Endosperm Structure Research Articles

Water stress resilience in Mauritia flexuosa (Arecaceae) embryos: New insights into the persistence of recalcitrant seed banks

The neotropical palm Mauritia flexuosa produces seeds that show the association between recalcitrance and dormancy. Despite the intolerance to desiccation, the seeds can maintain persistent banks in flooded environment soils (veredas) in the Cerrado biome. As the mechanisms involved in the persistence of recalcitrant seed banks are still poorly understood, the objective of this work was to evaluate the response of M. flexuosa embryos to water deficit and saturation stresses. Embryos of M. flexuosa with water content typical of dispersion or subjected to hydration were exposed to moderate and severe water potentials (Ψw= −1.5 MPa and Ψw= −2.1 MPa), in addition to water saturation (Ψw= 0 MPa). Anatomical, histochemical and ultrastructural evaluations were performed on the embryos after 24 h. Membrane integrity estimation, endo-β-mannanase activity and oxidative stress indicators (H2O2 and MDA contents, CAT, SOD and APX activity) were also evaluated. The endosperm structure contributes to the maintenance of embryo hydration, while abundant mucilage reserves favor resilience to desiccation. Post-dispersal hydration makes embryos less vulnerable to oxidative stress, which is due to the non-enzymatic antioxidant system. Both moderate water stress and post-dispersal water absorption induce an increase in metabolism and the mobilization of reserves, which indicate that hydration/dehydration cycles can favor overcoming dormancy. M. flexuosa embryos show resilience to water deficit, and that is crucial for the persistence of seeds in the soil in seasonal environments, however, successful germination is dependent on high hydration, which prevents structural and physiological damage.

Seed development-related genes contribute to high yield heterosis in integrated utilization of elite autotetraploid and neo-tetraploid rice.

Autotetraploid rice holds high resistance to abiotic stress and substantial promise for yield increase, but it could not be commercially used because of low fertility. Thus, our team developed neo-tetraploid rice with high fertility and hybrid vigor when crossed with indica autotetraploid rice. Despite these advances, the molecular mechanisms underlying this heterosis remain poorly understood. An elite indica autotetraploid rice line (HD11) was used to cross with neo-tetraploid rice, and 34 hybrids were obtained to evaluate agronomic traits related to yield. WE-CLSM, RNA-seq, and CRISPR/Cas9 were employed to observe endosperm structure and identify candidate genes from two represent hybrids. These hybrids showed high seed setting and an approximately 55% increase in 1000-grain weight, some of which achieved grain yields comparable to those of the diploid rice variety. The endosperm observations indicated that the starch grains in the hybrids were more compact than those in paternal lines. A total of 119 seed heterosis related genes (SHRGs) with different expressions were identified, which might contribute to high 1000-grain weight heterosis in neo-tetraploid hybrids. Among them, 12 genes had been found to regulate grain weight formation, including OsFl3, ONAC023, OsNAC024, ONAC025, ONAC026, RAG2, FLO4, FLO11, OsISA1, OsNF-YB1, NF-YC12, and OsYUC9. Haplotype analyses of these 12 genes revealed the various effects on grain weight among different haplotypes. The hybrids could polymerize more dominant haplotypes of above grain weight regulators than any homozygous cultivar. Moreover, two SHRGs (OsFl3 and SHRG2) mutants displayed a significant reduction in 1000-grain weight and an increase in grain chalkiness, indicating that OsFl3 and SHRG2 positively regulate grain weight. Our research has identified a valuable indica autotetraploid germplasm for generating strong yield heterosis in combination with neo-tetraploid lines and gaining molecular insights into the regulatory processes of heterosis in tetraploid rice.

