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Rhizoctonia solani Kühn is a soil-borne fungal pathogen that causes disease in a wide range of plants worldwide. Strains of the fungus are traditionally grouped into genetically isolated anastomosis groups (AGs) based on hyphal anastomosis reactions. This article summarizes aspects related to the infection process, colonization of the host and mole...
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... vegetative hyphae that can attack a wide range of crops (Keijer, 1996). In certain situa- tions, R. solani can produce basidiospores that will cause disease and also serve as a source for rapid and long-distance dispersal of the fungus. The basidiospores germinate to produce hyphae that infect leaves during periods of high rela- tive humidity (Fig. 2). Although most Rhizoctonia diseases are initiated by mycelium and/or sclerotia, several important dis- eases of tobacco and other crops, such as beans and sugar beet, are a result of basidiospore infection ( González-García et al., 2006;Harveson et al., ...
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Evaluation of Trichoderma Isolates for Biological Control of Rhizoctonia Root
Rot of Bean in Zanjan
M. Khodae1- R. Hemmati2*
Received:22-06-2013
Accepted:05-08-2015
Introduction: Rhizoctonia solani is one of the major pathogens causing root rot in the main bean-growing
regions in Zanjan province. Under favorable conditions, yield losses in commerci...
There is growing evidence that the application of biocontrol organisms (e.g., Pseudomonas and Bacillus spp., arbuscular mycorrhizal fungi-AMF) is a feasible option to reduce incidence of plant pathogens in an integrated control strategy. However, the utilization of these microorganisms, in particular AMF, may be threatened by the application of fun...
The interaction of binucleate Rhizoctonia (BNR) anastomosis group (AG)-A isolate W7, Rhizoctonia solani AG-4 and cucumber seedlings were investigated to elucidate the mechanism of biocontrol of Rhizoctonia solani by BNR. Hypocotyls of Cucumis sativus L. cv. Jibai were inoculated with a virulent isolate of R. solani AG-4 isolate C4 and examined with...
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Pseudomonas CMR12a was previously selected as an efficient biocontrol strain producing phenazines and cyclic lipopeptides (CLPs). In this study, biocontrol capacity of Pseudomonas CMR12a against Rhizoctonia root rot of bean and the involvement of phenazines and CLPs in this ability were tested. Two different anastomosis groups (AGs) of Rhizoctonia...
Citations
... Soil acidity and root exudation have been found to play important roles in reversing spore dormancy. Gonzalez et al. discovered that ferulic, gallic, and salicylic acids all encouraged the generation of conidia in dangerous fungi [79]. The most prevalent varieties of rhizospheric pathogenic fungi include Fusarium, Rhizoctonia, Pythium, and Phytophthora [80][81][82]. ...
Sustainable agriculture represents the responsible utilization of natural resources while safeguarding the well-being of the natural environment. It encompasses the objectives of preserving the environment, fostering economic growth, and promoting socioeconomic equality. To achieve sustainable development for humanity, it is imperative to prioritize sustainable agriculture. One significant approach to achieving this transition is the extensive utilization of microbes, which play a crucial role due to the genetic reliance of plants on the beneficial functions provided by symbiotic microbes. This review focuses on the significance of rhizospheric microbial communities, also known as the rhizomicrobiome (RM). It is a complex community of microorganisms that live in the rhizosphere and influence the plant's growth and health. It provides its host plant with various benefits related to plant growth, including biocontrol, biofertilization, phytostimulation, rhizoremediation, stress resistance, and other advantageous properties. Yet, the mechanisms by which the RM contributes to sustainable agriculture remain largely unknown. Investigating this microbial population presents a significant opportunity to advance toward sustainable agriculture. Hence, this study aims to provide an overview of the diversity and applications of RM in sustainable agriculture practices. Lately, there has been growing momentum in various areas related to rhizobiome research and its application in agriculture. This includes rhizosphere engineering, synthetic microbiome application, agent-based modeling of the rhizobiome, and metagenomic studies. So, developing bioformulations of these beneficial microorganisms that support plant growth could serve as a promising solution for future strategies aimed at achieving a new green revolution.
