Characteristics of Grain Physicochemical Properties and the Starch Structure in Rice Carrying a Mutated Gene.

The gelatinization temperature (GT) of endosperm starch influences rice eating and the cooking quality (ECQ). encoding soluble starch synthase IIa (SSIIa) is the major gene determining grain GT in rice. Herein, we identified a spontaneous mutant named , which resulted from a G/T single-nucleotide polymorphism (SNP) in exon 1 of the allele from the high-GT rice cultivar. Compared with grains from the near-isogenic line (NIL), NIL() grains exhibited a high GT (2.3 °C) and improved retrogradation properties. The NIL() grain starch contained an increased proportion of amylopectin intermediate chains (DP 13-24) at the expense of short chains (DP < 12), resulting in enhancements in both the crystallinity and the lamellar peak intensity compared with low-GT rice grains. Moreover, both NIL() and NIL() grains also featured a significantly lower apparent amylose content (AAC), harder gel consistency (GC), higher pasting curve, and poorer taste values in comparison to Nip() grains. Taken together, this work provides novel insights underlying the allelic variation of the gene in rice.