Amylose Content Research Articles

Particle size reduction influences starch and protein functionality, and nutritional quality of stone milled whole wheat flour from hard red spring wheat

Flour particle size (PS) distribution plays a crucial role in determining the functional properties of starch, protein, and influences the nutritional properties, which ultimately is reflected in the end-product quality. For stone-milled whole wheat flour (WWF) bakers often prefer finer PS for improved color and texture, despite this can sometimes negatively affect other quality aspects. Therefore, understanding the contribution of PS reduction on the functional properties of stone-milled WWF is crucial. This study investigated Hard Red Spring (HRS) WWF of which the mean PS was reduced from 151 μm to 117 μm, the possible finest PS by a “Kombi mill type A 500 MSM” stone mill. PS reduction increased starch damage from 6.58% to 6.71%. Also, the amylose content reduced from 31.7% to 29.4%. However, an increase in syneresis, solubility, oil-holding capacity, and peak viscosity was observed. Glutopeak and wet gluten showed an increased gluten strength. Glutenin/gliadin, polymeric/monomeric protein ratios, and percentage of unextractable polymeric protein were increased by 2.10%, 4.11%, and 4.55%, respectively, indicating increased availability of proteins with relatively larger molecular sizes by PS reduction. The relative proportion of glutenin and gliadin subgroups were also changed. Dietary fiber and resistant starch contents were found to be lower. However, the reduction in phytic acid and FODMAPs is considered beneficial. PS reduction ultimately improved bread loaf volume and crumb structure. Overall, PS reduction of WWF by stone-milling brought positive changes to several functional properties of protein and starch and positively improved the dough rheology and end-product quality.

Identification and analysis of nine new flo2 allelic mutants in rice

FLO2 is involved in grain development and storage substance synthesis in rice, and therefore can regulate grain size and quality. In this study, we identified 4 new flo2 allelic mutants with nonsense and frameshift mutation in the exon of 6, 10, 11 and 21 and 5 new flo2 allelic mutants with alternative splicing and frameshift mutation at the splicing site of intron 13, 14, 16 and 17. Compared with wild-type rice, the outer endosperm of flo2 mutants was transparent, and the inner endosperm was floury. Different mutation sites and types of FLO2 significantly decreased kernel width, thickness and weight to some extent. The contents of storage protein, starch, amylose and amylopectin showed significant decrease at different levels among 9 flo2 mutants. The expressions of most storage protein synthesis genes and starch synthesis-related genes were significantly down-regulated, and exhibited different ranges of variation among different flo2 mutants. This study could add helpful information for the roles of flo2 alleles in rice quality regulation and provide abundant germplasm resources for rice quality breeding.

Changes of eating quality of four types of rice with different amylose content under different storage temperatures

SummaryThe environment in which rice is stored has a big influence on rice quality. Four rice cultivars with various amylose content types were kept at low temperatures (LT, 4 °C) and room temperature (RT, 20 °C) in this study: NAC: (Low‐amylose content <2%), LAC: (low‐amylose content, about 10%), MAC: (medium‐amylose content, about 17%) and HAC: (high‐amylose content, about 25%). After storage at two temperatures and comparison to the harvest year, the amylose content of 4 types increased, and the change range of the HAC was the lowest. The gel consistency held at LT was higher than that at RT. Under LT storage, the breakdown values of MAC and HAC greatly increased (0.47%–0.65%), but NAC significantly reduced. The enthalpy of gelatinisation (▵Hg) drastically reduced (7.81%–49.10%) from the harvest year. Regeneration enthalpy increased at the grain after being sealed for a year at LT (except HAC) and reduced noticeably at RT. With the exception of ▵Hg and pasting temperature, the DSC profiles had a positive correlation with gel consistency. HPV, CPV and SBV showed a positive correlation with amylose content. As a result, the ideal storage temperature should be chosen based on the amylose type and use of the rice during storage.

