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BACKGROUND: Succinate dehydrogenase inhibitor (SDHI) fungicides play important roles in the control of plant fungal diseases. However, they are facing serious challenges from issues with resistance and cross‐resistance, primarily attributed to their frequent application and structural similarities. There is an urgent need to design and develop SDHI fungicides with novel structures. RESULTS: Aiming to discover novel potent SDHI fungicides, 31 innovative pyrazole β‐ketonitrile derivatives with diphenyl ether moiety were rationally designed and synthesized, which were guided by a 3D‐QSAR model from our previous study. The optimal target compound A23 exhibited not only outstanding in vitro inhibitory activities against Rhizoctonia solani with a half‐maximal effective concentration (EC50) value of 0.0398 μg mL−1 comparable to that for fluxapyroxad (EC50 = 0.0375 μg mL−1), but also a moderate protective efficacy in vivo against rice sheath blight. Porcine succinate dehydrogenase (SDH) enzymatic inhibitory assay revealed that A23 is a potent inhibitor of SDH, with a half‐maximal inhibitory concentration of 0.0425 μm. Docking study within R. solani SDH indicated that A23 effectively binds into the ubiquinone site mainly through hydrogen‐bonds, and cation–π and π–π interactions. CONCLUSION: The identified β‐ketonitrile compound A23 containing diphenyl ether moiety is a potent SDH inhibitor, which might be a good lead for novel fungicide research and optimization. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

As targeted mutagenesis techniques become more prevalent for various filamentous fungi, the use of physical mutagen to induce random genetic variations across whole-genome remains an ideal option for genetic improvement. The aim of this study was to investigate the use of gamma radiation to enhance the antagonistic ability of Trichoderma against plant pathogenic fungi. The spore suspensions of Trichoderma koningiopsis VTCC 31435 was irradiated at doses ranging from 0 to 2500 Gy using a gamma Co-60 source at the Hanoi Irradiation Center. The results showed that the number of surviving spores depends on the irradiation dose. Spore numbers decreased sharply in the dose range of 100 to 1200 Gy, at higher doses, the variation in spore numbers was less pronounced. The required radiation dose to kill 90% of the total number of fungal spores (D10) of the T. koningiopsis VTCC 31435 strain was approximately 250 Gy. At a dose of 2500 Gy, the number of fungal but surviving spores decreased by about 7 Log units compared to the non-irradiated. After irradiation, morphological changes, as well as growth characteristics, were observed in some of the radiation-resistant obtained colonies. Using cellophane membrane assay and dual culture methods, five potential radiation-resistant mutants with better antagonistic ability against the fungus Rhizoctonia solani, which causes sheath blight in rice, were identified Notably, among these, the potential mutant VTCC(a) I-1 exhibited the highest antifungal activity of media-permeable metabolites (ICMA) and mycelial growth inhibition activity (IMG) against R. solani. The ICMA and IMG values of this mutant increased by 154.12% and 148.68%, respectively, compared to the wild-type strain and remained stable for at least six consecutive generations. The research results suggest that gamma irradiation may have potential applications in enhancing the antagonistic abilities against pathogenic fungi and other beneficial biological properties in Trichoderma sp. [ABSTRACT FROM AUTHOR]

BACKGROUND: Rice sheath blight caused by Rhizoctonia solani is a severe threat to the yield and quality of rice. Due to the unscientific abuse of common fungicides causing resistance and environmental issues, the development of new fungicides is necessary. In this study, we used citral as the lead compound, designed and synthesized a series of novel citral amide derivatives, and evaluated their antifungal activity and mode of action against R. solani. RESULT: Bioassay results indicated that the antifungal activities of most citral amide derivatives against R. solani were significantly improved compared to citral, with EC50 values ranging from 9.50–27.12 mg L−1. Among them, compound d21 containing the N‐(pyridin‐4‐yl)carboxamide group exhibited in vitro and in vivo fungicidal activities, with curative effects at 500 mg L−1 as effectively as the commercial fungicide validamycin·bacillus. Furthermore, d21 prolonged the lag phase of the growth curve of R. solani, reduced the amount of growth, and inhibited sclerotium germination and formation. Mechanistically, d21 deformed the mycelia, increased cell membrane permeability, and inhibited the activities of antioxidant and tricarboxylic acid cycle (TCA)‐related enzymes. Metabolome analysis showed the abundance of some energy‐related metabolites within R. solani increased, and simultaneously the antifungal substances secreted by itself reduced. Transcriptome analysis showed that most genes encoding ATP‐binding cassette (ABC) transporters and peroxisomes upregulated after the treatment of d21 and cell membrane destruction. CONCLUSION: This study indicates that novel citral amide derivatives possess antifungal activity against R. solani and are expected to develop an alternative option for chemical control of rice sheath blight. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Kuttanad in India is known as ‘the rice bowl of Kerala’ and renowned for its unique rice cultivation system that is below sea level. However, rice production in this wetland ecosystem is seriously threatened by sheath blight disease caused by the fungus Rhizoctonia solani, which has resulted in a significant decline in grain quality and a 50% loss in yield. In the present study, we isolated two endophytic Bacillus subtilis strains, NIIST B616 and NIIST B627, from the roots of rice plants growing in the Kuttanad region and tested their efficacy in controlling sheath blight disease. We found that rice plants inoculated with a combination of both Bacillus strains and R. solani had a 64.71% lower disease incidence and a 31.02% higher harvest index than plants treated with R. solani alone. An analysis of defence-related enzymes and chemicals revealed that treatment with both isolates together greatly enhanced levels of l-phenylalanine ammonia-lyase (PAL; 2.8 fold), peroxidase (POX; 7.4 fold), polyphenol oxidase (PPO; 4.5 fold), and total phenol (8.5 fold) compared with plants treated solely with R. solani, indicating that these isolates significantly increased plant defence responses through induced systemic resistance (ISR), and this finding was validated through a split-root experiment. More detailed analysis using gas chromatography–tandem mass spectrometry (GC-MS/MS) and liquid chromatography–tandem mass spectrometry (LC-MS/MS) techniques revealed that cyclo-(Pro-Leu) and cyclo-(Pro-Phe) were the major components responsible for the antifungal properties of the two isolates and their capacity to trigger ISR in plants. Thus, the Bacillus strains and their metabolites may be deemed viable alternatives for controlling the prevalence of sheath blight disease in rice plants and augmenting rice production at unique locations such as Kuttanad. [ABSTRACT FROM AUTHOR]

Rice sheath blight is one of the most important fungal disease‐causing yield losses up to 50%. An Oryza rufipogon‐derived introgression line (Pusa 1908‐13‐12‐5) identified to be highly resistant to sheath blight was used for developing a RIL population by crossing with a highly susceptible rice cultivar, Pusa Basmati 1 (PB 1). The RIL population was genotyped with 80K Rice Pangenome (RPAN) single nucleotide polymorphism (SNP) array and phenotyped for disease response under artificial inoculation for 2 consecutive years. Inclusive composite interval mapping could identify six quantitative trait loci (QTLs) for two traits, namely, relative lesion height and relative yield loss per plant. Among these QTLs, four were major QTLs and three are novel QTLs. Three major QTLs were co‐localised within 1.4 Mb region on chromosome 1. In silico analysis revealed the presence of 12 candidate genes with potential role in disease resistance. Kompetitive Allele Specific PCR (KASP™) assay was developed for the linked SNPs and used for validation in an independent BC1F2:3 population (PB 1121/Pusa 1908‐13‐12‐5). One SNP (AX‐182186537) on chromosome 1 was validated, which offers scope for its utilisation in marker‐assisted breeding. [ABSTRACT FROM AUTHOR]

