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BACKGROUND: Kernel dehydration is an important factor for the mechanized harvest in maize. Kernel moisture content (KMC) and kernel dehydration rate (KDR) are important indicators for kernel dehydration. Although quantitative trait loci and genes related to KMC have been identified, where most of them only focus on the KMC at harvest, these are still far from sufficient to explain all genetic variations, and the relevant regulatory mechanisms are still unclear. In this study, we tried to reveal the key proteins and metabolites related to kernel dehydration in proteome and metabolome levels. Moreover, we preliminarily explored the relevant metabolic pathways that affect kernel dehydration combined proteome and metabolome. These results could accelerate the development of further mechanized maize technologies. RESULTS: In this study, three maize inbred lines (KB182, KB207, and KB020) with different KMC and KDR were subjected to proteomic analysis 35, 42, and 49 days after pollination (DAP). In total, 8,358 proteins were quantified, and 2,779 of them were differentially expressed proteins in different inbred lines or at different stages. By comparative analysis, K-means cluster, and weighted gene co-expression network analysis based on the proteome data, some important proteins were identified, which are involved in carbohydrate metabolism, stress and defense response, lipid metabolism, and seed development. Through metabolomics analysis of KB182 and KB020 kernels at 42 DAP, 18 significantly different metabolites, including glucose, fructose, proline, and glycerol, were identified. CONCLUSIONS: In sum, we inferred that kernel dehydration could be regulated through carbohydrate metabolism, antioxidant systems, and late embryogenesis abundant protein and heat shock protein expression, all of which were considered as important regulatory factors during kernel dehydration process. These results shed light on kernel dehydration and provide new insights into developing cultivars with low moisture content.
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Desidratação , Zea mays , Zea mays/metabolismo , Desidratação/genética , Proteoma/metabolismo , Proteômica , Locos de Características QuantitativasRESUMO
Common smut caused by Ustilago maydis is one of the dominant fungal diseases in plants. The resistance mechanism to U. maydis infection involving alterations in the cell wall is poorly studied. In this study, the resistant single segment substitution line (SSSL) R445 and its susceptible recurrent parent line Ye478 of maize were infected with U. maydis, and the changes in cell wall components and structure were studied at 0, 2, 4, 8, and 12 days postinfection. In R445 and Ye478, the contents of cellulose, hemicellulose, pectin, and lignin increased by varying degrees, and pectin methylesterase (PME) activity increased. The changes in hemicellulose and pectin in the cell wall after U. maydis infection were analyzed via immunolabeling using monoclonal antibodies against hemicellulsic xylans and high/low-methylated pectin. U. maydis infection altered methyl esterification of pectin, and the degree of methyl esterification was correlated with the resistance of maize to U. maydis. Furthermore, the relationship between methyl esterification of pectin and host resistance was validated using 15 maize inbred lines with different resistance levels. The results revealed that cell wall components, particularly pectin, were important factors affecting the colonization and propagation of U. maydis in maize, and methyl esterification of pectin played a role in the resistance of maize to U. maydis infection.
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Doenças das Plantas , Ustilago , Doenças das Plantas/microbiologia , Esterificação , Zea mays/metabolismo , Pectinas/metabolismo , Ustilago/metabolismo , Parede Celular/metabolismoRESUMO
Members of the WRKY transcription factor (TF) family are unique to plants and serve as important regulators of diverse physiological processes, including the ability of plants to manage biotic and abiotic stressors. However, the functions of specific WRKY family members in the context of maize responses to fungal pathogens remain poorly understood, particularly in response to Ustilago maydis (DC.) Corda (U. maydis), which is responsible for the devastating disease known as corn smut. A systematic bioinformatic approach was herein employed for the characterization of the maize WRKY TF family, leading to the identification of 120 ZmWRKY genes encoded on 10 chromosomes. Further structural and phylogenetic analyses of these TFs enabled their classification into seven different subgroups. Segmental duplication was established as a major driver of ZmWRKY family expansion in gene duplication analyses, while the Ka/Ks ratio suggested that these ZmWRKY genes had experienced strong purifying selection. When the transcriptional responses of these genes to pathogen inoculation were evaluated, seven U. maydis-inducible ZmWRKY genes were identified, as validated using a quantitative real-time PCR approach. All seven of these WKRY proteins were subsequently tested using a yeast one-hybrid assay approach, which revealed their ability to directly bind the ZmSWEET4b W-box element, thereby controlling the U. maydis-inducible upregulation of ZmSWEET4b. These results suggest that these WRKY TFs can control sugar transport in the context of fungal infection. Overall, these data offer novel insight into the evolution, transcriptional regulation, and functional characteristics of the maize WRKY family, providing a basis for future research aimed at exploring the mechanisms through which these TFs control host plant responses to common smut and other fungal pathogens.
