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The elevated level of CO 2 (eCO 2) and arbuscular mycorrhizal fungi (AMF) have been known as successful eco-friendly agents for plant growth and development as well as quality enhancers. The current investigation was designed to study the influence of eCO 2 (620 μmol CO 2 mol−1 air) and AMF on sucrose and phenylpropanoid metabolism, including coumarins, the most important bioactive metabolite in Ammi majus. eCO 2 and AMF were applied, and different parameters have been assessed in A. majus such as changes in mycorrhizal colonization, plant biomass production, photosynthesis, and levels of N, P, and Ca besides the key metabolites and enzymes in sucrose and coumarins metabolic pathways. The present outcomes revealed that eCO 2 and AMF individually or combined enhanced the plant biomass and photosynthesis as well as nutrient concentrations. Furthermore, the levels of sucrose, soluble sugars, glucose, fructose, and the activities of some key enzymes in their metabolism besides phenylpropanoids metabolites in shoot and root of A. majus have been enhanced by eCO 2 and AMF especially when combined. Moreover, upregulation of sucrose is linked to phenylpropanoids metabolic pathway via upregulation of phenylalanine ammonia-lyase activity suggesting high coumarin biosynthesis. Generally, the synergistic effect of both treatments was noted for most of the investigated parameters compared to the individual effect. It could be concluded that the combined application of eCO 2 and AMF affects A. majus global metabolism and induces accumulation of phyto-molecules, coumarin, which might improve its medicinal and pharmacological applications. • eCO 2 and AMF enhanced sucrose and PAL activity in A.majus therefore affects global metabolism and induces coumarin accumulation. [ABSTRACT FROM AUTHOR]

Industrial activities have led to a gradual and global increase in soil aluminum (Al) and atmospheric CO 2 concentrations. Al bioavailability strongly depends on the soil pH, which in turn is affected by atmospheric CO 2 levels. In spite of the concurrent impact which Al and elevated CO 2 (eCO 2) could have on plants, their interaction and how it might affect the growth of economically important crop species has not been investigated. Here, we have investigated the combined impact of soil Al and eCO 2 exposure on key C3 (wheat, oat) and C4 (maize, sorghum) crops, at the physiological and biochemical level. Compared to C3 plants, C4 plants accumulated less Al by stimulating soil Al retention through exudation of root organic acids. Consequently, Al-exposed C4 plants maintained photosynthetic performance and anti-oxidative capacity. Exposure to eCO 2 reduced the stress responses of C3 and C4 crops to Al exposure. Elevated CO 2 decreased Al accumulation and oxidative damage in all cereals, and ameliorated C3 plant growth. This was reflected on the biochemical level, where eCO 2 inhibited ROS production and restored RuBisCo activity in C3 crops only. Overall, our data suggest that, compared to C3 crops, C4 cereals are more tolerant to soil Al exposure under current ambient CO 2 (aCO 2) levels whereas future eCO 2 levels might stimulate Al tolerance in C3 crops. [Display omitted] • Al differentially accumulated in C3 and C4. • Al differentially induced oxidative damage in C3 and C4. • eCO2 suppressed Al uptake and antagonized its phytotoxicity. • eCO2 inhibited ROS production and restored RuBisCo activity in C3 plants. • C4 plants appear more tolerant to soil Al exposure. [ABSTRACT FROM AUTHOR]

Contamination of agricultural fields with bismuth (Bi) reduces crop yield and quality. Arbuscular mycorrhizal fungi (AMF) are known to enhance plant growth and crop production, even under stressful conditions such as soil contamination with heavy metals. The objective of this study was to investigate the effect of AMF on the mitigation of Bi-phytotoxicity in wheat (Triticum aestivum) and beans (Phaseolus vulgaris) and to provide a comprehensive evaluation of the physiological and biochemical basis for the growth and development of AMF-induced plants under Bi stress conditions. Wheat and bean were treated by Bi and AMF individually and in combination. Then the physiological and biochemical responses in the shoot and roots of the two crop species were studied. Evident retardations in plant growth and key photosynthesis-related parameters and accumulation of MDA, H 2 O 2 , as markers of oxidative stress, were observed in plants subjected to Bi. AMF colonization reduced the uptake and translocation of Bi in the plant organs by enhancing the exudation of polyphenols and organic acids into the rhizospheric soil. Mycorrhized wheat and bean plants were able to attenuate the effects of Bi by improving metal detoxification (phytochelatins, metallothionein, total glutathione, and glutathione-S-transferase activity) and antioxidant defense systems (both enzymatic and non-enzymatic) and maintaining C assimilation and nutrient status. The current results suggest the manipulation of AMF as a powerful approach to alleviate the phytotoxicity of Bi in legumes and grasses. • Arbuscular mycorrhizal fungi (AMF) stimulate bean, and wheat responses to bismuth (Bi) and alleviate its phytotoxicity. • AMF colonization on wheat and bean reduced Bi uptake by enhancing the exudation of polyphenols and organic acids into the rhizosphere. • AMF colonization improved plant metal detoxification, antioxidant defense systems and maintaining C assimilation and nutrient status. • AMF colonization was more effective in bean than in wheat, as evidenced by lower Bi uptake in bean indicating the influence of plant species in response to stress conditions. [ABSTRACT FROM AUTHOR]