Search Results (1,233)

Brown spot, caused by the seedborne fungus Bipolaris oryzae, remains a major constraint in rice production. Here, we used in vitro and in vivo assays to evaluate the biocontrol potential of three Bacillus strains (Ba. cereus OQ725688.1, Ba. velezensis OP938696.1, and Ba. subtilis OP937353.1) against Bi. oryzae in two rice cultivars (“Rubelita” and “Predileta”). Ba. cereus showed the highest in vitro mycelial inhibition (≈95%), whereas Ba. velezensis was the most effective under greenhouse conditions, reducing disease severity by up to 60% and increasing seedling vigor by 51% compared with infected controls. “Predileta” showed the strongest response to bacterial treatment, maintaining severity scores below 2 even under high inoculum pressure. Functional assays confirmed that all strains displayed amylolytic, catalase, and phosphate-solubilizing activities, with Ba. velezensis uniquely expressing strong cellulase and protease activities. Genome analysis of Ba. velezensis OP938696.1 revealed multiple biosynthetic gene clusters for antifungal polyketides and lipopeptides. These integrated biochemical and genomic traits demonstrate the novelty and potential of this Neotropical strain as a multifunctional agent capable of suppressing Bi. oryzae while enhancing rice seedling performance. Incorporating such a native strain into seed and soil management offers a sustainable strategy for rice protection in Neotropical systems. Full article

Flag leaf angle (FLA) in rice (Oryza sativa L.) is one of the important traits affecting F₁ seed production by mechanization. Here, we report the map-based cloning and functional characterization of the FLA1 (FLAG-LEAF-ANGLE 1) gene, which resides at a major-effect quantitative trait locus (QTL). Through cell morphological observations and exogenous hormone treatment assays, we demonstrate that gibberellin (GA) modulates rice FLA by altering both the number of cell layers and cell length. Combining genetic and molecular biological analyses with genetic complementation and gene overexpression assays, we elucidated and validated the biological function of FLA1. In addition, we found that FLA1 is constitutively expressed and encodes a protein localized to both the cell membrane and nucleus. Via RT-qPCR assays, we further demonstrated that the FLA1^fla-R allele from the rice accession fla-R enhances GA biosynthesis by upregulating the expression of CLA1 and GA20ox2. Furthermore, yeast two-hybrid assays revealed that auxin-repressed protein 1 (ARP1) interacts with FLA1, suggesting a potential role of this interaction in the modulation of rice FLA. Collectively, our results demonstrate that optimizing rice FLA via molecular manipulation of FLA1 can resolve the problem of flag leaf shearing during F₁ hybrid rice seed production without compromising F₁ hybrid seed yield, thereby facilitating mechanized F₁ hybrid rice seed production. Full article

Rice blast and bacterial blight are two major diseases that seriously threaten rice production. Developing rice germplasm with enhanced resistance to multiple diseases while maintaining favorable agronomic traits is essential for sustainable breeding. In this study, two rice landraces from Motuo County, Xizang Autonomous Region, China, Benglinba and Gare, were used to simultaneously edit OsERF922 and Xa41 using a structurally optimized dual-target CRISPR/Cas9 vector, pRGEB32-2T. A total of 32 and 28 T₀ transgenic plants were generated in the Benglinba and Gare backgrounds, respectively. Targeted mutagenesis generated eight homozygous oserf922 mutants and three homozygous xa41 mutants in Benglinba, and four and five homozygous mutants in Gare. Twelve double homozygous mutant lines (nine Benglinba and three Gare) were selected for further analysis. Disease resistance assays showed that these double mutants exhibited significantly enhanced resistance to the rice blast fungus strain GDYJ7 and the bacterial blight pathogen strain GDXO-1, with markedly reduced lesion size or lesion length compared with wild-type plants (p < 0.001, Student’s t-test). Importantly, three independent T-DNA-free double mutant lines from each genetic background displayed no significant differences from their corresponding wild types in major agronomic traits, including plant height, effective panicle number, panicle length, seed-setting rate, or thousand-grain weight (p > 0.05). Grain quality parameters, such as brown rice rate, milled rice rate, amylose content, and gel consistency, were also unaffected. Overall, this study generated rice materials with enhanced resistance to rice blast and bacterial blight while maintaining elite agronomic and quality traits, providing valuable germplasm resources and a feasible strategy for the precise improvement of disease resistance in rice landraces from Xizang Autonomous Region. Full article

