The use of actinomycetes for improving soil fertility and plant production is an attractive strategy for developing sustainable agricultural systems due to their effectiveness, eco-friendliness, and low production cost. Out of 17 species isolated from the soil rhizosphere of legume crops, 4 bioactive isolates were selected and their impact on 5 legumes: soybean, kidney bean, chickpea, lentil, and pea were evaluated. According to the morphological and molecular identification, these isolates belong to the genus Streptomyces. Here, we showed that these isolates increased soil nutrients and organic matter content and improved soil microbial populations. At the plant level, soil enrichment with actinomycetes increased photosynthetic reactions and eventually increased legume yield. Actinomycetes also increased nitrogen availability in soil and legume tissue and seeds, which induced the activity of key nitrogen metabolizing enzymes, e.g., glutamine synthetase, glutamate synthase, and nitrate reductase. In addition to increased nitrogen-containing amino acids levels, we also report high sugar, organic acids, and fatty acids as well as antioxidant phenolics, mineral, and vitamins levels in actinomycete treated legume seeds, which in turn improved their seed quality. Overall, this study shed the light on the impact of actinomycetes on enhancing the quality and productivity of legume crops by boosting the bioactive primary and secondary metabolites. Moreover, our findings emphasize the positive role of actinomycetes in improving the soil by enriching its microbial population. Therefore, our data reinforce the usage of actinomycetes as biofertilizers to provide sustainable food production and achieve biosafety.

Infestation by parasitic weeds is one of the most important environmental challenges threatening cropping systems worldwide. Among these, branched broomrape (Orobanche ramosa), a root holoparasitic weed, detrimentally affects many crops especially tomato (Lycopersicon esculentum) and causes severe crop losses. The positive role of silicon nanoparticles (SiNPs) in the growth and yield of plants grown under stressful conditions has been reported. However, no study has investigated the impact of SiNPs on plant–weed interaction. In this study, we conducted a green-house experiment to assess the physiological implications of SiNPs on tomato under the Orobanche challenge. Orobanche infection alone markedly inhibited tomato growth and photosynthesis (P < 0.0001) and induced oxidative damage via increased photorespiration (P < 0.0001) and NADPH oxidase activities (P < 0.01). Interestingly, SiNPs significantly reduced the infection severity by reducing both the number and biomass of Orobanche tubercles (13 and 31% decrease, respectively). Moreover, SiNPs dramatically ameliorated the physiological and biochemical disorders imposed by Orobanche in tomato. Consistently, SiNPs strengthened the cell wall of host roots by upregulating lignin biosynthesis that acts as a physical barrier against tubercle haustorial penetration. On the other hand, SiNPs caused a noticeable decrease in ROS production and improved both enzymatic and non-enzymatic detoxification systems, the thing that was more pronounced in roots than in shoots of infected tomato plants. Such organ-specific responses were confirmed by cluster analysis. Overall, this study suggests that tomato plants treated with SiNPs will be more tolerant to Orobanche infection through enhanced structural and metabolic responses.

Ocimum basilicum is a valuable source of bioactive metabolites with high preventive and therapeutic effectiveness. Here we aimed to investigate the effect of phenological stages (vegetative and flowering stages) on essential oil composition and biological activities of two varieties of O. basilicum (Fino Verde variety and Genovese varieties). To this end, the level of essential oils, flavonoids and phenols, as well as antioxidant and antifungal activities were measured. At the metabolic level, essential oil at vegetative stage of O. bailicum Fino Verde and Genovese variety was constituted by 22 and 26 compounds representing 71.68% and 82.54% of the total oil, respectively. Where germacrene D (10.07%), bicyclogermacrene (6.07%) and β-elemene (4.88%) were the most present components in Fino Verde variety. Moreover, 22.19% are oxygenated monoterpenes represented mainly by the linalool (15.18%) and 1.8 cineole (6.36%) in Genovese variety. The individuals of essential oils were significantly increased to 40 components in Fino Verde variety (98.01% of total essential oil) and decreased to 15 components (95.6% of total essential oil) in Genovese variety at flowering stage. At this stage, the oxygenated monoterpenes (78.4%) were the major fraction represented by linalool (40.1%) and 1.8 cineole (30.96%) in Fino Verde variety, however 64.69% were esters which mainly represented by the methyl cinnamate (64.69%), and 16.83% of oxygenated monoterpenes and Linalool (12.7%) were recorded for Genovese variety. Genovese variety showed the highest levels at both vegetative and flowering stage compared to Fino Verde variety. At flowering stage, the two varieties showed high antioxidant and antifungal activities. Overall, O. basilicum properties offer prospects for their use as a source, particularly at flowering stage to extend new medicines based on natural bioactive molecules.