Starch Granule Size Research Articles

Effect of Climatic Conditions on Wheat Starch Granule Size Distribution, Gelatinization and Flour Pasting Properties

The aim of this study was to determine the effects of different varieties, year and location of growing, and their interactions, on wheat starch and flour properties, and to analyze the relationship between these attributes. The set of 92 wheat samples chosen to cover wide ranges in the parameters commonly used for the assessment of wheat flour and starch properties was reduced to a representative set of 27 samples. The obtained results showed that wheat variety and year significantly affected maximum viscosity (MV), alpha–amylase activity (AA), amylose content (AM), volume proportion of A-, B- and C-starch granules, as well as gelatinization temperatures, while the year and location by year interaction had a significant effect on the falling number (FN). In this work, a number of significant correlations were observed among analyzed starch and flour properties. AA was mostly influenced by the changes in packing of starch granules and granule size distribution, while gelatinization temperatures were affected by particle size distribution. Additionally, when testing the suitability of the parameters for the estimation of alpha–amylase activity, it was determined that Amylograph was more reliable in predicting alpha–amylase than FN because it provided a better description of the state of flour starch complex.

FUNCTIONAL PROPERTIES AND POTENTIAL UTILIZATION OF STARCH ISOLATED FROM CHAYOTE FRUIT

Chayote, Sechium edule (Jacq.) Sw., is anoverlooked food‎ plant despite its various ‎potentialities. This study investigated the characteristics of starch isolated from ‎chayote fruit cultivated in Algiers which is known for its Mediterranean ‎climate. The granules morphology, functional properties and amylose content of Algerian chayote fruit starch were examined. Spherical, oval and polygonal shapes and smooth surface were observed using three imaging techniques: a normal and polarized light microscopy with Lucia ‎software and Scanning Electron Microscopy (SEM).‎ Starch granules size was in the rang 3.56-‎‎37.24 μm, and for the chayote tubers, it‎ was 7-50 μm. The amylose content (‎20.36%‎) ‎‎is different from that of the chayote tubers (12.81%), but ‎close‎‎‎ to those of ‎conventional sources. The Algerian chayote fruit starch showed higher swelling strength and lower ‎melting ‎index.‎ The Rapid Visco Analyzer pasting profile revealed a lower peak ‎viscosity (2158.3 cP) than that from chayote tubers (14746 cP).‎ However, Differential Scanning Calorimetry analysis showed higher gelatinisation temperatures (66.89 °‎C) and ‎transition enthalpy (‎15.79‎ J/g)‎. X-ray diffraction profile showed B-type.‎ The digestibility (D∞), hydrolysis index, HI, and average glycemic index, (GI), were estimated at 50.66 %, 52.16% and 70.16 ‎%‎ respectively.‎ The results showed that starch has an ‎acceptable nutritional value with significant in vitro digestion properties and it is suitable for human health and nutrition.‎ The starch of Algerian chayote fruit showed interesting ‎functional characteristics which makes it suitable for relevant applications in both the field food and cosmetics industries. It can, also, be a raw material for starch processing.

Arabidopsis thaliana B-GATA factors repress starch synthesis and gravitropic growth responses.

Plants perceive the direction of gravity during skotomorphogenic growth, and of gravity and light during photomorphogenic growth. Gravity perception occurs through the sedimentation of starch granules in shoot endodermal and root columella cells. In this study, we demonstrate that the Arabidopsis thaliana GATA factors GNC (GATA, NITRATE-INDUCIBLE, CARBON METABOLISM-INVOLVED) and GNL/CGA1 (GNC-LIKE/CYTOKININ-RESPONSIVE GATA1) repress starch granule growth and amyloplast differentiation in endodermal cells. In our comprehensive study, we analysed gravitropic responses in the shoot, root and hypocotyl. We performed an RNA-seq analysis, used advanced microscopy techniques to examine starch granule size, number and morphology and quantified transitory starch degradation patterns. Using transmission electron microscopy, we examined amyloplast development. Our results indicate that the altered gravitropic responses in hypocotyls, shoots and roots of gnc gnl mutants and GNL overexpressors are due to the differential accumulation of starch granules observed in the GATA genotypes. At the whole-plant level, GNC and GNL play a more complex role in starch synthesis, degradation and starch granule initiation. Our findings suggest that the light-regulated GNC and GNL help balance phototropic and gravitropic growth responses after the transition from skotomorphogenesis to photomorphogenesis by repressing the growth of starch granules.

