Search Results (232)

Rice depends on its root system to perceive drought, a major environmental constraint that leads to severe yield losses worldwide. To dissect the underlying molecular basis, we conducted a comparative analysis of drought-sensitive (WAB) and drought-tolerant (IR65) rice genotypes that exhibited divergent drought tolerance at the seedling stage. After exposure to 15% PEG6000 (−0.4 MPa) for two days, the shoot and root architectural traits of IR65 were better than those of WAB seedlings. Measurements of physio-biochemical parameters (SOD, CAT, POD, APX, H₂O₂, and proline) suggest that IR65 seedling roots exhibit greater ROS scavenging and osmotic adjustment capacity than WAB, aligning with tolerance to PEG-induced water deficiency. Transcriptomic assessments of roots identified 802 commonly differentially expressed genes (DEGs) during the drought time course (12, 24, and 48 h) in WAB and IR65. They were clustered into eight groups based on their expression profiles and mainly enriched in phytohormone signaling, protein phosphorylation, and transcription factors. Using weighted gene co-expression network analysis (WGCNA), nine significant modules were identified based on n = 382 of the DEGs. A total of 12 DEGs up-regulated in IR65 were distributed in five modules, and five of them were selected for rapid functional validation through in vivo yeast expression. The results showed that transgenic yeasts were tolerant to simulated drought conditions (135 mM PEG3350), indicating that these genes would be potential targets for rice improvement in drought tolerance in the future. Full article

Salinity stress is one of the major obstacles to glycophytic crop production worldwide, including rice. It alters cellular metabolism, causing significant crop destruction that results in substantial reductions in yield. The overexpression of C₄ enzymes, such as phosphoenolpyruvate carboxykinase (PEPCK), at high levels in C₃ transgenic plants through genetic engineering can decrease oxidative stress while increasing photosynthetic capabilities. In this research, we evaluate the efficiency of transgenic rice plants (Oryza sativa L. cv. IR64) overexpressing PEPCK genes in mitigating salinity stress and increasing photosynthetic efficiency. The T1 transgenics showed increased levels of several biochemical factors, including ascorbate peroxidase (APX), catalase (CAT), proline, glutathione reductase (GR), and guaiacol peroxidase (GPX) activities. This was accompanied by reduced levels of malondialdehyde (MDA), hydrogen peroxide (H₂O₂), and electrolytic leakage, suggesting an effective antioxidant defense mechanism against the oxidative damage driven by salt stress. Photosynthetic parameters—such as chlorophyll content, net photosynthetic rate, intercellular CO₂ content, and stomatal conductance—were elevated in transgenic plants compared to control plants. The transgenics also exhibited superior agronomic characteristics. Our findings provide conclusive evidence of the PEPCK gene’s potential role in regulating salt stress response and tolerance in rice plants. Full article

Immature rice is a distinctive cereal product widely consumed in Asian countries due to its natural green color, soft texture, unique flavor, and high nutritional value. However, its fragile structure and pigment sensitivity create significant processing challenges. This study investigates the effects of infrared (IR) roasting temperature (550–650 °C) and time (20–40 min) on the physicochemical, nutritional, and cooked-rice qualities of immature rice (Oryza sativa L., cv. RD6). A two-factor study with three level of factorials was designed and response surface methodology (RSM) was used to evaluate roasting variables and to identify optimal processing conditions (p ≤ 0.05). Increasing roasting severity decreased rice yield, moisture content, water activity, and chlorophyll content, while promoting grain darkening, increasing phenolic content, and enhancing cooked-rice expansion and hardness. Several responses exhibited significant linear and quadratic relationships with roasting conditions, with model coefficients of determination (R²) ranging from 0.676 to 0.829. Multi-response optimization using desirability analysis identified the optimal roasting condition as 650 °C for 20 min, which produced predicted values that closely matched experimental validation (p > 0.05). These results demonstrate that IR roasting provides an effective green-energy processing approach for producing value-added immature rice while maintaining desirable color, nutritional properties, and cooked-rice texture. Full article