Enzymatic loosening mechanism of endosperm weakening plays a key role in promoting carrot (Daucus carota L.) seed germination by hydro-electro hybrid priming

As an innovative physical priming technique, hydro-electro hybrid priming (HEHP) tends to significantly promote the seed germination of carrot. Endosperm weakening at micropylar endosperm is a critical regulatory mechanism for seed germination, but it is unclear whether it plays a role in promoting seed germination through HEHP treatment. In the present work, we conducted association analysis between transcriptome and proteome data of the previous studies and found that HEHP promoted the mannose metabolism in carrot seeds, with key enzymes involved in mannan degradation called β-mannanase (MAN) and the coding genes were both significantly upregulated in HEHP treatment. Based on this, the subcellular structure of micropylar endosperm, the activity of key enzymes in mannan degradation and the expression pattern of MAN coding genes during the germination process were further studied. The results showed that carrot seeds subjected to the priming treatments exhibited more significant endosperm weakening during germination, with significant degradation of the cell wall of micropylar endosperm, and among the three key enzymes involved in mannan degradation, only MAN activity showed significant differences at micropylar endosperm and non-micropylar endosperm. In addition, the priming treatments, especially the HEHP treatment, significantly upregulated the expression of MANs before sowing, and the expression levels of MANs at micropylar endosperm were significantly higher than those at non-micropylar endosperm. Ultimately, it is confirmed that the rapid germination of carrot seeds is closely related to the enzymatic loosening mechanism of endosperm weakening, and that MAN plays a key role in this process. The results ulteriorly deepen the understanding of the rapid germination mechanism of carrot seeds treated with HEHP.

Endosperm structure and Glycemic Index of Japonica Italian rice varieties.

Given that rice serves as a crucial staple food for a significant portion of the global population and with the increasing number of individuals being diagnosed with diabetes, a primary objective in genetic improvement is to identify and cultivate low Glycemic Index (GI) varieties. This must be done while ensuring the preservation of grain quality. 25 Italian rice genotypes were characterized calculating their GI "in vivo" and, together with other 29 Italian and non-Italian genotypes they were studied to evaluate the grain inner structure through Field Emission Scanning Electron Microscopy (FESEM) technique. Using an ad-hoc developed algorithm, morphological features were extracted from the FESEM images, to be then inspected by means of multivariate data analysis methods. Large variability was observed in GI values (49 to 92 with respect to glucose), as well as in endosperm morphological features. According to the percentage of porosity is possible to distinguish approximately among rice varieties having a crystalline grain (< 1.7%), those intended for the preparation of risotto (> 5%), and a third group having intermediate characteristics. Waxy rice varieties were not united by a certain porosity level, but they shared a low starch granules eccentricity. With reference to morphological features, rice varieties with low GI (<55) seem to be characterized by large starch granules and low porosity values. Our data testify the wide variability of Italian rice cultivation giving interesting information for future breeding programs, finding that the structure of the endosperm can be regarded as a specific characteristic of each variety.

Mechanical properties of corn: Correlation with endosperm hardness

AbstractThe purpose of this study was to explore the effects of different factors on the compressive mechanical properties of corn kernels. Explore the relationship between endosperm hardness and compressive mechanical properties of corn kernels by polynomial regression analysis. The results showed that the variety and kernel orientation had a significant effect on the compressive mechanical properties of corn kernels. Flint corn had a stronger ability to resist damage than floury corn. As the loading rate increased from 5 to 25 mm/min, the rupture force and rupture energy of corn kernels changed accordingly. The hardness of horny endosperm was significantly higher than that of floury endosperm. The dense starch‐protein network structure of horny endosperm leads to higher hardness. According to the fitting results, the compressive mechanical properties of corn kernels could be predicted using the hardness of the horny endosperm within a certain range.Practical applicationsAs a widely planted food crop in the world, corn is not only an important food crop, but also a high‐quality feed for livestock and poultry. The compressive mechanical properties (elastic modulus, compressive failure force, failure energy, etc.) of corn kernels were explored, and the relationship between endosperm hardness and its mechanical properties was analyzed. It can provide technical parameters for mechanical processing equipment, reduce the loss of corn grain in the processing process, and improve its economic value.

