Search Results (211)

Rice (Oryza sativa L.) production is constantly threatened by devastating diseases such as rice blast, bacterial blight, and brown planthopper infestation. The AP2-type transcription factor OsHTR (also known as SMOS1/SHB/RAL1/NGR5/GR5) has been previously implicated in hormonal signaling networks and nitrogen use efficiency; however, its role in disease resistance remains largely unexplored. In this study, we functionally characterized OsHTR in disease resistance using knockout (KO) and overexpression (OE) transgenic lines in the ZH11 background. Transcriptome analysis revealed that differentially expressed genes in the htr mutant were significantly enriched in plant–pathogen interaction pathways, with multiple NBS-LRR and NB-ARC resistance-related genes upregulated. Real-time PCR validation confirmed the upregulation of 15 candidate resistance genes in the htr mutant. Comprehensive resistance evaluations suggested that HTR-KO lines exhibited enhanced resistance to rice blast and bacterial blight compared to wild-type ZH11 and HTR-OE lines, which displayed moderate susceptibility. In contrast, all lines remained highly susceptible to brown planthopper, indicating a disease-specific regulatory function of OsHTR. Furthermore, targeted knockout of individual upregulated resistance-related genes (LOC_Os10g04090, LOC_Os12g29690, LOC_Os02g11980, and LOC_Os11g11770) and OsHTR-interacting gene LOC_Os06g03710 confirmed their distinct contributions to blast and bacterial blight resistance but did not establish them as direct targets of OsHTR. Collectively, our results indicate that OsHTR functions as a negative regulator of disease resistance in rice, likely acting through transcriptional repression of defense-related genes, although direct binding remains to be demonstrated. This study uncovers a novel regulatory module connecting AP2-type transcription factors to disease resistance and provides valuable genetic resources for molecular breeding of broad-spectrum-resistant rice cultivars. Full article

Developing zinc oxide-based nano-bactericides as alternatives to conventional chemical bactericides for controlling rice bacterial diseases has become a major research focus. In this study, ZnO nanoparticles were initially surface-modified and subsequently covalently conjugated with chitooligosaccharide (COS) via imine bonds to get a pH-responsive zinc oxide–chitooligosaccharide (ZnO–COS) delivery system. A series of physicochemical characterizations, including FTIR, UV-vis, XRD, and TGA, confirmed the successful synthesis of ZnO–COS NPs. Building on this foundation, the pH-responsive release behavior, foliar deposition performance, antibacterial activity, and biosafety of the nanoparticles were systematically investigated. The prepared ZnO–COS NPs exhibited pronounced acid-triggered Zn²⁺ release, together with enhanced wettability, spreadability, and retention on rice leaf surfaces, owing to COS incorporation. In both in vitro and in vivo assays against Xanthomonas oryzae pv. oryzae (Xoo), ZnO–COS NPs demonstrated effective antibacterial activity associated with bacterial cell damage and the activation of antioxidant defense responses in plants. Consequently, ZnO–COS NPs achieved a preventive efficacy of 56.0% against rice bacterial blight, surpassing those of ZnO (33.3%) and COS (14.3%). Furthermore, safety assessment confirmed the good biocompatibility of ZnO–COS NPs towards rice seed germination and seedling growth. In summary, the synthesised ZnO–COS NPs integrated pH-responsive release, improved foliar deposition, and enhanced antioxidant capacity of rice, offering a promising strategy for mitigating bacterial diseases in rice. Full article

Rice sheath blight (RSB), caused by Rhizoctonia solani, causes 10–50% yield losses globally. Using 16S rRNA sequencing of 100 rice cultivars, we found that resistant varieties harbor significantly more diverse bacterial communities (3230 OTUs; 2064 unique) than susceptible cultivars (599 OTUs; 36 unique). Resistant varieties were enriched in beneficial Burkholderiaceae, Bacillaceae, and Pseudomonadaceae, while Sphingobacteriaceae and Enterobacteriaceae were predominant in the susceptible rice varieties. From the 260 bacterial isolates, Burkholderia vietnamiensis J14EPLEAF2 presented potent antifungal activity (77% inhibition), suppressed lesion development, and abolished sclerotia formation. This strain displayed multiple plant growth-promoting traits, enhanced seed germination, and primed defense responses by upregulating PR5 and PR10. Hypersensitive response assays confirmed B. vietnamiensis as non-pathogenic, unlike B. gladioli and B. cepacia. This study identifies B. vietnamiensis J14EPLEAF2 as a promising, safe biocontrol agent for sustainable rice disease management. Full article

