Generating waxy rice starch with target type of amylopectin fine structure and gelatinization temperature by waxy gene editing

The high molecular weight and large particle size and high crystallinity of starch increase gelatinization temperature and retrogradation in glutinous rice

The gelatinization and retrogradation properties of glutinous rice starch are important factors that affect its quality. In this study, the thermal properties, viscosity properties and retrogradation of starch from 152 natural glutinous varieties were investigated, and further explored the effects of starch structure on gelatinization temperature (GT) and retrogradation. The results demonstrated a strong positive linear correlation between thermal properties and retrogradation of glutinous rice. The high molecular weight, high crystallinity and large particle size of starch have significant positive effects on the thermal properties and retrogradation of amylopectin. Varieties of glutinous rice with high molecular weight starch, large starch particle sizes, and high crystallinity exhibited high GT and retrogradation rates (R%). Additionally, there was a significantly negative correlation between the range of gelatinization temperature and gelatinization enthalpy in raw starch, while a larger temperature range in retrograded starch corresponded to greater gelatinization enthalpy. The recrystallization of retrograded starch exhibited higher crystal heterogeneity and a broader range of melting points compared to raw glutinous starch. These findings provide valuable insights for breeding glutinous rice varieties with desirable retrogradation traits, particularly those with low R%.

Identification of the Granule-Bound Starch Synthase (GBSS) Genes Involved in Amylose Biosynthesis in Tartary Buckwheat (Fagopyrum tataricum (L.) Gaertn.)

Tartary buckwheat is a nutrient-rich pseudo-cereal whose starch contents, including amylose and amylopectin contents, and their properties hold significant importance for enhancing yield and quality. The granule-bound starch synthase (GBSS) is a key enzyme responsible for the synthesis of amylose, directly determining the amylose content and amylose-to-amylopectin ratio in crops. Although one has already been cloned, the GBSS genes at the genome-wide level have not yet been fully assessed and thoroughly analyzed in Tartary buckwheat. This study comprehensively analyzed the FtGBSSs in Tartary buckwheat. Based on the genome data of Tartary buckwheat, five FtGBSS genes, namely FtGBSS-1 to FtGBSS-5, were identified on three chromosomes, exhibiting about 1800 bp lengths in their CDSs and numerous exons and introns in gene structures. Amino acid analyses revealed high homology in ten GBSS proteins from Tartary buckwheat, rice, maize, and Arabidopsis thaliana, with a specific starch synthase catalytic domain and ten conserved motifs. The Tartary buckwheat GBSS proteins had a closer relationship with GBSS proteins from monocot based on evolutionary relationship analysis. Expression analyses suggested that the FtGBSS genes showed distinct tissue-specific expression patterns in Tartary buckwheat and rice-Tartary buckwheat. Among them, FtGBSS-1, FtGBSS-2, and FtGBSS-4 were higher expressed in the root, stem, or flower, suggesting that they have a role in the amylose synthesis of these tissues. Notably, FtGBSS-3 and FtGBSS-5 were more highly expressed in seeds than in other tissues, suggesting that they have a pivotal role in amylose synthesis of the seeds of Tartary buckwheat. Furthermore, the cis acting elements in the promoters of FtGBSSs and their binding transcription factors (TFs) were investigated. A protein-protein interaction network was constructed and co-expression was analyzed based on the gene expression patterns of the FtGBSSs, and the identified TFs, belonging to bZIP, ERF, bHLH, and MADS-box TF families, were identified within this network, and their expression patterns were significantly correlated to the expression patterns of two seed-specific FtGBSS genes (FtGBSS-3 and FtGBSS-5). Finally, FtGBSS1-5 was successfully transformed into rice through transgenic manipulation, and the FtGBSS1-5 overexpression lines showed an increase in amylose content accompanied by a reduction in amylopectin and total starch contents compared with WT. Overall, this research not only deepens our understanding of the molecular mechanisms of amylose synthesis in Tartary buckwheat, but also provides scientific insights for enhancing crop amylose content and quality through molecular breeding.