Effects of Non-Allelic Interactions of O2 and SU2 Mutant Genes on Grain Biochemical Composition in Various Corn Inbreds

The use of combinations of non-allelic mutant genes of the maize endosperm structure creates opportunities for improving the quality of corn grain in comparison not only with forms of the common type but also with monogenic endospermic mutants. In this study, the effect of a combination of mutant genes O2 (Opaque-2) and SU2 (Sugary-2) according to the biochemical composition of the grain was studied. For the research, a series of inbreds - carriers of a combination of mutant genes O2SU2, inbreds - carriers of monogenic mutations O2 and SU2, as well as maize inbreds of the common type of two-year reproduction were used. In the experiments, the content of protein, starch, and oil and the main characteristics of their quality were studied. It was found that the inbred carriers of the O2SU2 combination are superior to the inbred carriers of monogenic mutations O2 and SU2 in terms of complex biochemical characteristics. In comparison with mutants O2 they were distinguished by an increased content of protein (by 12.3% on average), amylose in starch (by 38.9% on average), starch digestibility (by 24.4% on average), oil content (by 18.4% on average) and oleate content in oil (by 29.9% on average). In comparison with the carriers of SU2 mutation, they had a higher content of lysine and tryptophan in the total grain protein (on average, by 19.4% &amp; 14.3%, respectively). The main characteristics of grain quality in carriers of a combination of mutant genes O2SU2 were characterized by quantitative variability, which can modify the effect of non–allelic interaction of mutant genes O2 and SU2. The obtained results indicate the effectiveness of using non-allelic interactions between the O2 and SU2 mutant genes to improve the quality of corn grain.

Identification of wheat seed endosperm texture using hyperspectral imaging combined with an ensemble learning model

Differences in wheat endosperm structure contribute to differences in wheat flour texture and directly affect aspects such as flour quality, processing, and use. Therefore, the accurate classification of wheat based on endosperm texture is of immense practical interest. In this study, hyperspectral imaging technology (400–1000 nm) was combined with ensemble learning to classify wheat with different endosperm textures using spectral and shape features. Two feature extraction algorithms, competitive adaptive reweighted sampling and successive projection algorithm, were used to extract feature wavelengths. Furthermore, unknown characteristic data (new varieties of wheat) were fed into the model for classification. The results showed that feature fusion can markedly improve classification accuracy. The full-wavelength, subspace-based ensemble learning model based on the fusion of spectral and shape features had the best performance, and its classification accuracy reached 92.10%. In addition, the accuracy of all models for predicting new varieties decreased. However, the subspace-based ensemble learning model showed the best performance for identifying new wheat varieties with 88.03% accuracy. Thus, ensemble learning effectively classified both multiple known and new varieties of wheat with different endosperm textures. These results and this technology can help farmers and food manufacturers optimize their crop selection and processing strategies.

CT-Based Phenotyping and Genome-Wide Association Analysis of the Internal Structure and Components of Maize Kernels

The structure of the maize kernels plays a critical role in determining maize yield and quality, and high-throughput, non-destructive microscope phenotypic characteristics acquisition and analysis are of great importance. In this study, Micro-CT technology was used to obtain images of maize kernels. An automatic CT image analysis pipeline was then developed to extract 20 traits related to the three-dimensional structure of kernel, embryo, endosperm, and cavity. The determination coefficients for five volume-related traits (embryo, endosperm, silty endosperm, embryo cavity, and endosperm cavity) were 0.95, 0.95, 0.77, 0.73, and 0.94, respectively. Further, we analyzed the phenotypic variations among a group of 303 inbred lines and conducted genome-wide association studies (GWAS). A total of 26 significant SNP loci were associated with these traits that are closely related to kernel volume, and 62 candidate genes were identified. Functional analysis revealed that most candidate genes corresponding to cavity traits encoded stress resistance proteins, while those corresponding to embryo and endosperm traits encoded proteins involved in regulating plant growth and development. These results will improve the understanding of the phenotypic traits of maize kernels and will provide new theoretical support for in-depth analysis of the genetic mechanism of kernel structure traits.

Phenotypic differences in the appearance of soft rice and its endosperm structural basis.

