Issam Nouairi

BACKGROUND: Silicon (Si) has been demonstrated to be an important element to enhance crop tolerance against salinity. Nevertheless, mechanisms underlying Si's mitigation of salt stress remains insufficiently explored and understood. This study aims to provide new insights into Si's impact on salt‐stressed Sorghum bicolor (L.) supplied or not with 0.5 mmol L ⁻¹ of sodium silicate (Na ₂ SiO ₃ ) by combining the assessment of photosystems performance, fatty acid metabolism as linked to membrane integrity, and molecule's chemical structure stability. RESULTS: Relative to sodium chloride (NaCl) treatment alone, Si supply enhanced biomass production; increased chlorophyll a , chlorophyll b , and carotenoid contents by 35%, 26%, and 61%, respectively ( P < 0.01); and increased proline and total soluble sugar contents ( P < 0.05). Notably, results shed new light into Si‐optimized photochemical balance between photosystems by further enhancing photosystem II (PSII) photochemical yield (Y(II)), electron transport rate (ETR(II)) and diminished non‐photochemical energy dissipation processes (Y(NPQ) and Y(NO)), while recovering photosystem I (PSI) photochemical yield (Y(I)) and electron transport rate (ETR(I)), primarily via the alleviation of the donor‐side limitation (decrease in Y(ND)). Moreover, Si supplementation preserved membrane integrity, reducing malondialdehyde (MDA) levels by 15% ( P < 0.01), as demonstrated by enhanced linoleic acid (C18:2) and linolenic acid (C18:3) contents ( P < 0.05). Further, results showed a previously unreported observation of Si's protective effect on the chemical structure of molecules by suppressing the induced salt modifications. CONCLUSION: In summary, this study broadens our understanding of Si's enhanced salt tolerance, showing improved balance of photosystem's performance, maintaining membrane stability and fatty acid metabolism, and preserving the integrity of chemical secondary structures. © 2026 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Broomrapes (Orobanche spp.) are root parasitic plants that threaten agricultural production in many parts of the world. In this study, the effect of two orobanche species, Orobanche crenata and O. foetida, on faba bean plants was studied in Tunisia. The two orobanche species inhibited both biomass production and pod formation, decreased the chlorophyll (Chl) content and total lipid (TL), and enhanced electrolyte leakage (EL) and lipid peroxidation. Concomitantly, orobanche parasitism induced a lower degree of fatty acid (FA) unsaturation due to a shift in the FA composition. On the other hand, with regard to orobanche seeds, oleic and linoleic acids were the predominant FA in the two orobanche species. After orobanche seed germination and penetration of host tissues, all the orobanche development stages showed a decrease in the TL content and changes in the FA composition in comparison to orobanche seeds. The level of TL was equal to or lower in all parasite development stages (except for S4) than that in the roots and leaves of healthy faba bean plants. These results suggest that the negative effect of orobanche infestation on faba bean development can be attributed to the reduced chlorophyll content and alteration in membrane stability attested by the reduced TL level and FA unsaturation.

The present study was carried out in order to investigate the behaviour of six faba bean (Vicia faba Minor) genotypes (Saber 02, Locale, Baachar, Badii, Chourouk and Najeh) in response to salinity and flooding (hypoxia), either alone or combined, to identify tolerant genotypes and to select efficient faba bean-rhizobia symbiosis under salinity and/or hypoxia conditions. faba bean genotypes were cultivated in three agricultural soils with either low (160 µs/cm) or moderate (1850 µs/cm) salt content and submitted or not to a 30-day long flooding period. Growth parameters and photosynthetic performance were analyzed at the end of the flowering period. At harvest time, the Najeh genotype showed the highest dry mass production in both control and hypoxia conditions (7.90 and 6.75 g/plant, respectively), whereas Saber 02 showed the lowest (3.75 and 2.25 g/plant, respectively). Differences between genotypes were less marked in salinity or combined salinity/flooding conditions. Principal component analysis of the analyzed parameters revealed that the Najeh genotype presents the best growth and the lowest photosynthetic perturbation and lipid peroxidation levels, whether under control or hypoxic conditions, whereas Saber 02 and Locale genotypes were less productive. Ninety bacteria strains were isolated from Vicia faba root nodules. Of these, 47 strains were identified as rhizobia, and 20 were able to re-nodulate the host plant. After the characterization, identification and selection process, four strains were selected as the best faba bean symbiotic partners based on their symbiotic efficiency and salt tolerance behaviours. Our results suggest that faba bean tolerant genotypes in symbiosis with these strains could be useful in enhancing legume cultivation under saline and hypoxia field conditions.