... The disease incidence rate of tobacco plants can reach more than 80%, and even more 100% [12], reduce the value of tobacco leaves. R. solani belongs to the Hyphomycetes, Agonomycetales, Agonomycetaceae and Rhizoctonia [13]. It does not produce conidium, and its sexual generation is Thanatephorus cucumber (Frank) Donk [14]. ...
... It does not produce conidium, and its sexual generation is Thanatephorus cucumber (Frank) Donk [14]. The genetic differentiation of R. solani is complex and its life history is relatively unique [13], and a phenomenon commonly occurring in filamentous fungi has been pointed out as hyphal anastomosis, which is characterized by the exchange of genetic material [15]. In a case study, it has been reported that the mycelial anastomosis phenomenon taxa of R. solani and established the system of mycelial anastomosis group (anastomosis group, AG for short) [16]. ...
Background
Rhizoctonia solani is an important plant pathogen worldwide, and causes serious tobacco target spot in tobacco in the last five years. This research studied the biological characteristics of four different anastomosis groups strains (AG-3, AG-5, AG-6, AG-1-IB) of R. solani from tobacco. Using metabolic phenotype technology analyzed the metabolic phenotype differences of these strains.
Results
The results showed that the suitable temperature for mycelial growth of four anastomosis group strains were from 20 to 30oC, and for sclerotia formation were from 20 to 25oC. Under different lighting conditions, R. solani AG-6 strains produced the most sclerotium, followed by R. solani AG-3, R. solani AG-5 and R. solani AG-1-IB. All strains had strong oligotrophic survivability, and can grow on water agar medium without any nitrutions. They exhibited three types of sclerotia distribution form, including dispersed type (R. solani AG-5 and AG-6), peripheral type (R. solani AG-1-IB), and central type (R. solani AG-3). They all presented different pathogenicities in tobacco leaves, with the most virulent was noted by R. solani AG-6, followed by R. solani AG-5 and AG-1-IB, finally was R. solani AG-3. R. solani AG-1-IB strains firstly present symptom after inoculation. Metabolic fingerprints of four anastomosis groups were different to each other. R. solani AG-3, AG-6, AG-5 and AG-1-IB strains efficiently metabolized 88, 94, 71 and 92 carbon substrates, respectively. Nitrogen substrates of amino acids and peptides were the significant utilization patterns for R. solani AG-3. R. solani AG-3 and AG-6 showed a large range of adaptabilities and were still able to metabolize substrates in the presence of the osmolytes, including up to 8% sodium lactate. Four anastomosis groups all showed active metabolism in environments with pH values from 4 to 6 and exhibited decarboxylase activities.
Conclusions
The biological characteristics of different anastomosis group strains varies, and there were significant differences in the metabolic phenotype characteristics of different anastomosis group strains towards carbon source, nitrogen source, pH, and osmotic pressure.
... Rhizoctonia solani AG-3 TB, causing tobacco target spot disease, has historically induced significant yield and quality losses worldwide [1][2][3]. Figure 1 depicts the life cycle and disease progression of a tobacco pathogen [4]. The mycelium of the pathogen grows in the soil and forms sclerotia [5]. ...
... The seedling stage of tobacco is particularly susceptible to target spot disease. Once infected, the seedling's roots rot, the stems become thin, and it may develop into damping-off disease, leading to seedling death [4]. ...
... It is known that fungal cells and spores can rapidly take up elemental sulfur [45]. Li's study showed that a higher concentration of SO 4 2− had a significant effect on the induction of sporangia of Phytophthora nicotianae [46]. Excessive sulfur spraying on the leaves may enhance the plant's photosynthetic capacity and increase photosynthetic products. ...