Climate change poses significant challenges to global agricultural systems, exerting profound impacts on crop yields and water resource management, which are particularly pronounced in cold-region rice-growing systems. This study employed the AquaCrop model to assess the spatiotemporal distribution characteristics of rice yield, crop water requirement (ET_c), irrigation water requirement (Ir), and water use efficiency (WUE) in Heilongjiang Province under the RCP4.5 and RCP8.5 scenarios from 2021 to 2080. The results indicate that the average rice yield in Heilongjiang Province will increase by approximately 2% to 5%, with more significant gains observed in the western and southern regions. However, climate warming will cause ET_c to increase by 3–7%, leading to a rise in Ir of about 5–12%, which is particularly pronounced under the RCP8.5 scenario. Compared to RCP4.5, the yield under RCP8.5 will increase by 1–2%, but the increase in Ir will be more significant. Despite these changes, WUE remains within a relatively constrained range (approximately 1.55~1.75 kg·m⁻³), as yield increases are largely offset by corresponding rises in ET_c. Overall, the findings reveal a pronounced yield–water trade-off in cold-region rice systems under future climate scenarios, indicating that yield gains may be accompanied by heightened Ir. Full article

Paddy field water management and rice phenology strongly affect crop productivity and environmental processes, requiring continuous and quantitative monitoring. This study combined satellite synthetic aperture radar (SAR) observations and ground-based Global Navigation Satellite System (GNSS) interferometric reflectometry (GNSS-IR) over a paddy field to analyze their sensitivities to water-level variations and phenological dynamics. Sentinel-1 (C-band) and ALOS-2/PALSAR-2 (L-band) SAR time series were compared with continuous GNSS-IR observations acquired using geodetic-grade instrumentation. For GNSS-IR, Lomb–Scargle periodogram (LSP) analysis of SNR data was applied to derive two indicators: (i) the dominant spectral peak (f_water) frequency associated with the effective reflecting surface, and (ii) a normalized spectral integral (GNSS Phenology Indicator, GPI) representing vegetation-induced scattering and attenuation effects. The temporal evolution of LSP spectra exhibited systematic changes with rice phenological progression, including peak broadening and the emergence of multiple peaks as vegetation developed. For water level variations, L-band SAR co-polarized backscatter (VV and HH) and the GNSS-IR spectral peak exhibited comparable relationships with in situ water level, whereas C-band SAR showed weaker sensitivity. For phenological dynamics, GPI showed temporal behavior similar to that of the SAR polarization ratio (VH/VV), with clear responses around key growth stages, such as heading and harvest. These results suggest that SAR polarization-based indicators and GNSS-IR spectral characteristics can be interpreted within a consistent electromagnetic framework: co-polarized L-band SAR responses correspond to the water-surface-related GNSS-IR peak, whereas cross-polarized indicators correspond to GPI. This study demonstrated the potential of GNSS-IR as complementary information for physically interpreting SAR scattering mechanisms, highlighting a pathway toward more integrated microwave-based monitoring of land surface processes. Full article

The utilization of brown rice from long-term stored paddy is severely limited by lipid deterioration, which is primarily characterized by a high free fatty acid value (FAV). Although microwave treatment shows promise in mitigating lipid deterioration, its underlying mechanism in degraded grains remains poorly understood. This study systematically investigated the efficacy and mechanism of microwave treatment using a multi-analytical approach. Brown rice from long-term stored paddy (Longjing-46, stored for 6 years) was treated using a laboratory microwave oven (420 W or 560 W, 1–5 min). The reduction in FAV was quantified, lipid structural changes were analyzed by FT-IR spectroscopy, and lipid metabolic alterations were profiled using untargeted lipidomics. Results showed that microwave treatment significantly reduced FAV in a time- and power-dependent manner, with a maximum reduction of 76.3%. Treatment at 420 W for 4 min was identified as the optimal condition. FT-IR analysis confirmed that the treatment inhibited lipid oxidation and hydrolysis at the molecular level. Importantly, lipidomics revealed that the mechanism extended beyond simple enzyme inactivation. Microwave treatment induced a reprogramming of the lipid metabolic network, characterized by the synergistic downregulation of key lipid species and the activation of the autophagy pathway. This study provides a comprehensive, lipid-centric explanation of microwave-mediated quality improvement in long-term stored brown rice, integrating enzyme inactivation with metabolic network reprogramming. The findings offer a novel scientific basis for applying this technology to valorize degraded grain stocks, contributing to the reduction in postharvest loss. Full article