Starch exploration in Nelumbo nucifera and Trapa natans: Understanding physicochemical and functional variations for future perspectives

The current research emphasis on identifying unconventional starch sources with varied properties to broaden industrial applications. The focus of this research is on the search for alternative sources of starch with different properties in order to expand their potential use in the industrial sector. Starch was extracted from Trapa natans and Nelumbo nucifera and analyzed for their physicochemical and functional properties. They had similar protein (0.35 %) and ash contents, but the nitrogen-free extract was slightly higher in Nelumbo starch (87.58 %) than in Trapa starch (85.09 %). The amylose and amylopectin contents were 23.89 % and 76.11 % in Trapa starch and 15.70 % and 84.30 % in Nelumbo starch, respectively. Fourier-transform infrared spectroscopy identified both as polysaccharides. The characteristic absorption bands assigned to the stretching of OH groups (3324 cm−1; 3280 cm−1), the asymmetric and symmetric stretching of aliphatic chain groups (2925 cm−1; 2854 cm−1), the bending vibration of CHO groups (1149 cm−1; 1144 cm−1) were present in both the starch samples, with the exception of CH3 which could not be detected in Trapa natans starch. X-ray diffraction confirmed hexagonal and orthorhombic crystal structures in Nelumbo nucifera and Trapa natans starch. Scanning electron microscopy revealed a smooth oval and a rough cuboidal shape for lotus and chestnut starch, respectively. Rheological analysis showed that both starch solutions exhibited gel behavior, with Trapa showing stronger gel behavior after the crossover point. These results suggest potential applications in various industries, including the food industry and beyond.

Amylopectin content rather than amylose or protein content is critical to determining the starch digestion rate in high-amylose rice

The starch digestion properties of cooked rice are associated with the chemical compositions of the rice grain. However, limited information is available on the chemical composition governing starch digestion properties in high-amylose rice. To overcome this knowledge gap, correlation plot analysis and partial correlation analysis were utilized to assess the correlations between active digestion duration, total glucose production, and glucose production rate of cooked rice to amylose, amylopectin, and protein content of rice grains throughout 17 high-amylose varieties. The correlation plot analysis identified significant positive or negative linkages between total glucose production and the glucose production rate of cooked rice with grain amylose, amylopectin, and protein content. Nevertheless, partial correlation analysis only characterized a significant positive correlation between glucose production rate and grain amylopectin content. The findings of this study indicate that grain amylopectin content rather than grain amylose or protein content is critical for the determination of the rate of starch digestion in high-amylose rice.

Karakteristik Fisik, Kimia, Fungsional, dan Sensori Nasi Gurih Instan Dibandingkan dengan Nasi Putih Instan

Variations of processing rice into cooked rice had long been developed. One of the rice products that had been widely circulated in the community was savory rice. Savory rice with an instantization processed was more practical in serving. This research aimed to determine the physical, chemical, functional, and sensory characteristics of instant savory rice compared to instant white rice. The stages of processing instant savory rice included washing, soaking, cooking, freezing, and drying. The freezing process was carried out at -20 °C for 24 h. The drying process for instant savory rice used a fluidized bed dryer for 3 h. Instant white rice was used as a control. The porosity level of instant savory rice was lower than instant white rice as indicated by the yield (95.77%), bulk density (0.57 g/mL), rehydration time (14.34 min), rehydration ratio (2.86), expansion volume ratio (2.26), and water absorption capacity (69.50%). Instant savory rice contained moisture content (8.48%), ash content (3.93%), fat content (5.56%), protein content (7.54%), and starch digestibility (54.84%) which was higher than instant white rice. Instant savory rice had carbohydrate content (82.97%), amylose content (32.39%), amylopectin content (46.59%), starch content (79.98%), and resistant starch content (1.90%) lower than instant white rice. In terms of sensory test results revealed that instant savory rice after rehydration was preferred by consumers compared to instant white rice regarding color, aroma, taste, texture, and overall with a score of 5.39-5.84.

IMPROVEMENT OF HIGH AMYLOSE CONTENT IN CH1 RICE VARIETY BY MARKER ASSISTED PSEUDO-BACKCROSS BREEDING

The objective of this research was to introgression of high amylose content into CH1 rice variety by using pseudo-backcrossing breeding. Crossing between CH1 and RD49 was performed to produce F1 progenies. After that, the progenies will backcross to CH1 to develop BC1F1 population. Then, the selected plants from the BC1F1 population were continuously selfed to develop BC1F2 and BC1F3 populations, respectively. For marker assisted selection, the OSR19 DNA marker that is specific to Wx gene was used for assisting the selection of plants with high amylose content in foreground selection to choose favorite genotype. Total 67 SSR markers used genetic background selection was done twice in BC1F1 and BC1F2 populations. The results showed that selection could be achieved for BC1F1 and BC1F2 plants having high amylose content and first highest ranking of genetic background similar to recurrent parent exhibited 91.04 and 97.76 percent, respectively. The marker assisted selection could accelerate 4 generations in backcross breeding program. The BC1F3 seeds of 6 selected lines were planted in paddy field for preliminary yield test. It was found that agronomic characters and yield of the selected lines were not statistically different from those of CH1 variety and high amylose content as donor parent.