Molecular and biochemical characterization of rice developed through conventional integration of nDart1-0 transposon gene

Mutations, the genetic variations in genomic sequences, play an important role in molecular biology and biotechnology. During DNA replication or meiosis, one of the mutations is transposons or jumping genes. An indigenous transposon nDart1-0 was successfully introduced into local indica cultivar Basmati-370 from transposon-tagged line viz., GR-7895 (japonica genotype) through conventional breeding technique, successive backcrossing. Plants from segregating populationsshowed variegated phenotypes were tagged as BM-37 mutants. Blast analysis of the sequence data revealed that the GTP-binding protein, located on the BAC clone OJ1781_H11 of chromosome 5, contained an insertion of DNA transposon nDart1-0. The nDart1-0 has “A” at position 254 bp, whereas nDart1 homologs have “G”, which efficiently distinguishes nDart1-0 from its homologs. The histological analysis revealed that the chloroplast of mesophyll cells in BM-37 was disrupted with reduction in size of starch granules and higher number of osmophillic plastoglobuli, which resulted in decreased chlorophyll contents and carotenoids, gas exchange parameters (Pn, g, E, Ci), and reduced expression level of genes associated with chlorophyll biosynthesis, photosynthesis and chloroplast development. Along with the rise of GTP protein, the salicylic acid (SA) and gibberellic acid (GA) and antioxidant contents(SOD) and MDA levels significantly enhanced, while, the cytokinins (CK), ascorbate peroxidase (APX), catalase (CAT), total flavanoid contents (TFC) and total phenolic contents (TPC) significantly reduced in BM-37 mutant plants as compared with WT plants. These results support the notion that GTP-binding proteins influence the process underlying chloroplast formation. Therefore, it is anticipated that to combat biotic or abiotic stress conditions, the nDart1-0 tagged mutant (BM-37) of Basmati-370 would be beneficial.

The effect of intermittent drying with variable resting times on quality parameters of corn obtained after storage

This study aimed to assess the effect of continuous and intermittent drying with different rest times on the quality parameters of stored corn grains. The grains were collected at a moisture content of 25.37 g/100 g and subjected to drying at a temperature of 373 K and air flow rate of 1.5 m3/(min m2). Drying was carried out using five different rest times (0, 4, 8, 12 and 16 h) and continued until the grains reached a final moisture content of 14 ± 0.3 g/100 g. After drying, the grains were stored under laboratory conditions and assessed at 0, 90, 180 and 270 d. The following conclusions were reached: the rest technique reduced grain damage after drying and during storage without substantially compromising proximal composition; longer rest times resulted in darker grains, while storage decreased the hue and increased the colour intensity of grains. Storage diminished the positive effect of intermittent drying on the arrangement, size and agglomeration of starch granules.

Changes in the structural and physicochemical characterization of pea starch modified by Bacillus-produced α-amylase

