Dr. Mahmoud M. Y. Madany

Marrubium vulgare is a valuable source of natural bioactive molecules with high preventive and therapeutic effectiveness. Therefore, this study aimed to study the chemical polymorphism of natural populations of M. vulgare in Tunisia by quantitative chemical markers and the estimation of divergence between populations. Phytochemical analyses of the eight natural populations of Tunisian Marrubium vulgare prospected in different bioclimatic stages, revealed 42 compounds of essential oils representing 96.08% to 100% of the total oil. Hydrocarbon sesquiterpenes were the main fraction of all the populations studied and $\beta$-bisabolene was the major compound (from 30.11% to 71.35% of the total oil). The phytochemical investigation of the M. vulgare plant indicated the presence of essential oil with significant percentages of phenolic compounds. A significant quantitative and qualitative variation in the essential oils is detected for both major and minor compounds. The principal components analysis (PCA) performed in the single and combined traits provides a good distinction among populations, not according to their geographical and/or bioclimatic origins. Moreover, the phytochemical analysis of the leaves showed that the Tunisian populations, i.e., the populations of Kasserine, Kef, and Beja, were very rich in phenolic compounds (from 20.8 to 44.65 mg GAE/g DW). Flavonoids compounds were also the main class of total polyphenols present in all the tested populations (from 8.91 to 37.48 mg RE/g DW). The quantitative genetic diversity estimated by the population's structure, based on PCA analysis, was an adaptation to the changes in the environmental conditions. Overall, our study indicated that natural populations of M. vulgare had different chemotypes of essential oils and they were rich in phenolic compounds, particularly flavonoids, which opens a new prospect for industrial use and differential exploitation of this species.

Soil contamination with indium (In) oxide nanoparticles (In2O3-NPs) threatens plant growth and development. However, their toxicity in plants under ambient (aCO2) and elevated (eCO2) conditions is scarcely studied. To this end, this study was conducted to investigate In2O3-NPs toxicity in the young and old leaves of C3 (barley) and C4 (maize) plants and to understand the mechanisms underlying the stress mitigating impact of eCO2. Treatment of C3 and C4 plants with In2O3-NPs significantly reduced growth and photosynthesis, induced oxidative damage (H2O2, lipid peroxidation), and impaired P and Fe homeostasis, particularly in the young leaves of C4 plants. On the other hand, this phytotoxic hazard was mitigated by eCO2 which improved both C3 and C4 growth, decreased In accumulation and increased phosphorus (P) and iron (Fe) uptake, particularly in the young leaves of C4 plants. Moreover, the improved photosynthesis by eCO2 accordingly enhanced carbon availability under the challenge of In2O3-NPs that were directed to the elevated production of metabolites involved in antioxidant and detoxification systems. Our physiological and biochemical analyses implicated the role of the antioxidant defenses, including superoxide dismutase (SOD) in stress mitigation under eCO2. This was validated by studying the effect of In2O3-stress on a transgenic maize line (TG) constitutively overexpressing the AtFeSOD gene and its wild type (WT). Although it did not alter In accumulation, the TG plants showed improved growth and photosynthesis and reduced oxidative damage. Overall, this work demonstrated that C3 was more sensitive to In2O3-NPs stress; however, C4 plants were more responsive to eCO2. Moreover, it demonstrated the role of SOD in determining the hazardous effect of In2O3-NPs.

Vanadium (V) can be beneficial or toxic to plant growth and the interaction between arbuscular mycorrhizal fungi (AMF) and V stress was rarely investigated at physiological and biochemical levels of plant groups (C3 and C4) and organs (roots and shoots). We tested the potential of AMF to alleviate the negative effects of V (350 mg V/Kg soil) on shoots and roots of rye and sorghum. Relative to sorghum (C4), rye (C3) showed higher levels of V and lower levels of key elements under V stress conditions. V inhibited growth, photosynthesis, and induced photorespiration (increased HDR & GO activities) and oxidative damage in both plants. AMF colonization reduced V stress by differently mitigating the oxidative stress in rye and sorghum. This mitigation was accompanied with increases in acid and alkaline phosphatase activities in plant roots and increased organic acids and polyphenols exudation into the soil, thus reduced V accumulation (29% and 58% in rye and sorghum shoot, respectively) and improved absorption of mineral nutrients including Ca, Mg and P. AMF colonization improved photosynthesis and increased the sugar accumulation and metabolism. Sugars also acted as a supplier of C skeletons for producing of antioxidants metabolite such as ascorbate. At the antioxidant level, rye was more responsive to the mitigating impact of AMF. Higher antioxidants and detoxification defence system (MTC, GST, phenolics, tocopherols and activities of CAT, SOD and POX) was recorded for rye, while sorghum (C4) improved its GR activity. The C3/C4-specificity was supported by principal component analysis. Together, this study provided both fundamental and applied insights into practical strategies to mitigate the phytotoxicity hazards of V in C3 and C4 grasses. Moreover, our results emphasize the importance of AMF as an environment-friendly factor to alleviate stress effects on plants and to improve growth and yield of unstressed plants.

