Explore the vast range of titles available.

Okra ( Abelmoschus esculentus (Linn.) Moench), a globally cultivated vegetable crop valued for its nutrient-rich pods, is facing emerging threats from seedling damping-off and blight in subtropical regions of South China. In 2022, fungal isolates representing five genera ( Trichoderma , Rhizoctonia , Rhizopus , Macrophomina , and Rhizomucor ) were obtained from symptomatic seedlings in Guangdong Province. The pathogenicity test revealed that three Rhizoctonia isolates (ACCC 35247, ACCC 35460 and ACCC 35461) could induce typical damping-off symptoms, inhibit seed germination and cause hypocotyl necrosis, consistent with symptoms observed under natural field conditions. Based on morphological and molecular characterization, along with phylogenetic analysis of the ITS region, the pathogen was identified as Rhizoctonia solani (teleomorph: Thanatephorus cucumeris (Frank) Donk). The mycelial and sclerotia lethal temperature of the pathogen was 45 °C and 48 °C respectively, and the optimal temperature (T opt ) for mycelial growth was 28.22 °C. Sensitivity of the pathogen to seven fungicides was evaluated in vitro using a mycelial radial growth assay, the EC 50 values for each fungicide were estimated. According to the EC 50 values of seven fungicides, there was significant difference in the inhibitory effect of each fungicide on the pathogen, and the pathogen was most sensitive to trifloxystrobin + tebuconazole (1:2), with the mean EC 50 value being 0.43 mg·L −1 . This study provides critical insights into the disease management of R. solani induced damping-off in okra.

ABSTRACT The necrotrophic fungal pathogen Rhizoctonia solani anastomosis group 3 (AG3‐TB) is a major cause of global tobacco crop yield losses. Secreted proteins produced by filamentous fungi, as important virulence factors, play a core role in the interaction between plants and pathogens. In this study, we identified a secretory protein, RsDN3377, which localised to the intercellular space and induced cell death in Nicotiana benthamiana. Heterologous expression in Escherichia coli coupled with matrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry analysis confirmed RsDN3377 possessed deacetylase activity. In addition, RsDN3377 was an essential pathogenicity factor for mycelial development by double‐stranded RNA‐mediated gene silencing. Through yeast two‐hybrid and bimolecular fluorescence complementation assays, we demonstrated that RsDN3377 interacted with the calcium‐binding protein NtCML19. In addition, transgenic Yunyan 87 overexpressing NtCML19 exhibited enhanced resistance to R. solani AG3‐TB infection. Microscale thermophoresis analysis verified the calcium‐binding activity of NtCML19. These lines of evidence indicate that the deacetylase RsDN3377 is secreted by R. solani AG3‐TB, and this protein, critical for promoting fungal mycelial development and pathogenicity, was disrupted by its resistance‐related interaction with NtCML19. The deacetylase RsDN3377 is recognised by the calcium‐binding protein NtCML19, which enhances host resistance against Rhizoctonia solani infection by inducing cell death and reactive oxygen species (ROS) accumulation.

Rhizoctonia solani is a soil-borne fungus causing sheath blight. In consistent with its necrotrophic life style, no rice cultivars fully resistant to R. solani are known, and agrochemical plant defense activators used for rice blast, which upregulate a phytohormonal salicylic acid (SA)-dependent pathway, are ineffective towards this pathogen. As a result of the unavailability of genetics, the infection process of R. solani remains unclear. We used the model monocotyledonous plants Brachypodium distachyon and rice, and evaluated the effects of phytohormone-induced resistance to R. solani by pharmacological, genetic and microscopic approaches to understand fungal pathogenicity. Pretreatment with SA, but not with plant defense activators used in agriculture, can unexpectedly induce sheath blight resistance in plants. SA treatment inhibits the advancement of R. solani to the point in the infection process in which fungal biomass shows remarkable expansion and specific infection machinery is developed. The involvement of SA in R. solani resistance is demonstrated by SA-deficient NahG transgenic rice and the sheath blight-resistant B. distachyon accessions, Bd3-1 and Gaz-4, which activate SA-dependent signaling on inoculation. Our findings suggest a hemi-biotrophic nature of R. solani, which can be targeted by SA-dependent plant immunity. Furthermore, B. distachyon provides a genetic resource that can confer disease resistance against R. solani to plants.

