Explore the vast range of titles available.

With the improvement of people's living standards and rice trade worldwide, the demand for high-quality rice is increasing. Therefore, breeding high quality rice is critical to meet the market demand. However, progress in improving rice grain quality lags far behind that of rice yield. This might be because of the complexity of rice grain quality research, and the lack of consensus definition and evaluation standards for high quality rice. In general, the main components of rice grain quality are milling quality (MQ), appearance quality (AQ), eating and cooking quality (ECQ), and nutritional quality (NQ). Importantly, all these quality traits are determined directly or indirectly by the structure and composition of the rice seeds. Structurally, rice seeds mainly comprise the spikelet hull, seed coat, aleurone layer, embryo, and endosperm. Among them, the size of spikelet hull is the key determinant of rice grain size, which usually affects rice AQ, MQ, and ECQ. The endosperm, mainly composed of starch and protein, is the major edible part of the rice seed. Therefore, the content, constitution, and physicochemical properties of starch and protein are crucial for multiple rice grain quality traits. Moreover, the other substances, such as lipids, minerals, vitamins, and phytochemicals, included in different parts of the rice seed, also contribute significantly to rice grain quality, especially the NQ. Rice seed growth and development are precisely controlled by many genes; therefore, cloning and dissecting these quality-related genes will enhance our knowledge of rice grain quality and will assist with the breeding of high quality rice. This review focuses on summarizing the recent progress on cloning key genes and their functions in regulating rice seed structure and composition, and their corresponding contributions to rice grain quality. This information will facilitate and advance future high quality rice breeding programs.

Plant breeders regularly evaluate multiple traits across multiple environments, which opens an avenue for using multiple traits in genomic prediction models. We assessed the potential of multi-trait (MT) genomic prediction model through evaluating several strategies of incorporating multiple traits (eight agronomic and malting quality traits) into the prediction models with two cross-validation schemes (CV1, predicting new lines with genotypic information only and CV2, predicting partially phenotyped lines using both genotypic and phenotypic information from correlated traits) in barley. The predictive ability was similar for single (ST-CV1) and multi-trait (MT-CV1) models to predict new lines. However, the predictive ability for agronomic traits was considerably increased when partially phenotyped lines (MT-CV2) were used. The predictive ability for grain yield using the MT-CV2 model with other agronomic traits resulted in 57% and 61% higher predictive ability than ST-CV1 and MT-CV1 models, respectively. Therefore, complex traits such as grain yield are better predicted when correlated traits are used. Similarly, a considerable increase in the predictive ability of malting quality traits was observed when correlated traits were used. The predictive ability for grain protein content using the MT-CV2 model with both agronomic and malting traits resulted in a 76% higher predictive ability than ST-CV1 and MT-CV1 models. Additionally, the higher predictive ability for new environments was obtained for all traits using the MT-CV2 model compared to the MT-CV1 model. This study showed the potential of improving the genomic prediction of complex traits by incorporating the information from multiple traits (cost-friendly and easy to measure traits) collected throughout breeding programs which could assist in speeding up breeding cycles.

Nitrogen fertilizer is an important agronomic measure to regulate rice yield and grain quality. Grain filling is crucial for the formation of rice yield and grain quality. However, there are few studies on the effects of excessive nitrogen application (ENA) on grain filling rate and grain quality. A two-year field experiment was conducted to reveal the difference in grain filling characteristics and grain quality of superior grains (SG) and inferior grains (IG), as well as their responses to nitrogen fertilizer. We determined the grain appearance, the rice yield, the grain filling characteristics of SG and IG, and grain quality. We found that with the increasing nitrogen application level, grain yield of both varieties first increased and then decreased. The average yield of excessive nitrogen application (345 kg N ha−1) was 2.68–6.31% lower than that of appropriate nitrogen application (270 kg N ha−1). ENA reduced the grain filling rate by 12.7–25.8%, and the grain filling rate of SG was higher than that of IG. Increasing nitrogen application increased the processing quality and appearance quality of rice grain, but ENA deteriorated the appearance quality, eating quality and nutritional quality. The amylose content and taste value of SS were 3.1–9.7% and 7.1–20.2% higher than those of IS, respectively. The protein components of SG were lower than those of IG. Taken together, our results revealed that ENA leads to the lowering of rice grain yield and grain quality by suppressed grain filling of inferior grains.