Vermicompost (VC) produced by African nightcrawler earthworms (Eudrilus eugeniae) is a natural fertilizer with a rich microbial community. Trichoderma asperelloides PSU-P1 is an effective antagonistic microorganism with multifaceted activity mechanisms. This research aimed to develop Trichoderma-bioenriched vermicompost (TBVC) to promote plant growth and induce the defense response in the Thai rice variety "Chor Khing". T. asperelloides PSU-P1 was tested against Rhizoctonia solani, the pathogen of sheath blight disease, using a dual-culture assay. The results showed that T. asperelloides PSU-P1 effectively inhibited R. solani in vitro growth by 70.48%. The TBVC was prepared by adding a conidial suspension (108 conidia/mL) to vermicompost. The viability of Trichoderma persisted in the vermicompost for 6 months and ranged from 1.2 to 2.8 × 107 CFU/mL. Vermicompost water extracts significantly enhanced seed germination, root length, and shoot length compared to a control group (p < 0.05). Plants that received the TBVC displayed significantly longer shoot and root lengths and higher total chlorophyll content than control plants (p < 0.05). The TBVC induced defense response by increasing the enzyme activity of peroxidase (POD) and polyphenol oxidase (PPO) in comparison with control plants. Rice grown in the TBVC had a significantly reduced incidence of sheath blight caused by R. solani in comparison with control rice (p < 0.05). Furthermore, the fungal community of rice plants was analyzed via the high-throughput next-generation sequencing of the internal transcribed spacer (ITS). The fungal community in the TBVC had greater alpha diversity than the community in the VC. Phylum Ascomycota was dominant in both samples, and a heat map showed that Trichoderma was more prevalent in the TBVC than in the VC. Our results indicate that the enrichment of VC with Trichoderma increases growth, enhances the defense response, and reduces the incidence of sheath blight disease in the Thai rice variety "Chor Khing". [ABSTRACT FROM AUTHOR]

In this study, the compound 1-(4-(tert-butyl) phenyl)-3-hydroxy-2-methylpyridine-4 (1H) - one (hereinafter referred to as HAINU-19) was used as the active ingredient to prepare the microemulsion and determine its antifungal activity. First, through the screening solvents, co-solvents, and transparent, the formulation of 2.5% HAINU-19 microemulsion (mass fraction) was determined as follows: 2.5% HAINU-19, 15% ethanol, 10% cyclohexanone, 20% transparent (1601# : 500# : AC1810 = 3 : 3 : 1), with distilled water making up to 100%. All indicators meet national standards. The bioassay result of pot experiments showed that the protective and curative effects of 2.5% HAINU-19 microemulsion on wheat stripe rust were 100% at 1000, 500, and 250-fold dilutions, and curative effects were 76.67%, 81.00%, and 82.33%, respectively. The field trial results showed that the 2.5% HAINU19 microemulsion had a control efficacy of 86.13% on rice sheath blight at a 100-fold dilution and 71.24% at a 200-fold dilution. This study can provide an experimental basis and technical support for the development and application of the antifungal compound HAINU-19. [ABSTRACT FROM AUTHOR]

Rice sheath blight is a serious disease caused by Rhizoctonia solani that reduces rice yield. Currently, there is a lack of efficient and environmentally friendly control methods. In this study, we found that Bacillus velezensis (B. velezensis) Y6 could significantly inhibit the growth of mycelium in Rhizoctonia solani, and its control efficiency against rice sheath blight was 58.67% (p < 0.01) in a pot experiment. Lipopeptides play an important role in the control of rice sheath blight by B. velezensis Y6, among which iturin and fengycin are essential, and iturin W, a novel lipopeptide in B. velezensis, plays a major role in lipopeptide antagonism to Rhizoctonia solani. In the field, we also found that inoculation with B. velezensis Y6 can increase rice yield (dry weight) by 11.75%. Furthermore, the transcriptome profiling results of the rice roots revealed that there were a total of 1227 differential genes (DEGs) regulated when treated with Y6, of which 468 genes were up-regulated and 971 genes were down-regulated in rice roots compared with the control. Among them, the DEGs were mainly distributed in biological processes (BP) and were mainly enriched in response to stimulus (GO:0050896), response to stress (GO:0006950), and response to abiotic stimulus (GO:0009628). According to the KEGG pathway analysis, there were 338 DEGs classified into 87 KEGG functional pathway categories. Compared with the control, a large number of enriched genes were distributed in phenylpropanoid biosynthesis (map00940), glutathione metabolism (map00480), glycolysis/gluconeogenesis (map00010), and amino sugar and nucleotide sugar metabolism (map00520). In summary, this investigation provides a new perspective for studying the molecular mechanism of B. velezensis in controlling rice sheath blight. [ABSTRACT FROM AUTHOR]

Rice sheath blight, caused by Rhizoctonia solani Kihn (R. solani), poses a significant threat to rice production and quality. Autotetraploid rice, developed through chromosome doubling of diploid rice, holds great potential for enhancing biological and yield traits. However, its resistance to sheath blight in the field has remained unclear. In this study, the field resistance of 35 autotetraploid genotypes and corresponding diploids was evaluated across three environments from 2020 to 2021. The booting stage was optimal for inoculating period based on the inoculation and analysis of R. solani at five rice growth stages. We found autotetraploids generally exhibited lower disease scores than diploids, indicating enhanced resistance after chromosome doubling. Among the 35 genotypes, 16 (45.71%) displayed increased resistance, 2 (5.71%) showed decreased resistance, and 17 (48.57%) displayed unstable resistance in different sowing dates. All combinations of the genotype, environment and ploidy, including the genotype-environment-ploidy interaction, contributed significantly to field resistance. Chromosome doubling increased sheath blight resistance in most genotypes, but was also dependent on the genotype-environment interaction. To elucidate the enhanced resistance mechanism, RNA-seq revealed autotetraploid recruited more down-regulated differentially expressed genes (DEGs), additionally, more resistance-related DEGs, were down-regulated at 24 h post inoculation in autotetraploid versus diploid. The ubiquinone/terpenoid quinone and diterpenoid biosynthesis pathways may play key roles in ploidy-specific resistance mechanisms. In summary, our findings shed light on the understanding of sheath blight resistance mechanisms in autotetraploid rice. [ABSTRACT FROM AUTHOR]

Rice sheath blight, caused by the soil-borne fungus Rhizoctonia solani (teleomorph: Thanatephorus cucumeris, Basidiomycota), is one of the most devastating phytopathogenic fungal diseases and causes yield loss. Here, we report on a very high prevalence (100%) of potential virus-associated double-stranded RNA (dsRNA) elements for a collection of 39 fungal strains of R. solani from the rice sheath blight samples from at least four major rice-growing areas in the Philippines and a reference isolate from the International Rice Research Institute, showing different colony phenotypes. Their dsRNA profiles suggested the presence of multiple viral infections among these Philippine R. solani populations. Using next-generation sequencing, the viral sequences of the three representative R. solani strains (Ilo-Rs-6, Tar-Rs-3, and Tar-Rs-5) from different rice-growing areas revealed the presence of at least 36 viruses or virus-like agents, with the Tar-Rs-3 strain harboring the largest number of viruses (at least 20 in total). These mycoviruses or their candidates are believed to have single-stranded RNA or dsRNA genomes and they belong to or are associated with the orders Martellivirales, Hepelivirales, Durnavirales, Cryppavirales, Ourlivirales, and Ghabrivirales based on their coding-complete RNA-dependent RNA polymerase sequences. The complete genome sequences of two novel RNA viruses belonging to the proposed family Phlegiviridae and family Mitoviridae were determined. [ABSTRACT FROM AUTHOR]

[Objectives] Aiming at the lack of disease description in rice diseases and pests image classification technology, a lightweight rice diseases and pests image description model was proposed in this paper to describe rice diseases and pests image more specifically. [Methods] Ten common rice pests and diseases, such as rice bacterial blight, rice bacterial streak disease, rice bakanae disease, rice three chemical borers, rice blast, rice false smut, rice sheath blight, rice planthopper, rice thrip and rice brown spot were studied, and Chinese description data set of rice pests and diseases image was constructed. Firstly, the multimodal pre-training model CLIP was used to generate image vectors, which contained basic image information and rich semantic information. The mapping network was used to map the image vectors into the text space to generate text prompt vectors. Finally, the language model GPT-2 generates image descriptions according to the prompt vectors. [Results] The test results showed that the indexes of the model in this paper were significantly superior to other models in the image description data set of rice pests and diseases. Compared with the traditional CNN_ LSTM model, the indexes of BLEU-1, BLEU-2, BLEU-3, BLEU-4, ROUGE and METEOR improved 0.26, 0.27, 0.24, 0.22, 0.22 and 0.14, respectively. And the generated image description had the advantages of accurate, detailed and rich semantics. The model was tested by using actual rice field pictures. The actual field scenes were more complex and diverse, and the generated image description index only slightly decreased compared with the data set index, which was still higher than other comparison models. The overall recognition accuracy of the model was 97.28%. [Conclusions] The image description method of rice diseases and pests based on multimodal pre-training model can accurately describe the rice diseases and pests, and provide a new idea for the detection of rice diseases and pests. [ABSTRACT FROM AUTHOR]