Extreme weather variability across different climatic regions severely threatens rice yield and nitrogen use efficiency (NUE). To clarify the response of rice traits to climatic factors and optimize adaptive strategies, this study conducted field experiments in Nanjing (subtropical monsoon climate, 2022–2024) and Sanya (tropical marine climate, 2024). Nine rice genotypes covering indica, japonica, and hybrid genetic backgrounds were used, and the least absolute shrinkage and selection operator (LASSO) regression model was applied to identify the key drivers among climatic factors (air temperature, solar radiation, rainfall) and nitrogen application rates. Results showed growth stage-specific responses of rice to climatic stress: high-temperature stress during the flowering stage and low-temperature stress during the filling stage were key yield-limiting factors, while rainfall during the seedling stage and solar radiation during the tillering stage positively promoted yield and NUE. Nitrogen metabolic enzyme activities during the filling stage were the core physiological link connecting environmental stress and yield (R² = 0.776–0.795). Furthermore, three genotypes (YZ2, IR30, and YZ3) were observed to show more positive associations with yield and NUE. This study clarifies the differential associative effects of climatic factors in tested environments and seasons, providing theoretical support and genetic resources for rice adaptive improvement under diverse climatic conditions. Full article

Salinity–alkalinity stress is one of the major abiotic stresses that limit rice production in the world. The salinity–alkalinity tolerance of rice at the germination stage has a direct effect on the survival and final yield of seedlings in direct sowing. However, there are few reports of quantitative trait locus (QTL) mapping and mapping-based cloning of alkaline tolerance at the bud burst stage. Here, new alkaline tolerance loci were constructed for F_2:3 and BC₃F₄ by using IR36 and Long-Dao124 (LD124) rice varieties with significant differences in alkaline tolerance. Through linkage analysis and a fine-mapping strategy, qAT3 was identified as the major QTL for alkaline tolerance at the bud burst stage, which could explain 14.79% of the phenotypic variation on average. Then the interval was fine-mapped to 110.265 kb, and the candidate gene LOC_Os03g03150 was predicted by quantitative real-time polymerase chain reaction (qRT-PCR) analysis and sequencing analysis. This provides a key theory for the molecular breeding of alkali-tolerant genes and the study of the molecular mechanism of alkali tolerance in LD124. Full article

Background/Objectives: First row transition metal ions have recently regained attention in coordination chemistry as alternatives to gadolinium-based paramagnetic contrast agents, motivated by emerging safety concerns associated with certain Gd³⁺-based contrast agents. In this study, we report the development of a novel homoleptic diketonate Fe³⁺ complex functionalized with biocompatible indole moieties. We investigate its potential as a paramagnetic relaxation agent by evaluating its ability to modulate the T₁ and T₂ relaxation times of water proton. Methods: Iron(III) tris-1,3-(1-methylindol-3-yl)propanedionate [Fe(BIP)₃] was synthesized via a thermal method from bis(1-methylindol-3-yl)-1,3-propanedione (HBIP) using Fe(ClO₄)₃∙6 H₂O as the metal source. The complex was characterized by UV-Vis, IR and NMR spectroscopy, differential scanning calorimetry–thermogravimetric analysis, and single-crystal X-ray diffraction. Fe(BIP)₃ aggregation behavior in aqueous environment, including size and morphology of aggregates, was investigated using dynamic light scattering and scanning electron microscopy. Incorporation of the aggregates into phospholipid vesicles was evaluated by fluorescence resonance energy transfer and fluorescence correlation spectroscopy. The paramagnetic properties of monomeric Fe(BIP)₃ were probed in solution by nuclear magnetic resonance recurring to the Evans bulk magnetization method. Results: The designed synthetic procedure successfully afforded Fe(BIP)₃, which was fully characterized by UV-Vis and IR spectroscopy, as well as single-crystal X-ray diffraction. Aqueous solutions of Fe(BIP)₃ spontaneously formed rice-grain-shaped nanoscale aggregates of hydrodynamic radius ≈ 30 nm. Incorporation of these aggregates into phospholipid vesicles enhanced their stability. The longitudinal r₁ and transverse r₂ relaxivities of Fe(BIP)₃ aggregates were assessed to be 1.92 and 52.3 mM⁻¹s⁻¹, respectively, revealing their potential as paramagnetic relaxation agents. Conclusions: Fe(BIP)₃ aggregates, stabilized through incorporation into phospholipid vesicles, demonstrate promising potential as novel paramagnetic relaxation agents in aqueous environments. Full article

