Impacts of Inherent Components and Nitrogen Fertilizer on Eating and Cooking Quality of Rice: A Review

OsGATA7 and SMOS1 cooperatively determine rice taste quality by repressing OsGluA2 expression and protein biosynthesis

Taste is crucial for the economic value of rice (Oryza sativa L.) and determines consumer preference. However, the mechanisms underlying taste formation have remained unclear. Here, we show that OsGATA7 contributes to desirable taste quality by affecting the swelling properties, texture, and taste value of cooked rice. OsGATA7 binds to the promoter of SMOS1, and activates its expression, thereby regulating taste quality. Furthermore, SMOS1 binds to the promoter of the protein biosynthesis gene OsGluA2, and recruits the PRC2 complex to repress its expression, leading to increased protein content. The overexpression of both OsGATA7 and SMOS1 reduces protein content and enhances taste quality. The haplotypes OsGATA7Hap1 and SMOS1Hap1 maintain low protein content and improve taste scores. Collectively, these findings reveal a regulatory mechanism for taste quality formation mediated by the OsGATA7-SMOS1 protein content module, and identify the elite haplotypes OsGATA7Hap1 and SMOS1Hap1 as a means to improve taste quality.

Analysis of the effects of light and panicle fertilizer on rice eating quality based on morphological structural changes in starch and protein during cooking

Light and panicle fertilizer are crucial environmental factors that influence rice eating quality. Currently, there is a lack of systematic research on how light and panicle fertilizer alter the morphological structures of starch and protein during cooking, subsequently affecting rice taste. To address this gap, field experiments were conducted under varying conditions of light (100 % light, L1; 50 % light, L2) and panicle fertilizer (no panicle fertilizer, N1; 81 kg/ha of panicle fertilizer, N2), followed by cooking after harvest. The results showed that, compared to L1N1, the water migration (low T2), starch and protein structural disruption (slow decline in 1047/1022 cm-1) were limited in L1N2, L2N1, and L2N2 during the cooking, making rice hard to cook. Eventually, compared to L1N1, L1N2, L2N1 and L2N2 exhibited lower peak viscosity but higher strength gel networks (higher G' and G''), leading to a decline in rice eating quality. In summary, reduced light intensity and applied panicle fertilizer restricted the disruption of starch and protein structures during rice cooking, which hindered rice cooking processes, ultimately leading to a decrease in rice eating quality. Furthermore, it is noteworthy that the combination of reduced light and applied panicle fertilizer further exacerbated the decline in rice eating quality.

Impact of high-speed shear homogenization pretreatment on structure, functional characteristics, and interfacial properties: A case of Rice Glutelin

In this study, rice glutelin (RG) was pretreated using high-speed shear homogenization (HSSH) to enhance its functional characteristics and interfacial properties through structural modification. Its structure was characterized using techniques such as SDS-PAGE, FT-IR, SEM, interface analyzer, dynamic and electrophoretic light scattering. The results indicated that HSSH preserved the primary structure of RG but significantly affected its secondary structure. It increased the surface hydrophobicity and conformational flexibility, enhanced electrostatic repulsion, reduced the particle size, and produced a loose and porous microstructure. These alterations resulted in variations in the functional and interfacial properties of RG. After HSSH treatment at 12,000 rpm for 2 min, RG exhibited optimal improvements in solubility (5.56 %), WHC (6.00 g/g) and OHC (2.20 g/g), EAI (10.19 m2/g) and ESI (341.98 min), as well as FC (16.20 %) and FS (64.21 %). However, excessive HSSH treatment induced the formation of aggregates, which is detrimental to the improvement of these properties.