Half of the world's population depends on rice for their calories. Protecting rice in the growth period from damage caused by phytopathogens is faced with a great challenge under the frequent extreme climate. To find novel fungicides to control rice diseases, 35 novel phenylthiazole‐1,3,4‐oxadiazole‐thioether (sulfone) derivatives were synthesized and evaluated for their efficacy against destructive fungal and bacterial diseases of rice. Bioassay results demonstrated that most of G‐series compounds possessed excellent antifungal and antibacterial activities. In particular, compounds G1 (EC50 = 2.22 μg/mL, R.s) and G7 (EC50 = 2.76 μg/mL, R.s) showed the most promising antifungal activities in vitro and exhibited superior protective and curative activities against rice sheath blight in vivo compared with commercial carbendazim. Surprisingly, compound G2 exhibited the remarkable antibacterial activity against Xanthomonas oryzae pv. oryzae (Xoo) with an EC50 value of 1.98 μg/mL, and demonstrated superior protective activity (88.08%) than thiodiazole copper (79.39%) against rice bacterial leaf blight at 200 μg/mL. The abovementioned results fully manifested that the phenylthiazole‐1,3,4‐oxadiazole‐sulfone structure, especially compounds G1 and G2, had the potential to develop as commercial agents for controlling rice fungal and bacterial diseases. [ABSTRACT FROM AUTHOR]

Rice sheath blight, caused by Rhizoctonia solani AG1-IA, is a major disease in rice-growing areas worldwide. Effectors of phytopathogenic fungi play important roles during the infection process of fungal pathogens onto their host plants. However, the molecular mechanisms by which R. solani effectors regulate rice immunity are not well understood. Through prediction, 78 candidate effector molecules were identified. Using the tobacco rattle virus-host induced gene silencing (TRV-HIGS) system, 45 RNAi constructs of effector genes were infiltrated into Nicotiana benthamiana leaves. The results revealed that eight of these constructs resulted in a significant reduction in necrosis caused by infection with the AG1-IA strain GD-118. Additionally, stable rice transformants carrying the double-stranded RNA construct for one of the effector genes, AGLIP1 , were generated to further verify the function of this gene. The suppression of the AGLIP1 gene increased the resistance of both N. benthamiana and rice against GD-118, and also affected the growth rate of GD-118, indicating that AGLIP1 is a key pathogenic factor. Small RNA sequencing showed that the HIGS vectors were processed into siRNAs within the plants and then translocated to the fungi, leading to the silencing of the target genes. As a result, AGLIP1 might be an excellent candidate for HIGS, thereby enhancing crop resistance against the pathogen and contributing to the control of R. solani infection. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa) stands as a crucial staple food worldwide, especially in Bangladesh, where it ranks as the third-largest producer. However, intensified cultivation has made high-yielding rice varieties susceptible to various biotic stresses, notably sheath blight caused by Rhizoctonia solani, which inflicts significant yield losses annually. Traditional fungicides, though effective, pose environmental and health risks. To address this, nanotechnology emerges as a promising avenue, leveraging the antimicrobial properties of nanoparticles like silver nanoparticles (AgNPs). This study explored the green synthesis of AgNPs using Ipomoea carnea leaf extract and silver nitrate (AgNO3), and also examined their efficacy against sheath blight disease in rice. The biosynthesized AgNPs were characterized through various analytical techniques such as UV-vis spectrophotometer, X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Particle size analyzer, Zeta potential, Scanning Electron Microscope (SEM), Field Emission Scanning Electron Microscope (FESEM), Transmission Electron Microscope (TEM) for confirming their successful production and crystalline nature of nanoparticles. The results of UV-visible spectrophotometers revealed an absorption peak ranging from 421 to 434 nm, validated the synthesis of AgNPs in the solution. XRD, DLS, and TEM estimated AgNPs sizes were ~45 nm, 66.2nm, and 46.38 to 73.81 nm, respectively. SEM and FESEM demonstrated that the synthesized AgNPs were spherical in shape. In vitro assays demonstrated the significant inhibitory effects of AgNPs on mycelial growth of Rhizoctonia solani, particularly at higher concentrations and pH levels. Further greenhouse and field experiments validated the antifungal efficacy of AgNPs against sheath blight disease in rice, exhibiting comparable effectiveness to commercial fungicides. The findings highlight the potential of AgNPs as a sustainable and effective alternative for managing rice sheath blight disease, offering a safer solution amidst environmental concerns associated with conventional fungicides. [ABSTRACT FROM AUTHOR]

Sheath blight (ShB) is one of the three major diseases in rice and is prevalent worldwide. Lesions spread vertically from leaf sheaths near the water surface towards the upper parts. This increases the need to develop an approach for the early detection of infection. Hyperspectral remote sensing has been proven to be a potential technology for the early detection of diseases but remains challenging due to redundant information and weak spectral signals. This study proposed a stepwise screening method of spectral features for the early detection of ShB using rice canopy hyperspectral data over two years of successive experiments. The procedure consists of the selection of key wavebands using three algorithms and a further filtration of key wavelengths and vegetation indices considering feature importance, separability, and high correlation. Sheath-blight infection can disrupt the canopy architecture and influence the biochemical parameters in rice plants. The study reported that obvious variations in the chlorophyll content and LAI of rice plants occurred under early stress of ShB, and the sensitive features selected had strong correlations with these two growth factors. By fusing support vector machine with the optimal features, the detection model for early ShB exhibited an overall accuracy of 87%, showing higher accuracy at the current level of early-stage detection of rice ShB at the field scale. The proposed method not only provides methodological support for early detecting rice ShB but also serves as a reference for diagnosing other stalk diseases in crops. [ABSTRACT FROM AUTHOR]

Rhizoctonia solani, the causative agent of sheath blight disease in rice, poses a significant threat to agricultural productivity. Traditional management approaches involving chemical fungicides have been effective but come with detrimental consequences for the ecosystem. This study aimed to investigate sustainable alternatives in the form of antifungal peptides derived from Solanaceous plant species as potential agents against R. solani. Peptide extracts were obtained using an optimized antimicrobial peptide (AMP) extraction method and desalted using the solid-phase extraction technique. The antifungal potential of peptide-rich extracts from Solanum tuberosum and Capsicum annum was assessed through in vitro tests employing the agar well diffusion method. Furthermore, peptide-protein docking analysis was performed on HPEPDOCK and HDOCK server; and molecular dynamics simulations (MDS) of 100 ns period were performed using the Gromacs 2020.4. The results demonstrated significant inhibition zones for both extracts at concentrations of 100 mg/mL. Additionally, the extracts of Solanum tuberosum and Capsicum annum had minimum inhibitory concentrations of 50 mg/mL and 25 mg/mL, respectively with minimum fungicidal concentrations of 25 mg/mL. Insights into the potential mechanisms of key peptides inhibiting R. solani targets were gleaned from in-silico studies. Notably, certain AMPs exhibited favorable free energy of binding against pathogenicity-related targets, including histone demethylase, sortin nexin, and squalene synthase, in protein-peptide docking simulations. Extended molecular dynamics simulations lasting 100 ns and MM-PBSA calculations were performed on select protein-peptide complexes. AMP10 displayed the most favorable binding free energy against all target proteins, with AMP3, AMP12b, AMP6, and AMP15 also exhibiting promising results against specific targets of R. solani. These findings underscore the potential of peptide extracts from S. tuberosum and C. annum as effective antifungal agents against rice sheath blight caused by R. solani. [ABSTRACT FROM AUTHOR]

Transcription factors are key molecules involved in transcriptional and post-transcriptional regulation in plants and play an important regulatory role in resisting biological stress. In this study, we identified a regulatory factor, OsZF8, mediating rice response to Rhizoctonia solani (R. solani) AG1-IA infection. The expression of OsZF8 affects R. solani rice infection. OsZF8 knockout and overexpressed rice plants were constructed, and the phenotypes of mutant and wild-type (WT) plants showed that OsZF8 negatively regulated rice resistance to rice sheath blight. However, it was speculated that OsZF8 plays a regulatory role at the protein level. The interacting protein PRB1 of OsZF8 was screened using the yeast two-hybrid and bimolecular fluorescence complementation test. The results showed that OsZF8 effectively inhibited PRB1-induced cell death in tobacco cells, and molecular docking results showed that PRB1 had a strong binding effect with OsZF8. Further, the binding ability of OsZF8-PRB1 to ergosterol was significantly reduced when compared with the PRB1 protein. These findings provide new insights into elucidating the mechanism of rice resistance to rice sheath blight. [ABSTRACT FROM AUTHOR]