As a devastating disease worldwide, rice bacterial leaf blight—caused by Xanthomonas oryzae pv. oryzae (Xoo)—leads to substantial reductions in grain yield. The increasing resistance to conventional bactericides necessitates the development of novel and sustainable control agents. This study evaluated 58 novel alkyl sulfonamide compounds against Xoo. In the turbidimetric assay at 100 mg/L, several compounds showed potent antibacterial activity. Among them, SYAUP-116 and SYAUP-212 exhibited in vitro inhibition comparable to that of streptomycin sulfate at the same concentration. Furthermore, in EC₅₀ determination assays, both compounds yielded lower EC₅₀ values than zinc thiazole. Among the 58 compounds tested, SYAUP-491 exhibited an in vitro EC₅₀ of 6.96 mg/L and achieved 74.1% in vivo therapeutic efficacy at 200 mg/L, representing the most promising lead for further characterization. Molecular docking, based on prior proteomic data, indicates potential stable binding to ribosomal proteins (50S L33/L34 and 30S S5), with the strongest interaction observed for L33 (binding free energy: −5.73 kcal/mol). This suggests a putative mechanism involving ribosome targeting and protein synthesis inhibition, which may be facilitated by hydrophobic interactions and halogen bonds derived from its trifluoromethyl and sulfonamide groups. SYAUP-491 demonstrates significant potential as a novel bactericide for rice bacterial leaf blight, warranting further research on structure-activity optimization, target validation, and field performance. Full article

Bacterial blight (BB), caused by Xanthomonas oryzae pv. Oryzae (Xoo), is one of the most devastating diseases in rice worldwide. Common wild rice (Oryza rufipogon Griff.) inhabiting the high-temperature and high-humidity environments of Hainan Island has evolved strong disease resistance through natural selection, representing a valuable genetic reservoir for resistance breeding. However, large-scale characterization of resistance phenotypes, resistance genes, and their combinations remains limited. In this study, we evaluated BB resistance in 1511 Hainan common wild rice accessions against three Xoo strains (HNX004, PXO99^A, and Z173) and analyzed the distribution of ten major known resistance genes (Xa1, Xa3, Xa4, xa5, Xa7, Xa10, xa13, Xa21, Xa23, and Xa27). Phenotypic evaluation revealed distinct strain-specific resistance patterns. Broad-spectrum resistance analysis (defined as moderate resistance or higher) revealed that 35 accessions (2.32%) were resistant to all strains, and 378 accessions (25.02%) showed resistance to two strains. Genotyping of known resistance genes revealed that, except for one accession, which lacked all tested genes but showed resistance to strain PXO99^A, all other accessions carried every tested gene except Xa21 and xa13. Interestingly, different Xoo strains exhibited distinct requirements for resistance genes, revealing a clear strain-specific resistance pattern. Notably, the number of resistance genes did not correlate with resistance level. Instead, specific complementary combinations, particularly Xa1 + Xa10 + Xa23 + Xa4 + Xa7, conferred the strongest broad-spectrum resistance. Our results demonstrate that gene quality and specific complementary combinations are more important than the absolute number of resistance genes. The identified resistant accessions and favorable gene combinations provide valuable resources for rice breeding programs. Full article

Accurate field-scale crop disease detection is crucial for precise decisions and for highly efficient multi-scale collaboration. UAV-based multispectral imaging technology offers advantages in terms of high efficiency and low cost. Deep learning shows potential for deep representation and fusion of spectral and spatial features. However, traditional manual disease surveys are limited by efficiency and cost, making it difficult to meet the large sample sizes required by deep learning. Therefore, we proposed a method for rice bacterial leaf blight detection using UAV-based multispectral imagery. This method integrates a cross-scale sample-label transfer, and a spectral–spatial dual-branch feature fusion architecture (DualRiceNet). We first used RTK positioning to transfer disease labels from near-ground RGB images to high-altitude multispectral images, effectively expanding the dataset and alleviating the scarcity of labeled samples. DualRiceNet employed a cross-attention mechanism to couple its spectral and spatial branches, thereby isolating disease-specific spatial–spectral patterns from complex interference from the farmland background. DualRiceNet achieved an overall accuracy (OA) of 92.3% on the same-distribution test set. In an independent scenario test set spanning multiple differences in geography, time, phenology, and variety, the model maintained the highest OA of 80.0%. Our method demonstrated an excellent generalization ability to real-world environmental variations in rice fields. Full article