Starch accounts for up to 90% of the dry weight of rice endosperm and is a key determinant of grain quality. Although starch biosynthesis enzymes have been comprehensively studied, transcriptional regulation of starch‐synthesis enzyme‐coding genes (SECGs) is largely unknown. In this study, we explored the role of a NAC transcription factor, OsNAC24, in regulating starch biosynthesis in rice. OsNAC24 is highly expressed in developing endosperm. The endosperm of osnac24 mutants is normal in appearance as is starch granule morphology, while total starch content, amylose content, chain length distribution of amylopectin and the physicochemical properties of the starch are changed. In addition, the expression of several SECGs was altered in osnac24 mutant plants. OsNAC24 is a transcriptional activator that targets the promoters of six SECGs; OsGBSSI , OsSBEI , OsAGPS2 , OsSSI , OsSSIIIa and OsSSIVb . Since both the mRNA and protein abundances of OsGBSSI and OsSBEI were decreased in the mutants, OsNAC24 functions to regulate starch synthesis mainly through OsGBSSI and OsSBEI. Furthermore, OsNAC24 binds to the newly identified motifs TTGACAA, AGAAGA and ACAAGA as well as the core NAC‐binding motif CACG. Another NAC family member, OsNAP, interacts with OsNAC24 and coactivates target gene expression. Loss‐of‐function of OsNAP led to altered expression in all tested SECGs and reduced the starch content. These results demonstrate that the OsNAC24‐OsNAP complex plays key roles in fine‐tuning starch synthesis in rice endosperm and further suggest that manipulating the OsNAC24‐OsNAP complex regulatory network could be a potential strategy for breeding rice cultivars with improved cooking and eating quality.

Cereal yield and grain quality may be impaired by environmental factors associated with climate change. Major factors, including elevated CO2 concentration ([CO2]), elevated temperature, and drought stress, have been identified as affecting C3 crop production and quality. A meta-analysis of existing literature was performed to study the impact of these three environmental factors on the yield and nutritional traits of C3 cereals. Elevated [CO2] stimulates grain production (through larger grain numbers) and starch accumulation but negatively affects nutritional traits such as protein and mineral content. In contrast to [CO2], increased temperature and drought cause significant grain yield loss, with stronger effects observed from the latter. Elevated temperature decreases grain yield by decreasing the thousand grain weight (TGW). Nutritional quality is also negatively influenced by the changing climate, which will impact human health. Similar to drought, heat stress decreases starch content but increases grain protein and mineral concentrations. Despite the positive effect of elevated [CO2], increases to grain yield seem to be counterbalanced by heat and drought stress. Regarding grain nutritional value and within the three environmental factors, the increase in [CO2] is possibly the more detrimental to face because it will affect cereal quality independently of the region.

Parboiling improves rice grain hardness and reduces susceptibility to Sitophilus oryzae infestation by gelatinizing the starch and enhancing resistance.A newly designed electric machine was used to parboil four Egyptian rice cultivars—Sakha 108, Giza 178, Super 300, and Egyptian Yasmin—at 70, 75, and 80 °C and determine their susceptibility to Sitophilus oryzae L. (Coleoptera: Curculionidae) infestation. Results indicated that heating affected most traits in all four rice cultivars during both study seasons 2021 and 2022. Super 300 rice cultivar exhibited the highest hulling values (81.23 and 81.42%) when heated to 80 °C, while the Yasmin rice cultivar showed the lowest values for hulling (77.66 and 77.45%) at 70 °C. while Giza 178 cultivar showed a significant decrease in broken percentage (90.85 and 94.02%) compared to control when heated to 80 °C. The results also indicated that the Yasmin rice cultivar had the highest values for white belly, hardness, and gel consistency at 80 °C, while the Sakha 108 cultivar showed the lowest values for these traits at 70 °C. Furthermore, the protein, elongation, and water uptake characters significantly responded to the different investigated treatments. Yasmin cultivar at 80 °C showed the highest significant values for protein (9.26 and 9.47%), elongation (65.02 and 65.44%), and water uptake (453.2 and 455.1 ml water/100 g milled grains) in both seasons. Sakha 108 cultivar had the lowest values for these traits at 70 °C. The S. oryzae insects responded differently to the rice cultivars. Using Dobie’s Index of Susceptibility, all cultivars were classified as resistant to S. oryzae infestation. Super 300 was moderately resistant before parboiling but resistant after heat treatment. In conclusion, the study underscores the influence of pre-storage parboiling on rice weevil infestation, suggesting that heat treatment could serve as an effective control measure. These findings emphasize the importance of parboiling conditions in enhancing rice grain quality and bolstering resistance to insect infestation.