In this study, changes in structural and physicochemical properties of pea starch treated with Bacillus-produced α-amylase were determined. The results showed that enzymatically modified pea starch had lower amylose content and granule size but higher branching degree and relative crystallinity. After enzyme hydrolysis, the distribution of A and B1 chains slightly decreased, while the distribution of B2 and B3 chains increased lightly. Enzymatic hydrolysis preferentially occurred in the amorphous region and cannot change the crystalline structure of pea starch. Moreover, pea starch showed lower light transmittance, peak viscosity, breakdown viscosity, pasting temperature, shear viscosity, storage modulus and loss modulus, while the oil adsorption capacity and gelatinization enthalpy significantly increased with increasing α-amylase hydrolysis time. Correlation analysis indicated that α-amylase hydrolysis had different effects on different pea varieties. This research could provide ideas for exploring new applications for enzymatically modified pea starch in food industry. Industrial relevanceThis study found that Bacillus-produced α-amylase significantly changed the amylose content, granule size and viscosity of pea starch, which was helpful to further investigate the modified starch. This technology is expected to widen the applications of pea starch modified by Bacillus-produced α-amylase in food industry, for example as thickener, stabilizer and beverage, to improve the texture, stability and shelf-life of various food products.

Genome-Editing of FtsZ1 for Alteration of Starch Granule Size in Potato Tubers.

Genome-editing has enabled rapid improvement for staple food crops, such as potato, a key beneficiary of the technology. In potato, starch contained within tubers represents the primary product for use in food and non-food industries. Starch granules are produced in the plastids of tubers with plastid size correlated with the size of starch grana. The division of plastids is controlled by proteins, including the tubulin-like GTPase FtsZ1. The altered expression of FtsZ1 has been shown to disrupt plastid division, leading to the production of "macro-plastid"-containing plants. These macro-chloroplast plants are characterized by cells containing fewer and enlarged plastids. In this work, we utilize CRISPR/Cas9 to generate FtsZ1 edited potato lines to demonstrate that genome-editing can be used to increase the size of starch granules in tubers. Altered plastid morphology was comparable to the overexpression of FtsZ1 in previous work in potato and other crops. Several lines were generated with up to a 1.98-fold increase in starch granule size that was otherwise phenotypically indistinguishable from wild-type plants. Further, starch paste from one of the most promising lines showed a 2.07-fold increase in final viscosity. The advantages of enlarged starch granules and the potential of CRISPR/Cas9-based technologies for food crop improvement are further discussed.

Analysis of Starch Structure and Pasting Characteristics of Millet Thick Wine during Fermentation.

Starch is the main substrate in millet thick wine (MTW). In order to control the fermentation process of MTW, it is critical to monitor changes in the starch structure and physicochemical characteristics during the fermentation of MTW. In the present study, the structural characteristics of MTW starch were analyzed by scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and rapid viscosity analysis (RVA). The results of SEM and CLSM showed that large starch granules in MTW swelled, developed cavities, and ruptured or even vanished with the prolongation of the fermentation time, whereas the size and shape of small starch granules barely changed, only falling off the pomegranate-seed-like aggregates. With the increase in fermentation time, the relative crystallinity of starch in MTW gradually increased. In addition, the short-range ordered structures underwent complex changes. Changes in the starch morphology and ordered structure led to an increase in the peak viscosity time and the initial gelatinization temperature. The present results reveal the beneficial effect of fermentation on MTW processing and suggest its potential applications in other millet-based fermented products.

Ultrasonic-assisted binding of canistel (Lucuma nervosa A.DC) seed starch with quercetin

In order to provide a reference for improving the physicochemical properties of starch, the study of starch polyphenol complex interaction has aroused considerable interest. As a common method of starch modification, ultrasound can make starch granules have voids and cracks, and make starch and polyphenols combine more closely. In this research, canistel seed starch was modified by ultrasonic treatment alone or combined with quercetin. The molecular structure, particle characteristics and properties of starch were evaluated. With the increase of ultrasonic temperature, the particle size of the dextrinized starch granules increased, but the addition of quercetin could protect the destruction of starch granule size by ultrasonic; X-ray diffraction and infrared spectra indicated that quercetin was bound to the surface of canistel seed starch through hydrogen bonding, and the complex and the original starch had the same crystal structure and increased crystallinity; by molecular simulation, quercetin bound inside the starch molecular helix preserved the crystalline helical configuration of starch to some extent and inhibited the complete unhelicalization of starch molecules. Meanwhile, hydrogen bonding was the main driving force for the binding of starch molecules to quercetin, and van der Waals interactions also promoted the binding of both. In the physicochemical properties, as the temperature increased after the combination of ultrasonic modified starch combined with quercetin, the solubility, swelling force and apparent viscosity of the compound increased significantly, and it has higher stability and shear resistance.