Rhizoctonia solani AG-3 TB primarily causes tobacco target spot disease by producing a large number of sexual spores. However, inducing sexual spore formation under in vitro conditions has been challenging, impeding further research on its control. In this study, field experiments were conducted to assess the effects of different concentrations of chemical and biological fungicides on the production of sexual spores of R. solani AG-3 TB on tobacco plants. The results demonstrated that four chemical fungicides (propiconazole-morpholine guanidine, bordeaux mixture, thiophanate-methyl, and mancozeb) significantly induced sexual spore formation. Among them, increasing the concentrations of the first three fungicides resulted in an increase in the number of sexual spores, while increasing the concentration of mancozeb led to a decrease in spore count. The pathogenic fungus produced more sexual spores during the night than during the day. Temperature, humidity, and light conditions influenced spore production. Additionally, the infection rate of sexual spores was directly proportional to their concentration and inoculation time, but their survival time did not exceed 6 h in vitro. Importantly, Streptomyces rectiolaceus A8 significantly suppressed sexual spore formation, achieving an 83.63% control efficacy in the field and producing antimicrobial substances against R. solani AG-3 TB. In conclusion, appropriate concentrations of chemical fungicides can induce sexual spore formation, while A8 can inhibit their production, showing potential value for controlling tobacco target spot disease.
... K e y w o r d s: Bacillus subtilis, tobacco target spot, Rhizoctonia solani, plant growth promotion, biocontrol potential 1 30 controlling tobacco target spot disease is using chemical fungicides. Iprodione, mancozeb, phenazine-1-carboxylic acid valine, and other fungicides act against R. solani (Csinos and Stephenson 1999;Gonzalez et al. 2011;Zhu et al. 2022). ...
Fungal diseases form perforated disease spots in tobacco plants, resulting in a decline in tobacco yield and quality. The present study investigated the antagonistic effect of Bacillus subtilis CTXW 7-6-2 against Rhizoctonia solani , its ability to promote the growth of tobacco seedlings, and the expression of disease resistance-related genes for efficient and eco-friendly plant disease control. Our results showed that CTXW 7-6-2 had the most vigorous growth after being cultured for 96 h, and its rate of inhibition of R. solani growth in vitro was 94.02%. The volatile compounds produced by CTXW 7-6-2 inhibited the growth of R. solani significantly (by 96.62%). The fungal growthinhibition rate of the B. subtilis CTXW 7-6-2 broth obtained after high-temperature and no-high-temperature sterile fermentation was low, at 50.88% and 54.63%, respectively. The lipopeptides extracted from the B. subtilis CTXW 7-6-2 fermentation broth showed a 74.88% fungal growth inhibition rate at a concentration of 100 mg/l. Scanning and transmission electron microscopy showed some organelle structural abnormalities, collapse, shrinkage, blurring, and dissolution in the R. solani mycelia. In addition, CTXW 7-6-2 increased tobacco seedling growth and improved leaf and root weight compared to the control. After CTXW 7-6-2 inoculation, tobacco leaves showed the upregulation of the PDF1.2 , PPO , and PAL genes, which are closely related to target spot disease resistance. In conclusion, B. subtilis CTXW 7-6-2 may be an efficient biological control agent in tobacco agriculture and enhance plant growth potential.
... Rhizoctonia solani is a soil-borne pathogen that has a wide host range and can cause many crop diseases, resulting in huge yield losses and economic damage (Gonzalez et al. 2011;Aydın 2022;Jia et al. 2023). In addition, this pathogen can survive for years as mycelium in organic material and as sclerotia in soil (Anderson 1982). ...
Trichoderma harzianum is a well-known biological control strain and a mycoparasite of Rhizoctonia solani. To explore the mechanisms of mycoparasitism, the genome and transcriptome of T. harzianum T4 were both assembled and analyzed in this study. The genome of T. harzianum T4 was assembled into 106 scaffolds, sized 41.25 Mb, and annotated with a total of 8118 predicted genes. We analyzed the transcriptome of T. harzianum T4 against R. solani in a dual culture in three culture periods: before contact (BC), during contact (C), and after contact (AC). Transcriptome sequencing identified 1092, 1222, and 2046 differentially expressed genes (DEGs), respectively. These DEGs, which are involved in pathogen recognition and signal transduction, hydrolase, transporters, antibiosis, and defense-related functional genes, are significantly upregulated in the mycoparasitism process. The results of genome and transcriptome analysis indicated that the mycoparasitism process of T. harzianum T4 was very complex. T. harzianum successfully recognizes and invades host cells and kills plant pathogens by regulating various DEGs at different culture periods. The relative expression levels of the 26 upregulated DEGs were confirmed by RT-qPCR to validate the reliability of the transcriptome data. The results provide insight into the molecular mechanisms underlying T. harzianum T4’s mycoparasitic processes, and they provide a potential molecular target for the biological control mechanism of T. harzianum T4.