This study evaluated the antifungal activity of NPs against Botrytis cinerea, the causal agent of grey mould, which is an important fungal diseases in several crops. In addition, a green method for the synthesis of zinc oxide nanoparticles (ZnO NPs) employing aqueous extract of olive leaves (Olea europaea) was developed. Foliar extract was used as reducing biological agents for synthesising ZnO NPs. The ZnO NPs were characterised by a number of techniques, including UV–Vis spectrophotometry, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM) coupled with energy dispersive X-ray microanalysis (EDXMA). In addition, we determined the in vitro antifungal capacity of the synthesised ZnO NPs, by measuring the inhibitory effect on the growth of B. cinerea. Moreover, the protective and antifungal efficacy of ZnO NPs concentrations (0, 100, 200, 400, 800 and 1000 μg/ml) was recorded under in vivo condition by foliar spray on detached leaves and whole faba bean (Vicia faba L. major) plants. Results showed that XRD analysis confirmed the presence of pure crystalline shapes of ZnO NPs. Spherical to hexagonal ZnO NPs, as depicted by SEM, were found to have diameters in the range of 11.0 to 60.0 nm, while XRD revealed a dominant average size of 17.41 nm in the sample. FTIR analysis suggested that phenols, flavonoids, glycosides and proteins may also play a major role in the formation of ZnO nanoparticles. According to the radial growth test, results showed that at the highest concentrations of ZnO NPs (400, 800 and 1000 ppm), the mycelial growth of B. cinerea was significantly inhibited after 12 days of incubation. Moreover, evaluation of the preventive effect of ZnO NPs foliar spray application on faba bean plants inoculated with B. cinerea, showed that the disease severity, the number of infected leaves, the shoot length, the shoot dry weight (DW), the total protein and malondialdehyde (MDA) content in leaves were negatively affected compared to the control (infected plants). Overall, the results of this study clearly indicate that the biosynthesized ZnO NPs have a promising antifungal activity which could be used as a fungicide for the protection of faba bean against B. cinerea.

Our research aimed to reveal the capacity of intercropping with Medicago sativa-rhizobia in the amelioration of grapevine growth in agricultural and a Cd/Pb contaminated soils. A local variety of grapevine was cultivated in monocropping and in intercropping with Medicago sativa inoculated or not with its associated rhizobia. Intercropping with alfalfa induced a significant increase in shoot and root biomass of grapevine in the agricultural soil. However, in the contaminated soil, a slight increase in root biomass was observed. Concerning photosynthesis apparatus, we showed that the presence of Cd and Pb in the soil induced a significant decrease in both CO2 assimilation rate and stomatal conductance. Interestingly, intercropping with alfalfa only and with rhizobia alleviate this effect. Similar results are obtained for chlorophyll and carotenoid content. This was associated with a significant decrease in the malondialdehyde level in leaves and roots of grapevine cultivated in intercropping with alfalfa with and without inoculation in the two soils as compared the monoculture treatment. Comparison between treatments revealed also that intercropping with alfalfa induced a decrease in the activities of some enzymes implicated in the defence to the oxidative stress such as catalase and superoxide dismutase. Regarding soluble protein content, it is needed to signal the improvement of this parameter with the intercropping system in the contaminated soil when compared to the monocropping treatment. This work highlights the importance of the use of legumes in intercropping with grapevine as intercrop plant non-competitive for soil nutrient and proving N supply for associated plants.

