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Fusarium wilt caused by Fusarium oxysporum f. sp. niveum is one of the most devastating fungal diseases affecting watermelon (Citrullus lanatus L.). The present study aimed to identify potent antagonistic bacterial strains with substantial antifungal activity against F. oxysporum f. sp. niveum and to explore their potential for biocontrol of Fusarium wilt in watermelon. Out of 77 isolates from watermelon rhizosphere, six bacterial strains—namely, DHA4, DHA6, DHA10, DHA12, DHA41, and DHA55—exhibited significant antifungal activity against F. oxysporum f. sp. niveum, as well as other phytopathogenic fungi, including Didymella bryoniae, Sclerotinia sclerotiorum, Fusarium graminearum, and Rhizoctonia solani. These Gram-positive, rod-shaped, antagonistic bacterial strains were able to produce exo-enzymes (e.g., catalase, protease, and cellulase), siderophore, and indole-3-acetic acid and had the ability to solubilize phosphate. In greenhouse experiments, these antagonistic bacterial strains not only promoted plant growth but also suppressed Fusarium wilt in watermelon. Among these strains, DHA55 was the most effective, achieving the highest disease suppression of 74.9%. Strain DHA55 was identified as Bacillus amyloliquefaciens based on physiological, biochemical, and molecular characterization. B. amyloliquefaciens DHA55 produced various antifungal lipopeptides, including iturin, surfactin, and fengycin, that showed significant antifungal activities against F. oxysporum f. sp. niveum. Microscopic observations revealed that B. amyloliquefaciens DHA55 exhibited an inhibitory effect against F. oxysporum f. sp. niveum on the root surface of watermelon plants. These results demonstrate that B. amyloliquefaciens DHA55 can effectively promote plant growth and suppress the development of watermelon Fusarium wilt, providing a promising agent for the biocontrol of Fusarium wilt in watermelon.

Plants host diverse but taxonomically structured communities of microorganisms, called microbiome, which colonize various parts of host plants. Plant-associated microbial communities have been shown to confer multiple beneficial advantages to their host plants, such as nutrient acquisition, growth promotion, pathogen resistance, and environmental stress tolerance. Systematic studies have provided new insights into the economically and ecologically important microbial communities as hubs of core microbiota and revealed their beneficial impacts on the host plants. Microbiome engineering, which can improve the functional capabilities of native microbial species under challenging agricultural ambiance, is an emerging biotechnological strategy to improve crop yield and resilience against variety of environmental constraints of both biotic and abiotic nature. This review highlights the importance of indigenous microbial communities in improving plant health under pathogen-induced stress. Moreover, the potential solutions leading towards commercialization of proficient bioformulations for sustainable and improved crop production are also described.

The use of nanofabricated materials is being explored for the potential in crop disease management. Chemically synthesized micronutrient nanoparticles (NPs) have been shown to reduce crop diseases; however, the potential of biogenic manganese NPs (bio‐MnNPs) in disease control is unknown. Here, the potential and mechanism of bio‐MnNPs in suppression of watermelon Fusarium wilt, caused by Fusarium oxysporum f. sp. niveum (Fon) are reported. Bio‐MnNPs are synthesized by cell‐free cultural filtrate of a waterrmelon rhizosphere bacterial strain Bacillus megaterium NOM14, and are found spherical in shape with a size range of 27.0–65.7 nm. Application of bio‐MnNPs at 100 µg mL−1 increases Mn content in watermelon roots/shoots and improves growth performance through enhancing multiple physiological processes, including antioxidative capacity. Bio‐MnNPs at 100 µg mL−1 suppress Fusarium wilt through inhibiting colonization and invasive growth of Fon in watermelon roots/stems, and inhibit Fon vegetative growth, conidiation, conidial morphology, and cellular integrity. Bio‐MnNPs potentiate watermelon systemic acquired resistance by triggering the salicylic acid signaling upon Fon infection, and reshape the soil microbial community by improving fungal diversity. These findings demonstrate that bio‐MnNPs suppress watermelon Fusarium wilt by multiple ex planta and in planta mechanisms, and offer a promising nano‐enabled strategy for the sustainable management of crop diseases.

