Solani Growth Research Articles

Antifungal Efficacy of Kappaphycus alvarezii and Other Macro-algae against Alternaria solani Induced Early Blight in Tomato (Solanum lycopersicum L.)

Aims: To evaluate the antifungal activity of various seaweed extracts against A. solani under in vitro conditions. Methodology: The pathogen A.solani was isolated and its pathogenicity confirmed through inoculation on tomato plants. Molecular characterization was performed using PCR amplification and sequencing of the Internal Transcribed Spacer (ITS) region. Seaweed species, including Sargassum wightii, Kappaphycus alvarezii, Gracilaria edulis, Caulerpa racemosa, and Ulva lactuca, were collected, processed, and extracted using various solvents. The antifungal activity of these seaweed extracts was assessed using the Poisoned Food Technique, measuring the inhibition of A. solani growth. Results: Among the seaweed extracts tested, Kappaphycus alvarezii demonstrated the highest antifungal activity, with a maximum mycelial growth inhibition of 76% at a 5% concentration. Sargassum wightii also showed significant antifungal properties, with a 71.10% reduction in mycelial growth. Conclusion: The study reveals the promising potential of seaweed extracts, particularly Kappaphycus alvarezii and Sargassum wightii, as natural antifungal agents against A. solani. These findings suggest that seaweed-based bio-stimulants could serve as effective, eco-friendly alternatives to chemical fungicides in managing early blight disease in tomatoes are in tomato crops and highlights the potential of seaweed extracts as a natural antifungal agent.

Root Rot Management in Common Bean (Phaseolus vulgaris L.) Through Integrated Biocontrol Strategies using Metabolites from Trichoderma harzianum, Serratia marcescens, and Vermicompost Tea

Common bean (Phaseolus vulgaris L.) is an essential food staple and source of income for small-holder farmers across Africa. However, yields are greatly threatened by fungal diseases like root rot induced by Rhizoctonia solani. This study aimed to evaluate an integrated approach utilizing vermicompost tea (VCT) and antagonistic microbes for effective and sustainable management of R. solani root rot in common beans. Fourteen fungal strains were first isolated from infected common bean plants collected across three Egyptian governorates, with R. solani being the most virulent isolate with 50% dominance. Subsequently, the antagonistic potential of vermicompost tea (VCT), Serratia sp., and Trichoderma sp. was assessed against this destructive pathogen. Combinations of 10% VCT and the biocontrol agent isolates displayed potent inhibition of R. solani growth in vitro, prompting in planta testing. Under greenhouse conditions, integrated applications of 5 or 10% VCT with Serratia marcescens, Trichoderma harzianum, or effective microorganisms (EM1) afforded up to 95% protection against pre- and post-emergence damping-off induced by R. solani in common bean cv. Giza 6. Similarly, under field conditions, combining VCT with EM1 (VCT + EM1) or Trichoderma harzianum (VCT + Trichoderma harzianum) substantially suppressed disease severity by 65.6% and 64.34%, respectively, relative to untreated plants. These treatments also elicited defense enzyme activity and distinctly improved growth parameters including 136.68% and 132.49% increases in pod weight per plant over control plants. GC–MS profiling of Trichoderma harzianum, Serratia marcescens, and vermicompost tea (VCT) extracts revealed unique compounds dominated by cyclic pregnane, fatty acid methyl esters, linoleic acid derivatives, and free fatty acids like oleic, palmitic, and stearic acids with confirmed biocontrol and plant growth-promoting activities. The results verify VCT-mediated delivery of synergistic microbial consortia as a sustainable platform for integrated management of debilitating soil-borne diseases, enhancing productivity and incomes for smallholder bean farmers through regeneration of soil health. Further large-scale validation can pave the adoption of this climate-resilient approach for securing food and nutrition security.