Structure and properties of ZrO2-Al2O3-MgO porous ceramic for biomedical applications

Starch consolidation casting (SCC), which involves pouring starch-containing slurries into an impermeable mould, is a flexible, easy, not harmful, not expensive, and firmly established method for manufacturing ceramic green structures. The procedure depends on the fact that the starch granules, when heated to about 80 °C, start to swell and absorb the water from the ceramic slurries. Following sintering, the starch granules have been completely destroyed by burning, resulting in the formation of porous-structured ceramics. In the current study, porous zirconia-alumina–magnesia (77.5 wt% ZrO2, 2.5 wt% MgO, and 20 wt% Al2O3) ceramic composites have been produced using starch consolidation casting method at different suspension concentration (60, 65, and 70 wt%). Potato or tapioca starches with varying quantities (10, 20, and 30 wt% related to the solid ceramics) were used as a pore and body forming agents. The sintered microstructures were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Furthermore, the research activity investigates how the apparent density and apparent porosity of the porous ceramic structure that has been produced are affected by the addition of different proportions of starches in different suspension concentrations. The XRD result after sintering reveals monoclinic zirconia, indicating that the tetragonal phase of zirconia is not stabilized by MgO and returns to monoclinic upon cooling. Magnesia does not act as a stabilizer for zirconia, but it is combined with alumina to produce a spinel structure. Maximum apparent porosity value of around 73% were demonstrated for porous-structured ceramics made with (30 wt%) potato starch and (60 wt%) suspension concentration. The SEM analysis of porous-structured ceramics revealed the presence of pore fills in the shape of miniature sintered ceramic shells within the pores. These shells form throughout the drying and burn-out processes, when the starch granules undergo a process that causes them to shrink. For nominal starch quantities of approximately 10 wt%, starch swelling is noticeable, and the pores left behind by sintering are bigger than the starch granules. Swelling is limited for greater amounts of starch by the amount of available space and/or water, and the matrix shrinkage that occurs during sintering more than compensates for the swelling impact, resulting in ceramic pores much smaller than the initial starch granule size. SEM and high-pressure mercury porosimetry results indicated that the prepared porous-structured ceramics have a bimodal pore structure. The maximum compressive strength at around 15.87 MPa for a sample containing 10 wt% tapioca starch and 70 wt% suspension concentration. Compressive strength drastically reduced when starch content increased from 10 to 30 wt% and suspension concentration reduced from 70 to 60 wt%.

Intrinsic and extrinsic factors drive differences in the gelatinisation behaviour of barley and malt starch

We studied the impact of malting on barley starch gelatinisation properties and whether observed differences are due to changes in extrinsic or intrinsic factors. We isolated the total starch and large and small starch granules fractions from barley and malt samples and subjected them to DSC. The peak gelatinisation temperature for malt starch was, on average, 1.2 °C higher than for barley starch. The malting process and endosperm breakdown products were each responsible for half of this difference. The presence of water-extractable, non-starch components (sugars, minerals, protein and starch hydrolysis products,…) increased the intrinsic starch gelatinisation temperatures by 2.2–4.7 °C for barley and 3.6–5.3 °C for malt. The small starch granule fractions from barley had a 3.1 °C higher peak gelatinisation temperature than large granule fractions. No effect of malting was observed here. These findings indicate that matrix effects and starch granule size must be considered when addressing starch conversion during brewing.