In view of the significant differences among genotypes in the appearance of soft rice, it is necessary to conduct research on the differences in the appearance quality of soft rice and their mechanisms. It can provide a theoretical basis for the selection and breeding of superior appearance varieties at a later stage. In order to clarify the differences in appearance phenotypes between different soft rice genotypes and structural basis of endosperm structures behind the differences, four soft rice varieties were selected in this study, including two varieties with good-appearance and two varieties with cloudy appearance. The differences in appearance phenotypes and endosperm structure in mature grains of soft rice with different appearance phenotypes were scientifically analyzed. The development process of their endosperm differences at the filling stage was investigated. The results show that the difference in the rice appearance of soft rice varieties mainly lay in the chalk-free seed transparency and chalkiness. These differences were caused by two completely different types of endosperm structure. Fewer and smaller starch grain cavities were responsible for higher chalk-free transparency of soft rice grains, denser starch granules arrangement caused lower chalkiness of soft rice grains. Ten days after flowering, the starch granules in the back and heart of good-appearance soft rice were already significantly fuller and more closely packed than those of cloudy soft rice. At the same time, the number and area of starch granule holes were significantly smaller than those of cloudy soft rice. This difference gradually increased until maturity. Therefore, based on appearance evaluation, soft rice with good-appearance should have higher transparency and lower chalkiness. The endosperm starch granules should be full and tightly arranged. The number of starch grain cavities and the area should be smaller. These differences develop in the early stages of grouting and gradually increase.

Characteristics of the composite film of arabinoxylan and starch granules in simulated wheat endosperm

We found that cell wall components of wheat grains differed significantly across different grain-filling stages; specifically, we observed significant differences in water content and water migration rate (p < 0.05). A composite film of arabinoxylan and starch granules was prepared to simulate wheat endosperm structure. Scanning electron microscopy (SEM), X-ray diffractometer (XRD), and thermogravimetric analysis (TGA) showed that the crystallinity and structural stability of the film increased with increasing starch content. Water diffusion experiments of the films revealed that the water diffusion rate gradually decreased with increasing starch content. Therefore, the water mobility of the starch endosperm was lower than that of the aleurone layer. These findings provide a basis for further studies in the context of wheat grain water regulation.

Formation characteristics of endosperm structures in different rice genotypes

Formation characteristics of endosperm structures in different rice genotypes

Recent Research Advances in the Development of Chalkiness and Transparency in Rice

The appearance quality of rice represent the primary concern of consumers when choosing rice, as well as a necessary condition for high-quality rice. In the past, the focus of attention on rice appearance quality was mainly on chalkiness, and most previous reviews on rice appearance quality focused on the chalky phenotype of rice, while some more generalized chalkiness as the only indicator of rice appearance quality. This paper objectively analyses the definitions and interrelationships of rice appearance quality indicators at the present stage. Then, the formation mechanism and research status of rice appearance quality were analyzed from three aspects: endosperm structure, genetic background, and endosperm material basis. The two indicators (chalkiness and transparency) were selected, having the greatest influence on appearance, as the starting point. On this basis, the problems in the current research on rice appearance quality were analyzed and relevant suggestions are put forward, aiming to provide a theoretical basis for the overall improvement of rice appearance quality under large-scale production conditions.

Dynamic Transcriptome-Based Weighted Gene Co-expression Network Analysis Reveals Key Modules and Hub Genes Associated With the Structure and Nutrient Formation of Endosperm for Wax Corn.