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Doenças das Plantas , Ustilago , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Zea mays/genética , Zea mays/microbiologia , Fatores de Transcrição/genética , Ustilago/genética , FilogeniaRESUMO
X-ray absorption spectroscopy (XAS) is a premier technique for materials characterization, providing key information about the local chemical environment of the absorber atom. In this work, we develop a database of sulfur K-edge XAS spectra of crystalline and amorphous lithium thiophosphate materials based on the atomic structures reported in Chem. Mater., 34, 6702 (2022). The XAS database is based on simulations using the excited electron and core-hole pseudopotential approach implemented in the Vienna Ab initio Simulation Package. Our database contains 2681 S K-edge XAS spectra for 66 crystalline and glassy structure models, making it the largest collection of first-principles computational XAS spectra for glass/ceramic lithium thiophosphates to date. This database can be used to correlate S spectral features with distinct S species based on their local coordination and short-range ordering in sulfide-based solid electrolytes. The data is openly distributed via the Materials Cloud, allowing researchers to access it for free and use it for further analysis, such as spectral fingerprinting, matching with experiments, and developing machine learning models.
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Starch with a high amylose (AM) content (high AM starch, HAS) has attracted increasing research attention due to its industrial application potential, such as functional foods and biodegradable packaging. In the past two decades, HAS structure, functionality, and applications have been the research hotspots. However, a review that comprehensively summarizes these areas is lacking, making it difficult for interested readers to keep track of past and recent advances. In this review, we highlight studies that benefited from rapidly developing techniques, and systematically review the structure, functionality, and applications of HAS. We particularly emphasize the relationships between HAS molecular structure and physicochemical properties.
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Amilose , Amido , Amido/química , Amilose/química , Estrutura MolecularRESUMO
High-amylose maize starch (HAMS) can provide dietary fiber to foods. In this study, we investigated the effects of three HAMSs (Gelose 50, Hylon VII, and NAFU50) on the functionality of casein (CA) and/or whey protein (WP) networks in acidified milk gels using normal maize starch (NMS) as a control thickener. When compared with NMS, HAMSs performed better in increasing the resistant starch content (RS), storage modulus, loss modulus, and complex viscosity of all the milk gels. The results are attributed to the retention of the starch granular integrity of HAMSs during the preparation of the milk gels, as observed by microscopy. HylonVII exhibited the highest RS and viscosity in all milk gel systems, especially in WP gels (71.8 % RS and >3000 Pa.s at 1 Hz viscosity). Our data provide support for the potential of using HAMS to develop healthier yogurt products using functional thickeners from natural sources.
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Amilose , Zea mays , Animais , Viscosidade , Zea mays/metabolismo , Leite/metabolismo , Amido/metabolismo , Géis , DigestãoRESUMO
We investigated the effects of drought stress (DS) on maize varieties with different amylose content (AC). In starches with AC of 33 %, DS increased the contents of amylopectin (AP) chains with a degree of polymerization (DP) > 36 and decreased the AP chains with DP ≤ 36, while the AC was unchanged. DS decreased the crystallinity, the thickness of both amorphous and crystalline lamellae, and average granular size. In contrast, the digestibility increased. For starches with AC of 45 %, DS increased the content of AP chains with DP > 24 and AC, while the contents of AP chains with DP ≤ 24 decreased. DS produced starch with thinner crystalline lamellae, thicker amorphous lamellae, more elongated and larger granules. The digestibility of the starches decreased. In starches with AC of 53 %, moderate DS led to similar structural and functional changes as found for starches with AC of 45 %. Finally, severe DS resulted in the decrease of AC.