Role of Hydrogen Peroxide (H2O2) and Trichoderma koningii in Reducing Root Rot Disease of Tomato Causing by Fusarium solani

Two isolates of the pathogenic fungus Fusarium solani the causative of tomato root rot disease named Fs1 and Fs2 were isolated from tomato plants infected with root rot disease. Results showed that both examined isolates had significant effects on the percentage of seed germination of tomato and damping-off disease. Thus, isolate Fs1 was more effective than isolate Fs2, as it recorded a percentage of germination and damping-off 56.6 and 71.6% respectively, compared to the control treatment, which recorded 100 and 0% respectively. It was found that the use of hydrogen peroxide (H2O2) at concentrations of 50, 100 and 200 ppm had a significant effect on the fungal radial growth, dry weight (DW) and sporulation of F. solani. Antifungal activity of H2O2 appeared even at the lowest concentration (50 ppm), which inhibited radial growth to 49.33%, and decreased the dry weight to 498 mg, and the sporulation to 3.75×106 spores. Additionally, the results indicated significant inhibitory effects of hydrogen peroxide (H2O2) and the bioagent Trichoderma koningii on F. solani growth. It was noticed that H2O2 has compatible effects with T. koningii, where the antagonistic ability of T. koningii against F. solani increased when the concentration of H2O2 had increased. The results revealed that the treatment F. solani + H2O2 (200 ppm) + T. koningii significantly reduced the percentage of damping-off and plant survival to 9.40 and 5.39% respectively, in comparison with the control treatment and F. solani alone treatment, which reached 20.22, 14.48, 34.32 and 67.41% respectively.

Transcriptome analysis reveals the humic acids and chitosan suppressing Alternaria solani growth.

Understanding the inhibitory effects of natural organic substances on soil-borne pathogenic fungi and the relevant molecular mechanisms are highly important for future development of green prevention and control technology against soil-borne diseases. Our study elucidates the inhibitory effect of the combined application of humic acids (HAs) and chitosan on Alternariasolani and the light on the corresponding mechanism. The effect on A. solani growth by HAs incorporated with chitosan was investigated by plate culture and the corresponding mechanism was revealed using transcriptomics. The colony growth of A. solani was suppressed with the highest inhibition rate 33.33% when swine manure HAs was compounded with chitosan at a ratio of 1:4. Chitosan changed the colony morphology from round to irregularly. RNA-seq in the HAs and chitosan (HC) treatment revealed 239 differentially expressed genes compared with the control. The unigenes associated with enzymes activities related to growth and biological processes closely related to mycelial growth and metabolism were downregulated. RNA-seq also revealed that chitosan altered the expression of genes related to secondary metabolism, fungal cell wall formation and polysaccharide synthesis, and metabolism. Meanwhile, weighted gene co-expression network analysis showed that, genes expression in the module positively correlated with mycelial growth was significantly reduced in the HC treatment; and the results were verified by real-time quantitative polymerase chain reaction. The co-inhibition effect of HAs and chitosan on A. solani is associated with downregulated genes expression correlated with mycelial growth.

Engineering a recombinant chitinase from the marine bacterium Bacillus aryabhattai with targeted activity on insoluble crystalline chitin for chitin oligomer production

Chitin, an abundant polysaccharide in India, is primary by-product of the seafood industry. Efficiently converting chitin into valuable products is crucial. Chitinase, transforms chitin into chitin oligomers, holds significant industrial potential. However, the crystalline and insoluble nature of chitin makes the conversion process challenging. In this study, a recombinant chitinase from marine bacteria Bacillus aryabhattai was developed. This enzyme exhibits activity against insoluble chitin substrates, chitin powder and flakes. The chitinase gene was cloned into the pET 23a plasmid and transformed into E. coli Rosetta pLysS. IPTG induction was employed to express chitinase, and purification using Ni-NTA affinity chromatography. Optimal chitinase activity against colloidal chitin was observed in Tris buffer at pH 8, temperature 55°C, with the presence of 400 mM sodium chloride. Enzyme kinetics studies revealed a Vmax of 2000 μmole min−1 and a Km of 4.6 mg mL−1. The highest chitinase activity against insoluble chitin powder and flakes reached 875 U mg−1 and 625 U mg−1, respectively. The chitinase demonstrated inhibition of Candida albicans, Fusarium solani, and Penicillium chrysogenum growth. Thin Layer Chromatography (TLC) and LC-MS analysis confirmed the production of chitin oligomers, chitin trimer, tetramer, pentamer, and hexamer, from chitin powder and flakes using recombinant chitinase.

Biocontrol and Growth Promotion Potential of Bacillus subtilis CTXW 7-6-2 against Rhizoctonia solani that Causes Tobacco Target Spot Disease.

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.