Silica extracted from rice straw was utilized to synthesize nanoscale ZSM-5 zeolite, which was further modified with platinum (Pt) or gold (Au). The structural properties of the materials were examined using XRD, SEM, and BET analysis, while acidity distribution was determined by in situ FT-IR through pyridine adsorption. The zeolitic samples were evaluated as catalysts for isopropanol conversion in the temperature range of 150–275 °C. Modification of HZSM-5 with Au and Pt introduced additional active metal sites and enhanced the acidity of the catalyst, thereby lowering the activation energy for dehydration reactions and improving catalytic performance. Both acetone and propene were produced from isopropanol conversion across all catalysts, with oligomerization occurring at temperatures above 200 °C. Among the catalysts, HZSM-5 modified with 4% Pt or 4% Au exhibited superior conversion rates and selectivity to propene, achieving 92% selectivity at 200 °C. The enhanced propylene selectivity and stability of Au/HZSM-5 are associated with preserved medium-strength acid sites, as evidenced by in situ FT-IR pyridine adsorption, particularly the band at 1457 cm⁻¹. Theoretical studies indicated that incorporating noble metals such as Au and Pt enhances the stability of the zeolite structure, which is consistent with the experimental results, suggesting new potential for advanced catalysis and material science applications. Full article

Temperature and relative humidity can significantly affect quality of paddy rice during storage. Limited studies established the link between storage time, environmental fluctuations, changes in grain and flour physicochemical properties, and culinary performances. In a West African context, IR 841 paddy rice variety was stored under humid–sub-humid (HSH), and dry (DRY) conditions for 12 months. Over 12 months, rice stored under DRY conditions experienced greater environmental fluctuations than rice stored under HSH conditions. Grain water absorption capacity (WAC) increased during storage under DRY conditions, rising from 3.3 ± 0.3 to 3.8 ± 0.3 g/g DM between 0 and 12 months. Flour amylose content and soluble solids remained relatively stable from month 0 to 6 in all conditions, and further under HSH conditions. The observed changes led to improved grain cooking performance after 6 months of storage under DRY conditions. After 12 months, a decrease in rice flour WAC and a peak in viscosity were observed, while mean particle size increased from 42 ± 1 to 67 ± 3 μm under HSH conditions and from 31 ± 3 to 83 ± 3 μm under DRY conditions. Storage time may reduce the breadmaking capacity of rice flour. Overall, environmental fluctuations under DRY conditions strongly affected rice grain and flour properties. Full article

Promising approach for the expansion of the functional food sector is combining various ingredients with potential health benefits. The aim of this study was to create protein aggregates by freeze-drying encapsulation. Rice or pea proteins were used as carriers for encapsulation of chokeberry juice polyphenols. Additionally, disaccharides (sucrose and trehalose) were added to explore possible enhancement of encapsulation of polyphenols. Two methods were employed for complexation of ingredients prior to freeze-drying: one based on complexation of all ingredients at the same time and the other on complexation first of proteins with disaccharides and then with chokeberry juice. All parameters affected the binding of polyphenols on proteins. Total polyphenols, proanthocyanidins, individual polyphenols, and antioxidant potentials of created protein aggregates were determined. When rice protein was the main carrier, the addition of disaccharides caused a decrease in total polyphenols and proanthocyanindins contents (22.41–24.01 mg GAE/g and 6.36–7.28 mg PB2E/g, respectively) in comparison to aggregates without their addition (28.03 mg GAE/g and 8.57 mg PB2E/g, respectively). In the case of pea proteins, a different trend was observed. Aggregates without disaccharide addition had a lower amount of total polyphenols and proanthocyanindins (21.25 mg GAE/g and 5.56 mg PB2E/g, respectively) than those with disaccharide addition (21.42–26.44 mg GAE/g and 6.37–9.45 mg PB2E/g, respectively). Interactions between compounds were proven through IR spectra, and they included changes in amid structures, as well as hydrogen bonds and hydrophobic interactions. Such formulated plant-based protein aggregates can be used in the food industry for the enrichment of foods with polyphenols, incensement of antioxidant potential, and prolonging stability of products. Full article