In this study, tebuconazole@hollow mesoporous nano silica (Teb@HMS) sustained release granules were prepared. The morphology, structure, and properties were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), specific surface area analyzer (BET), thermogravimetric analyzer (TGA), and other instruments. The release behavior of tebuconazole in sustained-release granules was investigated by high-performance liquid chromatography (HPLC) analysis. The inhibitory activity of Teb@HMS on Rhizoctonia solani was determined by mycelial growth inhibition, potted experiments, and field control efficacy experiments. The safety of Teb@HMS was evaluated through rice seed germination experiments and zebrafish experiments. It was shown that the prepared drug-loaded nanosilica particles exhibited a regular hollow mesoporous structure. The drug loading rate for tebuconazole was 52.02% and the sustained release time was up to 400 hours. Meanwhile, Teb@HMS reduced the toxicity of tebuconazole to non-target rice seeds and zebrafish. The antifungal activity of Teb@HMS was significantly better than the positive control tebuconazole. On the 18th day of pot and field trails, Teb@HMS protection efficacy reached 61.79% and 70.42%, respectively. This study provides technical support and theoretical guidance for the application of hollow mesoporous nano silica sustained-release granules in pesticide reduction and green and sustainable prevention and control of plant diseases. [ABSTRACT FROM AUTHOR]

A breakthrough "Green Revolution" in rice enhanced lodging resistance by using gibberellin-deficient semi-dwarf varieties. However, the gibberellic acid (GA) signaling regulation on rice disease resistance remains unclear. The resistance test showed that a positive GA signaling regulator DWARF1 mutant d1 was more susceptible while a negative GA signaling regulator Slender rice 1 (SLR1) mutant was less susceptible to sheath blight (ShB), one of the major rice diseases, suggesting that GA signaling positively regulates ShB resistance. To isolate the regulator, which simultaneously regulates rice lodging and ShB resistance, SLR1 interactors were isolated. Yeast two-hybrid (Y2H), bimolecular fluorescence complementation (BiFC), and Co-IP assay results indicate that SLR1 interacts with Calcineurin B-like-interacting protein kinase 31 (CIPK31). cipk31 mutants exhibited normal plant height, but CIPK31 OXs showed semi-dwarfism. In addition, the SLR1 level was much higher in CIPK31 OXs than in the wild-type, suggesting that CIPK31 OX might accumulate SLR1 to inhibit GA signaling and thus regulate its semi-dwarfism. Recently, we demonstrated that CIPK31 interacts and inhibits Catalase C (CatC) to accumulate ROS, which promotes rice disease resistance. Interestingly, CIPK31 interacts with Vascular Plant One Zinc Finger 2 (VOZ2) in the nucleus, and expression of CIPK31 accumulated VOZ2. Inoculation of Rhizoctonia solani AG1-IA revealed that the voz2 mutant was more susceptible to ShB. Thus, these data prove that CIPK31 promotes lodging and ShB resistance by regulating GA signaling and VOZ2 in rice. This study provides a valuable reference for rice ShB-resistant breeding. [ABSTRACT FROM AUTHOR]

This article explores the relationship between the fungus Ustilaginoidea virens and the WRKY transcription factor OsWRKY31 in rice plants. The researchers discovered that a specific protein, UvSec117, is a key factor in the virulence of U. virens and interacts with OsWRKY31. They also found that OsWRKY31 positively regulates rice's resistance to various diseases. Through further experiments, they identified the target genes of OsWRKY31, which are involved in induced systemic resistance and the salicylic acid/jasmonic acid signaling pathways. This research provides valuable insights into the molecular mechanisms of rice's resistance to grain-infecting pathogens and has implications for breeding disease-resistant rice varieties. [Extracted from the article]

Rhizoctonia solani is a polyphagous necrotrophic fungal pathogen that causes sheath blight disease in rice. It deploys effector molecules as well as carbohydrate‐active enzymes and enhances the production of reactive oxygen species for killing host tissues. Understanding R. solani ability to sustain growth under an oxidative‐stress‐enriched environment is important for developing disease control strategies. Here, we demonstrate that R. solani upregulates methionine biosynthetic genes, including Rs_MET13 during infection in rice, and double‐stranded RNA‐mediated silencing of these genes impairs the pathogen's ability to cause disease. Exogenous treatment with methionine restores the disease‐causing ability of Rs_MET13‐silenced R. solani and facilitates its growth on 10 mM H2O2‐containing minimal‐media. Notably, the Rs_MsrA gene that encodes methionine sulfoxide reductase A, an antioxidant enzyme involved in the repair of oxidative damage of methionine, is upregulated upon H2O2 treatment and also during infection in rice. Rs_MsrA‐silenced R. solani is unable to cause disease, suggesting that it is important for the repair of oxidative damage in methionine during host colonization. We propose that spray‐induced gene silencing of Rs_MsrA and designing of antagonistic molecules that block MsrA activity can be exploited as a drug target for effective control of sheath blight disease in rice. [ABSTRACT FROM AUTHOR]

Rice sheath blight is a fungal disease caused mainly by Rhizoctonia solani AG1-IA. Toxins are a major pathogenic factor of R. solani, and some studies have reported their toxin components; however, there is no unified conclusion. In this study, we reported the toxin components and their targets that play a role in R. solani AG1-IA. First, toxins produced by R. solani AG1-IA were examined. Several important phytotoxins, including benzoic acid (BZA), 5-hydroxymethyl-2-furanic aid (HFA), and catechol (CAT), were identified by comparative analysis of secondary metabolites from AG1-IA, AG1-IB, and healthy rice. Follow-up studies have shown that the toxin components of this fungus can rapidly disintegrate the biofilm structure while maintaining the content of host plant membrane components, thereby affecting the organelles, which may also explain the lack of varieties highly resistant to sheath blight. [ABSTRACT FROM AUTHOR]

The enhancement of pesticide utilization efficiency for improved biological activity, while promoting crop growth to enhance disease resistance, holds significant importance in agricultural production. In this study, we developed an enzyme-responsive azoxystrobin (AZOX) delivery system using iron-based mesoporous materials as porous carriers and pectin (Pec) as an encapsulation agent to manage rice sheath blight. The resultant AZOX-AFS-Pec nanoparticles (NPs) exhibit high loading capacity and could intelligently release AZOX in acidic conditions in the presence of pectinase. Notably, AZOX-AFS-Pec NPs demonstrated improved wetting and adhesion properties on rice blades, thereby augmenting AZOX utilization. Furthermore, AZOX-AFS-Pec NPs enhanced fungicidal activity against rice sheath blight, with pot experiments revealing comparable control efficacy on rice sheath blight to AZOX suspension concentration (SC). Specifically, AZOX-AFS-Pec NPs exhibited superior prevention and prolonged protection against rice sheath blight compared to AZOX SC. Additionally, continuous release of Fe2+ and Fe3+ by AZOX-AFS-Pec NPs increased chlorophyll content and promoted rice growth. Moreover, these NPs increased salicylic acid (SA) levels in rice plants, fortifying disease resistance. Importantly, AZOX-AFS-Pec NPs demonstrated over a 2-fold reduction in acute toxicity to earthworms compared to AZOX SC. Therefore, stimuli-responsive AZOX-AFS-Pec NPs show great promise for enhancing pesticide effectiveness against pathogens, improving crop traits, and fortifying disease resistance. [ABSTRACT FROM AUTHOR]

