Search Results (119)

Sweet–waxy maize is a highly valuable specialty maize type with an increasing market demand, but conventional breeding methods for producing sweet–waxy maize are restricted by severe bottlenecks, such as long breeding cycles and linkage drag. This study was conducted to rapidly create sweet–waxy maize germplasm using CRISPR/Cas9 genome-editing technology. We used a CRISPR/Cas9 system to target maize Sh2 (regulating the super-sweet kernel trait) and Wx (controlling the waxy kernel trait), which are two key genes in the starch biosynthesis pathway. Two small-guide RNAs (sgRNAs) designed for each gene were incorporated into CRISPR/Cas9 vectors, which were then introduced into maize via Agrobacterium-mediated transformation. We obtained Cas9-free T₃ homozygous sh2 and wx mutant lines with significant increases in kernel soluble sugar and amylopectin contents, respectively, but no adverse changes to major agronomic traits. Using these Cas9-free lines, we developed a new type of sweet–waxy maize germplasm, in which waxy and sweet kernels on the same ear segregated at a 3:1 ratio. Our results indicate that CRISPR/Cas9-mediated editing of Sh2 and Wx can efficiently generate sweet–waxy maize germplasm with no detectable linkage drag. The study methods would be useful for optimizing the molecular breeding of novel and innovative maize germplasm. Full article

Intercropping maize with legume cover crops has been shown to increase soil organic carbon (SOC) and alter soil microbial communities, potentially affecting soil aggregate stability. However, whether different legume cover crop varieties vary in their effects on SOC enhancement and aggregate stability improvement, and whether such variation is associated with their capacity to enhance distinct microbial taxa, remains unclear. Here, we conducted a five-year field experiment comprising maize monoculture (MM) and six intercropping systems in which maize was grown with different legume cover crop varieties. We aimed to assess the role of bacterial, non-AMF, and arbuscular mycorrhizal fungal (AMF) community composition in influencing SOC and aggregate stability, measured as mean weight diameter (MWD). On average, the six intercropping systems significantly increased SOC by 28% compared with MM, with no significant differences among legume varieties. However, MWD varied significantly depending on the specific legume used. Specifically, intercropping with red clover or sesbania resulted in MWD values similar to MM, whereas intercropping with soybean, hairy vetch, common vetch, or yellow sweet clover led to significantly higher MWD. Notably, MWD was positively correlated with the proportion of C within macroaggregates (>0.25 mm), and this effect was linked to the enrichment of specific microbial taxa—including the bacterium RB41, the non-AMF Trichoderma, and AMF (unclassified Glomerales, Glomus2, and Glomus3)—in systems with high MWD. These findings indicate that while SOC accrual under intercropping is robust across legume varieties, aggregate stability is contingent upon the identity of the legume and its associated microbiota. Selecting legume varieties with a greater ability to increase the abundance of specific microorganisms that enhance C allocation into macroaggregates can simultaneously improve both SOC accumulation and aggregate stability in maize-based intercropping systems. Full article

Genome-wide association studies (GWAS) are essential for identifying genomic regions associated with agronomic traits, but Linear Mixed Model (LMM)-based GWAS face challenges in capturing complex gene interactions. This study explores the potential of machine learning (ML) methodologies to enhance marker identification and association modeling in plant breeding. Unlike LMM-based GWAS, ML approaches do not require prior assumptions about marker–phenotype relationships, enabling the detection of epistatic effects and non-linear interactions. The research sought to assess and contrast approaches utilizing ML (Decision Tree—DT; Bagging—BA; Random Forest—RF; Boosting—BO; and Multivariate Adaptive Regression Splines—MARS) and LMM-based GWAS. A simulated F₂ population comprising 1000 individuals was analyzed using 4010 SNP markers and ten traits modeled with epistatic interactions. The simulation included quantitative trait loci (QTL) counts varying between 8 and 240, with heritability levels set at 0.5 and 0.8. These characteristics simulate traits of candidate crops that represent a diverse range of agronomic species, including major cereal crops (e.g., maize and wheat) as well as leguminous crops (e.g., soybean), such as yield, with moderate heritability and a high number of QTLs, and plant height, with high heritability and an average number of QTLs, among others. To validate the simulation findings, the methodologies were further applied to a real Coffea arabica population (n = 195) to identify genomic regions associated with yield, a complex polygenic trait. Results demonstrated a fundamental trade-off between sensitivity and precision. Specifically, for the most complex trait evaluated (240 QTLs under epistatic control), Ensemble methods (Bagging and Random Forest) maintained a Detection Power (DP) exceeding 90%, significantly outperforming state-of-the-art GWAS methods (FarmCPU), which dropped to approximately 30%, and traditional Linear Mixed Models, which failed to detect signals (0%). However, this sensitivity resulted in lower precision for ensembles. In contrast, MARS (Degree 1) and BLINK achieved exceptional Specificity (>99%) and Precision (>90%), effectively minimizing false positives. The real data analysis corroborated these trends: while standard GWAS models failed to detect significant associations, the ML framework successfully prioritized consensus genomic regions harboring functional candidates, such as SWEET sugar transporters and NAC transcription factors. In conclusion, ML Ensembles are recommended for broad exploratory screening to recover missing heritability, while MARS and BLINK are the most effective methods for precise candidate gene validation. Full article

