Rice grain quality: Where we are and where to go?

Grain quality has become one of the foci in rice breeding worldwide since it is crucial for farmers, millers and consumers. Previous studies have revealed that rice gain quality is mainly determined with several major characteristics including milling, physical appearance, eating and cooking, sensory and nutritional value. In genetics, rice grain quality is a complex trait controlled by polygene/QTL. Better understanding the mechanism underlying the grain quality is fundamental for developing new breeding strategies. Therefore, abundant studies had been conducted to discover the factors that control the quality traits, and led to dozens of QTL identified and several major genes cloned. This has enabled development of the functional markers to facilitate selection of the complex traits. But breeding for rice varieties with desired grain quality needs to pyramid multiple and beneficial loci or alleles, some of which are still untapped. In this chapter, we first summarize the literatures on rice grain quality traits and the relevant phenotyping approaches, and then review the progress in genetic dissection of these traits. This review also presented the breeding attempts using marker-assisted selection, genomics-assisted breeding approaches, as well as genome editing technologies, and finally provided innovative insights into the future of rice grain quality breeding by using the modern technology with integration of machine learning and genomic selection.