Assessing the In vitro Antagonistic Effects of Trichoderma and Pseudomonas Bioagents on Rice Sheath Blight Pathogen

Sheath blight, caused by the fungus Rhizoctonia solani, is a devastating disease that poses a significant threat to rice production worldwide. In recent years, biocontrol agents such as Trichoderma and Pseudomonas have gained attention for their potential to manage sheath blight while minimizing the environmental impact associated with chemical pesticides. The present investigation assessed the effect of Trichoderma harzianum and Pseudomonas fluorescens on Rhizoctonia solani in vitro after collection and mass multiplication from different locations. The dual culture assay revealed complex interactions between R. solani and biocontrol agents such as T. harzianum and Pseudomonas fluorescens. T. harzianum exhibited significant antagonistic activity, as evidenced by the inhibition of R. solani growth, hyphal coiling around R. solani mycelia, and direct mycoparasitic interactions. Pseudomonas fluorescens, on the other hand, demonstrated an indirect antagonistic effect by producing siderophores and antibiotics that hindered the growth of Rhizoctonia solani. Trichoderma harzianum isolate (IRRI-1) was found to be most inhibitory for Rhizoctonia solani in vitro followed by Trichoderma harzianum (SV-3) and Pseudomonas fluorescens (PF-2). These observations provide insights into the mechanisms underlying the biocontrol potential of T. harzianum and Pseudomonas fluorescens against R. solani. In conclusion, the dual culture assay proved to be an effective method for studying the interactions between R. solani and biocontrol agents. The findings contribute to our understanding of the underlying mechanisms of biocontrol agents and offer valuable information for the development of sustainable agricultural strategies aimed at managing plant diseases caused by R. solani.

Ectopic Expression of Gastrodia Antifungal Protein in Rice Enhances Resistance to Rice Sheath Blight Disease.

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.

Antifungal Activity of Essential Oils on Helminthosporium solani Causing Potato Silver Scurf under In Vitro and In Vivo Conditions

Potato silver scurf, caused by the fungus Helminthosporium solani, is an important storage disease of potato (Solanum tuberosum L.), reducing the market value of tubers. Using in vitro and in vivo assays, the presented experiments aimed to determine the effect of selected essential oils (EOs: α-pinene, carvacrol, cinnamaldehyde, D-carvone, eucalyptol, L-linalool, L-menthol, L-menthone, (R)-(+)-limonene, and thymol) on H. solani growth. All EOs inhibited pathogen growth, but their antifungal activities differed significantly. Thymol, carvacrol, and cinnamaldehyde had the strongest inhibitory effects on mycelial growth under in vitro conditions. (R)-(+)-limonene displayed the weakest inhibition. The effectiveness of those EOs with the greatest antifungal activity was confirmed by in vivo experiments. EOs were applied through dressing and fumigation, with EOs bound to a biopolymer for dressing. Dressing and fumigation brought a highly statistically significant reduction in H. solani infection intensity and sporulation intensity on tubers. Although EOs had an insignificant effect on potato cooking quality, the taste of EO-dressed tubers was degraded by an off-odor and off-taste. EOs could provide an ecological alternative for reducing H. solani tuber infection during storage.

An antibiotic produced by Pseudomonas fluorescens CFBP2392 with antifungal activity against Rhizoctonia solani.

Pseudomonas fluorescens CFBP2392 has been recognized as a potential biocontrol agent due to its ability to suppress damping-off and root rot disease. This isolate has antibacterial activity in vitro as many other strains from the Pseudomonas fluorescens complex. In this work, the antibacterial and antifungal activity of the strain were explored. Dual culture assays evidenced the antifungal activity of the strain against different phytopathogens: Alternaria sp., Pythium ultimun, Fusarium oxysporum, and Rhizoctonia solani. Purification of an antifungal fraction was performed by preparative HPLC from the chemical extraction of growth media. The fraction showed altered R. solani growth and ultrastructure. Transmission electron microscopy revealed the purified compound induced hypertrophied mitochondria, membranous vesicles, and a higher number of vacuoles in R. salani cytoplasm. In addition, co-cultivation of P. fluorescens CFBP2392 with R. solani resulted in an enlarged and deformed cell wall. To gain genomic insights on this inhibition, the complete genome of P. fluorescens CFBP2392 was obtained with Oxford Nanopore technology. Different biosynthetic gene clusters (BGCs) involved in specialized metabolites production including a lokisin-like and a koreenceine-like cluster were identified. In accordance with the putative BGCs identified, sequence phylogeny analysis of the MacB transporter in the lokisin-like cluster further supports the similarity with other transporters from the amphisin family. Our results give insights into the cellular effects of the purified microbial metabolite in R. solani ultrastructure and provide a genomic background to further explore the specialized metabolite potential.