Rice blast, caused by the fungal pathogen Pyricularia oryzae, remains one of the most destructive diseases threatening global rice production. Although the deployment of resistant cultivars is widely regarded as the most effective and sustainable control strategy, resistance based solely on host genetics often has limited durability due to the rapid adaptation of the pathogen. Increasing evidence suggests that plant-associated microbial communities contribute to host health and disease resistance, yet the role of seed-associated microbiota in shaping rice blast resistance remains insufficiently understood. In this study, we investigated seed endophytic bacterial communities across multiple indica–japonica hybrid rice varieties from the Yongyou series that exhibit contrasting levels of resistance to rice blast. By integrating amplicon sequencing, we identified distinct seed bacterial assemblages associated with blast-resistant and blast-susceptible varieties were identified. Notably, the microbial communities in blast-resistant varieties exhibited significantly higher Shannon index, with a median value of 3.478 compared to 2.654 in susceptible varieties (p < 0.001), indicating a greater diversity and more balanced community structure compared to those in susceptible varieties. Several bacterial taxa consistently enriched in resistant varieties showed negative ecological associations with P. oryzae, both at the local scale and across publicly available global metagenomic datasets. These findings indicate that seed endophytic bacterial communities are non-randomly structured in relation to host resistance phenotypes and may contribute to rice blast resistance through persistent ecological interactions with the pathogen. This work highlights the potential importance of seed-associated microbiota as intrinsic components of varietal resistance and provides a microbial perspective for improving durable disease resistance in rice breeding programs. Full article

Speed breeding represents a pivotal technology for enhancing crop breeding efficiency. This study systematically examined the regulation of LED light environments, planting density, and gibberellic acid (GA₃) on rice growth cycle progression in plant factories, establishing an integrated speed breeding protocol. The experimental design comprised three components: (1) coupling seedling age (9–25 days, variety-dependent) with LED environments and planting densities (25–100 plants/tray); (2) combining light intensity gradients (450 and 900 μmol·m⁻²·s⁻¹) with photoperiod control; (3) applying GA₃ gradients (0–120 ppm) to enhance immature seed germination. Results indicated that high planting densities (>50 plants/tray) prolonged the growth cycle and decreased yield, whereas 25 plants/tray optimally balanced growth cycle shortening and yield maximization. Under short-day induction, Nipponbare (Nip) and Wufeng B (WFB) reached heading at 39 and 58 days after sowing (DAS), respectively. Stage-specific light responses were observed: 450 μmol·m⁻²·s⁻¹ during the basic vegetative phase (BVP) promoted morphological development, whereas 900 μmol·m⁻²·s⁻¹ during the photoperiod-sensitive phase (PSP) accelerated tillering and panicle differentiation. GA₃ treatment (60 ppm) enhanced the germination rate of immature seeds by 31%. The optimized lightregimes comprised natural light + 900 μmol·m⁻²·s⁻¹ (NL–900) and 450 μmol·m⁻²·s⁻¹ + 900 μmol·m⁻²·s⁻¹ (450–900), combined with density control (25 plants/tray) and GA₃-mediated immature seed utilization, shortened the generation time to 54 days and 70 days for Nip and WFB, respectively. This integrated protocol establishes an efficient strategy for rice speed breeding in plant factories. Full article

The larvae and damage symptoms of Cnaphalocrocis medinalis and Cnaphalocrocis patnalis exhibit a high degree of similarity, which often leads to confusion between the two species. This has posed challenges for research on their population dynamics and the development of effective control measures. To better understand their morphological and damage characteristics, population dynamics, species identification based on COI gene fragments, and potential future distribution, a searchlight trap monitoring program was conducted for C. medinalis and its closely related species C. patnalis across four sites in Longhua, Haitang, and Yazhou districts in Hainan Province from 2021 to 2023. The MaxEnt model was utilized to predict the potential global distribution of both species, incorporating known occurrence points and climate variables. The trapping results revealed that both species reached peak abundance between April and June, with a maximum of 1500 individuals captured in May at Beishan Village, Haitang District. Interannual population fluctuations of both species generally followed a unimodal pattern. Genetic analyses revealed distinct differences in the mitochondrial COI gene fragment, confirming that C. medinalis and C. patnalis are closely related yet distinct species. The population peak of C. patnalis occurred slightly earlier than that of C. medinalis, and its field damage was more severe. Infestations during the booting to heading stages of rice significantly reduced seed-setting rates and overall yield. Model predictions indicated that large areas of southern Eurasia are suitable for the survival of both species, with precipitation during the wettest month identified as the primary environmental factor shaping their potential distributions. At present, moderately and highly suitable habitats for C. medinalis account for 2.50% and 2.27% of the global land area, respectively, whereas those for C. patnalis account for 2.85% and 1.19%. These results highlight that climate change is likely to exacerbate the damage caused by both rice leaf-roller pests, particularly the emerging threat posed by C. patnalis. Overall, this study provides a scientific basis for invasion risk assessment and the development of integrated management strategies targeting the combined impacts of C. medinalis and C. patnalis. Full article

