Toward Understanding the Genetic and Molecular Bases of the Eating and Cooking Qualities of Rice

Abstract

Apparent amylose content (AAC), gelatinization temperature (GT), gel consistency, and pasting viscosity are important predictors of the eating and cooking qualities of rice. Great progress has been made in our understanding of the genetic and molecular bases of rice eating and cooking qualities. The Wx gene encoding granule-bound starch synthase is the major gene controlling AAC, gel consistency, and pasting viscosity; it also regulates GT as a minor gene. Starch synthase IIa (SSIIa) is the major gene responsible for GT and amylopectin branch chain length distribution; it also has minor effects on AAC, gel consistency, and pasting viscosity. The functional nucleotide polymorphisms in Wx and SSIIa and their associations with physicochemical properties have been well characterized. Molecular breeding using these functional markers of Wx and SSIIa has resulted in the development of new high-quality rice cultivars (breeding lines). A multienzyme complex model is proposed to explain different AAC-GT combinatio...