Synthesis and Anti-Plant Pathogenic Fungal Activity of Flavokawain-Derived Flavones and Related Flavones Against Rhizoctonia solani

Flavones are organic compounds in the flavonoid family that have a diverse range of biological functions. In this research, many flavones with various substituents were designed and synthesized from flavokawains A, B, and C, and their chalcone derivatives via an iodine-catalyzed oxidative cyclization process. All synthetic flavones were investigated for antifungal activities against Rhizoctonia solani, a plant pathogenic fungus. At 400 µg, most of the substances did not inhibit the tested species and R. solani growth was inhibited by only o-bromoflavone (40) by 74.88±0.91%. This indicated that the detrimental effect of flavones depends on the type and position of substituent, with the ortho bromo group showing the most promise. The molecular docking study on the succinate dehydrogenase (SDH) enzyme revealed that the bromophenyl moiety (ring B) is a key molecular substructure of the flavone fungicide. The findings of this study will be used to develop novel plant pathogenic fungicides.

Morpho-Molecular Study and Biochemical Management of Fusarium Solani in Bell Pepper

Bell pepper (Capsicum annum L.) is one of the most important vegetable crops in Pakistan. This crop is prone to many fungal diseases, such as Phytophthora blight, Fusarium wilt, Verticillium wilt, Powdery mildew, and Anthracnose. Among all of them, Fusarium wilt is the most devastating disease of bell pepper that is responsible for heavy yield reduction. This study is aimed to identify and manage Fusarium solani in bell pepper, in vitro as well as in pots experiment. For this purpose, sampling, isolation, purification, and morpho-molecular identification were performed. Molecular characterization of F. solani was achieved by using ITS primers. The results showed that the nucleotide sequence of these isolates showed 100% homology to Fusarium solani. In vitro management was done by the application of Trichoderma harzianum and synthetic fungicides (Thiophanate methyl, Mancozeb+Metalaxyl, Fosetyl aluminum, Difenoconazole, and Sulphur). Five concentrations (100 ppm, 200 ppm, 400 ppm, 800 ppm, and 1000 ppm) were employed using dual culture and food poisoning method, respectively. LSD was used in combination with four replications. Data was taken after 3, 5, 7, and 10 days. The results showed that T. harzianum inhibited F. solani growth up to 87.98% after 10 days. As compared to the biological treatment, Thiophanate methyl showed maximum inhibition (100%) after 3 days at 100 ppm. Later on, its efficacy at 100 ppm was reduced after 5, 7, and 10 days. The inhibition after 10 days was calculated to be 72.89%. At 200, 400, 800, and 1000 ppm, the percentage of inhibition was up to 100%. Furthermore, Mancozeb + Metalaxyl showed maximum inhibition (100%) after 3 days at 1000 ppm. Similarly, Fosetyl aluminum showed maximum inhibition (100%) after 3 days at 1000 ppm. Whereas, Difenoconazole showed maximum inhibition (100%) after 3 days at 800 ppm. Later on, the efficacy at 800 ppm was reduced after 7 and 10 days. The inhibition after 10 days was calculated to be 87.72%. At 1000 ppm, the percentage of inhibition was up to 100%. Finally, sulphur showed maximum inhibition 82.7% after 3 days at 1000 ppm. Later on, its efficacy at 1000 ppm was reduced after 5, 7, and 10 days. The inhibition after 10 days was calculated to be 62.62%.

Effectiveness of Bacillus pseudomycoides strain for Biocontrol of Early Blight on tomato plants