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Amilopectina , Amilose , Amilopectina/química , Amilose/química , Secas , Amido/química , Zea mays/químicaRESUMO
The fermentation of Qu (FQ) could efficiently produce enzymatically modified starch at a low cost. However, it is poorly understood that how FQ influences the waxy maize starch (WMS) structure and the digestion behavior. In this study, WMS was fermented by Qu at different time and starches were isolated at each time point, and its physico-chemical properties and structural parameters were determined. Results showed that the resistant starch (RS), amylose content (AC), the average particle size [D(4,3)] the ratio of peaks at 1,022/995 cm-1, and the onset temperature of gelatinization (T o ) were increased significantly after 36 h. Conversely, the crystallinity, the values of peak viscosity (PV), breakdown (BD), gelatinization enthalpy (ΔH), and the phase transition temperature range (ΔT) were declined significantly after 36 h. It is noteworthy that smaller starch granules were appeared at 36 h, with wrinkles on the surface, and the particle size distribution was also changed from one sharp peak to bimodal. We suggested that the formation of smaller rearranged starch granules was the main reason for the pronounced increase of RS during the FQ process.
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This paper evaluated the relationship between multi-scale structure and high-pressure gelation properties of nine types of starches with different amylose (AM) content and crystalline polymorphic structure by RVA 4800. Higher average chain lengths of long amylopectin (AP) chains (DPâ¯>â¯36) and AM content, and lower relative content of short AP chains (DPâ¯≤â¯36) contributed to the higher peak temperature and peak time at 95-140⯰C, and lower peak viscosity, through viscosity, and final viscosity at 95-110⯰C. Rheological and texture parameters including storage modulus, loss modulus, hardness, and gumminess, had no significant correlation with starch structural parameters at 95-120⯰C, but were instead controlled by AM molecular structure at 130-140⯰C. AM content was mainly responsible for the rheological behaviors of starch gels at 130-140⯰C, and short and intermediate AM chains were mainly associated with the texture of starch gels at the temperature ranges.
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Amilopectina , Amido , Amilopectina/química , Amilose/química , Géis/química , Amido/química , Temperatura , ViscosidadeRESUMO
In this study, we report important relationships between kernel starch and kernel dehydration rate for eight maize inbred lines with different dehydration characteristics. High-throughput RNA sequencing data of starch biosynthesis-related genes showed that kernel moisture content and dehydration rate were both associated with differential expression of most starch biosynthetic genes. Especially, kernel moisture content was positively correlated with the increased expression of SBEI and SBEIIb, thereby potentially inducing biosynthesis of amylose with low molecular weight and amylopectin with low content of amylopectin chains with degree of polymerization (DP) 6-12 in inbred lines with fast kernel dehydration rate. We found a negative correlation between short amylopectin chains (DP 6-12) and the starch retrogradation rate. Hence, a low amount of amylopectin chains with DP 6-12 in the inbred lines with fast kernel dehydration rate was a plausible reason for their high short- and long-term retrogradation.
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Desidratação , Zea mays , Amilopectina , Amilose , Amido , Zea mays/genéticaRESUMO
Starch from 15 different rice genotypes with amylose content (AC) ranging 1.5%-30.6% were investigated for relationships between structures and properties. For parameters related to the granular level, the most important relationships were found for AC, average chain lengths (ACL) of the amylopectin (AP) fb1 chains having a length of DP 13-24, crystallinity, and the thickness of the crystalline (dc) and the amorphous lamellae (da) of the starch granule. AC and dc were negatively correlated with the peak gelatinization temperature (Tp), thermal enthalpy (ΔH), and peak viscosity (PV), but positively correlated with swelling power. ACLfb1 and da, as compared to AC and dc, had the opposite effects on these parameters, demonstrating important roles of specific molecular and lamellar structures on the starch granular stability. For the gelatinized systems, increasing ACLfb1 decreased retrogradation, while AC increased retrogradation by increasing the resistant starch (RS) content, storage modulus (G'), and setback (SB).