Rice cultivation has the ability to ameliorate saline soils, but this monoculture pattern can lead to negative plant–soil feedback. In a previous study, we investigated the effects of long-term rice cultivation on saline soil chemistry, salt ions, root characteristics, and agglomerate formation, and concluded that the optimal rice planting period is 5 years. However, we do not know which crop rotation is most effective in improving this negative soil feedback and enhancing soil quality. In this study, we carried out an experiment on saline land planted with rice over 5 years and set up four different rotations, including rice–Hunan Jizi, rice–maize, rice–sweet sorghum, and rice–soybean, with perennial rice planting as CK, to analyze soil texture under different treatments. Physicochemical properties and enzyme activities were also analyzed under different treatments, and the soil quality index (SQI) was constructed using principal component analysis and correlation analysis for comprehensive evaluation of each treatment. The results showed that (1) the saline-alkali soil texture of perennial rice planting in the Yinbei Plain was silty soil, and different rice drought rotation methods changed the soil texture from silty to silty loam, which improved the fractal dimension of the soil. The fractal dimension of saline-alkali soil was significantly positively correlated with the clay volume content, negatively correlated with silt volume content, and negatively correlated with sand volume content. (2) There was no risk of structural degradation (SI > 9%) in saline-alkali soil planted in perennial rice, and it appeared that RS (rice–soybean) could improve the stability coefficient of soil structure in the 0~40 cm soil layer. (3) Different rice and drought rotation methods could significantly affect the physical and chemical properties and enzyme activities of soil, and the quality of soil in the 0~40 cm soil layer was evaluated; RS (rice–soybean) and RC (rice–maize) were suitable for rice drought rotation in the Yinbei area. The structural equation model showed that salinity and soil nutrients were the key factors restricting the improvement of saline-alkali soil quality in Yinbei. These results will deepen the current understanding of bio-modified saline soils. Full article

Mycorrhizal symbiosis relies on the host’s supply of carbohydrates, while sugar transport within plants is governed by the SWEET sugar transporter family. Although the symbiotic association between arbuscular mycorrhizal fungi (AMF) and maize is critical for its growth and sugar regulation, different AMF species have varying impacts on the host. The aim of this study was to analyze the effects of inoculating six different AMF species [Diversispora epigaea (De), Rhizophagus intraradices (Ri), Paraglomus occultum (Po), Entrophospora etunicata (Ee), Glomus heterosporum (Gh), and Funneliformis mosseae (Fm)] on plant growth, leaf photosynthetic capacity, glomalin-related soil protein content, leaf sugar content, and SWEET gene expression of maize under potted conditions for two months. AMF species colonize maize roots and showed significant species-specific variation, where Ri and Fm colonized treatment had the greatest rates (66~68%). All six fungi significantly increased biomass and stem diameter, with Ee treatment yielding the thickest stems, and enhanced leaf photosynthetic performance and glomalin-related soil protein fractions to some extent, with species-specific enhancements. All AMF species in particular significantly increased leaf sucrose; all except Ri treatment significantly increased fructose; while only Po and Fm treatments significantly increased glucose. AMF inoculations consistently upregulated the expression of ZmSWEET1b/3a/3b/4a/4b/14a and 16 genes, consistently downregulated the expression of ZmSWEET6b/11b/12a/13a/13b/13c and 17b genes, and induced treatment-specific regulation in the other gene expression. Root AMF colonization clustered with sugars and specific ZmSWEETs, with ZmSWEET4a/15b and 14b central to sucrose/glucose based on principal component analysis, indicating that these genes have specific regulatory effects in response to AMF treatments. In short, AMF inoculation reprogrammed ZmSWEET expression in a species-specific manner, with core ZmSWEET genes mediating sugar accumulation to support symbiosis. Full article