Alternaria early blight is an air-borne and soil-borne pathogen that cause losses and damages that can reach up to 80% in tomato production. In our work, the immediate antagonistic effect of Bacillus pseudomycoides was inspected against Alternaria early blight of tomato. Bacillus pseudomycoides (Bp1) (OQ629426) gave inhibition efficacy against A. solani growth, being, 74.22 %. Invitro, Bp1 had the capability to produce the endogenous plant auxin (IAA) it was 18.9 (µg/100 mL), the quantity of GA 9.4 (µg/100 mL), 95.8 μ Deferroxamine mesylate. Tomato plants treated with B. pseudomycoides registered the least disease severity, being 50 and 40 % in Mancozeb + ALS and Bp1+ ALS treatments with high efficiency to control the severity between 75 and 100 % respectively. Tomato plants treated with B. pseudomycoides showed improved growth characteristics as compared with the untreated control. Plants with bacterial treatment conferred 45.6 cm shoot length, 2.9 (g∕plant) fresh weight and 0.7 (g∕plant) Dry weight. The highest increase in the activity of polyphenol oxidase (PPO) and peroxidase (POD) was observed in the infected leaves of tomato plants treated with B. pseudomycoides Bp1 (T4) (4.6, 6.9 m/g f. w.) respectively, followed by treatment of plants with Mancozeb (T3) (3.9, 5.4 m/g f. w.) respectively, compared to other treatments. This study suggested that B. pseudomycoides is a promising biocontrol agent against Alternaria early blight. This bacterium may represent an important source of potential antimicrobial bio-agent against Alternaria early blight disease, also it may play a role in the development of integrated control programs in future studies.

In vitro inhibition mechanism of Trichoderma asperellum isolates from corn against Rhizoctonia solani causing banded leaf and sheath blight disease and its role in improving the growth of corn seedlings

BackgroundOne of the primary corn diseases, banded leaf and sheath blight, is carried on by the pathogenic fungus Rhizoctonia solani. Efforts to control R. solani are more directed at environmentally friendly control using a biological control agent, such as Trichoderma spp. as antagonistic agents and plant growth promoter. This study aimed to identify T. asperellum isolates based on molecular characteristics and to determine the in vitro inhibition mechanism against R. solani and its role in enhancing the growth of corn seedlings.ResultsThe HMRP7, HMRF7A, HMEDF1B, HMEDF6A, and CHM01 isolates were identified as T. asperellum with a genetic distance coefficient value of 0.000 and a very high similarity of 100%. Meanwhile, the RsHM isolate was identified as R. solani with a homology level of > 90% and genetic distance coefficient values ranging from 0.000 to 0.032. The antagonistic ability showed that the five T. asperellum isolates were able to inhibit the growth of R. solani in vitro on PDA medium with an inhibition percentage of ≥ 50%, so they were categorized as antagonist agents. T. asperellum showed the antagonistic mechanism in inhibiting the R. solani growth through the action of parasitism. The five T. asperellum isolates tested on corn seedlings showed a significantly high difference from the control treatment on the observational variables of maximum growth potential (MGP), growth rate (GtR), growth simultaneity (GS), vigor index (VI), germination rate (GR), and median germination time (T50).ConclusionCHM01 isolate showed better potential than other isolates in inhibiting the growth of R. solani in vitro on PDA medium with a parasitism mechanism and enhancing the growth of corn seedlings.

Genome and Transcriptome Analysis to Elucidate the Biocontrol Mechanism of Bacillus amyloliquefaciens XJ5 against Alternaria solani.

Early blight, caused by Alternaria solani, is an important disease affecting tomatoes. Biological control offers an environmentally friendly approach to controlling pathogens. Herein, we identified a B. amyloliquefaciens strain XJ5 and investigated its biocontrol mechanism against A. solani. A. solani growth was significantly inhibited by XJ5, with the inhibition rate of cell-free culture supernatants reaching 82.3%. Furthermore, XJ5 crude protein extracts inhibited conidia germination and altered the mycelial morphology of A. solani. To uncover the potential biocontrol mechanism of XJ5, we analyzed its genome sequence and transcriptome. The genome of XJ5 comprised a 4.16 Mb circular chromosome and two circular plasmids. A total of 13 biosynthetic gene clusters and 127 genes encoding hydrolases were identified, suggestive of the ability of XJ5 to secrete antagonistic secondary metabolites and hydrolases. Transcript analysis revealed 174 differentially expressed genes on exposing A. solani to XJ5 crude protein extracts. The expression of genes related to chitin and mannose synthesis was downregulated, indicating that XJ5 metabolites may impact chitin and mannose synthesis in A. solani. Overall, these findings enhance our understanding of the interactions between B. amyloliquefaciens and phytopathogens and pave the way for the agricultural application of this promising biocontrol agent.

