Lalla Aicha Rifai’s research while affiliated with Chouaib Doukkali University and other places

This study aimed to investigate the effect of tomato planting density on susceptibility to Verticillium wilt and pepino mosaic virus diseases. Data analysis using ANOVA and Tukey’s test (P < 0.05) revealed significant differences between planting densities, highlighting a positive correlation between high planting density and increased susceptibility of three different tomato cultivars to Verticillium dahliae and pepino mosaic virus. There was a significant difference between plants grown under high and low density in their responses to the two pathogens. Growth parameters were higher in plants grown under high density compared to those grown under low density. However, disease severity, including leaf alterations and browning index caused by V. dahliae, was significantly reduced in tomato plants grown under low density compared to those grown under high density. Similarly, the severity of leaf mosaic, leaf scorching, and leaf nettle head symptoms caused by pepino mosaic virus were more pronounced in plants grown under high density and were associated with reduced photosynthetic parameters and a higher viral load, as detected by Double Antibody Sandwich - Enzyme Linked Immuno Sorbent Assay. In both pathosystems, the increased susceptibility observed in the three inoculated cultivars grown under high planting density was linked to elevated accumulation of reactive oxygen species and higher activity of Ascorbate peroxidase. These findings emphasize the importance of density management in greenhouse tomato production to mitigate disease severity.

This study aimed to examine the protective effects of a new biopolymer Cls-Alg@ZnO, composed of ZnO nanoparticles, cellulose, and alginate, on the growth and immunity of tomato plants in controlling bacterial speck disease caused by Pseudomonas syringae pv. tomato. Additionally, its antimicrobial activity was assessed against various cryptogams, including Alternaria solani, Cladosporium fulvum, Fusarium oxysporum f. sp. lycopersici, F. oxysporum f. sp. dianthi, F. oxysporum f. sp. melonis, Stemphylium sp., and Verticillium dahliae. The results revealed that Cls-Alg@ZnO (300 µg mL⁻¹) drastically reduced the mycelial growth of F.o. lycopersici, F.o. dianthi, Stemphylium sp., and V. dahliae by more than 70%. Cls-Alg@ZnO caused only slight inhibition of the radial growth of F.o. melonis and C. fulvum; however, it inhibited sporulation by 49% and 59%, respectively. When sprayed at 150 µg mL⁻¹ on tomato plants in the greenhouse, the biopolymer did not affect stem growth but significantly enhanced leaf biomass and improved net photosynthesis, stomatal conductance, transpiration rate, and Nitrate reductase activity. Furthermore, the biopolymer demonstrated the potential to inhibit the growth of P.s. tomato in planta. The number of leaf lesions and the severity of the disease were reduced by 68% and 34%, respectively, and these reductions were correlated with a significant decrease in the bacterial population in planta. Cls-Alg@ZnO did not affect the accumulation of H2O2 or lipid peroxidation induced by P.s. tomato. However, it promoted the activity of antioxidant enzymes, such as Ascorbate peroxidase and Guaiacol peroxidase. Our results suggest that this new biopolymer may be an effective biopesticide for plant protection.

The main of the present study was to prepare chitosan (Chit) and chitosan hydroxyapatite nanoparticle (Chit-nHap) to assess their activities against two major diseases affecting tomato crop: pepino mosaic virus (PepMV) and verticillium wilt caused by the fungus Verticillium dahliae. The synthesized compounds were characterized using X-rays diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electronic microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). In vitro, the application of various concentrations of Chit and Chit-nHap showed significant inhibition of radial mycelial growth against V. dahliae. However, Chit-nHap was found to be more effective than Chit. In greenhouse trials, the disease severity was significantly reduced when Chit and Chit-nHap were sprayed to the leaves at 150 and 250 μg.mL⁻¹. The highest concentration of Chit and Chit-nHap reduced leaf alteration index by more than 81% and browning index by 96%. Both compounds also reduced PepMV disease severity and virus accumulation. Protection afforded against PepMV was associated with differential accumulation of H2O2 and with potentiation of the activity of antioxidant enzymes such as catalase, ascorbate peroxidase, guaiacol peroxidase and polyphenol oxidase.

Plants interact with a great variety of microorganisms that inhabit the rhizosphere playing critical roles in several aspects of plant growth and protection against abiotic and biotic diseases. In this study, we performed a screening of bacteria associated with the rhizosphere of Prunus domestica trees to identify bacterial strains with plant growth-promoting activity. Ten strains isolated from the rhizosphere of P. domestica showed multiple in vitro plant growth promoting rhizobacteria (PGPR) activity such as the production of indole acetic acid, hydrogen cyanide, ammonia, solubilization of phosphates and antifungal activity against Verticillium dalhiae and Fusarium oxysporum f.sp. melonis. In planta, they significantly increased the growth (stem length, number of leaflets, leaf area and root weight) and biochemical (nitrate reductase activity, proline and chlorophyll content) parameters of tomato, as well as the rate of seed germination. Two selected strains (Pr7 and Pr8) with higher antagonistic activity against V. dalhiae and F. oxysporum f.sp. melonis protected tomato plants against Verticillium wilt and salt stress. In addition, they enhanced acclimatization of Vitis vinifera cv. Pinot noir and the peach root stock GF305 from in vitro to the greenhouse. 16S rRNA sequencing identified strains Pr7 and Pr8 as Pseudomonas stutzeri and Bacillus toyonensis, respectively. Since these two PGPR inoculants exhibited multiple traits beneficial to the examined host plants, they may be applied in the development of safe, and effective seed treatments as an alternative to chemical fungicides and fertilization but also for successful acclimatization of micropropagated plants.