The endosperm of corn kernel consists of two components, a horny endosperm, and a floury endosperm. In the experiment, a kind of floury endosperm corn was identified. The result of phenotypic trait analysis and determination of amino acid content showed that the floury endosperm filled with the small, loose, and scattered irregular spherical shape starch granules and contained higher content of amino acid. The starch biochemical properties are similar between floury corns and regular flint corn. By using dynamically comparative transcriptome analysis of endosperm at 20, 25, and 30 DAP, a total of 113.42 million raw reads and 50.508 thousand genes were obtained. By using the weighted gene co-expression network analysis, 806 genes and six modules were identified. And the turquoise module with 459 genes was proved to be the key module closely related to the floury endosperm formation. Nine zein genes in turquoise module, including two zein-alpha A20 (Zm00001d019155 and Zm00001d019156), two zein-alpha A30 (Zm00001d048849 and Zm00001d048850), one 50 kDa gamma-zein (Zm00001d020591), one 22 kDa alpha-zein 14 (Zm00001d048817), one zein-alpha 19D1 (Zm00001d030855), one zein-alpha 19B1 (Zm00001d048848), and one FLOURY 2 (Zm00001d048808) were identified closely related the floury endosperm formation. Both zein-alpha 19B1 (Zm00001d048848) and zein-alpha A30 (Zm00001d048850) function as source genes with the highest expression level in floury endosperm. These results may provide the supplementary molecular mechanism of structure and nutrient formation for the floury endosperm of maize.

Resistant‐Type Starch in Sorghum Foods—Factors Involved and Health Implications

AbstractSorghum grain has a higher content of resistant starch (RS) than other cereals and seems to be more slowly digestible. However, people consume foods where the grain has been processed by thermal and other treatments. This review addresses whether sorghum foods generally have unusually high levels of RS and slowly digestible starch (SDS), what intrinsic factors are responsible and how processing conditions affect RS and SDS, and the health‐related implications of sorghum food consumption. With non‐tannin type sorghums, if the endosperm structure is little disrupted during food processing, as with conventional wet cooking, then the food can exert positive health effects on glycemic response related to its high RS content. Thermally induced cross‐linking of the kafirin matrix proteins appears to be responsible for the low starch digestibility. However, when non‐tannin sorghum is processed using high‐shear technologies like extrusion cooking, the endosperm, and starch granule structure are disrupted, rendering the starch fully digestible. Regarding tannin‐type sorghums, the tannins have a strong inhibitory effect on starch digestibility, notably by binding with the starch, which can improve glycemic response and other health related parameters. Future research on RS in sorghum foods must focus on the mechanisms responsible and interactions between intrinsic‐ and processing‐related factors.

Maize STARCH SYNTHESIS REGULATING PROTEIN1 positively regulates starch biosynthesis in rice endosperm.

Starch is a major component of the endosperm, directly determining grain yield and quality. Although the key enzymes of starch synthesis have been identified and characterised, the regulatory mechanisms remain unclear. In this study, we identified the novel maize STARCH SYNTHESIS REGULATING PROTEIN1 (ZmSSRP1 ), which encodes a typical carbohydrate-binding module 48 (CBM48) protein. Expression analysis revealed that ZmSSRP1 was highly expressed in the maize endosperm, while transient expression in maize leaf protoplasts showed localisation in the plastids, dependent on the N-terminal transit peptide. In addition, overexpression of ZmSSRP1 in rice resulted in a decrease in grain thickness and the 1000-grain weight, as well as affecting the starch content and structure of the rice endosperm. The physicochemical properties of starch in the rice endosperm were also altered compared with the wild-type seeds. Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) was subsequently performed to determine the expression of starch synthesis-related genes, revealing upregulation of mRNA expression of most genes in the transgenic compared with wild-type lines. Collectively, these findings suggest that ZmSSRP1 acts as a potential regulator of starch synthesis, providing new insight for molecular breeding of high-yielding high-quality maize.