Heat stress during the panicle initiation stage hinders the formation of rice grains. It is speculated that heat exposure during the panicle initiation stage could influence grain quality in rice. To obtain preliminary knowledge on the effects of asymmetric heat on rice grain quality during the panicle initiation stage, four rice genotypes (Shanyou63, Liangyoupeijiu, Huanghuazhan, and Nagina22) were subjected to three heat treatments, i.e., high daytime temperature (HDT; 37.9 °C/24.5 °C), high nighttime temperature (HNT; 30.9 °C/30.5 °C), the combination of high daytime and nighttime temperature (HDNT; 38.5 °C/31.0 °C), and a control (CK, 31.5 °C/24.0 °C) in temperature-controlled greenhouses for 15 days during the panicle initiation stage. The milling and appearance qualities, which are crucial for commercial value, were studied. Heat treatments significantly reduced the amounts of brown rice, milled rice, and head rice and the grain length, grain width, chalky grain amount, and grain chalkiness in the rice genotypes Liangyoupeijiu, Nagina22, and Huanghuazhan during the panicle initiation stage, and the largest reductions in grain quality were frequently observed under HDNT treatment. The milling and appearance qualities in genotype Shanyou63 were negligibly affected by heat treatments and thus were regarded as tolerant to heat, and the rice genotypes Liangyoupeijiu, Huanghuazhan, and especially Nagina22 were susceptible to heat during the panicle initiation stage. We concluded that heat stress during panicle initiation impacted the milling and appearance qualities in rice, and differences existed among rice genotypes. The underlying mechanisms of the effects of heat on rice grain quality need further study.

The determination of equilibrium moisture content, associated with measuring the respiration of the grain mass in real time, is a possible indicator for the indirect prediction of the quality of grains stored in bag silos, ensuring an adequate storage time. Thus, with the aid of an Internet of Things prototype, multiple linear regression models, and artificial neural networks, the present study is aimed at predicting the quality of corn grain stored in a silo bag over time based on real-time monitoring of the equilibrium moisture content and the concentration of carbon dioxide (CO 2 ). For this, an IoT prototype is indexed to monitor the temperature and relative humidity of the air, as well as determine the equilibrium moisture content and the concentration of CO 2 . Monitoring the temperature and relative humidity of the intergranular air and obtaining the equilibrium moisture content of the grains in real time allows for an indication of the storage conditions of the grains in silo bags, as well as, possible deterioration risks. However, the measurement of CO 2 in real time makes it possible to predict the levels of deterioration and the reduction in the quality of the grains during storage. The hermeticity of the silo bag was insufficient to preserve the quality of the stored grains because of the variation in intergranular abiotic factors and changes in grain metabolism. Thus, a combination of equilibrium moisture content and an evaluation of CO 2 allowed a greater assertive effect in predicting the grain quality and estimating a safe storage time. Graphical Abstract

Grain quality is largely driven by grain infrastructure (technology) and handling practices (application of knowledge on handling). The use of inappropriate infrastructure and inappropriate handling protocols poses food safety and health-related risks. This review provides evidence for the link between drying and storage operations in the context of preserving grain quality. The purpose of this study was to evaluate the close grain quality relationship between drying and storage, with an appraisal of operations in Africa. This study further benchmarked successful and scalable models in Africa to infer guidance for promotion of optimal and effective drying and storage initiatives. While open-sun drying is undoubtedly the most adopted approach to grain drying for the rural-poor farmers, this study revealed greater success in grain storage, especially with the breakthrough at the introduction and adoption of small-scale hermetic storage technologies. Upon assessment of the cob, WFP Zero Food Loss Initiative, and AflaSight models implemented in Rwanda and Uganda, this study suggests: (i) the adoption of system thinking; (ii) the use of sustainable approaches such as gender inclusion, sustainable financing options, and use of existing infrastructures along-side novel interventions; and (iii) enabling policies and political will as strategic pathways for successful implementation of improved grain-quality interventions during drying and storage. In the short term, grain handlers must develop appropriate grain management protocols during open-sun drying to limit the impact of drying-related grain quality deterioration. Consortia-based implementation of the three models evaluated in this review could improve grain quality, food security and safety, and market linkages with premium grain markets, fostering economic growth and transformation.

Background Numerous scaffold-level sequences for wheat are now being released and, in this context, we report on a strategy for improving the overall assembly to a level comparable to that of the human genome. Results Using chromosome 7A of wheat as a model, sequence-finished megabase-scale sections of this chromosome were established by combining a new independent assembly using a bacterial artificial chromosome (BAC)-based physical map, BAC pool paired-end sequencing, chromosome-arm-specific mate-pair sequencing and Bionano optical mapping with the International Wheat Genome Sequencing Consortium RefSeq v1.0 sequence and its underlying raw data. The combined assembly results in 18 super-scaffolds across the chromosome. The value of finished genome regions is demonstrated for two approximately 2.5 Mb regions associated with yield and the grain quality phenotype of fructan carbohydrate grain levels. In addition, the 50 Mb centromere region analysis incorporates cytological data highlighting the importance of non-sequence data in the assembly of this complex genome region. Conclusions Sufficient genome sequence information is shown to now be available for the wheat community to produce sequence-finished releases of each chromosome of the reference genome. The high-level completion identified that an array of seven fructosyl transferase genes underpins grain quality and that yield attributes are affected by five F-box-only-protein-ubiquitin ligase domain and four root-specific lipid transfer domain genes. The completed sequence also includes the centromere.