Multi-scale structure and digestive property of bran starch in different particle size wheat bran

In this study, the multi-scale (granular, molecular, crystalline, lamellar and helical) structure and digestive property of starch isolated from wheat bran of different particle size, including plant scale (1110 μm), tissue scale (235 μm, 83 μm) and cell scale (19 μm), were investigated and compared with wheat flour starch. Bran milling modified bran starch to varying degrees. Tissue-scale milling of bran reduced the granule size of bran starch, but did not significantly modify its molecular, lamellar, crystalline and helical structure. However, cell-scale milling caused significant destruction of crystalline regions and double helix, and increase in starch digestibility. In addition, compared to wheat flour starch, wheat bran starch had more resistant starch and lower digestibility, which were highly correlated with its thinner lamellas, more double helix proportion and compact fractal. This study highlights the effect of supramolecular structure on bran starch digestibility and contributes to the application of bran starch.

Characterization of Oil Body and Starch Granule Dynamics in Developing Seeds of Brassica napus.

Brassica napus is the most important oilseed crop in the world, and the lipid was stored in the oil body (OB) in the form of triacylglycerol. At present, most of studies on the relationship between oil body morphology and seed oil content in B. napus was focused on mature seeds. In the present study, the OBs in different developing seeds of B. napus with relatively high oil content (HOC) of about 50% and low oil content (LOC) of about 39% were analyzed. It was revealed that the size of OBs was first increased and then decreased in both materials. And in late seed developmental stages, the average OB size of rapeseed with HOC was higher than that of LOC, while it was reversed in the early seed developmental stages. No significant difference was observed on starch granule (SG) size in HOC and LOC rapeseed. Further results indicated that the expression of genes that involved in malonyl-CoA metabolism, fatty acid carbon chain extension, lipid metabolism, and starch synthesis in the rapeseed with HOC was higher than that of rapeseed with LOC. These results give some new insight for understanding the dynamics of OBs and SGs in embryos of B. napus.

Characterization of isolated starch from Isatis indigotica Fort. root and anhydro-sugars preparation using its decoction residues.

Isatis indigotica Fort. root (Ban-lan-gen, IIR), a traditional Chinese medicine (TCM), has an ancient and well-documented history for its medicinal properties. Aside from epigoitrin, indole alkaloids, and their corresponding derivatives as medicinal ingredients, it also contains lots of biomass such as starch. Herein, a new starch was isolated from IIR and the physicochemical properties such as amylose content, moisture content, ash content, morphology, thermal properties, and crystallography were characterized systematically. The amylose content of IIR starch was 19.84 ± 0.85%, and the size and shape of starch granules is ellipsoidal shape with sizes from 2 to 10μm. IIR starch exhibited a C-type pattern and had 25.92% crystallinity (higher than that of corn starch). The gelatinization temperature of IIR starch was 58.68-75.41°C, and its gelatinization enthalpy was ΔH gel = 4.33J/g. After decocting, the IIR's residues can be used to prepare anhydro-sugars in a polar aprotic solvent. The total carbon yield of levoglucosan (LG), levoglucosenone (LGO), 5-hydroxymethylfurfural (HMF), and furfural (FF) could reach 69.81% from IIR's decoction residues in 1,4-dioxane with 15mM H2SO4 as the catalyst. Further, the residues after dehydration were prepared into biochar by thermochemical conversion and the BET surface area of biochar was 1749.46 m2/g which has good application prospect in soil improvement and alleviates obstacles of IIR continuous cropping.

Comparison of the physicochemical properties of starches from maize reciprocal F1 hybrids and their parental lines

Heterosis on maize yield and quality is highly variable and depends on parental selection. This study investigated and compared the starch structure and physicochemical properties among four sweet-waxy maize lines, four waxy maize lines, and their eight reciprocal F1 hybrids. Compared with the sweet-waxy maize, waxy maize and F1 hybrids had lower extent of branching of amylopectin and relative crystallinity, and larger starch granule size. Waxy maize starch had higher breakdown viscosity and retrogradation percentage, and lower setback viscosity and gelatinization enthalpy than the sweet-waxy maize starch. Meanwhile, the peak and setback viscosities, and retrogradation enthalpy of most F1 hybrid starches were higher than those of their female parent, while gelatinization enthalpy was the opposite. The F1 hybrid starches had higher onset temperature and retrogradation percentage and lower gelatinization enthalpy than their male parent in general. In conclusion, this study provides a framework for the production of new hybrids.