An efficient approach for the preparation of branched starch through thermophilic glycogen branching enzyme modification

Glycogen branching enzymes (GBEs, EC 2.4.1.18) play a crucial role in modifying the starch structure and enhancing its properties. The common approaches to starch modification by GBEs typically involve either fully gelatinization the starch at high temperatures (above 95 °C) and then cooling it before adding the enzymes or directly modifying the starch granules at medium-low temperatures (below 60 °C). However, both of these methods have their limitations. Therefore, in this study, we utilized thermally stable mutant Pyrococcus horikoshii (Ph) OT3 GBEs (The thermally stable Ph GBEs mutant were named as H415W and T508K, respectively) to directly act on an ungelatinized normal corn starch (NCS) emulsion at 70 °C, enabling simultaneous starch swelling and branching modification. The results showed that after modification at 70 °C, the crystalline structure of the starch almost completely disappeared, the short-branched chains increased, and the amylose content, rapid digestibility, and retrogradation enthalpy (ΔH) of the H415W- and T508K-modified starch were reduced by 8.2%, 20.35%, and 4.38 J/g when compared to the NCS. Furthermore, when compared to wild-type (WT)-modified starch (modification conducted at 60 °C), the amylose content, rapid digestibility, and retrogradation enthalpy (ΔH) of the H415W- and T508K-modified starch were reduced by 4%, 11.71% and 1.52 J/g, respectively. The branching efficiency of the starch was enhanced due to the achievement of simultaneous starch swelling and branching modification at 70 °C, resulting in an improved branching efficiency. These findings offer valuable insights for the industrial development of branched starch through enzymatic modification.

Physicochemical, functional, pasting, and amino acid compositions of milled rice, and extrusion behavior of milled rice from basmati and nonbasmati varieties

AbstractBackground and ObjectivesThis study was carried out to evaluate the difference in physiochemical, functional, cooking, textural, and pasting properties along with amino acid profile of nine basmati and nine nonbasmati rice varieties. Principle component statistical analysis was done to analyse the relationships among different properties of these varieties. Some verities containing high amylose content and good amino acid profile were selected for further development of extruded products (rice extrudates).FindingsVariations were observed in the physicochemical and functional properties of basmati and nonbasmati varieties. Low amylose rice varieties had higher cooking time, firmness, pasting temperature, and lower pasting viscosity. Selected high amylose‐containing varieties were showed higher bulk density but lower expansion ratio and hardness of rice extrudates. Result of this study will help industry for selection of rice for development of gluten‐free rice‐based breakfast cereals, puffed rice snacks, and so forth.ConclusionsAmong all varieties, PR122, PR128, PB3, PB4, and PB1121 exhibited higher levels of ash content, amylose content and protein content. Consequently, these varieties demonstrated longer CT, greater GSL, higher cooked grain firmness, and higher pasting PT, although they exhibited lower PV. PB1637, PB1509, PB1121, and PB4 displayed higher levels of essential AAs and sweet taste attributing amino acids, such as serine, glycine, and alanine, when compared to the other varieties. The results showed that rice containing higher amylose had lower expansion ratio of the extrudates, while higher bulk density and hardness. PR126 and CSR30 had the highest expansion ratio among the varieties that have been evaluated. Based on these results, PR126 and CSR30 could be used to make gluten‐free rice‐based breakfast cereals, rice snacks, and instant products.Significance and NoveltyPhysiochemical, functional, cooking, texture, pasting properties as well as amino acid profile were evaluated of different basmati and non‐basmati Indian (Punjab) varieties. Principle component (Relationship) analysis between various properties and different rice varieties was carried out. Extrusion is the most versatile processing technology used in the food industry to develop the product having better functional and sensory characteristics. The findings highlight the necessity of taking amylose content and amino acid composition into account when selecting rice types for preparation of extruded rice food.