Phytochemical analysis and antifungal potential of two Launaea mucronata (Forssk.) Muschl and Launaea nudicaulis (L.) Hook.fil. wildly growing in Anbar province, Iraq

Ethnopharmacological relevancePlant fungi are a serious problem in agriculture. Even though synthetic fungicides are an efficient control method, several negative side effects emerge from their extensive use, such as health problems, environmental pollution, and the emergence of resistant microorganisms. Thus, it is becoming more and more urgent to search for alternative control methods. Aim of the studyThe aim of our study was to analyze phytochemical composition and antifungal potential of Launaea mucronata (Forssk.) Muschl. and Launaea nudicaulis (L.) Hook. fil. wildly growing in Anbar province, Iraq. In addition, molecular analysis was used to identify the plants species and molecular docking analysis was investigated between the major phytochemicals present in these plants and three selected fungal proteins, in order to assess the antifungal activity of the selected biochemicals against these proteins. Materials and methodsMolecular analysis was performed using ITS sequencing protocol. The phytochemical analysis was done using GC-MS technique, while molecular docking analysis was performed by FRED application between selected compounds from each plant and three enzymes: 17β-hydroxysteroid dehydrogenase, endochitinase, and 14-α-demethylase. Finally, the antifungal activity was assessed by measuring inhibition percentage of Fusarium solani and Macrophomina phaseolina growth treated with ethanomethanolic extract of each plant. ResultsMolecular analysis identified the selected plants as L. mucronata and L. nudicaulis, with an ITS region of 600 bp. Phytochemical analysis of Launaea spp. reported the presence of 35 compounds in each ethanomethanolic extract, belonging to different classes. L. mucronata was mainly formed of lupeol (9.33%), whereas L. nudicaulis extract was dominated by the heterocyclic compound 4-(3-methoxyphenoxy)-1,2,5-oxadiazol-3-amine (20.2%). Furthermore, molecular docking analysis showed that 4H-pyran-4-one,2,3-dihydro-3,5-dihydroxy-6-methyl from L. mucronata and gulonic acid Ƴ-lactone from L. nudicaulis possessed the highest affinity score to 17-β-hydroxysteroid dehydrogenase (−4.584 and −7.811 kcal/mol, respectively). Sucrose from L. mucronata and glutaric acid, di(3,4-difluorobenzyl) ester from L. nudicaulis gave the highest affinity to endochitinase (−7.979 and - 8.446 kcal/mol, respectively). In addition, sterol 14-α-demethylase was affinitive to sucrose from L. mucronata and glutaric acid, di(3,4-difluorobenzyl) ester from L. nudicaulis via energetic score of −10.002 and −9.582 kcal/mol, respectively. Both extracts exhibited antifungal activity against F. solani and M. phaseolina in a dose-dependent manner. ConclusionsThis study confirms the antifungal potential of both Launaea spp. explained by the presence of phytochemicals with antimicrobial properties. These compounds have potential to be used as new drugs to treat infectious diseases caused by pathogens. Consequently, plants from Launaea genus could be a raw material for many studies such as therapeutic, taxonomical, drug modelling, and antifungal agent.

Molecular characterization of Fusarium solani causing stem and root rot disease of balloon flower (Platycodon grandiflorus) in Viet Nam

The most significant issue affecting balloon flower (Platycodon grandiflorus) in Vietnam’s mountainous provinces is stem and root rot disease. The purpose of this study was to identify the causal fungus Fusarium solani of balloon flower planted in Lao Cai province. F. solani’s identity was confirmed through DNA sequencing and phylogenetic analyses based on ITS sequences. PDA was the most suitable medium for F. solani growth and development of the three semi-solid media tested (CA, PDA, and CDA). The optimal temperature and pH conditions for its growth ranged from 25-30 °C with a maximum growth rate of 25 °C and pH 5.5-7.0 with a maximum growth rate of 6.5. This is the first report of F. solani causing balloon flower stem and root rot in Vietnam.

Efficient Role of Endophytic Aspergillus terreus in Biocontrol of Rhizoctonia solani Causing Damping-off Disease of Phaseolus vulgaris and Vicia faba.