P-cresol, indole and indole-3-acetic acid (IAA) are catabolites of amino acids, formed by the gut microbiome. Most of these aromatic hydrocarbon derivatives are excreted by the colon before reentering the body to form “exogenous” protein-bound uremic toxins (PBUTs), which aggravate chronic kidney disease (CKD). Removal efficiencies of these PBUT precursors from model phosphate-buffered saline solutions by three different surface-modified nanoporous carbon adsorbents (PCs) were studied. PCs were produced by physicochemical and/or acid base activation of carbonized rice husk waste. Removal rates achieved values of 32–96% within a 3 h contact time. High micro/mesoporosity and surface chemistry of the N- and P-doped biochars were established by N₂ adsorption studies, SEM/EDS analysis, XPS and FT-IR-spectroscopy. The ammoxidized PC-N1 had the highest adsorption capacity (1.97 mmol/g for IAA, 2.43 mmol/g for p-cresol and 2.42 mmol/g for indole), followed by “urea-nitrified” PC-N2, whilst the phosphorylated PC-P demonstrated the lowest adsorption capacity for these solutes. These results do not correlate with the total pore volume values for PC-N2 (0.91 cm³/g) < PC-P (1.56 cm³/g) < PC-N1 (1.84 cm³/g), suggesting that other parameters such as the micropore volume (PC-N1 > PC-N2 > PC-P) and the interaction of surface chemical functional groups with the solutes play key roles in the adsorption mechanism. N-doped PC-N1 and PC-N2 have basic functional groups with higher affinity with acidic IAA and p-cresol. The ion-exchange mechanism of phenolic and indolic compound chemisorption by nanoporous carbon adsorbents, modified with surface N- and P-containing functional groups, has been proposed. Full article

The System of Rice Intensification which promotes agro-ecological practices like alternate wetting and drying (AWD) to enhance root growth and resource efficiency, relies on the genotypic capacity of rice varieties to undergo physiological adaptation. This study elucidates the molecular basis of such adaptation by investigating the transcriptomic profile of four rice varieties to continuous flooding (CF) and AWD at 50 days after transplanting. Our analysis revealed distinct, organ-specific acclimation strategies. Roots underwent extensive transcriptional reprogramming, underscoring their role as the primary site of plasticity. Under CF, a conserved response involving cell wall reinforcement was accompanied by variety-specific strategies, ranging from sustained growth to enhanced anaerobic metabolism. Under AWD, roots shifted toward water stress management, with varieties employing distinct defensive (e.g., diterpenoid biosynthesis) and metabolic programs. Associated transcription factors (TFs) enriched under CF included Dof and MYB, whereas bZIP, HSF, and WRKY factors predominated under AWD. In leaves, acclimation to AWD involved more targeted adjustments, including modulation of nitric oxide signaling and photoprotective pathways, regulated by TFs such as WRKY, NAC, and HSF. Varieties with robust TF responses, such as IR64 and Hitachi hatamochi, showed comprehensive regulatory shifts, while others exhibited more constrained profiles. Overall, this study provides a molecular framework for understanding variety-specific adaptation to SRI-relevant water management practices and identifies key TFs as promising candidates for breeding climate-resilient rice. Full article

This study developed a process for producing prebiotic-fortified instant rice macaroni to diversify rice-based convenience foods. Resistant starch (RS) rice flour from three varieties—IR504 and two pigmented, anthocyanidin-rich rice cultivars (Huyet Rong and MS2019)—was blended with wheat flour and fixed ingredients (tapioca starch, salt, and vegetable oil at a ratio of 9g:1g:1g), together with hot water. The instant rice macaroni with the highest RS content (11.64%) was obtained using IR504 RS and wheat flour (44:6), gelatinized at 100 °C for 20 min, microwaved at 36 W/g for 30 s, retrograded at 4 °C for 24 h, and sterilized at 115 °C for 15 min. For anthocyanidin-containing macaroni, the combination of Huyet Rong RS and wheat flour (39:11) yielded 9.47% RS under similar retrogradation and sterilization conditions, but with a shorter gelatinization step (100 °C, 15 min) and longer microwave treatment (50 s at 27 W/g). The other optimized colored-RS formulation was based on MS2019 RS and wheat flour (21:29) processed under similar conditions. All optimized formulations exhibited lower estimated glycemic index (eGI) values of 64.1, 65.7, and 68.2, which were significantly lower than those of the control instant rice macaroni (78.2–85.9, p < 0.05). This study confirms the potential of developing instant rice macaroni rich in RS to enhance prebiotic effects that support the growth of beneficial intestinal bacteria, strengthen immune function, and improve nutritional quality through the incorporation of anthocyanidin-rich rice varieties and a processing procedure combining heat–moisture treatment with microwave heating. Full article