This study examines the socio-demographic characteristics, rice production practices, and breeding preferences of farmers across three major rice-growing regions of Vietnam: the Mekong Delta, Central Vietnam, and North Vietnam. A survey of 109 rice farmers captured information on cultivation status, livelihood activities, and preferred breeding traits for rice improvement. The results reveal clear regional differentiation in farm structure, production objectives, and varietal preferences. Rice farming in the Mekong Delta is predominantly commercially oriented, characterized by larger landholdings and greater male participation, whereas rice production in Central and Northern Vietnam is more subsistence-oriented, with higher female involvement. Farmers across regions consistently valued locally adapted rice varieties, but articulated region-specific trait priorities shaped by agro-ecological conditions. In the Mekong Delta, preferences emphasized soft grain quality and salinity tolerance, reflecting coastal production constraints. In Central Vietnam, farmers prioritized heat tolerance and resistance to pests and diseases, while in Northern Vietnam, cold tolerance and grain quality attributes, including aroma and harder texture, were most important. Major biotic stresses, particularly blast and bacterial blight, also showed significant regional variation in reported incidence. By linking these region-specific preferences to clearly defined Target Populations of Environments (TPEs), this study provides a practical framework for aligning breeding targets with real-world production conditions. The findings offer actionable guidance for participatory breeding and decentralized varietal evaluation under the Biodiversity for Opportunities, Livelihoods, and Development (BOLD) initiative, as well as other rice improvement programs. To our knowledge, this represents the first multi-region evidence from Vietnam that systematically integrates agro-ecological variation with a TPE-based breeding approach, supporting the development of climate-resilient, farmer-preferred rice varieties and more sustainable rice production systems. Full article

Pre-emergence control is one of the critical steps in the agricultural production of direct-seeding rice. To investigate the mechanism of pre-emergence flame control, a flame control test bench and a flame control and sowing integrated operation machine were designed and made. The experimental results demonstrate that tall fescue seeds achieved complete inactivation (100% rate) when exposed to a target temperature of 140 °C for 1 min. A temperature distribution analysis revealed that the 1 mm soil layer exhibited a lower temperature rise compared with the surface layer, while the 2 mm layer recorded the minimum temperature elevation. Among the tested nozzle–soil distances, 150 mm significantly improved the soil-heating efficacy over 200 mm, with 100 mm yielding the optimal performance. Statistical analysis confirmed that the nozzle–soil distance, seed burial depth, and operating speed exerted highly significant (p < 0.01) effects on the tall fescue seed inactivation rate. The seed burial depth emerged as the most influential factor, followed by the operating speed and nozzle–soil distance. Data from the field experiment further revealed a speed-dependent decline in the inactivation rates: 80.27% at 3 km·h⁻¹, 66.30% at 4 km·h⁻¹, and 46.10% at 5 km·h⁻¹, and SPSS analysis indicated that there were extremely significant differences between every pair of groups of data (p < 0.01). This study verified that pre-emergence flame control technology can effectively eliminate grass seeds on the soil surface and has a certain inhibitory effect on shallow-buried seeds, which contributes to the advancement of pre-emergence control technology. Full article