Pantoea stewartii subsp. stewartii (Pss) is a Gram-negative bacterium first documented in North America, and is the causal agent of Stewart’s disease in maize (Zea mays), especially in sweet corn. First identified in North America, it is primarily spread by insect vectors like the corn flea beetle (Chaetocnema Pulicaria) in the United States. However, Pss has since spread globally—reaching parts of Africa, Asia, the Americas, and Europe—mainly through the international seed trade. Although this trade is limited, it has still facilitated the pathogen’s global movement, as evidenced by numerous phytosanitary interceptions. Recent studies in Italy, as indicated in the EFSA journal, reported that potential alternative vectors were identified, including Phyllotreta spp. and the invasive Asian brown marmorated stink bug (Halyomorpha halys); the latter tested positive in PCR screenings, raising concerns due to its broad host range and global distribution. This information has prompted studies to verify the ability of Halyomorpha halys to vector Pss to assess the risk and prevent the further spread of Pss in Europe. In this study, we explored the potential transmission of Pss by the brown marmorated stink bugs in maize plants, following its feeding on Pss-inoculated maize, as well as the presence of Pss within the insect’s body. Full article

The low nitrogen-use efficiency (NUE) in sandy soils, due to high porosity and poor nutrient retention, necessitates proper management in fertilization. This study aims to evaluate the effect of biochar-coated urea (BCU) with different coating thicknesses and nitrogen doses on soil nitrogen content, nitrogen uptake, NUE, growth, and yield of sweet corn in sandy soil. The experiment used a factorial randomized block design with two factors, including biochar coating thicknesses (i.e., 14% and 29%) and fertilization doses (i.e., 50%, 100%, 150%, 200%, and 250%). The results showed that the 29% biochar coating thickness led to 9.9–21.3% higher plant height, N uptake, and N-use efficiency, but it led to 22.8% lower yield, as compared to the 14% biochar coating thickness. Additionally, the application of BCU doses of 100% and 150% (~161 and 241.5 kg N/ha) led to 9.2–97.3% higher maize growth, yield, N uptake, and NEU as compared to the other doses (i.e., 50%, 100%, 250%). This study confirmed that the combination of a 29% biochar coating thickness with 150% of the recommended BCU dose (~241.5 kg N/ha) was the best combination, resulting in the highest N uptake, growth, and yield of maize. Full article

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), is a highly destructive pest that poses serious threats and causes significant losses to the production of maize in China. This study evaluated the feeding and oviposition preferences of S. frugiperda when reared on four maize cultivars—sweet, waxy, common, and silage—across three consecutive generations. It also compared population adaptability among these cultivars and analyzed population parameters between the F1 and F3 generations. The findings revealed that all four F1 generation populations showed a preference for feeding and oviposition on sweet maize. However, over time, S. frugiperda exhibited a stronger preference, in terms of feeding and oviposition behaviors, for the natal host plant across three consecutive generations of rearing. The fall armyworm completed its life cycle and oviposited on all four maize varieties over three generations. The sweet cultivar population had the highest intrinsic rate of increase, finite rate of increase, net reproductive rate, larval survival rate, pupation rate, eclosion rate, fecundity, and pupal weight, while the silage cultivar population had the shortest larval stage, pre-adult stage, and adult lifespan and the pupal weight and the fecundity were the lowest. Overall, the population fitness was the highest on the sweet cultivar, and the lowest on the silage cultivar. Compared with F1, the F3 generation of the FAW had a significantly shorter developmental duration in four maize cultivars. Except for the waxy maize cultivars, the fecundity of the other three cultivars did not differ significantly between F1 and F3. This study provides fundamental information on the trend of fall armyworm population changes in maize fields and serves as a reference for rational maize cultivar planting decisions. Full article

Among various plants, corn is the primary host damaged by Spodoptera frugiperda J. E. Smith (Lepidoptera: Noctuidae). After long-term regional colonization, its larvae feed on sweet waxy corn and fresh corn for extended periods. A question arises: Does long-term feeding on different corn varieties affect their rhythms? Currently, there are no reports addressing these issues. To facilitate the formulation of effective prevention and control measures, Zhengdan 958 and Zhenghuangnuo were selected as representative varieties of normal and sweet waxy corn, respectively, for laboratory experiments. S. frugiperda were fed the leaves of these two corn types over nine consecutive generations, thereby establishing distinct S. frugiperda strains associated with each corn variety. Additionally, a strain fed an artificial diet served as the control group. Through a comparative analysis of the emergence, movement, nutritional foraging, dormancy, mating, and oviposition behaviors of adult fall armyworms from different populations, differences in the six behavioral peak times among the strains were identified. RT-qPCR analysis indicated significant differences in the expression levels of four circadian clock genes across different populations and tissues of the fall armyworm. Feeding on different host plants influenced the expression of circadian clock genes and their associated behavioral rhythms. Our study showed that sweet corn is more conducive to pupation, mating, and oviposition. Because of these differences in adult insect rhythms, sweet corn may have an impact on the reproduction of fall armyworms in the Huang–Huai–Hai corn-planting region. Full article

