Augmenting Salinity Tolerance in Rice Through Genetic Enhancement in the Post-genomic Era

Rice is a prime dietary cereal of almost 90% of Asian population and is grown in more than 110 countries. Soil salinity is a major challenge in rice cultivation across the world. More and more land is becoming saline in coastal and inland areas due to irrigation with saline ground water, inherent salt in the parent material of soil, excessive use of fertilizers and chemicals, sea water intrusion, and erratic rainfall. Therefore, a crop with enhanced tolerance to salinity can withstand the situation of high salinity and is a promised approach to manage crop cultivation in such areas. Genetic enhancement of rice to such increased salt content at both seedling and reproductive stage can be sourced from several landraces, wild relatives, and germplasms. Novel genetic approaches such as genome-wide association studies (GWAS), QTL mapping, allele mining, candidate gene prediction, and marker-assisted gene tagging have been applied to identify, isolate, validate, and characterize genomic loci governing salinity tolerance in rice. Next-generation breeding strategies, including marker-assisted selection (MAS), have been deployed to transfer salt-tolerant QTL (Saltol) into susceptible cultivars. In the present chapter, we have critically described the physiological, biochemical, and genetic basis of salinity tolerance in rice. The breeding approaches utilizing several methodologies for evaluating genotypes under salinity for practicing selection have also been described. The recent success of genomic-assisted breeding and future proposed use of advanced breeding methods such as genomic selection and haplotype selection has been mentioned in detail.