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Amilose/química , Oryza/química , Amido/química , Amilose/genética , Amilose/metabolismo , Configuração de Carboidratos , Oryza/genética , Oryza/metabolismo , Amido/genética , Amido/metabolismo , Termodinâmica , ViscosidadeRESUMO
BACKGROUND: Maize kernel filling, which is closely related to the process of double fertilization and is sensitive to a variety of environmental conditions, is an important component of maize yield determination. Silk is an important tissue of maize ears that can discriminate pollen and conduct pollination. Therefore, investigating the molecular mechanisms of kernel development and silk senescence will provide important information for improving the pollination rate to obtain high maize yields. RESULTS: In this study, transcript profiles were determined in an elite maize inbred line (KA105) to investigate the molecular mechanisms functioning in self-pollinated and unpollinated maize kernels and silks. A total of 5285 and 3225 differentially expressed transcripts (DETs) were identified between self-pollinated and unpollinated maize in a kernel group and a silk group, respectively. We found that a large number of genes involved in key steps in the biosynthesis of endosperm storage compounds were upregulated after pollination in kernels, and that abnormal development and senescence appeared in unpollinated kernels (KUP). We also identified several genes with functions in the maintenance of silk structure that were highly expressed in silk. Further investigation suggested that the expression of autophagy-related genes and senescence-related genes is prevalent in maize kernels and silks. In addition, pollination significantly altered the expression levels of senescence-related and autophagy-related genes in maize kernels and silks. Notably, we identified some specific genes and transcription factors (TFs) that are highly expressed in single tissues. CONCLUSIONS: Our results provide novel insights into the potential regulatory mechanisms of self-pollinated and unpollinated maize kernels and silks.
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Perfilação da Expressão Gênica , Zea mays , Pólen , Polinização/genética , Zea mays/genéticaRESUMO
Subgroups of starch granules from five maize phenotypes including waxy-, normal-, popcorn-, sweet corn- and high-amylose maize were sorted by flow cytometry (FC) utilizing the side scatter channel (SSC) and forward scatter channel (FSC). SSC and FSC mainly reflecting internal object complexity, and object size, respectively. Subgroups with higher FSC signal always showed higher SSC signal, indicating larger granules exhibited higher internal structural complexity. Wide-angle and small-angle X-ray scattering analysis showed that the subgroups showing high SSC signal intensity also had high lamellar scattering intensity, and low crystallinity. Vibrational transitions of bonds analyzed by Fourier Transform Infrared Spectroscopy (FT-IR) showed that the subgroups of maize starches, except sweet corn starch, with high SSC signal had high intensities at 1045 and 1022 cm-1. Hence, our data demonstrate that the structural complexity detected by the SSC signal is mainly associated with lamellar and crystalline features of starch granules.
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Citometria de Fluxo/métodos , Amido/química , Zea mays/metabolismo , Amilopectina/química , Amilose/química , Espalhamento de Radiação , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios XRESUMO
The molecular structure and the expression levels of starch biosynthesis-related genes of three types of high-amylose maize (HAM) genotypes and one normal maize (NM) genotype at 5-35 days after pollination (DAP) were studied. Size exclusion chromatography (SEC) analysis showed that the molecular size of amylopectin molecules in NM increased from 5 to 35 DAP and the amylose content in HAM genotypes increased from 15 to 35 DAP. Correlation analysis for both NM and HAMs combined showed that SBEIIb and ISAII were negatively correlated with the contents of amylose and long amylopectin chains (DP > 30) and positively correlated with the content of short amylopectin chains (DP ≤ 31) and the molecular size of amylopectin molecules. Correlation analysis for only the HAMs showed that amylose content was negatively correlated with SBEI and SSIIa. In both correlation analyses, SSIIa showed a negative correlation with the average chain lengths of amylose chains.