Multi-omic analysis reveals the effects of interspecific hybridization on the synthesis of seed reserve polymers in a Triticum turgidum ssp. durum × Aegilops sharonensis amphidiploid

BackgroundWheat grain endosperm is mainly composed of proteins and starch. The contents and the overall composition of seed storage proteins (SSP) markedly affect the processing quality of wheat flour. Polyploidization results in duplicated chromosomes, and the genomes are often unstable and may result in a large number of gene losses and gene rearrangements. However, the instability of the genome itself, as well as the large number of duplicated genes generated during polyploidy, is an important driving force for genetic innovation. In this study, we compared the differences in starch and SSP, and analyzed the transcriptome and metabolome among Aegilops sharonensis (R7), durum wheat (Z636) and amphidiploid (Z636×R7) to reveal the effects of polyploidization on the synthesis of seed reserve polymers.ResultsThe total starch and amylose content of Z636×R7 was significantly higher than R7 and lower than Z636. The gliadin and glutenin contents of Z636×R7 were higher than those in Z636 and R7. Through transcriptome analysis, there were 21,037, 2197, 15,090 differentially expressed genes (DEGs) in the three comparison groups of R7 vs Z636, Z636 vs Z636×R7, and Z636×R7 vs R7, respectively, which were mainly enriched in carbon metabolism and amino acid biosynthesis pathways. Transcriptome data and qRT-PCR were combined to analyze the expression levels of genes related to storage polymers. It was found that the expression levels of some starch synthase genes, namely AGP-L, AGP-S and GBSSI in Z636×R7 were higher than in R7 and among the 17 DEGs related to storage proteins, the expression levels of 14 genes in R7 were lower than those in Z636 and Z636×R7. According to the classification analysis of all differential metabolites, most belonged to carboxylic acids and derivatives, and fatty acyls were enriched in the biosynthesis of unsaturated fatty acids, niacin and nicotinamide metabolism, one-carbon pool by folate, etc.ConclusionAfter allopolyploidization, the expression of genes related to starch synthesis was down-regulated in Z636×R7, and the process of starch synthesis was inhibited, resulting in delayed starch accumulation and prolongation of the seed development process. Therefore, at the same development time point, the starch accumulation of Z636×R7 lagged behind that of Z636. In this study, the expression of the GSe2 gene in Z636×R7 was higher than that of the two parents, which was beneficial to protein synthesis, and increased the protein content. These results eventually led to changes in the synthesis of seed reserve polymers. The current study provided a basis for a greater in-depth understanding of the mechanism of wheat allopolyploid formation and its stable preservation, and also promoted the effective exploitation of high-value alleles.

Three nonconventional starch: Comparison of physicochemical properties and in vitro digestibility.

Extraction of starch from waste is also an effective way to recover resources and provide new sources of starch. In this study, starch was isolated from white kidney bean residue, chickpea residue, and tiger nut meal after protein or oil extraction, and the morphology of starch particles was observed to determine their physicochemical properties and in vitro digestibility. All these isolated starches had unique properties, among which white kidney bean starch (KBS) had a high amylose content (43.48%), and its structure was better ordered. Scanning electron microscopy revealed distinct granular morphologies for the three starches. KBS and chickpea starch (CHS) were medium-granular starches, whereas tiger nut starch was a small granular starch. Fourier transform infrared spectroscopy analysis confirmed the absence of significant differences in functional groups and chemical bonds among the three starch molecules. In vitro digestibility studies showed that CHS is more resistant to enzymatic degradation. Overall, these results will facilitate the development of products based on the separation of nonconventional starches from waste.

Advancements in Starch‐Based Aerogels and Hydrogels for Treatment of Water Containing Heavy Metals – A Short Review

AbstractRapid industrialization and profligate use of resources in the present era has led to increase in the concentration of toxic heavy metal ions in water bodies and has become a serious environmental concern. Starch hydrogels and aerogels with engineered functionality, porosity, regeneration characteristics, and high surface to volume ratio have rendered them potential candidates for the adsorption of heavy metal ions from wastewater streams. However, grafting, crosslinking, and composting of the starch aerogels and hydrogels to tailor them in response to various stimuli such as ionic strength, pH, and temperature has added an advantage in the treatment of wastewater containing heavy metal ions. This review critically analyses the various synthesis routes for the production of starch‐based aerogels and hydrogels with physico‐chemical characteristics (amylose content, gelatinization temperature, surface area, density, and porosity) and their applicability to adsorb heavy metal (Cd, Cu, Co, Ni, Cr, Pb, Zn, Fe, and Co) ions from wastewater. Future prospects in the development of economical and robust starch‐based aerogels and hydrogels in terms of their stability and reusability have also been discussed.