Impact of wheat starch granule size on viscoelastic behaviors of noodle dough sheet and the underlying mechanism

The contribution of starch to dough behaviors has been largely overshadowed by the role of gluten, receiving much less attention in comparison. The impact of wheat starch granule size on the viscoelastic behaviors of low-moisture noodle dough and its underlying mechanism were investigated. Dough with a high ratio of B-type starch granules (BS) had higher viscoelastic moduli (G″ and G′), percent stress relaxation (SR%), and smaller creep compliance (J max ), indicating higher viscoelasticity and strength. This might be related to the higher filling ability and water-binding capacity of B-type starch. Compared to large A-type starch granules (AS), small B-type granules would easily embed to form a more closely packed and uniform network structure. In addition, the differences in water distribution and hydration properties could affect the hydrophobicity of starch and the surface environments of the protein, thus influencing the polymer interactions in the doughs. The hydrogen bonds were the main con-covalent bonds in the low-moisture noodle dough. With increasing B-/A-type starch ratios, β-sheet and hydrogen bond contents significantly increased, while the GMP content showed a decrease, suggesting the enhanced hydrogen bond interaction in a high ratio of B-type starch dough could cooperate with intermolecular disulfide bonds to stabilize the network structure of gluten, improving the dough strength. These results demonstrated that the viscoelastic behaviors of dough sheets were related to the granule size distribution of wheat starch. Finally, a schematic model describing the mechanism of the influence of starch granule size on dough behaviors was built. • B-type wheat starch granules promoted uniform and compact gluten network formation. • Small B-type granules led to stronger hydrogen bond interaction in the noodle dough. • The enhanced interaction by hydrogen bonding could improve the dough strength. • Viscoelasticity of dough sheet increased with increasing B- to A-type starch ratios.

Starch Physicochemical Properties of Normal Maize under Different Fertilization Modes

Improving the quality with desired functions of natural starch through agronomic practice will meet the increasing need of people for natural, functional foods. A one-off application of slow-release fertilizer is a simple and efficient practice in maize production, though its influence on the starch quality is scarce. In the present study, the structural and functional properties of the starch of normal maize under two fertilization modes (one-off application of slow-release fertilizer at the sowing time (SF), and three applications of conventional fertilizer at the sowing time, and topdressing at the jointing and flowering stages (CF)) under the same fertilization level (N/P2O5/K2O = 405/135/135 kg/ha) were studied using Jiangyu877 (JY877) and Suyu30 (SY30) as materials. The observed results indicate that the size of starch granules was enlarged by fertilization and the size was the largest under CF in both hybrids. The amylose content was unaffected by CF and reduced by SF in both hybrids. In comparison to no fertilizer (0F), the peak 1/peak 2 ratio was decreased by CF in both hybrids, whereas the ratio under SF was unaffected in JY877 and decreased in SY30. The amylopectin average chain-length was reduced by fertilization and the reduction was higher under CF in JY877. The relative crystallinity was increased by CF in both hybrids and the value under SF was unaffected in SY30 and increased in JY877. The peak, trough, and final viscosities of starch were increased by fertilization in both hybrids. The starch thermal characteristics in response to fertilization modes were dependent on hybrids. The retrogradation enthalpy and percentage were increased by CF in both hybrids, whereas those two parameters under SF were increased in SY30 and decreased in JY877. In conclusion, starch with similar granule size, higher peak 1/peak 2 ratio, and lower relative crystallinity was obtained under SF than under CF for both hybrids. Longer amylopectin chain-length was observed in JY877, which induced lower pasting viscosities in SY30 and lower retrogradation characteristics in JY877.