Rice (Oryza sativa L.) root system plays a critical role in water and nutrient uptake, influencing overall plant growth and crop yield. In this study, we characterized the Osdrp2b mutant, which exhibits a short-root phenotype and was identified through map-based cloning. The Osdrp2b mutation was traced to the gene encoding a dynamin-related protein, and the mutant displayed reduced cell elongation and impaired cell division in the root tip. Further analysis revealed that ROS (reactive oxygen species) accumulation was elevated in the mutant roots, and treatment with ROS inhibitors restored root elongation in the Osdrp2b mutant, indicating that altered ROS homeostasis is associated with the phenotype. Transcriptomic analysis highlighted the differential expression of genes involved in cell wall organization and hydrogen peroxide catabolism. Agronomic evaluations of the Osdrp2b mutant demonstrated compromised shoot growth, reduced tiller number, and lower seed setting rates, indicating the impact of the mutation on rice yield. Overall, these results suggest that OsDRP2B is involved in regulating root growth, potentially through effects on ROS homeostasis and associated signaling networks. These findings provide a basis for future studies on improving rice root development and agronomic performance. Full article

Aflatoxin contamination of maize by Aspergillus section Flavi constitutes a major health and economic concern. While biological control using non-toxigenic strains has proven effective, the increasing global food demand underscores the need for alternative carrier materials to replace seeds and grains. The aims of the present study were (1) to develop an innovative macroporous starch polymer in which the biocontrol agent can grow and be transported to fields where the bioformulate is applied, and (2) to evaluate the effectiveness of this new formulate in reducing AF contamination in maize kernels in field trials, in comparison with the traditional formulate based on long-grain rice as a substrate. Several methods and different starch sources were tested, and the formulation consisting of 10% maize starch, 0.5% citric acid, 3% sucrose, 0.3% urea, and distilled water was the most effective. Furthermore, this bioformulate demonstrated a performance comparable to that of the traditional long-grain rice-based formulation, reducing AF accumulation by up to 81% in maize kernels under field conditions. The implementation of this macroporous starch polymer-based formulation, in combination with the biological control agent A. flavus AFCHG2, would not only reduce aflatoxin contamination in maize kernels but also minimise the use of food-grade seeds and grains for industrial purposes, thereby preserving their availability for human and animal nutrition. Consequently, this development could enhance the availability of these substrates for food and feed use, thereby contributing to improved safety and food security. Full article

Seed vigor is a key agronomic trait that integrates germination capacity and seedling establishment, critically influencing rice productivity. Inositol hexakisphosphate (IP₆) serves as a major phosphorus reservoir in seeds, yet its regulatory mechanism in seed vigor remains unclear. Here, we demonstrate that exogenous IP₆ application inhibited seed germination and seedling growth of japonica rice (Oryza sativa L. ssp. japonica cv. Zhonghua11) in a dose-dependent manner; 10 mM IP₆ reduced seed germination by 100%, while 100 μM IP₆ suppressed primary root length by 33.6% compared to the control. This inhibitory effect is likely mediated by antagonizing auxin signaling, as supported by suppressed DR5::GUS expression and altered transcription of auxin-responsive genes. OsIPK2, a key enzyme in IP₆ biosynthesis, showed high expression during early development in rice. RNA interference of OsIPK2 led to a 40.8–61.7% reduction in seed IP₆ content, 45.3–65% higher zinc (Zn) and iron (Fe) accumulation, and a 35.4–53.5% lower germination rate compared to wild-type (WT). Conversely, OsIPK2-RNAi seedlings exhibited enhanced growth and resistance to IP₆, which was associated with misregulation of auxin-responsive genes and a decrease in the repressive histone mark H3K27me3 at their loci. Furthermore, endogenous indole-3-acetic acid (IAA) levels significantly reduced in Ri-1 but unchanged in Ri-2, while abscisic acid (ABA) content and the IAA/ABA ratio remained unaltered compared to wild-type. Our findings reveal that OsIPK2 balances seed vigor and seedling development by modulating inositol phosphate metabolism, auxin responses, and epigenetic regulation, providing insights for improving seed quality in cereals. Whether the regulatory role of OsIPK2 in seed vigor is conserved across other rice subspecies requires further investigation. Full article

Soil salinity is a major abiotic stress that limits rice production, with severity varying among genotypes. It disrupts key physiological processes, particularly water uptake and membrane integrity. This study evaluated six rice genotypes to (i) determine the critical salinity threshold for seed germination and (ii) investigate the physiological mechanisms underlying genotypic variation. Seeds were exposed to saline solutions of up to 32 dS m⁻¹ under controlled conditions, and germination was recorded at 2, 5, 10, and 14 days after stress imposition. Additional assays at 0, 12, 18, and 24 dS m⁻¹ for 1, 3, and 5 days assessed water uptake, electrolyte leakage, and malondialdehyde (MDA) accumulation. The critical threshold for germination was consistent across genotypes (26.01–28.53 dS m⁻¹), except for Nona Bokra, which was more sensitive (20.5 dS m⁻¹). Salinity reduced seed water uptake and promoted membrane degradation, as evidenced by increased electrolyte leakage and MDA accumulation, with severity proportional to stress duration. Full article

