Omaima Bargougui’s research while affiliated with University of Kairouan and other places

Microbial inoculants, single or consortia, are groups of microorganisms or their product that can be directly applied in soil or in plant. They have a positive impact on both soil and plant by restoring soil fertility and improving plant performance. Bacteria and fungi are essential components of plant ecosystems. These microbes include different kinds of groups as follows: plant growth-promoting microorganisms (PGPMs), biological control agents (BCAs), and symbiosis (SM). Many mechanisms of these microbes can service plants for growing and protection against biotic and abiotic stress by producing antimicrobial, mycoparasitism, biostimulation, and other useful compounds. Biostimulation is one of the measures that help plants to confront different stress and boost the growth. Biostimulants gained increasing attention as an alternative to chemical fertilizers and pesticides, due to their ability to promote plant growth, enhance nutrient uptake, and improve plant defense against stresses both biotic and abiotic. This current review aims to fill the gap in the current knowledge by citing the various aspects of biostimulants by PGPM and BCAs that comprise action mechanisms, application modes, types of microorganisms, and their influences on the management of plant diseases as well as plant vigor. It is relevant to determine the challenges and opportunities associated with the wide and commercial application of microbial inoculants to be a valuable alternative in sustainable agriculture.

Climate change is exacerbating fluctuations in environmental conditions, leading to increased plant disease severity and risk in agricultural production. Tomatoes are particularly susceptible to the airborne fungal pathogen Alternaria solani, which causes early blight disease and significant yield losses. This study investigated the potential of Pseudomonas sp. culture filtrate as a biocontrol alternative to traditional pesticides for managing early blight in tomatoes. The antifungal activity of the filtrate was assessed using in vitro dual culture techniques and in vivo assay on tomato fruits. Laboratory experiments evaluated different concentrations (10, 20, and 40%) of the culture filtrate for their ability to inhibit A. solani mycelial growth, spore germination, and growth rate. Disease severity and lesion diameter were measured on tomato fruits to determine the filtrate's efficacy. The 40% concentration demonstrated the strongest antagonistic effect, significantly inhibiting mycelial growth (64.31%), spore germination (0.80 x 10 4 spores mL-1), and mycelial growth rate (1.17 mm h-1). Furthermore, in vivo application of the filtrate on tomato fruits led to a substantial reduction in disease severity (0.40) and lesion diameter (0.70 cm) compared to the positive control (4 and 5.15 cm, respectively). These findings suggest that Pseudomonas sp. culture filtrate has significant potential as an eco-friendly biofungicide for controlling early blight disease in stored tomatoes. This approach offers a valuable alternative to traditional chemical controls, which can have negative environmental consequences. Further research is warranted to investigate the efficacy of this biocontrol method under field conditions and explore its potential for broader application in tomato production.

Sustainable food production necessitates a safe and secure food system. Cultivating tomatoes, melons, and watermelons can enhance agricultural viability, food security, and their integration into diverse intercropping systems. However, Rhizoctonia solani, a necrotrophic plant pathogen with a broad host range, poses a significant threat to these crops, causing blights, damping-off, and rots. This study aimed to develop an eco-friendly strategy for managing R. solani damping-off (Rs26, Rs94, Rs13, Rs57, and Rs123). Following a pathogenicity assay to assess disease incidence in tomato, melon, and watermelon plants, an in vitro assay evaluated the efficacy of biological agents (Trichoderma harzianum, T. viride, Metarhizium sp., and Gliocladium sp.) in controlling R. solani. All R. solani isolates displayed varying degrees of pathogenicity across all crops compared to the control. Isolates Rs94 and Rs13 caused the most severe disease in watermelon (3.80 and 3.83, respectively), while Rs26 displayed the highest pathogenicity in tomato (3.84). Disease severity scores exceeding 2.59 across all R. solani isolates on melon indicate high susceptibility in this crop. All antagonistic fungi inhibited the growth of R. solani isolates to varying degrees. Notably, Trichoderma spp. displayed the most consistent and significant inhibition across all R. solani isolates, with reductions in mycelial growth ranging from 82.97% (Rs13/T. viride) to 94.67% (Rs26/T. harzianum). These findings hold promise for the development of an integrated and eco-friendly approach to managing R. solani damping-off.