Rhizoctonia solani is a destructive soil borne plant pathogen that infects various crops including rice. A total of 35 isolates of R. solani from rice and other different hosts were collected and established. Morphological characterization was done on PDA media by analyzing radial growth, sclerotial pattern and colony colour. Pathogenicity test was conducted in a susceptible variety of rice Pusa Basmati 1. Maximum lesion height (86%) was observed for isolate TP3 and TP26 whereas, the minimum disease was observed for the isolate TP30 (29.2%). Molecular markers namely, internal transcribed spacer (ITS), universal rice primer (URP) and simple sequence repeats (SSR) were used to determine the genetic diversity of the pathogen. The phylogenetic tree obtained based on ITS region sequences grouped R. solani isolates in a single main cluster and 6 subclusters. Based on URP and SSR markers, isolates of R. solani were grouped into three and six clusters respectively. The structure analysis and AMOVA analysis revealed greater genetic variation within populations (91%) compared to among populations (9%). The results demonstrated that R. solani isolates evaluated were pathogenic to rice, irrespective of the host, however, variation exists at molecular level. The findings highlighted the diversity and complexity of the genetic background of R. solani which will be helpful to develop management strategies against the sheath blight disease of rice. Further, R. solani isolates from the host species finger millet (Eleusine coracana), lablab bean (Lablab purpureus), and ginger (Zingiber officinale) were first time characterized from the North-Eastern state through this study. [ABSTRACT FROM AUTHOR]

Rice sheath blight is a serious disease caused by Rhizoctonia solani that reduces rice yield. Currently, there is a lack of efficient and environmentally friendly control methods. In this study, we found that Bacillus velezensis (B. velezensis) Y6 could significantly inhibit the growth of mycelium in Rhizoctonia solani, and its control efficiency against rice sheath blight was 58.67% (p < 0.01) in a pot experiment. Lipopeptides play an important role in the control of rice sheath blight by B. velezensis Y6, among which iturin and fengycin are essential, and iturin W, a novel lipopeptide in B. velezensis, plays a major role in lipopeptide antagonism to Rhizoctonia solani. In the field, we also found that inoculation with B. velezensis Y6 can increase rice yield (dry weight) by 11.75%. Furthermore, the transcriptome profiling results of the rice roots revealed that there were a total of 1227 differential genes (DEGs) regulated when treated with Y6, of which 468 genes were up-regulated and 971 genes were down-regulated in rice roots compared with the control. Among them, the DEGs were mainly distributed in biological processes (BP) and were mainly enriched in response to stimulus (GO:0050896), response to stress (GO:0006950), and response to abiotic stimulus (GO:0009628). According to the KEGG pathway analysis, there were 338 DEGs classified into 87 KEGG functional pathway categories. Compared with the control, a large number of enriched genes were distributed in phenylpropanoid biosynthesis (map00940), glutathione metabolism (map00480), glycolysis/gluconeogenesis (map00010), and amino sugar and nucleotide sugar metabolism (map00520). In summary, this investigation provides a new perspective for studying the molecular mechanism of B. velezensis in controlling rice sheath blight.

Reactive oxygen species (ROS) act as a group of signaling molecules in rice functioning in regulation of development and stress responses. Respiratory burst oxidase homologues (Rbohs) are key enzymes in generation of ROS. However, the role of the nine Rboh family members was not fully understood in rice multiple disease resistance and yield traits. In this study, we constructed mutants of each Rboh genes and detected their requirement in rice multiple disease resistance and yield traits. Our results revealed that mutations of five Rboh genes (RbohA, RbohB, RbohE, RbohH, and RbohI) lead to compromised rice blast disease resistance in a disease nursery and lab conditions; mutations of five Rbohs (RbohA, RbohB, RbohC, RbohE, and RbohH) result in suppressed rice sheath blight resistance in a disease nursery and lab conditions; mutations of six Rbohs (RbohA, RbohB, RbohC, RbohE, RbohH and RbohI) lead to decreased rice leaf blight resistance in a paddy yard and ROS production induced by PAMPs and pathogen. Moreover, all Rboh genes participate in the regulation of rice yield traits, for all rboh mutants display one or more compromised yield traits, such as panicle number, grain number per panicle, seed setting rate, and grain weight, resulting in reduced yield per plant except rbohb and rbohf. Our results identified the Rboh family members involved in the regulation of rice resistance against multiple pathogens that caused the most serious diseases worldwide and provide theoretical supporting for breeding application of these Rbohs to coordinate rice disease resistance and yield traits. [ABSTRACT FROM AUTHOR]

Sheath blight (ShB) disease, caused by Rhizoctonia solani Kühn, is one of the most serious rice diseases. Rice breeding against ShB has been severely hindered because no major resistance genes or germplasms are available in rice. Here, we report that introduction of Gastrodia antifungal protein (GAFP) genes from Gastrodia elata B1 into rice significantly enhances resistance to rice ShB. Four GAFP genes were cloned from G. elata B1, and all displayed a strong ability to inhibit R. solani growth in plate assays. Two versions, with or without a signal peptide, for each of the four GAFP genes were introduced into XD3 and R6547 rice cultivars, and all transgenic lines displayed stronger ShB resistance than the corresponding wild-type control in both greenhouse and field conditions. Importantly, GAFP2 showed the highest ShB resistance; GAFPs with and without its signal peptide showed no significant differences in enhancing ShB resistance. We also evaluated the agronomic traits of these transgenic rice and found that ectopic expression of GAFPs in rice at appropriate levels did not affect agronomic traits other than enhancing ShB resistance. Together, these results indicate that GAFP genes, especially GAFP2, have great potential in rice breeding against ShB disease. [ABSTRACT FROM AUTHOR]

Sheath blight is one of the most important rice diseases and its control is generally achieved by the use of fungicides, but the economic and environmental costs involved have led to a search for alternative management approaches. In this study, we evaluated the efficacy of eight defence inducers against the rice sheath blight pathogen, Rhizoctonia solani AG1‐IA. The results showed that 10 mM p‐aminobenzoic acid (PABA) and 3 mM vitamin B9 (VB9)‐treated plants had significantly lower disease indices, at 2.56 and 3.49, respectively, compared to the control at 5.36 in growth room conditions. The direct effect studies showed that PABA significantly suppressed fungal mycelial growth, sclerotial formation and hyphal regeneration ability. However, VB9 showed no effect on mycelial growth but promoted sclerotial formation and hyphal regeneration. Histological observation showed a decreased lesion size and lower amount of hyphal DNA in inducer‐treated leaves. Reverse transcription‐quantitative PCR revealed that OsPR1b was significantly induced by VB9 and the expression of OsPR5 was potentiated by PABA, which indicates that the salicylic acid pathway is possibly involved in VB9‐induced resistance, and the antifungal protein OsPR5 probably contributes partially to PABA protection against R. solani. Immediate control effects of PABA and VB9 were also found after disease establishment. Under greenhouse conditions, the control effects of PABA and VB9 were 29.8% and 40.5%, respectively. These findings reveal that the application of PABA and VB9 to complement plant resistance to sheath blight appears to be an effective strategy. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to optimize the medium composition and fermentation parameters of Trichoderma harzianum strain UN-2 producing β-glucanase, improve its β-glucanase production capacity, and study the antagonism of the crude enzyme solution of βglucanase on the pathogen of rice sheath blight and its field control effect, so as to clarify the application potential of T. harzianum strain UN2 in controlling rice sheath blight. [Method] In order to optimize the inducing conditions for the production of β-glucanase from T. harzianum strain UN-2, a single factor experiment was conducted to investigate the effects of carbon, nitrogen and metal ions on the production of β-glucanase from T. harzianum strain UN-2, and orthogonal experiments were used to determine the optimal temperature, pH, inoculation amount, bottled amount, shaking speed, and fermentation time for the production of glucanase from T. harzianum strain UN-2. The antifungal and preventive effects of crude β-glucanase solution on rice sheath blight were studied through in vitro antagonism and field experiments. [Result] The optimal carbon and nitrogen sources for the fermentation of β-glucanase from T. harzianum strain UN-2 were wheat bran and ammonium sulfate, respectively. Metal ions Ca2+ and Mg2+ had a significant promotional effect on the activity of β-glucanase induced from T. harzianum. The optimal culture medium for T. harzianum strain UN-2 to produce β-Glucanase were composed of 10.0 g/L wheat bran, 0.5 g/L β-glucan, 4.0 g/L ammonium sulfate, 1.5 mmol/L Ca2+,0.5 mmol/L Mg2+. And the optimal fermentation conditions for producing β-glucanase were as follows: 30 mL medium filled in 250 mL flask with 8 mL inoculum amount of the culture, initial pH 6.5, at 32 °C, with shaker speed 160 r/min, incubating for 64 hours. The crude β-glucanase solution induced from T. harzianum strain UN-2 had a significant inhibitory effect on the mycelial growth and sclerotia germination of Rhizoctonia solani and Rhizoctonia cerealis, and the field control effect on rice sheath blight caused by R. solani was 70.45%, which was equivalent to 5% Jinggangmycin treatment. The crude β-glucanase solution could improve rice seed setting rate and grain plumpness. [Conclusion】 Under the optimal fermentation conditions, the activity of β-glucanase induced from T. harzianum strain UN-2 is 97.68 U/mL, the crude β-glucanase solution has strong antifungal and preventive effects on rice sheath blight, and has a certain growth promotion effect on rice plants. [ABSTRACT FROM AUTHOR]

