Characterization of Fusarium Spp. Inciting Vascular Wilt of Tomato and Its Management by a Chaetomium-Based Biocontrol Consortium

Sustainable Management of Major Fungal Phytopathogens in Sorghum (Sorghum bicolor L.) for Food Security: A Comprehensive Review

Sorghum (Sorghum bicolor L.) is a globally important energy and food crop that is becoming increasingly integral to food security and the environment. However, its production is significantly hampered by various fungal phytopathogens that affect its yield and quality. This review aimed to provide a comprehensive overview of the major fungal phytopathogens affecting sorghum, their impact, current management strategies, and potential future directions. The major diseases covered include anthracnose, grain mold complex, charcoal rot, downy mildew, and rust, with an emphasis on their pathogenesis, symptomatology, and overall economic, social, and environmental impacts. From the initial use of fungicides to the shift to biocontrol, crop rotation, intercropping, and modern tactics of breeding resistant cultivars against mentioned diseases are discussed. In addition, this review explores the future of disease management, with a particular focus on the role of technology, including digital agriculture, predictive modeling, remote sensing, and IoT devices, in early warning, detection, and disease management. It also provide key policy recommendations to support farmers and advance research on disease management, thus emphasizing the need for increased investment in research, strengthening extension services, facilitating access to necessary inputs, and implementing effective regulatory policies. The review concluded that although fungal phytopathogens pose significant challenges, a combined effort of technology, research, innovative disease management, and effective policies can significantly mitigate these issues, enhance the resilience of sorghum production to facilitate global food security issues.

A benzo[b]thiophene-derived inhibitor of virus particle assembly via targeting capsid protein residue Arg157

As a biological macromolecule, the coat protein (CP) of potato virus Y (PVY) mediates the virus' primary pathogenic behaviors. It has been gradually realized that certain residues on the CP are crucial for functions such as virus particle movement and assembly. However, there are few reports of potential drugs successfully targeting these key residues with unique mechanisms of action. Here, we disclose the first new phytovirucide that acts on the key site Arg157 (R157) on the PVY CP. In this investigation, we developed a series of benzo[b]thiophene-based compounds, strategically introducing sulfonamide functionalities to enhance their antiviral performance. Through bio-screening, derivative C54 (EC50 = 69.2 μg/mL for inactive activity) emerged as notably more effective against PVY than the established antiviral agent ningnanmycin (EC50 = 79.6 μg/mL). Mechanistic studies revealed that C54 is an inhibitor of viral particle assembly by specifically binding to the CP residue R157, thereby disrupting its interaction with RNA. These results underscore the promise of C54 as a potent antiviral lead and provide a fresh perspective on the strategic design of inhibitors focusing on viral assembly processes.

Identification of Meloidogyne panyuensis (Nematoda: Meloidogynidae) infecting Orah (Citrus reticulata Blanco) and its impact on rhizosphere microbial dynamics: Guangxi, China

Root-knot nematode disease severely affects the yield and quality of the mandarin variety Citrus reticulata Blanco "Orah" in Guangxi, China. Nevertheless, the pathogen and the effects of this disease on microbial communities remain inadequately understood. This study identified the root-knot nematode Meloidogyne panyuensis in the rhizosphere of infected Orah using morphological and molecular biological methods. Soil chemical properties indicated that organic matter, total nitrogen (TN), total phosphorus (TP), available phosphorus (AP), total potassium (TK), and available potassium (AK) were significantly higher in the rhizosphere soil of M. panyuensis-infected Orah than in that of healthy plants. The relative abundance of the bacteria Bacillus, Sphingomonas, and Burkholderia-Caballeronia-Paraburkholderia, as well as the fungi Lycoperdon, Fusarium, Neocosmospora, Talaromyces, and Tetragoniomyces, was elevated in the rhizosphere soil of M. panyuensis-infected plants. Furthermore, organic matter, TN, available nitrogen (AN), TP, AP, TK, and AK exhibited positive correlationswith these bacteria and fungi in the rhizosphere soil of M. panyuensis-infected Orah. Potential biocontrol strains, such as Burkholderia spp., were identified by comparing the differences in rhizosphere microbial composition between healthy Orah and M. panyuensis-infected Orah. Our findings provide a foundation for the early warning and prevention of root-knot nematode disease in Orah.