Rice (Oryza sativa) production faces serious threats from multiple biotic stresses, particularly the brown planthopper, rice blast, and bacterial blight. Developing resistant cultivars is the most sustainable control strategy. Compared to race-specific resistance genes, disrupting susceptibility genes often confers broader and potentially more durable resistance. However, engineering broad-spectrum resistance against both insect pests and pathogens by editing susceptibility genes remains challenging. In this study, we employed multiplex CRISPR/Cas9 editing to simultaneously disrupt key susceptibility genes involved in distinct defense pathways: ACS2 (for brown planthopper), Bsr-D1, ERF922 or Pi21 (for fungal blast), and Xa5 (for bacterial blight). Three triple-mutant lines (abx, aex, and apx) were successfully generated, and all exhibited significantly enhanced resistance to brown planthopper, blast, and bacterial blight without compromising major agronomic traits compared to the wild type. Our work demonstrates the feasibility of multiplex susceptibility gene editing as a precise and efficient strategy for breeding rice varieties with synchronized, broad-spectrum resistance to both insect pests and pathogenic diseases. 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

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

Rice blast and bacterial blight cause severe harm to rice production, and the breeding of resistant varieties guarantees the safety of rice production. Meanwhile, multigene pyramiding breeding based on molecular marker-assisted selection is a crucial approach for rice breeding to combat multiple diseases. This study aimed to develop accurate and efficient PARMS markers for rice blast resistance genes Pita, Pigm, and Pi2, and bacterial blight resistance gene Xa23. A systematic genotyping analysis of the resistant alleles of these 4 genes was performed on 384 major cultivated varieties in production. The results showed that only 5.21% of the varieties harbored more than two resistant alleles simultaneously. Using traditional breeding strategies in combination with the developed PARMS markers, the high-quality three-line male sterile line Ruanfeng A (pyramiding Pita and Pigm) and the strong restorer line Gui 610 (pyramiding Pi2 and Xa23) were bred. Crossing these lines produced a new hybrid rice variety, Ruanfengyou 610. Ruanfengyou 610 pyramids 4 resistance genes (Pita/Pigm/Pi2/Xa23), exhibits resistance to both rice blast and bacterial blight, has prominent heterosis and excellent grain quality, and has strong application potential, which is of great significance for ensuring the safety of rice production. Full article

Rice (Oryza sativa) is one of the world’s major staple foods. However, stable rice production is constrained by various biotic and abiotic and stresses. Breeding and cultivation of rice varieties with resistance to multiple pathogens and environmental stresses is the most effective strategy to mitigate the adverse effect of pathogen attacks and abiotic stresses. Recently, researchers have focused on the exploitation of CRISPR/Cas9 technology to manipulate some negative defense-regulator genes to generate rice varieties with broad-spectrum resistance against rice pathogens. In this study, four negative regulator genes of rice blast, OsMads26, OsBsr-1, OsELF3-2 and OsERF922, were selected as CRISPR/Cas9 targets. By simultaneously knocking out all four genes via CRISPR/Cas9 technology, we created three mads26/bsr-1/elf3-2/erf922 quadruple knockout mutants. Our results demonstrated that all quadruple mutants exhibited much higher resistance not only to rice blast and bacterial blight but also to drought and salt stresses than the wildtype. Interestingly, grain yield of all three quadruple mutants was also drastically increased by 17.35% to 21.95%. Therefore, this study provides a novel strategy to rapidly improve rice varieties with broad-spectrum resistance to pathogens, elevated tolerance to abiotic stresses and enhanced yield potential. Full article

The bacterium Xanthomonas oryzae pv. oryzae is an important pathogen that causes wilt leaf blight disease in rice (Oryza sativa L.), leading to a reduction in rice yield. Therefore, this study aimed to investigate the potential of a surfactant complex composed of CO₂ nanobubbles (CO₂-NBs) coated with sorbitan monostearate (Sp60) and a crude extract of Trichoderma polyalthiae as active ingredient delivery agents for controlling leaf blight under both laboratory and greenhouse conditions. The addition of Sp60 and crude extract as surfactants significantly influenced the size uniformity and stability of CO₂-NBs at the nano level, with the nanobubbles remaining intact in water for up to 14 days. In addition, CO₂-NBs with crude extract and Sp60 reduced the severity of wilt, with an minimum inhibitory concentration (MIC) value of 64 µg/mL and an minimum bactericidal concentration (MBC) value of 128 µg/mL, and inhibited the disease by more than 50% in greenhouse conditions. Therefore, this study presents a creative and eco-friendly approach to managing bacterial leaf blight in rice that is innovative and relevant to sustainable plant protection. Full article