Reduced Nitrogen Application with Dense Planting Achieves High Eating Quality and Stable Yield of Rice

Rational nitrogen (N) application can enhance yield and improve grain eating quality in rice. However, excessive N input can deteriorate grain eating quality and aggravate environmental pollution, while reduced N application (RN) decreases rice yield. Reduced N application with dense planting (RNDP) is recommended for maintaining rice yield and improving N use efficiency. However, the effects of RNDP on the rice grain eating quality and starch structure and properties remain unclear. A two-year field experiment was conducted to investigate the effects of RNDP on the rice yield, grain eating quality, and starch structure and properties. Compared to conventional N treatment, RN decreased significantly the rice yield, while RNDP achieved a comparable grain yield. Both the RN and RNDP treatments improved significantly the rice eating quality. The high eating quality of RNDP was attributed to increased gel consistency, pasting viscosity, and stickiness after cooking as well as decreased protein content. A further analysis of starch structure and properties revealed that RNDP decreased the relative crystallinity, lamellar intensity, gelatinization enthalpy, and retrogradation enthalpy of starch. Therefore, RNDP achieved a stable rice yield and enhanced rice eating quality. These findings provide valuable insights into obtaining optimal quality and consistent yield in rice production under reduced N conditions.

A Novel Allele in the Promoter of Wx Decreases Gene Expression and Confers Lower Apparent Amylose Contents in Japonica Rice (Oryza sativa L.)

Wx is the key gene that controls amylose content (AC), and various alleles have been found in rice populations. Wxb is the major allele in japonica and produces moderate AC (15~18%). It was recently found that editing the promoter of Wx could produce a series of alleles that have different Wx activities. Although some studies have edited the promoter, few studies have focused on the natural variations in Wx. Here, we used the Rice3K database to investigate variations in the Wx promoter and found that the allele Wx1764178 (A/G) has a higher LD (linkage disequilibrium) with the two key SNPs (1765751, T/G; 1768006, A/C), which could produce different Wx alleles and influence AC, as reported previously. Further study showed that the Wx1764178 allele (A/G) is functional and influences the expression of Wx positively. Editing the A allele using CRISPR‒Cas9 produced 36 and 3 bp deletions and caused a decrease in the expression of Wx. The apparent amylose content (AAC) in the edited lines was decreased by 7.09% and 11.50% compared with that of the wild type, which was the japonica variety Nipponbare with Wxb and the A allele at 1764178, while a complementary line with the G allele showed a lower AAC than the A allele with no effect on other agronomic traits. The AAC of the edited lines showed a higher increase than that of the wild type (Nipponbare, Wxb) in low-nitrogen conditions relative to high-nitrogen conditions. We also developed a dCAPS marker to identify the allele and found that the G allele has widely been used (82.95%) in japonica-bred varieties from Jiangsu Province, China. Overall, we found a functional allele (Wx1764178, A/G) in the Wx promoter that could affect AAC in japonica cultivars and be developed as markers for quality improvement in rice breeding programs.

Consumer Preference for Rice Grain Quality in the South Kivu and Tanganyika Provinces, Eastern DR Congo

In Africa, rice has always been a staple food in some countries and the fastest growing food source there. In the Democratic Republic of Congo (DRC), in terms of cereal production, rice is ranked second after maize and is an important source of income for the rice farmer. The objective of this study was to analyze and understand consumers' preferences and behaviors towards local and imported rice in the South Kivu and Tanganyika provinces, DRC. Data collected on 1565 rice-consuming households in eastern DRC showed that there is a great opportunity for the rice value chain and food policy development, and the promotion of local rice consumption. Consumers focus on local rice because it is cheaper, but it does not always meet their desired needs. Indeed, only urban consumers were more willing to pay for higher-quality rice. The development of the demand for local rice calls for strong investment in improving production, post-harvest practices, and market aspects. It was found that over 90% of rice consumers know about local rice production and over 84% have consumed it. In rural areas, there is typically lower consumption of imported rice. However, as households require more rice, they tend to rely more on imported varieties due to their availability in the market. The most preferred rice attributes were flavor, aroma, purity, swelling capacity, breakage rate, and whiteness. Therefore, rice producers should consider the habits and needs of consumers to improve market demand. In addition, good packaging, labeling, and marketing can also enhance local rice preference and competitiveness in South Kivu and Tanganyika provinces in eastern DRC. The findings of this study indicated that research aimed at improving local rice varieties with regard to yield, disease resistance, and organoleptic qualities could enable the population to consume more locally produced rice, which is often more affordable than imported rice. This could in turn significantly reduce the need for rice imports. These results suggest that research carried out to improve the yield and organoleptic qualities of local rice in this area can allow it to be more competitive on the market and can reduce the importation of rice.