Creating of novel Wx allelic variations significantly altering Wx expression and rice eating and cooking quality

Granule-bound starch synthase I (GBSSI) encoding gene Waxy (Wx), which largely regulates the amylose content of rice grains, is a master module determining rice eating and cooking quality (ECQ). Fine-tuning amylose level of grains is an ideal strategy to improve rice quality. Through fine editing of Wxa promoter and 5'UTR by CRISPR/Cas9 system, we created 14 types of novel Wx allelic variations, of which MT7 and MT13 were able to alter Wx expression and amylose content of grains. MT7 showed fragment deletion and base insertions in CAAT-boxes, hardly detectable expression levels of GBSSI mRNA and protein, and generated 5.87% amylose in grains. MT13 had fragment deletions in the A-box and the TATA-box, low expression levels of GBSSI mRNA and protein, and generated 9.61% amylose in grains. Besides of the amylose content, MT7 and MT13 significantly reduced protein content and increased lipid content of grains compared with Wxa. A comparison of MT7, MT13 and other allelic lines demonstrated the importance of base insertion around the second CAAT-box and 31bp-deletion following the second TATA-box in modulating Wx expression. Thus, our study generated two novel Wx allelic variations which significantly alter Wx expression and amylose content of rice grains, providing not only new germplasms for soft rice breeding, but also insights into candidate cis elements of Wx.

Synthesis, structural characterization and in vitro digestion stability of a soluble soybean polysaccharide‑zinc chelate

The chelation reaction of soluble soybean polysaccharide (SSPS) with zinc was investigated. Using response surface methodology, the optimum parameters for SSPS-Zn synthesis were obtained: pH 5.3, SSPS-ZnCl2 mass ratio of 9.44:1, reaction temperature 50.44 °C, and reaction time 1.5 h, with the highest zinc content of 24.73 %. Compared with SSPS, SSPS-Zn increased in rhamnogalacturonan content and decreased in that of neutral monosaccharides (Fuc, Ara, Gal, Glu and Xyl). UV-vis spectra indicated that SSPS-Zn was lower than SSPS in protein content. FTIR spectra indicated that CO group of SSPS was bonded to Zn2+. X-ray diffraction spectra demonstrated that SSPS-Zn had higher crystallinity. Congo red reactions showed that SSPS possessed a triple-helix conformation while SSPS-Zn formed an irregular free-coiled conformation. EDX confirmed SSPS-Zn synthesis successfully. TGA curves exhibited that SSPS-Zn required higher temperature to undergo degradation. AFM revealed that SSPS-Zn was clustered while SSPS was filamentous. SEM micrographs showed the cracked fragments on the surface of SSPS-Zn. By in vitro simulation of gastrointestinal digestion, Zn2+ release reached 68.87 % after 2 h digestion. Consequently, the chelation of SSPS with zinc could change structure and provide a basis for research and application of novel zinc supplements.

Impact of flaxseed gum on the aggregate structure, pasting properties, and rheological behavior of waxy rice starch

This study examines the effects of flaxseed gum (FG) on the aggregate structure, pasting and rheological properties of waxy rice starch (WRS). Results display an increase in the ordered molecular structure (R1047/1024), relative crystallinity (RC), compactness (α), and microphase heterogeneity (ε, density degree of nanoaggregates, from 3.52 to 4.23) for WRS-FG complexes. These suggested FG facilitated the development of more organized molecular and crystalline structures of WRS, accompanied by the formation of ordered nanoaggregates with higher density (i.e., nano-aggregation structure). Also, FG addition resulted in the formation of enhanced gel network structure characterized by thicker layer walls and more uniform pores. These structural transformations contributed to a rise in gelatinization temperature (To, from 56.90 °C to 62.10 °C) and enthalpy (ΔH), as well as alterations in paste viscosities (PV, from 1285.00 mPa·s to 1734.00 mPa·s), and the rigidity of network structure (e.g., decreased loss tangent). These results indicate that FG could effectively regulate the techno-functional properties of WRS by rationally controlling the starch intrinsic structures of starch. And this study may improve the pasting and gelling properties of starch, thus driving the development of high-quality starchy foods and prolonging their shelf life, especially for glutinous rice flour products.