Endophytic mycopopulation isolated from India's Queen of herbs Tulsi (Ocimum sanctum) were explored and investigated for their diversity and antiphytopathogenic activity against widespread plant pathogens Botrytis cinerea, Sclerotinia sclerotiorum, Rhizoctonia solani and Fusarium oxysporum. 90 fungal isolates, representing 17 genera were recovered from 313 disease-free and surface sterilised plant segments (leaf and stem tissues) from three different geographic locations (Delhi, Hyderabad and Mukteshwar) during distinct sampling times in consequent years 2010 and 2011 in India. Fungal endophytes were subjected to molecular identification based on rDNA ITS sequence analysis. Plant pathogens such as F. verticillioides, B. maydis, C. coarctatum, R. bataticola, Hypoxylon sp., Diaporthe phaseolorum, Alternaria tenuissima and A. alternata have occurred as endophyte only during second sampling (second sampling in 2011) in the present study. Bi-plot generated by principal component analysis suggested tissue specificity of certain fungal endophytes. Dendrogram revealed species abundance as a function of mean temperature of the location at the time of sampling. Shannon diversity in the first collection is highest in Hyderabad leaf tissues (H' = 1.907) whereas in second collection it was highest from leaf tissues of Delhi (H' = 1.846). Mukteshwar (altitude: 7500 feet) reported least isolation rate in second collection. Nearly 23% of the total fungal isolates were considered as potent biocontrol agent. Hexane extract of M. phaseolina recovered from Hyderabad in first collection demonstrated highest activity against S. sclerotiorum with IC50 value of 0.38 mg/ml. Additionally, its components 2H-pyran-2-one, 5,6-dihydro-6-pentyl and palmitic acid, methyl ester as reported by GC-MS Chromatogram upon evaluation for their antiphytopathogenic activity exhibited IC50 value of 1.002 and 0.662 against respectively S. sclerotiorum indicating their significant role in antiphytopathogenic activity of hexane extract. The production of 2H-pyran-2-one, 5,6-dihydro-6-pentyl from M. phaseolina, an endophytic fungus is being reported for the first time.

ABSTRACT Rhizoctonia solani AG1 IA is a harmful necrotrophic fungus responsible for various crop diseases, including maize and rice sheath blight, which can lead to significant production losses. However, the pathogenic mechanisms and the roles of effectors in this pathogen remain poorly understood. In this study, we identified a glycoside hydrolase 16 family gene, RsEG146, from R. solani that was upregulated during its infection of Zea mays leaves. When transiently expressed through agroinfiltration, RsEG146 induced cell death in the leaves of tobacco (Nicotiana tabacum ‘Samsun’). The predicted signal peptide of RsEG146 was essential for its cell death‐inducing activity, while the conserved enzymic active site was not required. The chitin‐binding domain was critical for the cell death‐inducing activity of RsEG146, with Gly47 identified as the key residue. Substitution of Gly47 with aspartate, glutamate, or proline significantly impaired the cell death‐inducing activity of RsEG146. Additionally, transient and heterogeneous expression of RsEG146 enhanced the pathogenicity of Botrytis cinerea on tobacco, and silencing this gene through spray‐induced gene silencing (SIGS) reduced the severity of the disease in maize, indicating that RsEG146 functions as an effector. Furthermore, RsEG146 triggered a plant immune response in tobacco. This study demonstrates that RsEG146 is a potential effector and plays a crucial role in the interactions between R. solani AG1 IA and its host. We identified a glycoside hydrolase 16 family member RsEG146 from Rhizoctonia solani AG1 IA that acts as an effector by inducing Nicotiana tabacum cell death via its chitin‐binding domain.

Strawberry (Fragaria×ananassa) is one of the most important berry crops in the world. Root rot of strawberry caused by Rhizoctonia spp. is a serious threat to commercial strawberry production worldwide. However, there is no information on the genetic diversity and phylogenetic status of Rhizoctonia spp. associated with root rot of strawberry in Australia. To address this, a total of 96 Rhizoctonia spp. isolates recovered from diseased strawberry plants in Western Australia were characterized for their nuclear condition, virulence, genetic diversity and phylogenetic status. All the isolates were found to be binucleate Rhizoctonia (BNR). Sixty-five of the 96 BNR isolates were pathogenic on strawberry, but with wide variation in virulence, with 25 isolates having high virulence. Sequence analysis of the internal transcribed spacers of the ribosomal DNA separated the 65 pathogenic BNR isolates into six distinct clades. The sequence analysis also separated reference BNR isolates from strawberry or other crops across the world into clades that correspond to their respective anastomosis group (AG). Some of the pathogenic BNR isolates from this study were embedded in the clades for AG-A, AG-K and AG-I, while other isolates formed clades that were sister to the clades specific for AG-G, AG-B, AG-I and AG-C. There was no significant association between genetic diversity and virulence of these BNR isolates. This study demonstrates that pathogenic BNR isolates associated with root rot of strawberry in Western Australia have wide genetic diversity, and highlights new genetic groups not previously found to be associated with root rot of strawberry in the world (e.g., AG-B) or in Australia (e.g., AG-G). The wide variation in virulence and genetic diversity identified in this study will be of high value for strawberry breeding programs in selecting, developing and deploying new cultivars with resistance to these multi-genetic groups of BNR.