The fragmentary and whole substitution of wheat flour with flour blends is an alternative approach for producing cheaper, nutrient-rich, and comparatively advantageous gluten-free foods through fermentation. Dry samples of sweet potato, pigeon pea, and maize botanicals were purchased from local vendors, authenticated and processed before spontaneous fermentation at room temperature. The pH and microbiological growth patterns of the fermenting botanicals were evaluated every 12 h for 72 h, using standard test protocols. It revealed that the rates of growth of isolated microorganisms were affected by pH; all the botanicals fermented had a reduction in their pH values. Acids were produced during fermentation, leading to a reduction in pH. Bacteria growth on the fermenting samples on nutrient agar reveals that the bacterial load increased with fermentation time, from 7.52 Log₁₀ CFU/g to 10.6 Log₁₀ CFU/g (sweet potato); 6.3 Log₁₀ CFU/g to 10.54 Log₁₀ CFU/g (pigeon pea), and 6.3 Log₁₀ CFU/g to 10.54 Log₁₀ CFU/g (maize). On MacConkey agar, the bacterial load on all samples started after 24 h of fermentation, peaked at 48 h, and gradually reduced towards 72 h of fermentation. There was increase in fungal growth with time from 0 to 36 h across all samples. The microorganisms isolated can be categorized into lactic acid bacteria, spore formers, Enterobacteriaceae, Staphylococcace, yeast, and molds. Fermentation of botanicals over 72 h results in organic acid formation, which lowers pH; this attribute helps in checkmating undesirable microorganisms capable of affecting the production of gluten-free flours with good keeping qualities. Full article

The utilization of modified starches derived from ginger, sweet potatoes, and maize has been employed as a strategy to reduce the oil content in mayonnaise formulations. Amylose–lipid complexes and the native starches were synthesized, characterized, and subsequently incorporated into various mayonnaise formulations, replacing 50 and 80 percent of the oil. The sensory analysis showed that the mayonnaises produced with 50% and 80% modified corn starch were particularly well received. However, when compared to conventional mayonnaises, the viscosity of the mayonnaises prepared with 50% and 80% modified maize starch was found to be remarkably low. This outcome demonstrates that when preparing low-fat mayonnaise, it is not possible to substitute tuber starches for fat. Full article

The current rising food prices, influenced by importation costs, the global food crisis, as well as pre- and post-harvest losses, have contributed majorly to malnutrition and food insecurity. Therefore, utilizing technologies that harness our indigenous agro-products as composite flours to develop functional foods will address these issues. In this study, dry raw samples of perishable and healthy yellow potato, yellow maize and pigeon pea were obtained from the agricultural development program, Edo State, Nigeria, and authenticated and processed into gluten-free fermented composite flours. The flours were profiled physicochemically and nutritionally, providing valuable insight into their multiple benefits. An experimental design software (Design Expert 13.0.) was applied to achieve optimum blended flours regarding the ratio of sweet potato–pigeon pea–maize, and mix 5 (67.70:20.00:12.31) displayed more outstanding attributes than other blends for the production of biscuits, bread and cakes using creaming and mixing methods. Various standard tests for flours and products were appropriately carried out to evaluate the proximate, techno-functional, mineral, antioxidant, anti-nutrient, sensory and color values. Individual antioxidant parameters were improved across all products compared to wheat-based products (control) under the same production conditions, showing a statistical significance at p < 0.05. A similar trend was observed in the proximate, anti-nutritional and mineral contents, while all products had a desirable color outlook. A sensory evaluation revealed the general acceptability, while an in vivo animal experimental model revealed that all animals fed with the various product samples gained weight with improved general body organs and no evidence of disease. This research underscores the potential of harnessing agri-value chain approaches in developing functional foods and promoting food security. Full article