The wide spread of plant pathogens affects the whole world, threatening national food security. Various fungi including Rhizoctonia solani induce the fungal disease damping-off that negatively affects plant seedlings' growth. Recently, endophytic fungi are used as safe alternatives to chemical pesticides that harm plant and human health. Here, an endophytic Aspergillus terreus was isolated from Phaseolus vulgaris seeds to control damping-off diseases by improving the defense system in Phaseolus vulgaris and Vicia faba seedlings. Endophytic fungus was morphologically and genetically identified Aspergillus terreus, and it is deposited in GeneBank under accession OQ338187. A. terreus demonstrated antifungal efficacy against R. solani with an inhibition zone at 22.0 mm. Moreover, the minimum inhibitory concentrations (MIC) of ethyl acetate extract (EAE) of A. terreus were between 0.3125 and 0.625 mg/mL to inhibit R. solani growth. Precisely 58.34% of the Vicia faba plants survived when A. terreus was added compared with the untreated infected (16.67%). Similarly, Phaseolus vulgaris achieved 41.67% compared to the infected (8.33%). Both groups of treated infected plants showed reduced oxidative damage (reduced Malondialdehyde and hydrogen peroxide levels) as compared to untreated infected plants. Reduced oxidative damage was correlated with the increase in photosynthetic pigments and the antioxidant defense system including polyphenol oxidase, peroxidase, catalase, and superoxide dismutase enzyme activities. Overall, the endophytic A. terreus can be considered an effective tool to control the suppression of Rhizoctonia solani in legumes, especially Phaseolus vulgaris and Vicia faba, as an alternative to synthetic chemical pesticides that harm the environment and human health.

Seed vectored bacterial endophyte Bacillus pumilus protect sorghum (Sorghum bicolor L.) seedlings from a fungal pathogen Rhizoctonia solani

The goal of this study was to evaluate the role of seed endophytic bacteria (SEB) in fungal disease protection in sorghum seedlings. Total six SEB, including two Bacillus spp. (SM1 and SM6), and four Paenibacillus spp. (SM2, SM3, SM4, and SM5) were isolated from sorghum seeds. All isolates produced auxin while only SM3 isolate showed phosphate solubilization activity. All SEB inhibited the growth of tested fungal pathogens. Bacillus pumilus (SM1) and Bacillus subtilis (SM6) showed positive drop collapse assay, and presence of surfactin gene was also screened in their genomes. Further, lipopeptides extracted from SM1 and SM6 strongly inhibited Rhizoctonia solani growth in disc diffusion assay. Live-dead staining and fluorescence microscopy revealed the structural deformations and cell death in R. solani by lipopeptides. In microcosm assay, seeds inoculated with B. pumilus significantly protected the seedlings from Rhizoctonia infection. B. pumilus inoculated seedlings showed significant increase in the levels of PAL and SOD enzymes and their gene expressions (2.76, 2.00 and 4.61, 2.25 folds, respectively) compared to control. PR1 gene expression was also increased by 2.68 folds compared to the control. Present study concludes that sorghum seeds inhabit SEB like B. pumilus which is crucial in protecting seedlings from R. solani by producing lipopeptides, enhancing antioxidant and defense enzymes level and their gene expressions. This study is significant in terms of its originality which presents a first report on SEB of sorghum roles in seedlings protection against soil borne fungal pathogen like Rhizoctonia solani.

Recovery of the soil fungal microbiome after steam disinfection to manage the plant pathogen Fusarium solani.

Soil disinfection using high temperatures via steam is a promising approach to manage plant pathogens, pests, and weeds. Soil steaming is a viable option for growers who are moving away from dependence on chemical soil fumigants, especially in plant nursery or high tunnel environments. However, there are few studies that investigate how soil steaming causes substantial disturbance to the soil by killing both target pathogens and other soil biota. Steaming treatments also change the trajectory of the soil microbiome as it reassembles over time. Growers are interested in the health of soils after using steam-disinfection, especially if a virulent pathogen colonizes the soil and then flourishes in a situation where there are very few microbes to suppress its growth. Should recruitment of a virulent pathogen occur in the soil, this could have devasting effects on seed germination, seedling establishment and survival. Beneficial microbes are often used to prevent the colonization of plant pathogens, especially after a soil-steaming event. Here, we experimentally test how soil fungal communities assemble after steaming disinfection. We introduce to steam-treated soil Fusarium solani, an important fungal pathogen of soybean and Trichoderma harzianum, a known beneficial fungus used for soilborne pathogen suppression. Results show that F. solani significantly affects the relative abundance and diversity of the soil fungal microbiome, however, T. harzianum does not mitigate the amount of F. solani in the steam treated soil. Within the T. harzianum microbial addition, the soil fungal communities were similar to the control (steaming only). This result suggests inoculating the soil with T. harzianum does not drastically alter the assembly trajectory of the soil fungal microbiome. Other soil amendments such as a combination of Trichoderma spp. or other genera could suppress F. solani growth and shift soil microbiome composition and function post-steaming, however, more experimental research is needed.