This article explores the issue of rice sheath blight, a damaging disease caused by the fungus Rhizoctonia solani, which has resulted in significant crop losses in West Bengal, India. The article presents the findings of a study that examined the effectiveness and cost-efficiency of various fungicide combinations in controlling rice sheath blight in real-world conditions. The study determined that a combination of Mancozeb 52.6% and Hexaconazole 2.4% achieved the highest reduction in disease, followed by Hexaconazole 5% EC. The article highlights the importance of integrated approaches to disease management, including cultural practices, resistant varieties, and environmentally friendly methods. [Extracted from the article]

An experiment entitled "Studies on the management of rice diseases through local isolates of Trichoderma spp." was conducted during 2022-23 to evaluate the effect of local isolates of Trichoderma spp. to control the Sheath blight (Rhizoctonia solani) and Brown spot (Helminthosporium oryzae) disease of rice. Trichoderma species had a significant effect on controlling radial growths of Sheath blight and Brown spot disease of rice. Trichoderma isolate S-8 and S-10 (98.10%) significantly inhibited the radial growth of Sheath blight at 96 hours and it was on par with S-5 (97.47%). Trichoderma isolates S-8 and S-10 (98.10%) are very effective for the management of Sheath blight diseases of rice and S-6, S-7, S-9, and S-10 (95.80%) are effective for the management Brown spot disease of rice. [ABSTRACT FROM AUTHOR]

An uracil-azo derivative of quinoline, 1,3-dimethyl-5-(8′-quinolinyl-azo)-6-aminouracil (H2L, 1), was synthesized and then converted into its atropisomers, 1,3-dimethyl-8-(8′-quinolinyl)azaxanthine (α-atropisomer (2) and β-atropisomer (3)). It is indeed a notable accomplishment that the atropisomers were synthesized selectively under dissimilar reaction conditions. Additionally, an axially elongated 5-coordinated distorted square pyramidal copper(II)-complex, [CuII(HL)(H2O)2]NO3 (4), was synthesized from H2L, where it acts as a tridentate ligand. Single crystals of compounds 2–4 were analyzed for their stereochemical characterization. The compounds (2 and 3) belong to the same space group P21 with Z = 2. Based on a torsional angle about N3–N2–C1–C9, which is 48.7(2)° for the α-atropisomer (2) and −48.7(2)° for the β-atropisomer (3), respectively, they are revealed to be atropisomers. According to TD-DFT analysis, the α-atropisomer (2) is 0.05 kcal mol−1 more energetically stable than the β-atropisomer (3). The 5-coordinated Cu1 centre adopts a distorted square pyramidal geometry (space group P21/n, Z = 4), wherein the coordination sites were occupied by three-N and two O-donor atoms from the HL− moiety and the two H2O molecules, respectively. The polycrystalline sample of 4 was subjected to direct current (dc) variable-temperature magnetic susceptibility studies over the temperature range of 1.8–300 K. The magnetic study suggests that copper(II) ions in the crystal lattice have a weak antiferromagnetic interaction, demonstrating the complex to be a mononuclear species. According to the EPR study, the distorted square-pyramidal copper(II) complex may have a dx2−y2 orbital as a ground state. All the compounds have shown significant efficacy against the bacterial plant pathogen, Ralstonia solanacearum Smith. and the fungal plant pathogen, Rhizoctonia solani Kuhn., which cause bacterial wilting of solanaceous crops and sheath blight of rice, respectively. Besides, the atropisomers have demonstrated effectiveness against another bacterial plant pathogen, Xanthomonas oryzaepv. oryzae. that causes bacterial blight of rice. The atropisomers thus differ with respect to biological efficacy towards both bacterial and fungal diseases. [ABSTRACT FROM AUTHOR]

Rice sheath blight (ShB) is a devastating disease that severely threatens rice production worldwide. Induction of cell death represents a key step during infection by the ShB pathogen Rhizoctonia solani. Nonetheless, the underlying mechanisms remain largely unclear. In the present study, we identified a rice transcription factor, OsERF65, that negatively regulates resistance to ShB by suppressing cell death. OsERF65 was significantly upregulated by R. solani infection in susceptible cultivar Lemont and was highly expressed in the leaf sheath. Overexpression of OsERF65 (OsERF65OE) decreased rice resistance, while the knockout mutant (oserf65) exhibited significantly increased resistance against ShB. The transcriptome assay revealed that OsERF65 repressed the expression of peroxidase genes after R. solani infection. The antioxidative enzyme activity was significantly increased in oserf65 plants but reduced in OsERF65OE plants. Consistently, hydrogen peroxide content was apparently reduced in oserf65 plants but accumulated in OsERF65OE plants. OsERF65 directly bound to the GCC box in the promoter regions of four peroxidase genes and suppressed their transcription, reducing the ability to scavenge reactive oxygen species (ROS). The oserf65 mutant exhibited a slight decrease in plant height but increased grain yield. Overall, our results revealed an undocumented role of OsERF65 that acts as a crucial regulator of rice resistance to R. solani and a potential target for improving both ShB resistance and rice yield. [ABSTRACT FROM AUTHOR]

Extensive occurrence of rice sheath blight has been observed in China in recent years due to agricultural practices and climatic conditions, posing a serious threat to rice production. Assessing habitat suitability for rice sheath blight at a regional scale can provide important information for disease forecasting. In this context, the present study aims to propose a regional-scale habitat suitability evaluation method for rice sheath blight in Yangzhou city using multisource data, including remote sensing data, meteorological data, and disease survey data. By combining the epidemiological characteristics of the crop disease and the Relief-F algorithm, some habitat variables from key stages were selected. The maximum entropy (Maxent) and logistic regression models were adopted and compared in constructing the disease habitat suitability assessment model. The results from the Relief-F algorithm showed that some remote sensing variables in specific temporal phases are particularly crucial for evaluating disease habitat suitability, including the MODIS products of LAI (4–20 August), FPAR (9–25 June), NDVI (12–20 August), and LST (11–27 July). Based on these remote sensing variables and meteorological features, the Maxent model yielded better accuracy than the logistic regression model, with an area under the curve (AUC) value of 0.90, overall accuracy (OA) of 0.75, and a true skill statistics (TSS) value of 0.76. Indeed, the results of the habitat suitability assessment models were consistent with the actual distribution of the disease in the study area, suggesting promising predictive capability. Therefore, it is feasible to utilize remotely sensed and meteorological variables for assessing disease habitat suitability at a regional scale. The proposed method is expected to facilitate prevention and control practices for rice sheath blight disease. [ABSTRACT FROM AUTHOR]

To ascertain a simple and reliable artificial inoculation technique for web blight of mungbean, three methods namely foliar spray, soil inoculation and natural field screening at hotspot were evaluated using mungbean variety ML2056. In soil inoculation at 20g/100g of inoculum in top 5 cm of soil, pre- emergence mortality was 26.67 per cent. It exhibited 26.67, 33.33 and 46.67 per cent of seedling rot during third, fourth and fifth weeks after inoculation (WAI), respectively without showing any foliar symptoms. Under natural field conditions, incidence and severity of disease were 36.67 and 26.95 per cent, respectively with 19.46 per cent PDI fifth WAI. In case of foliar spray with 1x10[sup 7] viable propagules per ml, disease incidence and severity were 93.33 and 76.67 per cent, respectively with 92.59 per cent PDI. In case of natural field conditions at hotspot location, disease appeared late exhibiting foliar symptoms but not as severe as in foliar spray. In nutshell, the foliar spray of pathogen was found to be the reliable technique for artificial inoculation of web blight of mungbean. [ABSTRACT FROM AUTHOR]