Degree and nature of heterosis effects in corn lines by grain quality parameters

Aim. Widespread use of corn hybrids, which are of key importance for the food security in Ukraine, is one of the most successful examples of the heterosis phenomenon use. In order to recommend new and high-quality corn hybrids for production, it is necessary to assess the inheritance degree and heterosis effects for protein, starch and oil contents as well as for yield. Results and Discussion. To achieve the goal, we used the classic field techniques and methods of qualification examination of plant varieties for suitability for distribution in Ukraine. The protein, starch and oil contents in grain were determined on a InfratecTM 1241 Grain Analyzer (FOSS); the heterosis effects were calculated by D. S. Omarov’s methods. As a result of tester crosses, 65 experimental corn hybrids were obtained. Inbred lines VK13, VK69, AE801 and AE392 (carriers of the wx and ae mutations of endosperm structure, respectively) were the female forms. Inbred lines СО255, АК159, АК157, G255, FV243 and KhLG1203 were used as male components for the first time to obtain hybrids with high grain quality parameters. From the 2020−2021 studies, we found that, in terms of grain quality, the grain starch content-driven selection of parental pairs was the most rational approach, as the influence of parental forms on this trait consistently exceeded 50% across the study years. Conclusion. Hybrids VK13×UKhK678 and VK13×UKhK686 were noticeable for consistently high manifestation the heterosis effects for several parameters. As to the starch content in grain, superdominance of a parental form with stronger expression of the trait was recorded in hybrids VK13×UKhK678, VK13×UKhK686, VK19×FV243, and AE801×VK32; as to the oil content in grain, VК13×UKhК678, VК13×UKhК686, VК13×VК37, АЕ392×СО255, АЕ392×KhLG1203, and АЕ392×АК157 were distinguished. Inbred corn lines that should be used as parents of heterotic corn hybrids (KhLG1203, CO255, AK159 and AK157) were singled out.

Unique Glutelin Expression Patterns and Seed Endosperm Structure Facilitate Glutelin Accumulation in Polyploid Rice Seed

BackgroundRice is not only an essential food but also a source of high quality protein. Polyploidy is an evolutionary trajectory in plants, and enhancing glutelin by polyploidization is an attractive strategy for improving the nutritional value of rice seeds and presents a great potential for enhancing the commercial value of rice. Elucidating the mechanisms underlying glutelin synthesis and accumulation in tetraploid rice is of great significance.ResultsTo enhance the nutritional value of rice, we developed tetraploid rice and evaluated the contents of various nutrient elements in mature seeds. The results revealed a significant increase in protein contents, including the total seed storage proteins, glutelins, and amino acids in tetraploid rice when compared with those in diploid rice. Tandem mass tag-based quantitative proteomic analyses of seeds revealed that glutelins regulated by several glutelin genes in 9311-4x were significantly up-regulated (≥1.5-fold), which was further verified by immunoblot analyses. In addition, temporal expression patterns of various glutelin subunits in different rice lines were investigated. The results revealed significant differences in the expression patterns between diploid and tetraploid rice seeds. Cytohistological analyses results revealed that the thickness of aleurone cell layers increased significantly by 32% in tetraploid rice, the structures of protein storage vacuoles (PSVs) in sub-aleurone cells were more diverse and abundant than those of diploid rice. Temporal expression and proteomic analyses results revealed that protein disulfide isomerase-like 1–1 expression levels were higher in tetraploid rice than in diploid rice, and that the gene responded to oxidative folding with increased levels of proglutelin and appropriate distribution of seed glutelins in tetraploid rice.ConclusionThe results of the present study revealed that polyploidization increased glutelin content by influencing glutelin biosynthesis, transport, and deposition, while variations in glutelin accumulation between tetraploid and diploid rice were largely manifested in the initial time, duration, and relative levels of various glutelin gene expressions during seed filling stages. These findings provide novel insights into improving the protein quality and nutritional value of rice seeds by polyploid breeding.

Technological properties of grain and flour in bread wheat (Triticum aestivum L.) genotypes carrying two loci that determine the endosperm structure

