Management of the Root-Knot nematode, Meloidogyne incognita on Tomato in Egypt

Abstract: The efficacy of carbofuran at 1 mg a.i./kg soil, Serratia marcescens (1 x 10 9 bacterium cells/ml water) at 2 ml of the suspension/kg soil, and three different Trichoderma harzianum isolates each separately added at 50 ml./kg soil against the root-knot nematode Meloidogyne incognita on two tomato cultivars Super Strain B and Alisa was assessed in the glasshouse. Fresh and dry weight of shoots were higher (P ≤ 0.05) in nematode-free plants of the two cultivars than both M. incognita-infested plants and the above-mentioned treatments. Carbofuran followed by S. marcescens and T. harzianum generally decreased nematode development and reproduction parameters compared to the untreated control. Although chemical nematicide viz. carbofuran showed a significant effect in increase of growth parameters and in suppression of Meloidogyne incognita multiplication, it can be replaced to some extent by microbial antagonists viz. Serratia marcescens and Trichoderma harzianum isolates to comply with environmental issues confronting the use of chemicals. Our results revealed differences in activities of peroxidase and chitinase related to the above-mentioned treatments on both local (in roots) and systematic (in leaves) levels but late in the growing season as well

Biochemical Characterization, Antifungal Activity, and Relative Gene Expression of Two Mentha Essential Oils Controlling Fusarium oxysporum, the Causal Agent of Lycopersicon esculentum Root Rot

Tomato (Lycopersicon esculentum Mill.) is important food in daily human diets. Root rot disease by Fusarium oxysporum caused huge losses in tomato quality and yield annually. The extensive use of synthetic and chemical fungicides has environmental risks and health problems. Recent studies have pointed out the use of medicinal plant essential oils (EOs) and extracts for controlling fungal diseases. In the current research, Mentha spicata and Mentha longifolia EOs were used in different concentrations to control F. oxysporum. Many active compounds are present in these two EOs such as: thymol, adapic acid, menthol and menthyl acetate. These compounds possess antifungal effect through malformation and degradation of the fungal cell wall. The relative expression levels of distinctly upregulated defense-related WRKY genes (WRKY1, WRKY4, WRKY33 and WRKY53) in seedling root were evaluated as a plant-specific transcription factor (TF) group in different response pathways of abiotic stress. Results showed significant expression levels of WRKY, WRKY53, WRKY33, WRKY1 and WRKY4 genes. An upregulation was observed in defense-related genes such as chitinase and defensin in roots by application EOs under pathogen condition. In conclusion, M. spicata and M. longifolia EOs can be used effectively to control this plant pathogen as sustainable and eco-friendly botanical fungicides

Green Synthesized of Thymus vulgaris Chitosan Nanoparticles Induce Relative WRKY-Genes Expression in Solanum lycopersicum against Fusarium solani, the Causal Agent of Root Rot Disease

: Fusarium solani is a plant pathogenic fungus that causes tomato root rot disease and yield losses in tomato production. The current study's main goal is testing the antibacterial efficacy of chitosan nanoparticles loaded with Thyme vulgaris essential oil (ThE-CsNPs) against F. solani in vitro and in vivo. GC-MS analysis was used to determine the chemical constituents of thyme EO. ThE-CsNPs were investigated using transmission electron microscopy before being physicochemically characterized using FT-IR. ThE-CsNPs were tested for antifungal activity against F. solani mycelial growth in vitro. A pot trial was conducted to determine the most effective dose of ThE-CsNPs on the morph/physiological characteristics of Solanum lycopersicum, as well as the severity of fusarium root rot. The relative gene expression of WRKY transcript factors and defense-associated genes were quantified in root tissues under all treatment conditions. In vitro results revealed that ThE-CsNPs (1%) had potent antifungal efficacy against F. solani radial mycelium growth. The expression of three WRKY transcription factors and three tomato defense-related genes was upregulated. Total phenolic, flavonoid content, and antioxidant enzyme activity were all increased. The outfindings of this study strongly suggested the use of ThE-CsNPs in controlling fusarium root rot on tomatoes; however, other experiments remain necessary before they are recommended