... 10,[18][19][20][21] R. solani AG-3 causes water-soaked lesions on N. tabacum leaves, which subsequently develop into dark brown lesions with concentric rings, and some with chlorosis halo, and the focal center is often necrotic leading to leaf perforation. 10,22 Owing to the lack of effective fungicides and highly resistant varieties for the target spot disease, the general control method at present is the application of chemical agents, such as mancozeb, iprodione and 30% difenoconazole propiconazole EC. [23][24][25] Biological control is one of the main methods for controlling R. solani using a variety of approaches; for instance, Trichoderma mainly degrades R. solani on maize through competition and hyperparasitism, whereas Bacillus sp. SJ-5 enhances resistance to R. solani by promoting soybean growth and stimulating defense-related enzymes. ...
BACKGROUND
Rhizoctonia solani Kühn is a pathogenic fungus causing tobacco target spot disease, and leads to great losses worldwide. At present, resistant varieties and effective control strategy on tobacco target spot disease are very limited. Host‐induced gene silencing (HIGS) as well as the exogenous dsRNA can be used to suppress disease progression, and reveal the function of crucial genes involved in the growth and pathogenesis of the fungus.
RESULTS
The silencing of endoPGs or RPMK1 in host plants by TRV‐based HIGS resulted in a significant reduction in disease development in Nicotiana benthamiana. In vitro analysis validated that red fluorescence signals were consistently observed in the hyphae treated with Cy3‐fluorescein‐labeled dsRNA at 12, 24, 48 and 72 h postinoculation (hpi). Additionally, application of dsRNA‐endoPGs, dsRNA‐RPMK1 and dsRNA‐PGMK (fusion of partial endoPGs and RPMK1 sequences) effectively inhibited the hyphal growth of R. solani YC‐9 in vitro and suppressed disease progression in the leaves, and quantitative real‐time PCR confirmed that the application of dsRNAs significantly reduced the expression levels of endoPGs and RPMK1.
CONCLUSION
These results provide theoretical basis and new direction for RNAi approaches on the prevention and control of disease caused by R. solani. © 2024 Society of Chemical Industry.
... The genus Rhizoctonia belongs to phylum Basidiomycota. Rhizoctonia solani is the most well-known species in the multinuclear rhizoctonia community, which is divided into 14 identical groups based on hyphal fusion experiments (Gonzalez et al., 2011). Rhizoctonia solani is a soil-borne plant pathogen with a wide host range and geographical distribution. ...
... Wang et al. (2023) also found differences in community composition and multifunctionality between healthy and Alternaria solani-infected potato rhizosphere soils. The rootstock diseases of tobacco are mostly caused by fungi (Modjo and Hendrix, 1986;Gonzalez et al., 2011;Yang et al., 2020), and the pathogens may affect the soil microbial community by changing the rhizosphere secretions of crops in addition to directly attaching to the root surface and contacting the soil . Of course, such findings do not negate the conclusion that regional differences have a significantly greater impact than rootstock diseases in the analysis of microbial diversity, core taxa, and co-occurrence networks. ...
Introduction
Soil microorganisms are essential for crop growth and production as part of soil health. However, our current knowledge of microbial communities in tobacco soils and their impact factors is limited.
Methods
In this study, we compared the characterization of bacterial and fungal communities in tobacco soils and their response to regional and rootstock disease differences.
Results and discussion
The results showed that the diversity and composition of bacterial and fungal communities responded more strongly to regional differences than to rootstock diseases, while bacterial niche breadth was more sensitive than fungi to regional differences. Similarly, the core bacterial and fungal taxa shared by the three regions accounted for 21.73% and 20.62% of all OTUs, respectively, which was much lower than that shared by RD and NRD in each region, ranging from 44.87% to 62.14%. Meanwhile, the differences in topological characteristics, connectivity, and stability of microbial networks in different regions also verified the high responsiveness of microbial communities to regions. However, rootstock diseases had a more direct effect on fungal communities than regional differences.