Phelipanche aegyptiaca is one of the most devastating agricultural weed pests as it poses a serious threat to crop production. Although few studies addressed the potentiality of silicon nanoparticles (SiNPs)...Phelipanche aegyptiaca is one of the most devastating agricultural weed pests as it poses a serious threat to crop production. Although few studies addressed the potentiality of silicon nanoparticles (SiNPs) to ameliorate the challenge of Phelipanche infection, the exact mechanisms underlying SNPs-induced stress tolerance are still largely unknown. Therefore, our study was conducted to stand on the ramifications in the primary and secondary metabolism of pea (Pisum sativum) treated with SiNPs under the menace of Phelipanche infection. In general, Phelipanche infection reduced photosynthesis, which altered carbon and nitrogen metabolism including primary metabolism which is mandatory for maintaining pea growth. In addition to growth reduction, Phelipanche infection also induced membrane damage i.e., high lipid peroxidation. Contrarily, pre-treatment with SiNPs increased Si accumulation in pea root and shoot, which did not only diminish the infection rate but also significantly alleviated the deleterious effect of Phelipanche infection. SiNPs improved photosynthesis which, in turn, increased the sugar metabolism (e.g., Invertase, sucrose synthase, starch synthase and amylase). As a result, there was an increase in sugar consumption by dark respiration processes which, in turn stimulated organic acids accumulation. This was also provided a route for amino acids and fatty acid biosynthesis. For instance, we found increased phenylalanine content which induced lignin accumulation in pea root, that serves as a physical barrier against Phelipanche haustoria penetration. Moreover, there was an increase in osmoprotectants (e.g., proline and sucrose) and antioxidants (e.g., tocopherols) that reduced the sink strength of the parasite. It also maintained the cellular structure by reducing membrane lipid peroxidation. This was also supported by the observed decrease in photorespiration which induced ROS production as indicted by low gly/ser ratio. Overall, this study declared the potentiality of SiNPs in harnessing carbon and nitrogen metabolism differentially in pea organs to cope with the virulence of Phelipanche infection.

Like its bulk counterpart, tungsten (W) nanoparticles (WNPs) could induce environmental hazard to plant growth and yield, however no study investigated their phytotoxicity. On the other hand, plant growth-promoting bacteria (PGPB) can be effectively applied to reduce WNPS toxicity. Therefore, we aimed at investigating the phytotoxic effect of WPNs upon some leguminous plants and how could PGPB ameliorate this phytotoxic impact. Soil contaminated with WPNS induced the accumulation of W in all tested species, leading to marked retardation in both growth and photosynthesis as well as a noticeable oxidative damage. Five isolates of actinobacteria were isolated from Jazan, Saudi Arabia. Morphological and biochemical characterizations indicated that isolate (3) was the most bioactive one. Furthermore, PCR was performed to amplify 16S rDNA of the isolate 3 and the amplified sequence exhibited a high similarity with 16S rRNA gene from Saccharomonospora sp. Although, Saccharomonospora sp. did not affect growth of control plants, it markedly quenched the negative impact of WNPs. This was accompanied by a significant reduction in W levels in Saccharomonospora-treated plants. To cope with heavy metal stress, all tested legumes activated their osmolytes metabolism through the production of soluble sugars, proline, and polyamines, particularly in pea plants. Concomitantly, the biosynthetic key enzymes involved in sucrose, proline and spermidine polyamine biosynthesis experienced a remarkable elevation. These increases were further induced by co-application of Saccharomonospora sp. and WNPs. Overall, application of Saccharomonospora sp. under WNPs treatment induced similar metabolic responses in the three legume species, particularly pea plants, which triggered stress recovery.

