Interaction between genetic regions responsible for the starch properties in non-glutinous rice varieties in Hokkaido, Japan.

Starch properties are the major determinants of grain quality and food characteristics in rice (Oryza sativa L.). Understanding the interactions between genetic regions responsible for starch properties will lead to the development of rice cultivars with desirable characteristics. This study investigated the genetic effect and interaction between qAC9.3, a low-amylose quantitative trait locus (QTL), and the genetic region around Starch branching enzyme IIb (SbeIIb). Both these factors are responsible for the starch properties of the Hokkaido breeding population. The amylose content, pasting temperature, and amylopectin chain-length distribution were compared using F₅ lines derived from the cross between the lower amylose content and lower pasting temperature strain 'Hokkai332 (qAC9.3, SbeIIb)' and the higher amylose content and higher pasting temperature variety 'Kitagenki (-, SbeIIb^sr )'. The qAC9.3 genotype exhibited low amylose content and reduced the hardness of boiled rice but increased the ratio of amylopectin long chains and did not alter the pasting temperature. In contrast, the SbeIIb genotype was associated with pasting temperature but did not affect the amylose content and hardness of boiled rice. It was suggested that appropriately selecting genotypes of these genetic regions and QTL would allow the fine-tuning of starch properties of cooked rice suitable for future demand.