Integrated pest and disease management (IPDM) is a strategic approach that combines multiple pest and pathogen control methods to optimize their reduction while minimizing ecological and economic consequences. This multifaceted strategy serves as a fundamental component of sustainable agricultural systems, emphasizing the balanced integration of various methods to achieve effective and environmentally responsible pest and pathogen suppression. Modern agricultural practices, characterized by intensified production and monoculture systems, create optimal environments for pathogen proliferation and virulence. These conditions necessitate the IPDM strategies. Integrated pest and disease management is crucial for mitigating pathogen-induced losses and ensuring sustainable agricultural production. It aims to minimize reliance on chemical fungicides by promoting environment-friendly and economically viable strategies for disease control. This review delves into the major pathogens that affect the plants and the intricate relationship between IPDM and sustainable agriculture, examining the key principles, strategies, and benefits associated with integrating these disease management practices into the agricultural system. It underscores the crucial role of IPDM in minimizing environmental impacts, protecting beneficial organisms, fostering genetic diversity, and ensuring economic sustainability. By adopting integrated pest and disease management strategies, farmers can effectively manage plant diseases while simultaneously safeguarding the long-term health and productivity of their agricultural systems.

Beauveria bassiana and Metarhizium spp. are entomopathogenic fungi with potential applications beyond insect pest control, including plant disease suppression, plant growth promotion, and rhizosphere colonization. This study investigated the plant growth-promoting characteristics and extracellular enzyme activities of Metarhizium spp. and B. bassiana in relation to phytopathogen interactions and plant growth. Additionally, the efficacy of these fungi in mitigating damping-off and root rot caused by Rhizoctonia solani on cucumber plants was evaluated in vitro and in vivo. Results indicate that B. bassiana and M. anisopliae produce indole-3-acetic acid, hydrocyanic acid, and hydrolytic enzymes. Seed treatment with these fungi significantly reduced disease severity (3.85%–1.86%, respectively) and enhanced germination parameters [germination percentage (85.33%–86%, respectively), germination index (10.67–12.29, respectively), seedling length vigor index (86.41–109.44, respectively), and seedling weight vigor index (30.24–37.57, respectively)] compared to the control positive. Both fungi demonstrated high inhibition rates of R. solani mycelial growth (93.90%–90.46%, respectively). Greenhouse trials revealed that preventive treatments using B. bassiana and M. anisopliae increased catalase (104.40–105.52 units/mg protein/min, respectively), (4.58–5.77 units/mg protein/min, respectively), superoxide dismutase (40.65–41.74 units/mg protein/min, respectively), and polyphenol oxidase (0.539–0.559 units/mg protein/min, respectively) activities, as well as total phenolic (2.60–2.65 mg/g, respectively) and total sugar content (2.23–2.16 mg/g, respectively) in cucumber plants. Consequently, disease severity (9.51–6.99%, respectively) was reduced, and plant height (93.76–98.76 cm, respectively) increased compared to the positive control. These findings suggest that B. bassiana and M. anisopliae can enhance plant growth, stimulate plant defense mechanisms, and effectively control damping-off and root rot diseases, making them promising candidates for biological control strategies.

Fusarium dry rot (Fusarium solani) and Pythium aqueous rot (Pythium ultimum) are important post-harvest diseases responsible annually for regrettable qualitative and quantitative losses during potato (Solanum tuberosum L.) storage. Processing waste of citrus fruits is considered an eco-friendly and bio-safe alternative to traditional agro-chemicals due to their excellent repository of bioactive compounds. The present study assessed chemical composition , antifungal activities, antioxidant assays and total phenolic and flavonoid contents of essential oils and aqueous extracts from peels of Citrus limon and C. sinen-sis. The aqueous extracts were obtained by maceration, and phytochemical screening was performed by HPLC. The essential oils were extracted by hydro-distillation using the Clevenger apparatus and analyzed by Gas Chromatography-Mass Spectrometry. The total polyphe-nol and flavonoid contents and antioxidant potential of both citrus peel extracts were investigated spectrophoto-metrically. The antifungal activities performed by poisoned food technique and disk diffusion method against F. solani and P. ultimum. The results revealed that C. limon peel extracts exhibited higher polyphenol and flavonoids contents compared to C. sinensis. The antiox-idant activities of C. limon peels (82.91%) generated a highest activity than C. sinensis (73.51%). The phyto-chemical analysis of the aqueous extracts indicated the presence of significant concentrations of major phenolic acids (quinic, protocacchuic, caffeic, coumaric and frulic acid). Rutin, kampherol and quercetin considered as major flavonoids. Furthermore, phytochemical profile analysis of essential oil indicated that the major phyto-chemicals are a-limonene, b-pinene, ɣ-terpinene, b-linalool and a-citral. The peel extracts inhibited mycelia growth of F. solani and P. ultimum. Both post-harvest pathogens were classified as very sensitive to orange and lemon oils. The present study indicates that citrus peels are rich in numerous phytochemicals and bioactive components. In addition, they exhibited a promising potential on inhibiting growth of these pathogenic fungi. Therefore, bioactive compounds of citrus peels with significant antifungal activities have a promising future in Fusarium dry rot and Pythium aqueous rot management to substitute the agrochemicals.