Molecular Aspect of Good Eating Quality Formation in Japonica Rice

Abstract

The composition of amylopectin is the determinant of rice eating quality under certain threshold of protein content and the ratio of amylose and amylopectin. In molecular biology level, the fine structure of amylopectin is determined by relative activities of starch branching enzyme (SBE), granule-bound starch synthase (GBSS), and soluble starch synthase (SSS) in rice grain under the same ADP-Glucose level. But the underlying mechanism of eating quality in molecular biology level remains unclear. This paper reports the differences on major parameters such as SNP and insertion-deletion sites, RNA expressions, and enzyme activities associated with eating quality of japonica varieties. Eight japonica rice varieties with significant differences in various eating quality parameters such as palatability and protein content were used in this experiment. Association analysis between nucleotide polymorphism and eating quality showed that S12 and S13 loci in SBE1, S55 in SSS1, S58 in SSS2A were significantly associated with apparent amylose content, alkali digestion value, setback viscosity, consistency viscosity, pasting temperature, which explained most of the variation in apparent amylose content, setback viscosity, and consistency viscosity; and explained almost all variations in alkali digestion value and pasting temperature. Thirty-five SNPs and insertion-deletions from SBE1, SBE3, GBSS1, SSS1, and SSS2A differentiated high or intermediate palatability rice varieties from low palatability rice varieties. Correlation analysis between enzyme activities and eating quality properties revealed that SBE25 and SSS15/W15 were positively correlated with palatability, whereas GBSS10 and GBSS15 were negatively correlated. Gene expressions showed that SBE1 and SBE3 expressions in high palatability varieties tended to be higher than middle and low palatability varieties. Collectively, SBE1, SBE3, SSS1, and SSS2A, especially SBE1 and SBE3 could improve eating quality, but GBSS1 decreased eating quality. The results indicated the possibility of developing high palatability cultivars through modification of key genes related to japonica rice eating quality formation in starch biosynthesis.

Effects of Timing and Severity of Salinity Stress on Rice (Oryza sativa L.) Yield, Grain Composition, and Starch Functionality

“…27 The study also aimed to investigate plants grown in the greenhouse settings where the EC was controlled (Supporting Information Figure S1) in order to achieve clear understanding of how salt impacts grain parameters.…”

“…15,26,27 The effects of heat and drought on rice quality have been widely reported, but data on salinity are limited.…”

Molecular Marker-Assisted Selection of Rice Grain Quality on Rice (Oryza sativa L.) Lines Tolerant to Fe Toxicity Stress

“…Besides, sssiia also determines eating and cooking quality of rice by affecting amylose content AC and GC. alk gene is the major gene that controls GT, but as a minor gene, it affects AC and GC [4]. P-EQ6 that marks S3cl gene (mapped on chromosome 7) was significantly associated with organoleptic character that determines the taste and aroma of the rice.…”

“…pul and s3cl respectively contribute to starch and sucrose synthesis. Both genes are responsible for eating and cooking quality in rice by affecting AC and GC [4].…”

“…These rice lines are from multi-crossing population. However, the rice grain quality still needs to be improved, thus it can be an important consideration for consumers as well as for breeders [4]. Breeding is generally intended to improve yield, but on the other hand the obtained varieties are often less acceptable to both farmers and consumers because of undesirable seed quality [5].…”