown very sharp contrast in phenotype in parents and extreme RILs. A higher ratio of stress/control phenotypic data had been observed in extreme tolerant RILs, whereas the ratio was much lower in the opposite extreme lines indicating the probable regulation of seedling salinity-related parameters by QTL region(s). Also, an assessment of the parental genotypes with Saltol QTL-specific SSR markers revealed the possibility of the existence of a novel QTL region in our African rice accession. Hence, this study opens an avenue for the discovery and mapping of novel QTL/candidate genes for seedling salinity tolerance that can be further utilized in rice breeding programs for improvement in stress tolerance in high-yielding cultivars.