Characterization of rice cultivars using Raman spectroscopy and multivariate analysis

Rice is a widely consumed cereal known for its high carbohydrate content and the presence of essential nutritional elements such as proteins and lipids. The previous Raman spectroscopy (RS) studies on whole brown rice kernel have only been able to partially reveal nutritional content. This study employs RS to accurately assess the nutritional profiles of forty rice cultivars in powdered form, facilitating their characterization. The combination of RS and advanced chemometric techniques enables the discrimination of rice cultivars based on key biochemical attributes, including amylose and starch content, aromatic properties, protein content, and total antioxidant capacity, resulting in an impressive accuracy rate of 73%. Significant observations in the fingerprint region included specific Raman spectral features associated with glucose ring stretching at ∼478 cm−1 and indicative stretching vibrations for glycosidic bonds and amylose structures at ∼409 cm−1, ∼439 cm−1, ∼521 cm−1, and ∼868 cm−1. Furthermore, prominent spectral bands associated with amino acids such as phenylalanine (∼1004 cm−1, ∼1580 cm−1, ∼1606 cm−1), tryptophan (∼872 cm−1, ∼1360 cm−1, ∼1543 cm−1, ∼1620 cm−1), and tyrosine (∼853 cm−1, ∼1176 cm−1, ∼1556 cm−1) were observed. Additionally, characteristic peaks related to protein content, carotenoids, and amino acids were identified at ∼1084 cm−1, ∼1111 cm−1, ∼1162 cm−1, ∼1263 cm−1, ∼1310 cm−1, and ∼1404 cm−1. These findings underscore the potential of RS as a fully automated, rapid, and accurate tool for evaluating the nutritional content of rice cultivars.

Preserving plum perfection: Buckwheat starch edible coating with xanthan gum and lemongrass essential oil

The research focused on the fabrication of composite coatings using buckwheat starch (BS) and xanthan gum (XG) with incorporation of lemongrass (Cymbopogon citratus) essential oil (LEO) with varying concentration (0.75 %, 1.0 % and 1.25 % (w/v). BS was extracted from buckwheat groats (Fagopyrum esculentum) and its physico-chemical characteristics were determined. BS showed spherical and polygonal morphology and its XRD pattern was similar to starch extracted from other cereal sources. The amount of reducing sugar, starch and amylose content in extracted BS were 0.99 ± 0.33 %, 86.32 ± 0.22 % and 21.02 ± 1.89 % respectively, which indicates that BS is a suitable base material for the formation of edible coatings. XG was mixed with BS in different ratios (1:1, 2:1, 3:1 and 4:1) to optimize the best ratio of combination for composite coatings. The coating with a ratio of 2:1 was very smooth and was chosen for incorporation of LEO and the coatings physical, functional, mechanical, thermal and micro-structural characteristics were examined. The coating S5 with 1.25 % (w/v) concentration of LEO showed the best results with least moisture content (MC), minimum water vapor permeability (WVP) and maximum contact angle value. Moreover, the S5 formulation had the highest antioxidant (73.3 %) ability and maximum antimicrobial efficiency with inhibition zones of 22.09 ± 0.06 mm and 28.65 ± 0.14 mm against S. aureus and E. coli respectively. The coatings were then coated on plum fruit, and various parameters like weight loss, pH, shrinkage and TSS were calculated every 4th day during the 20 days of refrigeration period. The coated plums' ripening pace was delayed by the S5 formulation which improved moisture retention, maintained the plums' TSS value and overall pH. Therefore, composite coatings made up of BS, XG and 1.25 % (w/v) can be used as a cost-effective bio-active coating material for plum preservation under refrigeration conditions.