In the regions of southern Andhra Pradesh, rice brown spot, rice blast, and rice sheath blight have emerged as the most prevalent diseases. The goal of this research is to increase the precision and effectiveness of disease diagnosis by proposing a framework for the automated recognition and classification of rice diseases. Therefore, this work proposes a hybrid approach with multiple stages. Initially, the region of interest (ROI) is extracted from the dataset and test images. Then, the multiple features are extracted, such as color-moment-based features, grey-level cooccurrence matrix (GLCM)-based texture, and shape features. Then, the S-particle swarm optimization (SPSO) model selects the best features from the extracted features. Moreover, the deep belief network (DBN) model trained by SPSO is based on optimal features, which classify the different types of rice diseases. The SPSO algorithm also optimized the losses generated in the DBN model. The suggested model achieves a hit rate of 94.85% and an accuracy of 97.48% with the 10-fold cross-validation approach. The traditional machine learning (ML) model is significantly less accurate than the area under the receiver operating characteristic curve (AUC), which has an accuracy of 97.48%. [ABSTRACT FROM AUTHOR]

This document provides valuable information on the growth characteristics of Rhizoctonia solani, a pathogenic fungus that affects various crops. The study conducted in India focused on the cultural and morphological diversity of the fungus. It found that the fungus showed the highest mycelial growth on Potato Dextrose Agar media, followed by Glucose Peptone Agar media and V-8 Juice Agar media. The fungus also preferred neutral pH and normal temperatures for its growth. The research was conducted in collaboration with farmers' clubs and agricultural extension centers, making it relevant for understanding and managing Sheath Blight Disease in rice production. [Extracted from the article]

Mycoviruses, or fungal viruses, are prevalent in all significant fungal kingdoms and genera. These low-virulence viruses can be used as biocontrol agents to manage fungal diseases. These viruses are divided into 19 officially recognized families and 1 unclassified genus. Mycoviruses alter sexual reproduction, pigmentation, and development. Spores and fungal hypha spread mycoviruses. Isometric particles mostly encapsulate dsRNA mycoviruses. The widespread plant-pathogenic fungus Rhizoctonia solani, which has caused a rice sheath blight, has hosted many viruses with different morphologies. It causes significant crop diseases that adversely affect agriculture and the economy. Rice sheath blight threatens the 40% of the global population that relies on rice for food and nutrition. This article reviews mycovirology research on Rhizoctonia solani to demonstrate scientific advances. Mycoviruses control rice sheath blight. Hypovirulence-associated mycoviruses are needed to control R. solani since no cultivars are resistant. Mycoviruses are usually cryptic, but they can benefit the host fungus. Phytopathologists may use hypovirulent viruses as biological control agents. New tools are being developed based on host genome studies to overcome the intellectual challenge of comprehending the interactions between viruses and fungi and the practical challenge of influencing these interactions to develop biocontrol agents against significant plant pathogens. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.) is one of the world's most crucial food crops, as it currently supports more than half of the world's population. However, the presence of sheath blight (SB) caused by Rhizoctonia solani has become a significant issue for rice agriculture. This disease is responsible for causing severe yield losses each year and is a threat to global food security. The breeding of SB-resistant rice varieties requires a thorough understanding of the molecular mechanisms involved and the exploration of immune genes in rice. To this end, we conducted a screening of rice cultivars for resistance to SB and compared the transcriptome based on RNA-seq between the most tolerant and susceptible cultivars. Our study revealed significant transcriptomic differences between the tolerant cultivar ZhengDao 22 (ZD) and the most susceptible cultivar XinZhi No.1 (XZ) in response to R. solani invasion. Specifically, the tolerant cultivar showed 7066 differentially expressed genes (DEGs), while the susceptible cultivar showed only 60 DEGs. In further analysis, we observed clear differences in gene category between up- and down-regulated expression of genes (uDEGs and dDEGs) based on Gene Ontology (GO) classes in response to infection in the tolerant cultivar ZD, and then identified uDEGs related to cell surface pattern recognition receptors, the Ca2+ ion signaling pathway, and the Mitogen-Activated Protein Kinase (MAPK) cascade that play a positive role against R. solani. In addition, DEGs of the jasmonic acid and ethylene signaling pathways were mainly positively regulated, whereas DEGs of the auxin signaling pathway were mainly negatively regulated. Transcription factors were involved in the immune response as either positive or negative regulators of the response to this pathogen. Furthermore, our results showed that chloroplasts play a crucial role and that reduced photosynthetic capacity is a critical feature of this response. The results of this research have important implications for better characterization of the molecular mechanism of SB resistance and for the development of resistant cultivars through molecular breeding methods. [ABSTRACT FROM AUTHOR]

Rice sheath blight disease (ShB) is a serious threat to rice production, and breeding ShB-resistance varieties is the most effective strategy for ShB control. However, the molecular mechanisms of rice resistance to ShB are largely unknown. In this study, the NAC transcription factor NAC028 was shown to be sensitive to ShB infection. ShB inoculation assays revealed that NAC028 is a positive regulator of ShB resistance. To elucidate the molecular basis of NAC028 -mediated ShB resistance, another transcription factor (bZIP23) was identified as a NAC028-interacting protein. Results of the transcriptome and qRT-PCR analyses demonstrated that CAD8B , a key enzyme for lignin biosynthesis and ShB resistance, is regulated by both bZIP23 and NAC028. The combination of the yeast-one hybrid, ChIP-qPCR, and transactivation assays illustrated that both bZIP23 and NAC028 directly bind the CAD8B promoter and activate its expression. The transcriptional connection between bZIP23 and NAC028 was also investigated and the results of in vitro and in vivo assays demonstrated that NAC028 was one of the target genes of bZIP23, but not vice versa. The results presented here provide new insights into the molecular basis of ShB resistance and contribute to the potential targets for the ShB resistance breeding program. • NAC028 is positive regulator of rice resistance to sheath blight disease. • NAC028 interacts with bZIP23 to form transcription factor complex. • bZIP23 confers rice resistance to sheath blight disease. • NAC028-bZIP23 complex targets CAD8B to activates its expression. • NAC028 is one of target genes of bZIP23. [ABSTRACT FROM AUTHOR]

Leaf sheath blight disease (SB) of rice caused by the soil-borne fungus Rhizoctonia solani results in 10–30% global yield loss annually and can reach 50% under severe outbreaks. Many disease resistance genes and receptor-like kinases (RLKs) are recruited early on by the host plant to respond to pathogens. Wall-associated receptor kinases (WAKs), a subfamily of receptor-like kinases, have been shown to play a role in fungal defense. The rice gene WAK91 (OsWAK91), co-located in the major SB resistance QTL region on chromosome 9, was identified by us as a candidate in defense against rice sheath blight. An SNP mutation T/C in the WAK91 gene was identified in the susceptible rice variety Cocodrie (CCDR) and the resistant line MCR010277 (MCR). The consequence of the resistant allele C is a stop codon loss, resulting in an open reading frame with extra 62 amino acid carrying a longer protein kinase domain and additional phosphorylation sites. Our genotype and phenotype analysis of the parents CCDR and MCR and the top 20 individuals of the double haploid SB population strongly correlate with the SNP. The susceptible allele T is present in the japonica subspecies and most tropical and temperate japonica lines. Multiple US commercial rice varieties with a japonica background carry the susceptible allele and are known for SB susceptibility. This discovery opens the possibility of introducing resistance alleles into high-yielding commercial varieties to reduce yield losses incurred by the sheath blight disease. [ABSTRACT FROM AUTHOR]

Sheath blight of rice caused by Rhizoctonia solani Kuhn [teleomorph: Thanatephorus cucumeris (Frank) Donk] is a significant threat to rice cultivation, accounting for up to 50% yield losses. The present investigation demonstrates the early pathogenesis events and R. solani pre‐ and post‐penetration activities on moderately resistant (MR) and highly susceptible (HS) lines under field conditions. A pure culture of R. solani isolate (R1965) was inoculated inside the sheath at the maximum tillering stage for different time intervals (24, 48, 72 and 96 hpi). R. solani exhibited more profuse, dense, closely contact around surface grooves, lobate appressoria‐like structures and greater microsclerotia development on the HS line compared to the MR one. Using fluorescent, optical, and scanning electron microscopy, it was noticed for the first time that R. solani could intercept sheath papillae and employ them for attachment or penetration in two ways: (a) direct penetration by lobate or runner hyphae, appressorium and infection cushion and (b) indirect stomatal penetration. Assays using in vivo plant inoculation showed that disease lesion length was higher in the HS line than the MR line. Intraxylary hyphal colonization could be seen using microtomy to understand the cellular spatial dynamics of xylem colonization by R. solani. The penetration mechanism along with penetration hyphae of the R. solani inside HS rice lines describe in this paper for the first time using optical ultrastructure. These results supported for better understanding of host–pathogen interaction, penetration mechanism and colonization of R. solani in rice. [ABSTRACT FROM AUTHOR]