The present study was carried out to determine the influence of 2% aqueous honey (Apis dorsata Fabricius, 1793 [Hymenoptera: Apidae]) on larval growth and silk cocoon yield of fifth-instar larvae of the silkworm, Bombyx mori (Linnaeus, 1758) (Lepidoptera: Bombycidae). The larvae of silkworms (Chinese HUAKAND2) were divided into a control and an experimental groups (n = 20 in each group). Control group was fed with plain mulberry leaves throughout the fifth instar, whereas the experimental group was offered mulberry leaves dipped in 2% aqueous solution of honey every other day for 4 d (days 1, 3, 5, and 7). On the other days (days 2, 4, 6, and 8), plain mulberry leaves were offered to larvae. Results showed that the average weight gain in larvae of the experimental group was 348.23 and 204.54% in case of the control group. Uneaten mulberry leaves were weighed; the control group left 34.05% of their leaves and the treated group 28.54%. The cocoon formation in the honey-treated larvae was more uniform in shape than the control group. Furthermore, honey-treated larvae began to form cocoons 7.8 ± 0.23 h earlier than the control group. We also recorded an increase of 15.34% in average weight of cocoons of the experimental group when compared with the control. Average shell percentage of fresh silk cocoons of the control and experimental groups was 20.5 and 23.5%, respectively. It is concluded from the study that 2% aqueous honey has positive impact on the larval growth and cocoon yield of B. mori.

Present study was aimed to assess the bactericidal potential of sericin‐capped silver nanoparticles (Se‐AgNPs) synthesized by heat, light, and sonication. Se‐AgNPs were characterized by size analyzer, UV spectrophotometry, energy‐dispersive X‐ray spectroscopy, and Fourier transform infrared spectroscopy. Average size of Se‐AgNPs synthesized by heat, light and sonication was 53.60, 78.12, and 7.49 nm, respectively. All (10) bacterial strains were exposed to Se‐AgNPs prepared from different methods to compare their antibacterial potentials. Largest zone of inhibition (13 ± 1.15 mm) was observed for sonication‐based nanoparticles (NPs) against Klebseilla pneumoniae while the smallest zone of light assisted NPs against Serratia rubidaea (5 ± 1 mm). Bacterial strains were also exposed to different concentrations (0.2%, 0.3%, and 0.6%) of Se‐AgNPs which showed largest zone (12 ± 1 mm) of inhibition for 0.4% of Se‐AgNPs against Protius mirabilis and smallest zone (5 ± 1.154 mm) for 0.3% of Se‐AgNPs against Escherichia coli. Furthermore, effect of different temperatures (5°C, 37°C, and 60°C) and pH (3, 7, and 12) on the efficacy and stability of Se‐AgNPs was also evaluated against different bacterial strains. Sonication mediated NPs showed highest bactericidal results against K. pneumoniae (F3,8 = 6.154; p = 0.018) with smallest size NPs (7.49 nm) while lowest bactericidal results against S. rubidaea (5 ± 1 mm) were shown with largest size (78.12 nm) NPs prepared by natural light. These variations of bactericidal activities of NPs with difference size endorse that the Se‐AgNPs with smallest size have highest antibacterial activity than larger size NPs. Moreover, Se‐AgNPs maintain their bactericidal potency at wide range of temperature and pH, hence seemed stable.

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SUMOylation is an essential protein modification process that regulates numerous crucial cellular and biochemical processes in phytopathogenic fungi, and thus plays important roles in multiple biological functions. The present study characterizes the SUMOylation pathway components, including SMT3 (SUMO), AOS1 (an E1 enzyme), UBC9 (an E2 enzyme), and MMS21 (an E3 ligase), in Fusarium oxysporum f. sp. niveum (Fon), the causative agent of watermelon Fusarium wilt, in terms of the phylogenetic relationship, gene/protein structures, and basic biological functions. The SUMOylation components FonSMT3, FonAOS1, FonUBC9, and FonMMS21 are predominantly located in the nucleus. FonSMT3, FonAOS1, FonUBC9, and FonMMS21 are highly expressed in the germinating macroconidia, but their expression is downregulated gradually in infected watermelon roots with the disease progression. The disruption of FonUBA2 and FonSIZ1 seems to be lethal in Fon. The deletion mutant strains for FonSMT3, FonAOS1, FonUBC9, and FonMMS21 are viable, but exhibit significant defects in vegetative growth, asexual reproduction, conidial morphology, spore germination, responses to metal ions and DNA-damaging agents, and apoptosis. The disruption of FonSMT3, FonAOS1, FonUBC9, and FonMMS21 enhances sensitivity to cell wall-perturbing agents, but confers tolerance to digestion by cell wall-degrading enzymes. Furthermore, the disruption of FonSMT3, FonAOS1, and FonUBC9 negatively regulates autophagy in Fon. Overall, these results demonstrate that the SUMOylation pathway plays vital roles in regulating multiple basic biological processes in Fon, and, thus, can serve as a potential target for developing a disease management approach to control Fusarium wilt in watermelon.