Application of SNP Markers to Identify Genetic Variation on Mutant Lines of Adan-Krayan, Special Local Rice from North Kalimantan

Adan rice, a local rice from the Krayan highland of North Kalimantan is marked by its fine taste that consumers like. However, this rice can only be planted once a year due to its long lifespan. Efforts have been made to develop a short-lived version of Adan, to enable it to be planted twice a year. Adan Kelabit was initially exposed to gamma radiation, which produced several mutants. Field selection identified eight mutants with shorter lifespans than the Adan. In this study, these eight mutants were observed further. SNP markers were carried out to confirm the occurrence of mutations, while observations of agronomic characters and grain quality were carried out to determine the most promising lines. The molecular study showed mutations found in all chromosomes of the mutants and differentiated them from the original Adan, with the similarity level ranging from 0.746 to 0.843. However, this closeness is not correlated to the dosage of the gamma rays applied. The majority of the mutants have shorter plant height and higher yield potential. On average, the mutant is 11.5% shorter on heading date, 22.69% higher on tiller number, 27.14% higher on grain weight, and 26.64% higher on other parameters of yield potential. Apart from the shorter heading date, each mutant has its superiorities. The A25 and A28 mutant lines have much higher yield potential while maintaining the same level of amylose content as the Adan rice. These two mutants can be considered for further development or dissemination for farmer adoption.

Hot Water Treatment Preserves Chinese Chestnut (Castanea mollissima Blume) Quality during Storage by Increasing Its Sugar Accumulation and ROS-Scavenging Ability

Heat treatment is a widely used physical technology for postharvest fruit and crops. The Chinese chestnut cultivar “Kuili” has high sugar and amylose contents, and is popular among people. However, the chestnut quality decreases quickly after harvest. In order to maintain the chestnuts’ quality during storage, this study explores five hot water treatments for chestnuts: T1 (control, no treatment), T2 (50 °C), T3 (65 °C), T4 (75 °C), and T5 (90 °C) for 45 min. T1 was dried at ambient temperature, while the other heat treatments were dried at 30 °C for 30 min. After treatment, chestnuts were placed in plastic trays, covered with a 15 μm thick PVC film, and stored at 4 °C with 70% relative humidity; they remained in the same air for 120 days. Results indicated that T3 and T4 showed slight color changes while maintaining shell and kernel firmness, and their weight loss was reduced (+5–8%), as well as their decay rate (limited to within 20%). The T3, T4, and T5 treatments (from days 60 to 120) decreased their pest survival rates to <2%. Additionally, heat treatments facilitated the accumulation of total soluble sugar and increased the expression of sugar biosynthesis-related genes. Meanwhile, T3 and T4 delayed starch reduction (they maintained relatively higher contents, from 288 to ~320 mg g−1 DW) and altered some starch biosynthesis genes. Furthermore, T2, T3, and T4 exhibited higher antioxidant activity and lower hydrogen peroxide (H2O2) and superoxide anions (O2−) contents than T1. At the end of storage, the scores of T3 and T4 treatments were 55.1 and 52.3, and they ranked first and second among the five treatments, respectively. Therefore, these findings provide valuable insights for controlling postharvest losses in chestnuts.

Effect of Fenton reaction parameters on the structure and properties of oxidized wheat starch

Wheat starch was oxidized through a Fenton reaction by hydrogen peroxide and Iron II sulfate as a catalyst at various concentrations and reaction duration. The formation of carbonyl and carboxyl groups confirmed the starch oxidation as determined with Fourier-transform infrared (FTIR) spectroscopy. The degree of oxidation was estimated by carbonyl and carboxyl titration. The various oxidized wheat starches presented considerable variations in their oxidation level as a function of the catalyst concentration and oxidative process duration. The effect of the Fenton reaction parameters on the starch macromolecular chains and microstructure was evaluated by X-ray diffraction and amylose content estimation. Significant depolymerization of the starch macromolecules was observed, mainly in the starch amorphous phase, followed by a degradation of the crystalline phase at a higher oxidation level. SEM observations revealed changes in starch structure, which ranged from minor degradation of the starch granules to a more crosslinked morphology.

The Waxy Gene Has Pleiotropic Effects on Hot Water-Soluble and -Insoluble Amylose Contents in Rice (Oryza sativa) Grains.