Direct seeding of rice reduces labor intensity and cost, helping alleviate labor shortages in cold-region rice production. To investigate the effects of mechanical precision hill-direct seeding versus mechanical transplanting on yield and nutrient accumulation in cold regions, a set of field split-plot experiments were conducted with cultivation method as the main plot and rice variety as the sub-plot. Our comprehensive measurement results indicate that transplanting significantly increased yield by enhancing tiller number, filled grains per panicle, and grain weight per hill, with significant varietal differences observed. No significant difference in 1000-grain weight was found between the two cultivation methods. Except for Zn content, different cultivation methods have no significant effect on other measured nutrients such as N, P, K, Fe, starch, and fat. Transplanting significantly increased effective tiller number (an increase of 2.6 tillers per hill) and filled grains per panicle (an increase of 12.4 grains), with a significant variety–cultivation method interaction. Qijing 2 (QJ2) and Tiandao 261 (TD261) were more suitable for transplanting to achieve high yield potential, whereas Longgeng 3038 (LG3038) and Tianxiangdao 9 (TXD9) obtained relatively high yields under direct seeding. Therefore, appropriate cultivation methods should be selected based on varietal characteristics: transplanting is recommended for high-yield-potential varieties, while simplified direct seeding is advised for varieties tolerant to direct seeding. Overall, this is a comprehensive consideration and rational strategy based on balancing rice yield, revenue, and benefit, as well as ensuring both food security and farmer income of the entire country and society. Full article

Background/Objectives: FLOURY ENDOSPERM 2 (FLO2) is known to affect rice endosperm development and starch quality, yet its role in determining flour physicochemical behavior and endosperm structural integrity has not been quantitatively defined. This study aimed to elucidate how loss of FLO2 function alters starch organization and functional properties of rice flour. Methods: Two independent homozygous, T-DNA-free OsFLO2 knockout lines were generated in the japonica cultivar Dongjin using CRISPR/Cas9. Grain appearance was evaluated in mature seeds. Flour physicochemical properties were analyzed by Rapid Visco Analyzer (RVA) and differential scanning calorimetry (DSC). Amylopectin chain-length distribution was determined by isoamylase debranching followed by HPAEC-PAD, and endosperm microstructure was examined by scanning electron microscopy. Results: OsFLO2 mutants exhibited floury, opaque endosperms, with chalkiness increasing from 4.8% in the WT to 27–29%. RVA analysis showed a marked reduction in peak viscosity (1193 cP to 263–293 cP) and a decrease in pasting temperature (77.2 °C to 68.9–70.5 °C). DSC indicated a tendency toward reduced gelatinization enthalpy in the mutants. These changes were associated with a reduced proportion of short amylopectin chains (DP 6–12), decreased long chains (DP ≥ 37), and a relative increase in intermediate-long chains (DP 25–36), along with disrupted granule packing and a 1.33–1.36-fold increase in endosperm porosity. Conclusions: These results demonstrate that FLO2 plays an important role in maintaining the structural integrity of rice endosperm by harmonizing the microstructure of amylopectin with the thermal and gelatinization properties of starch. Full article

Small-grained rice varieties are highly valued in hybrid seed production and food markets because of their unique advantages in mechanized seed production and cooking qualities. Developing new varieties combining small grain size with high nutritional and cooking quality represents an important breeding objective. The OsVIN2 gene has been identified as a key regulator involved in carbohydrate metabolism and grain development in rice. In this study, a CRISPR/Cas9-mediated gene-editing approach was employed to precisely modify the OsVIN2 gene in the restorer line MH86 of high-quality rice varieties. Compared with the wild-type plants, the frameshift mutant seeds showed a significant reduction in length and width by 19.9% and 15.2%, respectively, leading to a 39.2% decrease in thousand-grain weight. Notably, the mutant exhibited improved quality traits, including a decrease of 16.6% in amylose content, an increase of 11.0% protein, and a 77.5% and 84.7% decrease in chalkiness rate and chalkiness degree, respectively. These results demonstrate that targeted editing of OsVIN2 is a promising approach for creating novel small-grained rice germplasm with superior quality attributes. Full article