Bacterial blight in rice, caused by Xanthomonas oryzae pv. oryzae (Xoo), poses a serious threat to global rice production. The ability of Xoo to form biofilms is a key factor for its virulence. The OryR protein is a LuxR-type quorum-sensing regulator essential for biofilm formation and Xoo pathogenicity. However, the three-dimensional structure of OryR remains poorly understood. This study integrates homology modeling, molecular dynamics (MD) simulations, and virtual screening to elucidate the structure of OryR and identify potential inhibitors that target its ligand-binding domain. MD simulations confirmed the structural stability of OryR, and comparative analysis with experimentally determined structures of ligand- or inhibitor-bound homologs revealed a binding site in OryR with a distinct hourglass-like shape for long-range contacts. Virtual screening of over 200,000 compounds from four chemical libraries identified several promising inhibitor candidates, with the top compounds showing strong binding energies in both molecular mechanics-generalized Born surface area (−68.3 kcal/mol) and molecular mechanics Poisson–Boltzmann surface area (−19.3 kcal/mol) calculations. Overall, this study provides insights into the OryR structure and highlights potential inhibitors that can be developed as novel agents to control bacterial blight. However, additional experimental validations are required to refine and optimize these leads for drug development. Full article

Biological control is an effective and environmentally friendly strategy for managing plant diseases. In this study, a broad-spectrum antagonistic bacterium, designated strain AN6, was isolated from rice plants and exhibited potent inhibitory activity against a variety of phytopathogens. In Oxford cup assays, AN6 suppressed the growth of Xanthomonas oryzae pv. oryzae (Xoo) by 73.60%, and its cell-free culture filtrate caused pronounced morphological deformation in the bacterial cells. Further in vitro assays, including dual-culture assays, volatile organic compound (VOC) assays, and cell-free supernatant (CFS) assays, demonstrated that AN6 also exerted strong antifungal effects against several pathogenic fungi. In addition, the strain was found to produce proteases and siderophores, which may contribute to its antagonistic capabilities. Taxonomic identification based on morphological traits, 16S rRNA and gyrA gene sequencing, average nucleotide identity (ANI), in silico DNA–DNA hybridization (isDDH), and phylogenetic analysis classified strain AN6 as Bacillus velezensis. Whole-genome sequencing revealed that AN6 harbors a 3,929,788 bp genome comprising 4025 protein-coding genes with a GC content of 46.50%. Thirteen biosynthetic gene clusters (BGCs) associated with the production of secondary metabolites—such as nonribosomal peptides, polyketides, and dipeptide antibiotics—were identified. The pot experiment further validated the biocontrol potential of AN6, achieving an 80.49% reduction in rice bacterial blight caused by Xanthomonas oryzae pv. oryzae. Collectively, these results indicate that B. velezensis AN6 is a promising candidate for development as a highly effective biocontrol agent for the integrated management of diverse plant diseases. Full article

Bacterial leaf blight (BLB), a destructive disease of rice caused by Xanthomonas oryzae pv. oryzae (Xoo), continues to limit rice productivity worldwide. Although biologically synthesized zinc oxide nanoparticles (ZnO NPs) have been extensively investigated, knowledge regarding the antibacterial activity and biocompatibility of commercially available ZnO NPs is still limited. In this study, commercial ZnO NPs were systematically characterized and evaluated for their antibacterial mechanisms and biocompatibility in mammalian cells. FE-SEM and TEM analyses revealed irregular polyhedral, hexagonal, and short rod-like morphologies with an average particle size of ~33 nm, consistent with crystallite sizes estimated by XRD. The nanoparticles exhibited pronounced antibacterial activity against Xoo, with a minimum inhibitory concentration (MIC) of 16 µg/mL and a clear dose-dependent response. Mechanistic assays confirmed multifaceted bactericidal actions involving membrane disruption, ROS generation, Zn²⁺ release, and ultrastructural damage. Biocompatibility testing in human dermal fibroblasts showed enhanced proliferation at 8–32 µg/mL, no cytotoxicity up to 256 µg/mL, and reduced viability only at ≥512 µg/mL. These findings represent the first mechanistic evaluation of commercial ZnO NPs against Xoo, together with cytotoxicity assessment in mammalian cells, highlighting their structural distinctness and dual functionality that combine potent antibacterial activity with minimal mammalian cytotoxicity. Overall, the results underscore their potential as safe nanobiocontrol agents for sustainable rice disease management. Full article