Rice (Oryza sativa) is a cereal crop with a starchy endosperm. Starch is composed of amylose and amylopectin. Amylose content (AC) is the principal determinant of rice quality, but varieties with similar ACs can still vary substantially in their quality. In this study, we analyzed the total AC (TAC) and its constituent fractions, the hot water-soluble amylose content (SAC) and hot water-insoluble amylose content (IAC), in two sets of related chromosome segment substitution lines of rice with a common genetic background grown in two years. We searched for quantitative trait loci (QTLs) associated with SAC, IAC, and TAC and identified one common QTL (qSAC-6, qIAC-6, and qTAC-6) on chromosome 6. Map-based cloning revealed that the gene underlying the trait associated with this common QTL is Waxy (Wx). An analysis of the colors of soluble and insoluble starch-iodine complexes and their λmax values (wavelengths at the positions of their peak absorbance values) as well as gel permeation chromatography revealed that Wx is responsible for the biosynthesis of amylose, comprising a large proportion of the soluble fractions of the SAC. Wx is also involved in the biosynthesis of long chains of amylopectin, comprising the hot water-insoluble fractions of the IAC. These findings highlight the pleiotropic effects of Wx on the SAC and IAC. This pleiotropy indicates that these traits have a positive genetic correlation. Therefore, further studies of rice quality should use rice varieties with the same Wx genotype to eliminate the pleiotropic effects of this gene, allowing the independent relationship between the SAC or IAC and rice quality to be elucidated through a multiple correlation analysis. These findings are applicable to other valuable cereal crops as well.

Genetic Effects of Grain Quality Enhancement in Indica Hybrid Rice: Insights for Molecular Design Breeding

Improving rice quality remains a crucial breeding objective, second only to enhancing yield, yet progress in quality improvement lags behind yield. The high temperature and ripening conditions in Southern China often result in poor rice quality, impacting hybrid rice production and utilization. Therefore, to address this challenge, analyzing the molecular basis of high-quality traits is essential for molecular design breeding of high-quality hybrid rice varieties. In this study, we investigated the molecular basis of grain shape, amylose content, gel consistency, gelatinization temperature, and aroma, which influence rice quality. We discovered that quality related alleles gs3, GW7TFA, gw8, chalk5, Wxb, ALKTT, and fgr can enhance rice quality when applied in breeding programs. Polymerization of gs3, GW7TFA, gw8, and chalk5 genes improves rice appearance quality. The gs3 and GW7TFA allele polymerization increasing the grain’s length-width ratio, adding the aggregation of gw8 allele can further reducing grain width. The chalk5 gene regulates low chalkiness, but low correlation to chalkiness was exhibited with grain widths below 2.0 mm, with minimal differences between Chalk5 and chalk5 alleles. Enhancing rice cooking and eating quality is achieved through Wxb and ALKTT gene polymerization, while introducing the fgr(E7) gene significantly improved rice aroma. Using molecular marker-assisted technology, we aggregated these genes to develop a batch of indica hybrid rice parents with improved rice quality are obtained. Cross-combining these enhanced parents can generate new, high-quality hybrid rice varieties suitable for cultivation in Southern China. Therefore, our findings contribute to a molecular breeding model for grain quality improvement in high-quality indica hybrid rice. This study, along with others, highlights the potential of molecular design breeding for enhancing complex traits, particularly rice grain quality.

Combining genome-wide association study and linkage mapping in the genetic dissection of amylose content in maize (Zea mays L.).

Integrated linkage and association analysis revealed genetic basis across multiple environments. The genes Zm00001d003102 and Zm00001d015905 were further verified to influence amylose content using gene-based association study. Maize kernel amylose is an important source of human food and industrial raw material. However, the genetic basis underlying maize amylose content is still obscure. Herein, we used an intermated B73 × Mo17 (IBM) Syn10 doubled haploid population composed of 222 lines and a germplasm set including 305 inbred lines to uncover the genetic control for amylose content under four environments. Linkage mapping detected 16 unique QTL, among which four were individually repeatedly identified across multiple environments. Genome-wide association study revealed 17 significant (P = 2.24E-06) single-nucleotide polymorphisms, of which two (SYN19568 and PZE-105090500) were located in the intervals of the mapped QTL (qAC2 and qAC5-3), respectively. According to the two population co-localized loci, 20 genes were confirmed as the candidate genes for amylose content. Gene-based association analysis indicated that the variants in Zm00001d003102 (Beta-16-galactosyltransferase GALT29A) and Zm00001d015905 (Sugar transporter 4a) affected amylose content across multi-environment. Tissue expression analysis showed that the two genes were specifically highly expressed in the ear and stem, respectively, suggesting that they might participate in sugar transport from source to sink organs. Our study provides valuable genetic information for breeding maize varieties with high amylose.