Comparison of extraction processes, characterization and intestinal protection activity of Bletilla striata polysaccharides

We optimized the extraction process of Bletilla striata polysaccharides using orthogonal design, Box-Behnken design (BBD), and genetic algorithm-back propagation (GA-BP), then compared and evaluated them to confirm that the combination of BBD and GA-BP neural networks was capable of increasing polysaccharide yields and antioxidant activity. The optimal extraction parameters were as follows: liquid-to-solid ratio of 15 mL/g, extraction power of 450 W, and extraction time of 34 min. Under these conditions, the polysaccharide yield and antioxidant activity were 8.29 ± 0.50 % and 26.20 ± 0.28 (mM FE/mg). Subsequently, the polysaccharide was purified to obtain purified Bletilla striata polysaccharides 1 (pBSP1) with a Mw of 255.172 kDa. Scanning electron microscope (SEM), ultraviolet-visible detector (UV), fourier transform infrared spectrometer (FTIR), high performance liquid chromatography (HPLC), X-ray diffraction (XRD), nuclear magnetic resonance (NMR) and periodate oxidation were used to analyze the structure of pBSP1. The results showed pBSP1 had a smooth surface and a rough interior, with a composition of α-D conformation glucose (18.23 %) and β-D conformation mannose (53.77 %), and an amorphous crystal structure. According to the results of thermogravimetric and rheological tests, pBSP1 exhibits good thermal stability and viscoelastic behavior. Furthermore, pBSP1 protected lipopolysaccharide (LPS)-induced GES - 1 and Caco2 cells, the results showed pBSP1(400 μg/mL) lowered TEER synthesis in Caco2 cells as well as apoptosis and reactive oxygen species (ROS) production in both cells, indicating that pBSP1 may have an intestine protective effect.

Structural analysis of a soluble polysaccharide GSPA-0.3 from the root of Panax ginseng C. A. Meyer and its adjuvant activity with mechanism investigation

A novel polysaccharide (GSPA-0.3) was isolated and purified from the root of cultivated Panax ginseng C. A. Meyer, and its structure, adjuvant activities, and mechanisms for inducing the maturation of mouse dendritic 2.4 cells (DC2.4) were extensively studied. Fraction GSPA-0.3, mainly composed by the galacturonic acid, galactose, arabinose, glucose, rhamnose, mannose, and xylose, had a molecular weight of 62,722 Da. The main chain of GSPA-0.3 was composed of →3)-α-L-Rhap-(1→, →4)-α-D-GalpA-(1→, and →3, 4)-α-D-GalpA-(1→. Branched chains comprised α-L-Araf-(1→3, 5)-α-L-Araf-(1→5)-α-L-Araf-(1→, α-D-Glcp-(1→6)-α-D-Glcp-(1→6)-α-D-Glcp-(1→, β-D-Galp-(1→4)-β-D-Galp-(1→4)-β-D-Galp-(1→, and α-D-GalpA-(1→ units connected to the C3 position of →3, 4)-α-D-GalpA-(1→. In vivo, GSPA-0.3 was found to stimulate the production of IgG, IgG1, and IgG2a; increase the splenocyte proliferation index; and promote the expression of GATA-3, T-bet, IFN-γ, and IL-4 in H1N1 vaccine-immunized mice. Moreover, GSPA-0.3 significantly increased the levels of neutralizing antibodies in the mice, and its adjuvant activity was found to be superior to aluminum adjuvant (Alum adjuvant). Mechanistic investigations showed that GSPA-0.3 activated the TLR4-dependent pathway by upregulating the expressions of TLR4, MyD88, TRAF-6, and NF-κB proteins and gens. The results presented herein suggested that GSPA-0.3 could significantly promote the efficacy of the H1N1 vaccine by modulating Th1/Th2 response via the TLR4-MyD88-NF-κB signaling pathway.

