Genomic-Assisted Breeding Tools for Grain and Nutritional Quality Improvement in Rice

More than half of the world’s population consumes rice as a staple food in their diet. Rice grain quality is receiving attention from both consumers and producers as living standards in rice-consuming regions has improved and this emerged as a critical rice breeding target. Grain quality traits have a strong influence on the market value of rice and the adoption of new varieties by farmers. Consumer preferences for specific nutritional, physical, eating, and cooking characteristics are at the root of these. Uniform grain width, length, colour (translucence or whiteness), and chalkiness are all desirable physical properties. Cooking and eating (organoleptic) characteristics such as; cooking time (gelatinization temperature and viscosity), the ability of rice to remain soft after cooking (gel consistency), and textural properties of cooked rice (amylose content and aroma) are also very important. Plant breeders are always working hard to meet these demands by developing new rice varieties. The genomics era provides many opportunities to assist breeders in addressing these challenges. While not complete, our understanding of the genetic basis underlying many grain quality traits is expanding. There have been reports of quantitative trait loci (QTL) controlling grain appearance, chalkiness, protein content, and grain length. Genomic-assisted Breeding techniques such as marker-assisted selection, QTL mapping, genome editing, genome wide association studies, and genetic engineering can provide further a better understanding of the genetic basis and thus help to improve rice grain nutritional quality traits.