Background.The end-use of the bread wheat grain depends on the endosperm properties determined by the alleles of the Pinaand Pinbgenes at the Halocus on chromosome 5D. The mealy (soft) endosperm is generated by the biosynthesis of puroindolines – complete proteins encoded by these genes. When milled, such grain breaks down into small starch granules covered with proteins. Mutations that disrupt the synthesis or structure of puroindolines determine the hardness and vitreousness of the grain. Earlier, we discovered a new locus for grain softness, Ha-Sp, introgressed from the diploid species Aegilops speltoidesTausch, which also determines the formation of the soft endosperm structure. By combining two active loci in one genotype, we produced a supersoft grain line (SSL). The aim of the present work was to verify the interaction of the two loci Haand HaSpin other wheat genotypes and evaluate the technological properties of grain and flour in comparison with the existing SSL line.Materials and methods.The F3–F8 hybrids from crosses of the soft-grain spring cultivars ‘Golubka’ and ‘Lutescens 62’, carriers of the Halocus, with the introgressive line 84/98w, carrier of the Ha-Splocus, were used in the work. Grain from three field seasons was studied according to milling parameters and physical properties of flour and dough.Results.At the early stages of selection (F3:4), the families with milling parameters typical of bread wheat were identified, as well as supersoft-grain families with a small flour particle size (9–10 μm) and low endosperm vitreousness (29–49%). Targeted selection made it possible to obtain lines similar to the SSL line in terms of milling performance and flour strength.Conclusion.For the first time, a set of supersoft-grain lines with special properties of grain and flour was obtained on the genetic basis of three spring cultivars. They may be in demand for a wide range of end-uses, including both food and nonfood production purposes.

Dependence of germination of wheat grains after the treatment by impulse pressure and long-term storage on the vitreousness of endosperm

The aim was identification of patterns of changes in the physical and chemical state of biopolymers in durum and soft wheat seeds after the treatment of impulse pressure (IP) and during the storage of seeds. It was found that durum wheat seeds accumulated microcracks over the structure of the glassy endosperm after the IP treatment, while soft wheat seeds reacted to IP treatment by “collapsing” air gaps in the loose endosperm, as well as by vitrification of amorphous areas that were in a highly elastic state and the transition of crystalline areas to vitreous ones. The vitreous content of durum seeds decreased, while that of soft seeds increased linearly after the treatment by IP and storage. Treatment of soft wheat seeds with IP and storage increased their germination, growth and quality of seedlings due to vitrification of the seed endosperm. The decrease in the vitreousness of durum wheat grain after the treatment with IP and storage led to deterioration in the quality of grain and sprouts during storage. So the glassy state in seeds is suggested to serve as a stabilizer. The rapid progress of deterioration may represent a weakening of the glassy state.

Kernel characterization and starch morphology in five varieties of Peruvian Andean maize

Peruvian Andean maize (PAM) has been commonly used as an ingredient that confers color, flavor, and texture in culinary. Nevertheless, no studies are focusing on agro-industrial interest characteristics to develop new products. This study aimed to evaluate the physicochemical, nutritional, and technological characteristics of kernels and the starch granule morphology of the five main PAM varieties: Chullpi, Piscorunto, Giant Cuzco, Sacsa, and Purple. PAM's characterization was performed according to the official methods, and its morphology was observed by scanning electron microscopy (SEM). Physically, the varieties of larger kernels (Giant Cuzco and Sacsa) presented a higher 1000-kernel weight and a lower hectoliter weight than those of smaller size (Piscorunto, Purple, and Chullpi). Nutritionally, PAM had higher ether extract (5%) and ash (2%) contents than other pigmented maizes. Likewise, they presented more significant amounts of essential amino acids, as leucine (10 mg/g protein) and tryptophan (up to 2 mg/g protein); unsaturated fatty acids, oleic (30%) and linoleic (53%); and minerals, as magnesium (104 mg/100 g). SEM showed that endosperm structure and starch morphology vary according to maize types and their grain location. Starch granules of floury PAM varieties were small and polyhedral in the sub-aleurone endosperm, whereas those of the central area were bigger and spherical. In Chullpi, it was observed a portion of vitreous endosperm with a compact structure. The low protein content (8.3%) and the endosperm structure of floury varieties of PAM influenced their pasting properties. Their pasting temperature was <69 to 71 °C>, peak viscosity < 3200 to 4400 cP>, and seatback <1250 to 1706 cP>; therefore, they do not retrograde easily. The results suggest that PAM has characteristics that would help elaborate regional products with added value, such as soups, willows, beverages, and porridges.