Heat-moisture treated waxy highland barley starch: Roles of starch granule-associated surface lipids, temperature and moisture

Roles of temperature, moisture and starch granule-associated surface lipids (SGASL) during heat-moisture treatment (HMT) of waxy highland barley starch were elucidated. Starch without SGASL showed a higher increase in ratio (1016/993 cm-1) (0.095-0.121), lamellar peak area (88), radius of gyration (Rg1, 0.9-1.8 nm) and power-law exponents (0.19-0.42) than native starch (0.038-0.047, 46, 0.1-0.6 nm, 0.04-0.14), upon the same increase in moisture or temperature. Thus, removing SGASL promoted HMT. However, after HMT (30 % moisture, 120 °C), native starch showed lower relative crystallinity (RC, 11.67 %) and lamellar peak area (165.0), longer lamellar long period (L, 14.99 nm), and higher increase in peak gelatinization temperature (9.2-13.3 °C) than starch without SGASL (12.04 %, 399.2, 14.52 nm, 4.7-6.1 °C). This suggested that the resulting SGASL-amylopectin interaction further destroyed starch structure. Starch with and without SGASL showed similar trends in RC, lamellar peak area, L and Rg1 with increasing temperature, but different trends with increasing moisture, suggesting that removing SGASL led to more responsiveness to the effects of increasing moisture. Removing SGASL resulted in similar trends (RC and lamellar peak area) with increasing moisture and temperature, suggesting that the presence of SGASL induced different effects on moisture and temperature.

Generation of aroma in three-line hybrid rice through CRISPR/Cas9 editing of BETAINE ALDEHYDE DEHYDROGENASE2 (OsBADH2)

Aroma or fragrance in rice is a genetically controlled trait; Its high appreciation by consumers increases the rice market price. Previous studies have revealed that the rice aroma is controlled by a specific gene called BETAINE ALDEHYDE DEHYDROGENASE (OsBADH2), and mutation of this gene leads to the accumulation of an aromatic substance 2-acetyl-1-pyrroline (2-AP). The use of genetic engineering to produce aroma in commercial and cultivated hybrids is a contemporary need for molecular breeding. The current study reports the generation of aroma in the three-line hybrid restorer line Shu-Hui-313 (SH313). We created knock-out (KO) lines of OsBADH2 through the CRISPR/Cas9. The analysis of KO lines revealed a significantly increased content of 2AP in the grains compared with the control. However, other phenotypic traits (plant height, seed setting rate, and 1000-grain weight) were significantly decreased. These KO lines were crossed with a non-aromatic three-line hybrid rice male sterile line (Rong-7-A) to produce Rong-7-You-626 (R7Y626), R7Y627 and R7Y628. The measurement of 2-AP revealed significantly increased contents in these cross combinations. We compared the content of 2-AP in tissues at the booting stage. Data revealed that young spike stalk base contained the highest content of 2-AP and can be used for identification (by simple chewing) of aromatic lines under field conditions. In conclusion, our dataset offers a genetic source and illustrates the generation of aroma in non-aromatic hybrids, and outlines a straightforward identification under field conditions.

Starch chain-length distributions determine cooked foxtail millet texture and starch physicochemical properties

Starch chain-length distributions play an important role in controlling cereal product texture and starch physicochemical properties. Cooked foxtail millet texture and starch physicochemical properties were investigated and correlated with starch chain-length distributions in eight foxtail millet varieties. The average chain lengths of amylopectin and amylose were in the range of DP 24-25 and DP 878-1128, respectively. The percentage of short amylopectin chains (Ap1) was negatively correlated with hardness but positively correlated with adhesiveness and cohesion. Conversely, the amount of amylose intermediate chains was positively correlated with hardness but negatively correlated with adhesiveness and cohesion. Additionally, the amount of amylose long chains was negatively correlated with adhesiveness and chewiness. The relative crystallinity (RC) of starch decreased with reductions in the length of amylopectin short chains in foxtail millet. Pasting properties were mainly influenced by the relative length of amylopectin side chains and the percentage of long amylopectin branches (Ap2). Longer amylopectin long chains resulted in lower gelatinization temperature and enthalpy (ΔH). The amount of starch branched chains had important effects on the gelatinization temperature range (ΔT). These results can provide guidance for breeders and food scientists in the selection of foxtail millet with improved quality properties.