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Amilose , Amido , Amilopectina , Estrutura Molecular , Zea mays/genéticaRESUMO
The relationship between molecular structure and crystalline and lamellar structures of fifteen types of rice starches was studied. GPC and HPAEC were used for the molecular chain analysis and WAXS, SAXS, and CP/MAS 13C NMR were employed for aggregation structural analysis. The amylopectin content and the average lengths of fb1-chains (the degree of polymerization (DP) 13-24) were positively correlated with the amount of double helices (r2 = 0.92 and 0.57, respectively). In contrast, amylose content was positively correlated with the amounts of amorphous materials in starch (r2 = 0.77). The amount of double helices, which constitute a major part of the crystalline matrix, was positively correlated with the lamellar ordering (r2 = 0.81), and negatively correlated with the thickness of crystalline lamellae (r2 = 0.90) and lamellar repeat distance (r2 = 0.84). Conversely, the amount of the amorphous matrix was correlated with these parameters in the opposite way (r2 = 0.50, 0.75, and 0.75, respectively).
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Light is the most important environmental cue signaling the transition from skotomorphogenesis to photomorphogenesis, thus affecting plant development and metabolic activity. How the light response mechanisms of maize seedlings respond to fluctuations in the light environment has not been well characterized to date. In this study, we built a gene coexpression network from a dynamic transcriptomic map of maize seedlings exposed to different light environments. Coexpression analysis identified ten modules and multiple genes that closely correlate with photosynthesis and characterized hub genes associated with regulatory networks, duplication events, domestication and improvement. In addition, we identified that 38% of hub genes underwent duplication events, 74% of which are related to photosynthesis. Moreover, we captured the dynamic expression atlas of gene sets involved in the chloroplast photosynthetic apparatus and photosynthetic carbon assimilation in different light environments, which should help to elucidate the key mechanisms and regulatory networks that underlie photosynthesis in maize. Insights from this study provide a valuable resource to better understand the genetic mechanisms of the response to fluctuations in the light environment in maize.
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Regulação da Expressão Gênica de Plantas/genética , Zea mays/genética , Cloroplastos/genética , Redes Reguladoras de Genes/genética , Luz , Fotossíntese/genética , Plântula/genética , Transcriptoma/genéticaRESUMO
Semipermeable silica membranes are attractive as protective coatings for metal electrocatalysts such as platinum, but their impact on the catalytic properties has not been fully understood. Here, we develop a first-principles formalism to investigate how silica membranes interact with the surface of platinum metal electrocatalysts to develop a better understanding of the membrane-metal interplay. By generalizing the concept of Pourbaix diagrams to electrochemical solid-solid interfaces, we establish which bonds are formed between the SiO2 membrane and Pt(111) surface in aqueous electrolytes for different pH values and potential biases. We find that the membrane termination changes as a function of the pH and potential, which affects the adhesion strength and the energy requirements for partial membrane detachment, controlling the Pt surface area that is accessible for reactant species. The charge transfer between the Pt surface and SiO2 membrane is also pH- and potential-dependent and results in changes of the Pt surface d-band states, which are known to correlate with catalytic activity. Our analysis reveals the complex response of a buried interface to the electrochemical environment and identifies trends that are expected to apply also to other membrane-coated electrocatalysts.
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Two high amylose (HAM) inbred lines with apparent amylose contents of 55 % and 62 %, respectively, were selected to explore the relationship between molecular structure and gene expression of starch-synthase involved enzymes. GPC analysis of debranched starches showed that the HAM starches (HAMSs) had shorter amylose chains and longer amylopectin chains than normal maize starch (NMS). FACE analysis showed that these HAMSs had a higher content of amylopectin chains of DP > 21. Quantitative Real-Time PCR analysis showed that the HAM lines had specifically low expression of the starch branching enzyme IIb (SBEIIb), and the starch synthase IIIa (SSIIIa) homologue, and high expression of the isoamylase 2 (ISA2), potentially suppressing the generation of amylopectin molecules through deficient branching and excessive debranching process, thereby increasing the relative amylose content. A high expression of GBSS1 was potentially associated with increased short amylose chain lengths in HAMSs.