Foliar Application of dsRNA Targeting Endogenous Potato (Solanum tuberosum) Isoamylase Genes ISA1, ISA2, and ISA3 Confers Transgenic Phenotype

Isoamylase (ISA) is a debranching enzyme found in many plants, which hydrolyzes (1-6)-α-D glucosidic linkages in starch, amylopectin, and β-dextrins, and is thought to be responsible for starch granule formation (ISA1 and ISA2) and degradation (ISA3). Lipid-modified PEI (lmPEI) was synthesized as a carrier for long double-stranded RNA (dsRNA, 250-bp), which targets the three isoamylase isoforms. The particles were applied to the plant via the foliar spray and were differentially effective in suppressing the expressions of ISA1 and ISA2 in the potato leaves, and ISA3 in the tubers. Plant growth was not significantly impaired, and starch levels in the tubers were not affected as well. Interestingly, the treated plants had significantly smaller starch granule sizes as well as increased sucrose content, which led to an early sprouting phenotype. We confirm the proposal of previous research that an increased number of small starch granules could be responsible for an accelerated turnover of glucan chains and, thus, the rapid synthesis of sucrose, and we propose a new relationship between ISA3 and the starch granule size. The implications of this study are in achieving a transgenic phenotype for endogenous plant genes using a systemic, novel delivery system, and foliar applications of dsRNA for agriculture.

Effects of Endogenous Cytokinin on Physicochemical Properties of Superior and Inferior Grain Starch in Rice

AbstractDifferent grain positions on the rice panicle have asynchronous flowering phenomenon. The difference between superior and inferior grains not only affects the yield, but also restricts the quality of rice. In this study, the cytokinin‐related transgenic lines VIN3‐LIKE 2 (OsVIL2)‐OX (increased endogenous cytokinin content), Oryza sativa A‐type response regulator (OsRR1)‐OX, and Early heading date 1 (Ehd1)‐OX (B‐type response regulator) are used to analyze nutrient accumulation and starch physicochemical properties of superior and inferior grains from the physiological level. The research conclusions are as follows: The overexpression transgenic plants of OsVIL2, OsRR1, and Ehd1 result in an increase of average starch granule size and solubility, but decrease in apparent amylose content of superior and inferior grains, which further reduce the surface order of superior and inferior grains, and increase the relative crystallinity of superior grains. Increased cytokinin content possibly accelerates the accumulation of carbohydrates in superior and inferior grains by promoting the expression of OsRR1. In addition, Ehd1 might be the main gene that affects the production of inferior grains, and Ehd1 is also involved in the regulation of the surface order structure and crystallinity of starch from superior and inferior grains by cytokinin.

Effects of the duration of post-silking drought on the starch physicochemical properties of waxy maize.

Drought is a major abiotic stress that affects the physicochemical properties of cereal starch. However, quantitative information on the effects of drought duration on the starch quality of waxy maize, a special maize-type starch composed of nearly pure amylopectin, has been lacking. The effects of post-silking drought duration 1-10 (DS10), 1-20 (DS20), and 1-30 (DS30) days after pollination on the physicochemical properties of starch were assessed from 2019 to 2020 using two waxy maize hybrids as materials. With extending drought duration, the starch granule size and average amylopectin chain length of Jingkenuo2000 (JKN2000) gradually increased, with those of Suyunuo5 (SYN5) being the highest for DS20, followed by DS30. All drought durations decreased the degree of branching of both hybrids, with the lowest value obtained for DS30 and DS20 in JKN2000 and SYN5, respectively. Relative crystallinity increased for DS30 in both hybrids but its responses for DS10 and DS20 differed. Pasting viscosities and gelatinization enthalpy were decreased and retrogradation percentage was increased by drought stress. The lowest pasting viscosities were observed for DS30, and the highest retrogradation percentage was found for DS10 in general. Post-silking drought led to the pasting and retrogradation properties deteriorating, with decreased pasting viscosities and increased retrogradation percentage. The decrease in viscosity was caused by enlarged granules. Meanwhile, the increased proportion of amylopectin chains with a degree of polymerization of 25-36 resulted in lower viscosity and higher retrogradation. © 2022 Society of Chemical Industry.