Rhizoctonia solani is a devastating soil-borne pathogen that seriously threatens the cultivation of economically important crops. Multiple strains with a very broad host range have been identified, but only 1 (AG1-IA, which causes rice sheath blight disease) has been examined in detail. Here, we analyzed AG4-HGI 3 originally isolated from Tartary buckwheat (Fagopyrum tataricum), but with a host range comparable to AG1-IA. Genome comparison reveals abundant pathogenicity genes in this strain. We used multiomic approaches to improve the efficiency of screening for disease resistance genes. Transcriptomes of the plant–fungi interaction identified differentially expressed genes associated with virulence in Rhizoctonia and resistance in Tartary buckwheat. Integration with jasmonate-mediated transcriptome and metabolome changes revealed a negative regulator of jasmonate signaling, cytochrome P450 (FtCYP94C1), as increasing disease resistance probably via accumulation of resistance-related flavonoids. The integration of resistance data for 320 Tartary buckwheat accessions identified a gene homolog to aspartic proteinase (FtASP), with peak expression following R. solani inoculation. FtASP exhibits no proteinase activity but functions as an antibacterial peptide that slows fungal growth. This work reveals a potential mechanism behind pathogen virulence and host resistance, which should accelerate the molecular breeding of resistant varieties in economically essential crops. Multiomic association analysis dissects the genetic basis of the virulence mechanism in Rhizoctonia solani and the jasmonic acid–mediated resistance against R. solani in Tartary buckwheat. [ABSTRACT FROM AUTHOR]

Rice sheath blight (ShB) disease poses a major threat to rice yield throughout the world. However, the defense mechanisms against ShB in rice remain largely unknown. ShB resistance is a typical quantitative trait controlled by multiple genes. With the rapid development of molecular methods, many quantitative trait loci (QTLs) related to agronomic traits, biotic and abiotic stresses, and yield have been identified by genome-wide association studies. The interactions between plants and pathogens are controlled by various plant hormone signaling pathways, and the pathways synergistically or antagonistically interact with each other, regulating plant growth and development as well as the defense response. This review summarizes the regulatory effects of hormones including auxin, ethylene, salicylic acid, jasmonic acid, brassinosteroids, gibberellin, abscisic acid, strigolactone, and cytokinin on ShB and the crosstalk between the various hormones. Furthermore, the effects of sugar and nitrogen on rice ShB resistance, as well as information on genes related to ShB resistance in rice and their effects on ShB are also discussed. In summary, this review is a comprehensive description of the QTLs, hormones, nutrition, and other defense-related genes related to ShB in rice. The prospects of targeting the resistance mechanism as a strategy for controlling ShB in rice are also discussed. [ABSTRACT FROM AUTHOR]

Sheath blight (ShB) of rice caused by Rhizoctonia solani Kühn is the most vital disease this is a serious issue in highyielding rice production systems. It is a significant issue with the rice producing system's high yielding types. The pathogen has a very wide host range and due to non-availability of resistant cultivars, the management of ShB primarily depends upon chemical control while the chemical control is not eco-friendly and is also dangerous for human health. However, the disease can be managed with botanical pesticides and biological agents. This study was planned with the objective to manage this disease with eco-friendly approaches. Different species of Trichoderma and plant extracts were evaluated under the laboratory conditions with dual culture technique and poisoned food technique respectively. Results showed that all bio-controls and plant extracts significantly inhibited mycelial growth of R. solani at different exposure intervals (5, 10 and 15 day) (P<0.05). In fungal bio-control, the highest percent inhibition was given by T. harzianum followed by T. atroviride on all incubation intervals. The lowest percent inhibition was 55%, 69 and 79% given by T. viride. All plant extracts significantly inhibited the mycelium growth of R. solani (P<0.05). Maximum percent inhibition was observed in case of neem followed by garlic, eucalyptus, and the minimum percent inhibition was exhibited by mint on 5, 10 and 15 days of incubation intervals. [ABSTRACT FROM AUTHOR]

OsPLS4 encodes a β-ketoacyl carrier protein reductase (KAR). The role of OsPLS4 in rice sheath blight (Rhizoctonia solani) remains unclear. Our preliminary studies showed that premature leaf senescence mutants (pls4) were highly susceptive to sheath blight in the early stage of rice development. To explore the role of this gene in the development of rice sheath blight, the transcriptome profiles of the rice pls4 mutant and wild type were compared by RNA-seq. The results revealed 2,569 differentially expressed genes (DEGs). The down-regulated genes were significantly enriched in the defense response-related biological processes. These down-regulated genes included the chitinase genes and WRKY genes, which were significantly changed in pls4 mutants. Furthermore, 467 genes induced significant alternative splicing (AS) events. Among them, intron retention (IR) affected gene expression levels and functions of the vitamin B6 (VB6) metabolism pathway related to sheath blight. This result suggests that IR plays an important role in the sheath blight resistance of mutant pls4. Together, these results indicate that pls4 could be involved in the biological process of sheath blight via DEGs and the fine-tuning of IR. The present study provides a molecular basis for further investigation of the resistance of rice to sheath blight. [ABSTRACT FROM AUTHOR]

The present study unravels the antifungal ability and physio-biochemical basis of resistance induced by botanical extracts against the sheath blight disease of rice incited by Rhizoctonia solani. In vitro screening of botanical extracts against R. solani revealed that an increase in the concentration of botanical extracts increased the inhibition of mycelial growth, though maximum inhibition occurred at 50% concentration. A. indica exhibited the highest mycocidal ability, followed by M. azedarach and T. ciliata. In field experiments, spraying of promising doses of botanical extracts led to a significant reduction in the severity index, AUDPC, and r-value when applied 2 days before inoculation. An increase in the endogenous SA content of treated plants gave an indication of the activation of SAR. The induction of resistance was accompanied by the accumulation of various host-related antioxidants and defence enzymes in susceptible cultivar. The results indicate that botanical extracts induce the early activation of disease resistance and that this is mediated through the expression of defence mechanisms. A. indica provided excellent control and reduced the disease severity, followed by extracts of M. azedarach. The results of the study are significant for developing an environmentally friendly biocide that could be considered an effective tool in integrated management programmes for a sustainable system of sheath blight control. [ABSTRACT FROM AUTHOR]

In green chemistry, filamentous fungi are regarded as a kind of robust microorganism for the biotransformation of natural products. Nonetheless, the screening of microorganisms is crucial for the effective biotransformation of natural products, such as phenazine compounds. The precursor metabolite of most phenazine derivatives in Pseudomonas spp. is phenazine-1-carboxylic acid (PCA), the key constituent of shenqinmycin, widely used to control rice sheath blight in southern China. In this study, a new fungus strain Aspergillus sclerotiorum was isolated, which can efficiently convert PCA into 3-hydroxy-phenazine 1-carboxylic acid (3-OH-PCA). Moreover, an effective whole cells biotransformation system was designed by screening optimal reaction conditions and carbon sources. Hence, Aspergillus sclerotiorum exhibited desirable adaptation by the consumption of different carbon sources and maximum whole-cell biomass (10.6 g/L DCW) was obtained as a biocatalyst from glucose. Optimal conditions for whole-cell biocatalysis of PCA were evaluated, including a PCA concentration of 1120 mg/L, a pH of 7.0, a temperature of 25 °C, a rotation rate of 200 rpm, and dry cell weight of 15 g/L for 60 h; thus, 1060 mg/L of 3-OH-PCA was obtained and the conversion efficiency of PCA was 94%. Hence, the results of the repeated batch mood revealed that the biotransformation efficiency of fungus pellets reduced with each subsequent cycle, but remained stable in all five cycles with the provision of a glucose supplement. These findings present the prospect of using filamentous fungi for the whole-cell biocatalysis of phenazine in enormous amounts and the efficient production of 3-OH-PCA. Moreover, these results laid the foundation for further research to disclose the genetic-based mechanism of the strain responsible for PCA biotransformation. [ABSTRACT FROM AUTHOR]