This study reports the potential of a soil bacterium, Bacillus subtilis strain SPB1, to produce lipopeptide biosurfactants. Firstly, the crude lipopeptide mixture was tested for its inhibitory activity against phytopathogenic fungi. A minimal inhibitory concentration (MIC), an inhibitory concentration at 50 % (IC50 %), and an inhibitory concentration at 90 % (IC90 %) values were determined to be 0.04, 0.012, and 0.02 mg/ml, respectively, for Rhizoctonia bataticola with a fungistatic mode of action. For Rhizoctonia solani, a MIC, an IC50 %, and IC90 % values were determined to be 4, 0.25, and 3.3 mg/ml, respectively, with a fungicidal mode of action. For both of the fungi, a loss of sclerotial integrity, granulation and fragmentation of hyphal mycelia, followed by hyphal shriveling and cell lysis were observed with the treatment with SPB1 biosurfactant fraction. After extraction, separation, and purification, different lipopeptide compounds were identified in the culture filtrate of strain SPB1. Mass spectroscopic analysis confirmed the presence of different lipopeptide compounds consisting of surfactin isoforms with molecular weights of 1007, 1021, and 1035 Da; iturin isoforms with molecular weights of 1028, 1042, and 1056 Da; and fengycin isoforms with molecular weights of 1432 and 1446 Da. Two new clusters of lipopeptide isoforms with molecular weights of 1410 and 1424 Da and 973 and 987 Da, respectively, were also detected. This study reported the ability of a B. subtilis strain to co-produce lipopeptide isoforms with potential use as antifungal compounds.

Rhizoctonia solani AG1IA is a major generalist pathogen that causes sheath blight. Its genome, which was the first to be sequenced from the Rhizoctonia genus, may serve as a model for studying pathogenic mechanisms. To explore the pathogen-host fitness mechanism of sheath-blight fungus, a comprehensive comparative transcriptome ecotype analysis of R. solani AG1IA isolated from rice, soybean and corn during infection was performed. Special characteristics in gene expression, gene ontology terms and expression of pathogenesis-associated genes, including genes encoding secreted proteins, candidate effectors, hydrolases, and proteins involved in secondary metabolite production and the MAPK pathway, were revealed. Furthermore, as an important means of pathogenic modulation, diverse alternative splicing of key pathogenic genes in Rhizoctonia solani AG1IA during infections of the abovementioned hosts was uncovered for the first time. These important findings of key factors in the pathogenicity of R. solani AG1IA ecotypes during infection of various hosts explain host preference and provide novel insights into the pathogenic mechanisms and host-pathogen selection. Furthermore, they provide information on the fitness of Rhizoctonia , a severe pathogen with a wide host range.

Reductive soil disinfestation (RSD) has been proven to be an effective and environmentally friendly way to control many soilborne pathogens and diseases. In this study, the RSDs using ethanol (Et-RSD) and alfalfa (Al-RSD) as organic carbons were performed in a Rhizoctonia solani -infected soil, and the dissimilarities of microbial communities during the RSDs and after planting two seasons of cucumber seedlings in the RSDs-treated soil were respectively investigated by MiSeq pyrosequencing. The results showed that, as for bacteria, Coprococcus , Flavisolibacter , Rhodanobacter , Symbiobacterium , and UC- Ruminococcaceae became the dominant bacterial genera at the end of Al-RSD. In contrast, Et-RSD soil involved more bacteria belonging to Firmicutes , such as Sedimentibacter , UC- Gracilibacteraceae , and Desulfosporosinus . For fungi, Chaetomium significantly increased at the end of RSDs, while Rhizoctonia and Aspergillus significantly decreased. After planting two seasons of cucumber seedlings, those bacteria belonging to Firmicutes significantly decreased, but Lysobacter and Rhodanobacter belonging to the phylum Proteobacteria as well as UC- Sordariales and Humicola belonging to Ascomycota alternatively increased in Al- and Et-RSD-treated soils. Besides, some nitrification, denitrification, and nitrogen fixation genes were apparently increased in the RSD-treated soils, but the effect was more profound in Al-RSD than Et-RSD. Overall, Et-RSD could induced more antagonists belonging to Firmicutes under anaerobic condition, whereas Al-RSD could continuously stimulate some functional microorganisms ( Lysobacter and Rhodanobacter ) and further improve nitrogen transformation activities in the soil at the coming cropping season.

This study investigates the antifungal properties of a liquid Cinchona-Based Formulation (CBF) against Rhizoctonia solani . CBF, a stable acidic extract of Cinchona bark (0.1 N HCl), effectively suppressed mycelial growth (58.75 ± 0.48%) and sclerotia biomass (22.1 ± 0.65 mg), with an EC 50 of 217.14 µg/mL. GC-MS and HPLC revealed quinine as the primary active alkaloid. Molecular docking revealed a strong binding affinity of quinine to the fungal tryptophan (Trp) transporters (− 6.5 to − 7.8 Kcal/mol). Supplementation of 400 µg/mL Trp in the media reversed the fungal growth with increased fungal dry weight (33.33 ± 1.53 mg), and sclerotia weight (67.67 ± 3.06 mg), highlighting Trp starvation as a key factor for reduced growth of the fungus. Expression of amino acid permease (rhAAP-I/II) increased 4–9 fold during Trp scarcity in fungus. CBF also elevated levels of ROS, which results in loss of Mitochondrial Membrane Potential (MMP). CBF reduced Cyt. P450 expression (2.73-fold) while increasing mitochondrial QCR and COX expression, indicating a combined impact of Trp scarcity and oxidative stress, demonstrating a dual antifungal mechanism of the CBF on the fungus. These results suggest CBF as a promising eco-friendly biopesticide for long-term disease management.