Molecular and genetic bases of rice cooking and eating quality: An updated review

Abstract

AbstractBackground and ObjectivesRice grain quality is a primary determinant of its market price and consumer acceptance. Although milling quality, appearance, cooking and eating quality (CEQ), and nutritional quality represent the main features of grain quality, rice CEQ is the most important feature in terms of price. Starch physicochemical properties and sensory evaluation have been widely applied to predict and assess rice CEQ. Understanding the genetic and molecular bases of CEQ formation will facilitate improvements in rice quality through a molecular breeding strategy.FindingsThe major genes responsible for rice CEQ formation have already been characterized in previous studies. Waxy (Wx) encoding granule‐bound starch synthase I (GBSSI) controls the apparent amylose content (AAC), starch synthase IIa (SSIIa) controls the gelatinization temperature, and fragrant gene (fgr) controls the aroma of cooked rice. Many natural variations (allelic variants) have been identified in these genes among rice germplasm. The protein content in rice grains is not only responsible for the nutritional quality but also CEQ. Two major genes that control the protein content have been identified and cloned. Pyramiding of different alleles by marker‐assisted selection and creation of new alleles by genome editing technology have facilitated improvements in new rice varieties with desirable CEQ.ConclusionsIn addition to presenting updates on the advances made in the important CEQ genes, we have identified some future challenges. These include the need to exploit new alleles in these genes, especially in Wx, to confer low AAC with a transparent appearance; identification of alleles in Wx that can improve the texture of cooked rice with high AAC and high‐resistant starch; formulation of methods to manipulate genes and modify agronomic practices to reduce the protein content to improve CEQ; and development of methods to breed climate‐smart rice with good, stable CEQ in changing environments.Significance and NoveltyThis article identifies some priorities for future research, which can enhance our understanding of the molecular basis of CEQ to improve this important rice quality attribute.