Achieving Salinity-Tolerance in Cereal Crops: Major Insights into Genomics-Assisted Breeding (GAB)

Abstract

Cereal crops including rice, wheat, corn, sorghum, pearl millet and small millet, are grown for food, feed and fuel in crop-livestock based agricultural systems around the world. Soil salinity occupies an important place among the soil problems that threaten the sustainability of agriculture in a wide area around the world. Salinity intensity is predicted to exacerbate further due to global warming and climate change, requiring greater attention to crop breeding to increase resilience to salinity-induced oxidative stress. Knowledge of physiological responses to varying degrees of oxidative stress has helped predict crop agronomic traits under saline ecosystems and their use in crop breeding programs. Recent developments in high-throughput phenotyping technologies have made it possible and accelerated the screening of vast crop genetic resources for traits that promote salinity tolerance. Many stress-tolerant plant genetic resources have been developed using conventional crop breeding, further simplified by modern molecular approaches. Considerable efforts have been made to develop genomic resources which used to examine genetic diversity, linkage mapping (QTLs), marker-trait association (MTA), and genomic selection (GS) in crop species. Currently, high-throughput genotyping (HTPG) platforms are available at an economical cost, offering tremendous opportunities to introduce marker-assisted selection (MAS) in traditional crop breeding programs targeting salinity. Next generation sequencing (NGS) technology, microenvironment modeling and a whole-genome sequence database have contributed to a better understanding of germplasm resources, plant genomes, gene networks and metabolic pathways, and developing genome-wide SNP markers. The use of developed genetic and genomic resources in plant breeding has paved a way to develop high yielding, nutrient-rich and abiotic stress tolerant crops. Present chapter provides an overview of how the strategic usage of genetic resources, genomic tools, stress biology, and breeding approaches can further enhance the breeding potential and producing salinity-tolerant crop varieties/lines.