Conclusion
This provided insight into the interactions between microbial communities, regional differences, and rootstock diseases, with important implications for maintaining soil health and improving tobacco yield and quality.
... After another 21 d of coculture, the disease symptoms caused by different pathogens were observed. All the three fungal pathogens could cause leaf spots and wilting (Gonzalez et al., 2011;Lee & Kwak, 2015;Chen et al., 2022). Moreover, G. zeae caused root rot (Wang et al., 2015). ...
... Phenotypes (a) and fresh weights (b) of L. radiata seedlings infected with different fungal pathogens and pre-inoculated with AA-ins or AA-sen or not inoculated (MOCK). In MOCK or AA-sen treatments, there are obvious leaf spots and wilting observed after infection of the seedlings by the three fungal pathogens (Gonzalez et al., 2011;Lee & Kwak, 2015;Chen et al., 2022); while root rot is also observed in MOCK-treated seedlings infected by G. zeae (Wang et al., 2015). Total chlorophyll content (c) in leaves and malondialdehyde content (d) in bulbs of L. radiata seedlings. ...
Alkaloids are a large group of plant secondary metabolites with various structures and activities. It is important to understand their functions in the interplay between plants and the beneficial and pathogenic microbiota.
Amaryllidaceae alkaloids (AAs) are unique secondary metabolites in Amaryllidaceae plants. Here, we studied the interplay between AAs and the bacteriome in Lycoris radiata, a traditional Chinese medicinal plant containing high amounts of AAs.
The relationship between AAs and bacterial composition in different tissues of L. radiata was studied. In vitro experiments revealed that AAs have varying levels of antimicrobial activity against endophytic bacteria and pathogenic fungi, indicating the importance of AA synthesis in maintaining a balance between plants and beneficial/pathogenic microbiota. Using bacterial synthetic communities with different compositions, we observed a positive feedback loop between bacteria insensitive to AAs and their ability to increase accumulation of AAs in L. radiata, especially in leaves. This may allow insensitive bacteria to outcompete sensitive ones for plant resources. Moreover, the accumulation of AAs enhanced by insensitive bacteria could benefit plants when challenged with fungal pathogens.
This study highlights the functions of alkaloids in plant–microbe interactions, opening new avenues for designing plant microbiomes that could contribute to sustainable agriculture.
... Rhizoctonia solani (R. solani) is a widely disseminated pathogen that is found in the soil and is commonly divided into 13 anastomosis groups (AG-1 to AG-13) [1][2][3][4][5]. Plants infected with R. solani can exhibit devastating symptoms such as sheath blight, foliage blight, stem canker, or root rot, resulting in economic losses [6,7]. According to the current ICTV taxonomy release (MSL #38 -2022), there are currently three mycovirus species whose members are associated with R. solani: Rhizoctonia solani alphaendornavirus 2 (genus Alphaendornavirus), Rhizoctonia solani orthocurvulavirus 1 (genus Orthocurvulavirus), and Rhizoctonia solani virus 717 (genus Betapartitivirus) (https:// ictv. ...
Rhizoctonia solani is a widely disseminated phytopathogen that is found in the soil and is capable of harming many important species of crops. Here, analysis of the R. solani AG-4 HG III strain A14 led to the identification of a novel mycovirus assigned the tentative name "Rhizoctonia solani partitivirus A14" (RsPV-A14), which was subjected to sequencing and associated analyses. This approach revealed that RsPV-A14 harbored two dsRNA segments, 2022 bp (dsRNA1) and 1905 bp (dsRNA2) in length. dsRNA1 was found to contain a single open reading frame (ORF1) that codes for a 622-amino-acid protein with conserved RNA-dependent RNA polymerase (RdRp) motifs, and dsRNA2 was found to contain an ORF (ORF2) that is predicted to code for a 558-amino-acid capsid protein (CP). BLASTp analysis using the putative RdRp of RsPV-A14 showed sequence similarity to partitiviruses, including Rosellinia necatrix partitivirus 7 (50.53% identity), an unclassified partitivirus. Phylogenetic analysis based on RdRp protein sequences suggested that RsPV-A14 is a novel member of the family Partitiviridae.