Sustainable production of naturally colored extruded breakfast cereals from blends of broken rice and vegetable flours

There is a growing demand for practical and healthy food products. Obtaining naturally colored breakfast cereals with the incorporation of functional ingredients is a promising alternative for consumers that are looking for healthiness. This study aimed to evaluate the feasibility of using vegetable flours, rich in pigments, to obtain naturally colored breakfast cereals through thermoplastic extrusion. Vegetables considered "unsuitable for the retail market", classified as "type B", were used to prepare different flours from carrot (CF), spinach (SF) and beetroot (BF). Extrudates were produced from a mixture of 90% broken rice (BR) and 10% vegetable flour (CF, SF or BF). Besides giving the extrudates a natural color, the use of vegetable flours also provided nutritional and functional enrichment due to increased mineral, protein, lipid, fiber and phenolic compound contents, and greater antioxidant capacity. However, some of these components, such as fibers, affect extrudate physical structure and technological characteristics, evidenced by reduced expansion, hardness, paste viscosity and greater interaction with water present in milk under consumption conditions. In general, the evaluated flours proved to be an alternative for imparting a natural color to extruded breakfast cereals, in addition to positively contributing to their nutritional and functional value.

Starch Modification with Molecular Transformation, Physicochemical Characteristics, and Industrial Usability: A State-of-the-Art Review

Starch is a readily available and abundant source of biological raw materials and is widely used in the food, medical, and textile industries. However, native starch with insufficient functionality limits its utilization in the above applications; therefore, it is modified through various physical, chemical, enzymatic, genetic and multiple modifications. This review summarized the relationship between structural changes and functional properties of starch subjected to different modified methods, including hydrothermal treatment, microwave, pre-gelatinization, ball milling, ultrasonication, radiation, high hydrostatic pressure, supercritical CO₂, oxidation, etherification, esterification, acid hydrolysis, enzymatic modification, genetic modification, and their combined modifications. A better understanding of these features has the potential to lead to starch-based products with targeted structures and optimized properties for specific applications.

CRISPR/Cas9-mediated editing of Wx and BADH2 genes created glutinous and aromatic two-line hybrid rice

Amylose content (AC) is one of the physicochemical indexes of rice quality, which is largely determined by the Waxy (Wx) gene. Fragrance in rice is favored because it adds good flavor and a faint scent. Loss of function of the BADH2 (FGR) gene promotes the biosynthesis of 2-acetyl-1-pyrroline (2AP), which is the main compound responsible for aroma in rice. Here, we used a CRISPR/Cas9 system to simultaneously knock out Wx and FGR genes in 1892S and M858, which are the parents of an indica two-line hybrid rice, Huiliangyou 858 (HLY858). Four T-DNA-free homozygous mutants (1892Swxfgr-1, 1892Swxfgr-2, M858wxfgr-1, and M858wxfgr-2) were obtained. The 1892Swxfgr and M858wxfgr were crossed to generate double mutant hybrid lines HLY858wxfgr-1 and HLY858wxfgr-2. Size-exclusion chromatography (SEC) data indicated that true AC of the wx mutant starches ranged from 0.22 to 1.63%, much lower than those of the wild types (12.93 to 13.76%). However, the gelatinization temperature (GT) of the wx mutants in backgrounds of 1892S, M858, and HLY858 were still high, and showed no significant differences with the wild type controls. The aroma compounds 2AP content in grains of HLY858wxfgr-1 and HLY858wxfgr-2 were 153.0 μg/kg and 151.0 μg/kg, respectively. In contrast, 2AP was not detected in grains of HLY858. There were no significant differences in major agronomic traits between the mutants and HLY858. This study provides guidelines for cultivation of ideal glutinous and aromatic hybrid rice by gene editing.