Seed priming is one of the potential physiological approaches to enhance seed germination under salt stress. The present study examined the role of two seed priming molecules, salicylic acid (SA) and hydrogen peroxide (H2O2), to enhance the salt tolerance in lentil seeds at germination stage. Salt stress caused significant decrease in germination percentage and primary root elongation. This decrease was associated with significant increase in lipid peroxidation and total lipid (TL) contents in embryonic axis. The catalase (CAT), guaiacol peroxydase (GPOX) and superoxide dismutase (SOD) activities remained unchanged or decreased significantly under the influence of salt stress, in both embryonic axis and cotyledons. Starch mobilization was not affected by salt stress. The two priming treatments effectively alleviated the negative effects of salt stress. SA and H2O2 applications after dose optimization resulted in significant enhancement of germination percentage and primary root elongation. No significant changes in starch, soluble sugars contents and SOD activity were detected following SA and H2O2 treatments. Seed priming treatments triggered the activities of GPOX and CAT and caused the reduction of lipid peroxidation especially in embryonic axis. TL content and especially the fatty acid C18:3 increased after SA applications. The better performance under salt stress of primed lentil seeds was associated with lower lipid peroxidation, and activation of enzymatic antioxidative defense system. Obtained results confirm the potential for using SA and H2O2 to improve germination and plant growth under salt stress conditions.

Iron (Fe) deficiency is one of the major environmental stresses affecting plant production in the world. The selection of tolerant genotypes is considered an effective remediation strategy for this stress. The present study was carried out in order to investigate the biodiversity within Medicago truncatula plants in response to Fe deficiency, to identify tolerant genotypes and to assess the main tolerance mechanisms. To do this, a screening test was performed on 20 M. truncatula genotypes cultivated in minimal medium. Biometric and physiological markers were analyzed, including plant biomass, chlorophyll and root architecture. Results showed a biodiversity among the 20 genotypes. Interestingly, Fe deficiency tolerance was highest in TN8.20 and A17 genotypes. However, the lowest tolerance behavior was observed in TN1.11 and TN6.18. In order to investigate the main tolerance mechanisms, an experiment was conducted in the hydroponic system on already selected genotypes. Assessment of Fe deficiency tolerance was performed mainly on plant growth parameters, Fe (III)‐chelate‐reductase activity, rhizosphere acidification and antioxidant system defense. The relative better tolerance of A17 and TN8.20 to Fe deficiency was positively correlated with their capacity to maintain higher Fe‐acquisition efficiency in roots via rhizosphere acidification and the stimulation of Fe (III)‐chelate‐reductase activity. Moreover, tolerant genotypes showed the lowest decreases in chlorophyll content and photosynthetic activity (CO ₂ assimilation) compared to the sensitive ones. The efficiency of antioxidant capacity of the tolerant genotypes was revealed in stimulation of catalase (CAT) and peroxidase (POX) activities as well as accumulation of polyphenols, leading to the maintenance of cell integrity under Fe deficiency.

Alleviation of cadmium-induced root genotoxicity and cytotoxicity by calcium chloride (CaCl₂) in faba bean (Vicia faba L. var. minor) seedlings were studied. Faba bean seeds were treated with H₂O or 2% CaCl₂ for 6 h before germination. Seeds were then exposed to 0 and 50 µM CdCl₂ concentrations for 7 days. Genotoxic damaging effects of Cd was examined through the determination of the mitotic index (MI), chromosomal aberrations (CA) and micronucleus (MN) in the meristem cells of faba bean roots. Similarly, effects of Cd stress on metal accumulation, total membrane lipid contents, total fatty acid composition (TFA), lipid peroxidation as indicated by malondialdehyde production, soluble protein and non-protein thiols (NP-SH) contents, hydrogen peroxide production and the activities of superoxide dismutase (SOD), catalase (CAT) and guaiacol peroxidase (GPX) were evaluated after 7 days of Cd stress in the seedling roots. Cd stress resulted in the reduction of MI, in addition to MN formation and CA induction in the roots of non-primed seeds (treated with H₂O). Moreover, Cd induced lipid peroxidation, H₂O₂ overproduction and loss of membrane lipid amount and soluble protein content, and changes in the TFA composition in roots of faba bean seedlings. SOD activity declined, but CAT and GPX activities increased. However, seed pre-treatment with CaCl₂ attenuated the genotoxic and cytotoxic effects of Cd on Vicia faba roots. The results showed that CaCl₂ induced reduction of Cd accumulation, improved cell membrane stability and increased the antioxidant defence systems, thus reducing and alleviating Cd genotoxicity and oxidative damage.