Microplastic influences the ménage à trois among the plant, a fungal pathogen, and a plant growth-promoting fungal species

Microplastics (MP) can influence a plethora of fungal species within the rhizosphere. Nevertheless, there are few studies on the direct impacts of MPs on soil fungi and their intricate interplay with plants. Here, we investigated the impact of polyethylene microspheres (PEMS) on the ecological interactions between Fusarium solani, a plant pathogenic fungus, and Trichoderma viride, a fungal plant growth promotor, within the rhizosphere of Solanum lycopersicum (tomato). Spores of F. solani and T. viride were pre-incubated with PEMS at two concentrations, 100 and 1000 mg L-1. Mycelium growth, sporulation, spore germination, and elongation were evaluated. Tomato seeds were exposed to fungal spore suspensions treated with PEMS, and plant development was subsequently assessed after 4 days. The results showed that PEMS significantly enhanced the sporulation (106.0 % and 70.1 %) but compromised the spore germination (up to 27.3 % and 32.2 %) and radial growth (up to -5.2% and -21.7 %) of F. solani and T. viride, respectively. Furthermore, the 100 and 1000 mg L-1 concentrations of PEMS significantly (p<0.05) enhanced the mycelium density of T. viride (9.74 % and 22.30 %, respectively), and impaired the germ-tube elongation of F. solani after 4 h (16.16 % and 11.85 %, respectively) and 8 h (4 % and 17.10 %, respectively). In addition, PEMS amplified the pathogenicity of F. solani and boosted the bio-enhancement effect of T. viride on tomato root growth. Further, PEMS enhanced the bio-fungicidal effect of T. viride toward F. solani (p<0.05). In summary, PEMS had varying effects on F. solani and T. viride, impacting their interactions and influencing their relationship with tomato plants. It intensified the beneficial effects of T. viride and increased the aggressiveness of F. solani. This study highlights concerns regarding the effects of MPs on fungal interactions in the rhizosphere, which are essential for crop soil colonization and resource utilization.

Deciphering Differences in Microbial Community Diversity between Clubroot-Diseased and Healthy Soils

Clubroot (Plasmodiophora brassicae) is an important soilborne disease that causes severe damage to cruciferous crops in China. This study aims to compare the differences in chemical properties and microbiomes between healthy and clubroot-diseased soils. To reveal the difference, we measured soil chemical properties and microbial communities by sequencing 18S and 16S rRNA amplicons. The available potassium in the diseased soils was higher than in the healthy soils. The fungal diversity in the healthy soils was significantly higher than in the diseased soils. Ascomycota and Proteobacteria were the most dominant fungal phylum and bacteria phylum in all soil samples, respectively. Plant-beneficial microorganisms, such as Chaetomium and Sphingomonas, were more abundant in the healthy soils than in the diseased soils. Co-occurrence network analysis found that the healthy soil networks were more complex and stable than the diseased soils. The link number, network density, and clustering coefficient of the healthy soil networks were higher than those of the diseased soil networks. Our results indicate that the microbial community diversity and network structure of the clubroot-diseased soils were different from those of the healthy soils. This study is of great significance in exploring the biological control strategies of clubroot disease.

Characterization of field isolates of Fusarium spp. from eggplant in India for species complexity and virulence

Eggplant wilt, despite emerging as a severe disease in India, the etiology must be better studied for its species' complexity and variability. The identity of fungal isolates associated with eggplants of India was established morphologically followed by sequencing and phylogenetic analysis. Three species, Fusarium falciforme, Fusarium incarnatum and Fusarium proliferatum, were observed for the first time in India. The isolates were tested for pathogenicity. Though all of them were pathogenic, the isolates displayed varying degrees of virulence. In further studies, the genetic relatedness of the isolates for virulence was assessed with candidate avirulent (SIX effectors), virulent (Fow1 and Fow2) and SSR markers. The SIX effector genes could not delineate the virulent isolates and were expressed in some non-F. oxysporum isolates for the first time. Likewise, the virulent genes, Fow1 for expression across the isolates and Fow2 for random expression across the isolates, were unsuitable markers for identifying the virulent groups. Hence, the F. oxysporum and F. solani isolates were genotyped with SSR markers. Though the clustering did not correlate with their virulence levels, the dendrogram grouping revealed variability among the F. oxysporum and F. solani isolates. This study concludes that although multiple species of Fusarium are associated with eggplant wilt in India, only F. oxysporum and F. solani are widespread in the surveyed areas. Though the three markers could not delineate the race specificity of the isolates, only the SSR makers could identify the genetic variability and hence, would help screen eggplant germplasm for fusarium wilt resistance.