Long-term excessive application of nitrogen fertilizers in sweet maize farmland in South China has led to low nitrogen absorption and high emissions of reactive nitrogen (RN). In this study, four kinds of organic materials, including maize straw, cow manure, biochar, and biogas residue, were applied to sweet maize farmland for three consecutive cropping seasons to substitute 20% of synthetic nitrogen fertilizer. We compared the effects of different nitrogen substitution practices on nitrogen use efficiency (NUE), nitrogen surplus (NSP), and nitrogen footprint (NF) in farmland, with conventional fertilization as the control (CK). Results demonstrated that nitrogen substitution practices increased crop nitrogen uptake by 18.80–52.37%, NUE by 16.00–43.03%, and nitrogen partial factor productivity (PFP_N) by 46.18–74.31%, while reducing nitrogen surplus and loss by 7.84–21.84% and 12.08–42.88%, respectively. From a life cycle assessment perspective, nitrogen footprint per unit area (NF_A) and per unit yield (NF_Y) decreased by 13.64–32.24% and 34.26–47.64%, respectively. The results demonstrated that partial substitution with organic fertilizers improved nitrogen utilization as well as reduced nitrogen surplus, loss and, footprint in the sweet maize cropping system in South China. Biochar substitution achieved the most significant improvements. This study provides a research basis for nitrogen management in the sweet maize cultivation system in South China and valuable information for achieving sustainable agricultural development in typical subtropical areas in East Asia. Full article

Selenium-enriched sweet maize is an important product to alleviate selenium deficiency in the human body. In this study, the effects of the basal application of selenium fertilizer on the selenium content and yield of maize were analyzed in a 2-year field trial using a two-factor, five-level, split-area experimental combination design with a different selenium fertilizer application rate (150–750 kg ha⁻¹) and depth (1–20 cm). It was found that the selenium application rate and depth significantly affected dry matter mass, selenium content, and selenium accumulation in maize. In particular, the Se3D4 treatment combination (a selenium application rate of 450 kg ha⁻¹ and depth of 15 cm) performed the best in increasing the selenium content and yield of the maize grain. The 2-year data showed that the selenium content of maize grain under Se3D4 treatment reached 3.59 mg kg⁻¹ and 3.24 mg kg⁻¹, which were 13.63 and 13.70 folds as the control, respectively, and the yield reached 6.28 t ha⁻¹ and 6.07 t ha⁻¹, which were 24.35% and 33.30% higher than the control, respectively. Therefore, by optimizing the application rate and depth of selenium fertilizer, the selenium content and yield of maize can be significantly increased. The results of this study provide a theoretical basis for the precise application of selenium fertilizer in the biofortification of sweet maize. Full article

Fresh sweet and waxy maize (Zea mays) are valuable specialty crops in southern China. Hyperspectral remote sensing offers a powerful tool for detecting maize foliar nutrients non-destructively. This study aims to investigate the capability of leaf spectroscopy (SVC HR-1024i spectrometer, wavelength range: 400–2500 nm) to retrieve maize foliar nutrients. Specifically, we (1) explored the effects of nitrogen application rates (0, 150, 225, 300, and 450 kg·N·ha⁻¹), maize cultivars (GLT-27 and TGN-932), and growth stages (third leaf (vegetation V3), stem elongation stage (vegetation V6), silking stage (reproductive R2), and milk stage (reproductive R3)) on foliar nutrients (nitrogen, phosphorus, and carbon) and leaf spectra; (2) evaluated the transferability of the regression and physical models in retrieving foliar nutrients across maize cultivars. We found that the PLSR (partial least squares regression), SVR (support vector machine regression), and RFR (random forest regression) regression model accuracies were fair within a specific cultivar, with the highest R² of 0.60 and the lowest NRMSE (normalized RMSE = RMSE/(Max − Min)) of 17% for nitrogen, R² of 0.19 and NRMSE of 21% for phosphorous, and R² of 0.45 and NRMSE of 19% for carbon. However, when these cultivar-specific models were used to predict foliar nitrogen across cultivars, lower R² and higher NRMSE values were observed. For the physical model, which does not rely on the dataset, the R² and NRMSE for foliar chlorophyll-a and -b (C_ab), carotenoid (C_xc), and equivalent water thickness (EWT) were 0.76 and 15%, 0.67 and 34%, and 0.47 and 21%, respectively. However, the prediction accuracy for foliar nitrogen, expressed as foliar protein in PROSPECT-PRO, was lower, with an R² of 0.22 and NRMSE of 27%, which was comparable to that of the regression models. The primary reasons for this limited transferability were attributed to (1) the insufficient number of samples and (2) the lack of strong absorption features for foliar nutrients within the 400–2500 nm wavelength range and the confounding effects of other foliar biochemicals with strong absorption features. Future efforts are needed to investigate the physical mechanisms underlying hyperspectral remote sensing of foliar nutrients and incorporate transfer learning techniques into foliar nutrient models. Full article