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.

Although it is well known that parasitic weeds such as Orobanche (broomrape) significantly reduce the yield of economically important crops, their infection-induced oxidative changes need more exploration in their host plants. Moreover, applying an eco-friendly approach to minimize the infection is not yet available. This study was conducted to understand the effect of Orobanche ramosa infection on oxidative and redox status of tomato plants and the impact of hormonal (indole acetic acid (IAA); 0.09 mM and salicylic acid (SA); 1.0 mM) seed-priming upon mitigating the infection threats. Although Orobanche invades tomato roots, its inhibitory effects on shoot biomass were also indicted. Orobanche infection usually induces oxidative damage i.e., high lipid peroxidation, lipoxygenase activity and H2O2 levels, particularly for roots. Interestingly, hormonal seed-priming significantly enhanced tomato shoots and roots growth under both healthy and infected conditions. Also, IAA and SA treatment significantly reduced Orobanche infection-induced oxidative damage. The protective effect of seed-priming was explained by increasing the antioxidant defense markers including the antioxidant metabolites (i.e., total antioxidant capacity, carotenoids, phenolics, flavonoids, ASC, GSH, tocopherols) and enzymes (CAT, POX, GPX, SOD, GR, APX, MDHAR, DHAR), particularly in infected tomato seedlings. Additionally, cluster analysis indicated the differential impact of IAA- and SA-seed-priming, whereas lower oxidative damage and higher antioxidant enzymes' activities in tomato root were particularly reported for IAA treatment. The principal component analysis (PCA) also proclaimed an organ specificity depending on their response to Orobanche infection. Collectively, here and for the first time, we shed the light on the potential of seed-priming with either IAA or SA to mitigate the adverse effect of O. ramosa stress in tomato plants, especially at oxidative stress levels.

The present work was conducted to evaluate the effect of aqueous extract of Alhagi maurorum at different rates (1, 5, 10, 15%, w/v) on the growth as well as some physiological parameters of pea (Pisum sativum L.). The pot experiment revealed that Alhagi maurorum aqueous extract reduced all growth parameters of pea plant along with photosynthesis pigments, insoluble sugars, total carbohydrate, total protein and total phenolics. On the other hand, soluble sugars, soluble protein, proline, flavonoids and antioxidant enzymes increased upon treatment with aqueous solution of Alhagi maurorum. The adverse effect of the extract on the growth of treated pea plants especially hydroquinone and sinapyl alcohol that were found in relatively high concentration in the extract were identified and quantified by the GC–MS of the methanolic extract of Alhagi maurorum.

n/a

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 theOrobanchechallenge.Orobancheinfection alone markedly inhibited tomato growth and photosynthesis (P< 0.0001) and induced oxidative damageviaincreased 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 ofOrobanchetubercles (13 and 31% decrease, respectively). Moreover, SiNPs dramatically ameliorated the physiological and biochemical disorders imposed byOrobanchein 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 toOrobancheinfection through enhanced structural and metabolic responses.

n/a

n/a

Many coumarins have been identified from natural sources, especially green plants. These compounds affect many plant activities and can also control growth processes. The effect of coumarin (COU) on germination, early growth, nutrient mobilization, and some physiologi- cal parameters of faba bean (Vicia faba L.) was researched. Seeds of faba bean were primed with different concentra- tions of COU (0.5, 1.0, 2.0, and 4.0 mM) to elucidate the effect on germination and nutrient mobilization. Accord- ingly, a greenhouse pot experiment was conducted to study the effect of 1.0 mM COU, as a seed priming treatment alone or in combination with foliar application, on the growth parameters, some biochemical constituents from primary and secondary metabolism and phytohormones of faba bean. The impact of COU was more pronounced on growth than germination, and was dependent on concen- tration and the mode of application. Both COU treatments significantly improved the level of primary and secondary metabolites as well as phytohormones. These data suggest that COU can affect the growth and physiology of faba bean either directly, as an active growth substance, or indirectly by its interaction with the metabolism of phytohormones.