The Imperative Use of Bacillus Consortium and Quercetin Contributes to Suppress Fusarium Wilt Disease by Direct Antagonism and Induced Resistance

Fusarium wilt diseases severely influence the growth and productivity of numerous crop plants. The consortium of antagonistic rhizospheric Bacillus strains and quercetin were evaluated imperatively as a possible remedy to effectively manage the Fusarium wilt disease of tomato plants. The selection of Bacillus strains was made based on in-vitro antagonistic bioassays against Fusarium oxysporum f.sp. lycoprsici (FOL). Quercetin was selected after screening a library of phytochemicals during in-silico molecular docking analysis using tomato LysM receptor kinases "SILKY12" based on its dual role in symbiosis and plant defense responses. After the selection of test materials, pot trials were conducted where tomato plants were provided consortium of Bacillus strains as soil drenching and quercetin as a foliar spray in different concentrations. The combined application of consortium (Bacillus velezensis strain BS6, Bacillus thuringiensis strain BS7, Bacillus fortis strain BS9) and quercetin (1.0 mM) reduced the Fusarium wilt disease index up to 69%, also resulting in increased plant growth attributes. Likewise, the imperative application of the Bacillus consortium and quercetin (1.0 mM) significantly increased total phenolic contents and activities of the enzymes of the phenylpropanoid pathway. Non-targeted metabolomics analysis was performed to investigate the perturbation in metabolites. FOL pathogen negatively affected a range of metabolites including carbohydrates, amino acids, phenylpropanoids, and organic acids. Thereinto, combined treatment of Bacillus consortium and quercetin (1.0 mM) ameliorated the production of different metabolites in tomato plants. These findings prove the imperative use of Bacillus consortium and quercetin as an effective and sustainable remedy to manage Fusarium wilt disease of tomato plants and to promote the growth of tomato plants under pathogen stress conditions.

Chaetoglobosin A Contributes to the Antagonistic Action of Chaetomium globosum Strain 61239 Toward the Apple Valsa Canker Pathogen Cytospora mali

Apple Valsa canker (AVC) weakens apple trees and significantly reduces apple production in China and other East Asian countries. Thus far, very few AVC-targeting biocontrol resources have been described. Here, we present a thorough description of a fungal isolate (Chaetomium globosum, 61239) that has strong antagonistic action toward the AVC causal agent Cytospora mali. Potato dextrose broth culture filtrate of strain 61239 completely suppressed the mycelial growth of C. mali on potato dextrose agar, and strongly constrained the development of AVC lesions in in vitro infection assays. ultra-performance liquid chromatography (UPLC) and HPLC-MS/MS investigations supported the conclusion that strain 61239 produces chaetoglobosin A, an antimicrobial metabolite that inhibits C. mali. Using genome sequencing, we discovered a gene cluster in strain 61239 that may be responsible for chaetoglobosin A production. Two of the cluster's genes-cheA, a PKS-NRPS hybrid enzyme, and cheB, an enoyl reductase-were individually silenced, which significantly decreased chaetoglobosin A accumulation as well as the strain's antagonistic activity against C. mali. Together, the findings of our investigation illustrate the potential use of Chaetomium globosum for the management of AVC disease and emphasize the significant contribution of chaetoglobosin A to the antagonistic action of strain 61239.

Amylolytic and antibacterial activity of filamentous fungi isolated from the rhizosphere of different plants grown in the Tamanghasset region

In the present study, we were interested in studying the amylolytic and antibacterial activity of some filamentous fungi isolated from the rhizosphere of cultivated plants in Tamanghasset region. Consequently, 11 pure strains belonging to the different fungal genera were isolated Alternaria, Aspergillus, Cladosporium, Curvularia, Fusarium, Mucor and Penicillium. Positive result of amylolytic activity was revealed on all the isolated strains, with important hydrolysis zones of 54.33 ± 1.15 mm, 54.00 ± 3.61 mm, 52.00 ± 6.08 mm and 51.33 ± 15.01 mm for Aspergillus sp.1, Curvularia sp., Fusarium sp.2 and Mucor sp. respectively. In addition, analysis of variance (ANOVA) of the means of hydrolysis zones diameters shows that the values linked by the same letter do not show any significant difference at P < 0.05. Antibacterial activity of the isolated fungal was demonstrated by the agar cylinder technique against four pathogenic bacterial strains. The results showed a variability of the inhibition zones, thus the most important results were recorded against S. aureus, E. coli and K. pneumonia for all fungi which produced inhibition zones ranging from 15.33 ± 0.00 to 23.66 ± 1.71 mm. while all isolate had the lowest inhibition zone against P. aeruginosa. In conclusion, the obtained results indicated the isolated filamentous fungi have the potential to inhibit the four pathogenic bacterial strains, S. aureus, E. coli, K. pneumonia and P. aeruginosa, while simultaneously showed significant amylolytic activity.